src/physfs.c

/**
 * PhysicsFS; a portable, flexible file i/o abstraction.
 *
 * Documentation is in physfs.h. It's verbose, honest.  :)
 *
 * Please see the file LICENSE.txt in the source's root directory.
 *
 *  This file written by Ryan C. Gordon.
 */

/* !!! FIXME: ERR_PAST_EOF shouldn't trigger for reads. Just return zero. */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "physfs.h"

#define __PHYSICSFS_INTERNAL__
#include "physfs_internal.h"


typedef struct __PHYSFS_DIRHANDLE__
{
    void *opaque;  /* Instance data unique to the archiver. */
    char *dirName;  /* Path to archive in platform-dependent notation. */
    char *mountPoint; /* Mountpoint in virtual file tree. */
    const PHYSFS_Archiver *funcs;  /* Ptr to archiver info for this handle. */
    struct __PHYSFS_DIRHANDLE__ *next;  /* linked list stuff. */
} DirHandle;


typedef struct __PHYSFS_FILEHANDLE__
{
    PHYSFS_Io *io;  /* Instance data unique to the archiver for this file. */
    PHYSFS_uint8 forReading; /* Non-zero if reading, zero if write/append */
    const DirHandle *dirHandle;  /* Archiver instance that created this */
    PHYSFS_uint8 *buffer;  /* Buffer, if set (NULL otherwise). Don't touch! */
    PHYSFS_uint32 bufsize;  /* Bufsize, if set (0 otherwise). Don't touch! */
    PHYSFS_uint32 buffill;  /* Buffer fill size. Don't touch! */
    PHYSFS_uint32 bufpos;  /* Buffer position. Don't touch! */
    struct __PHYSFS_FILEHANDLE__ *next;  /* linked list stuff. */
} FileHandle;


typedef struct __PHYSFS_ERRMSGTYPE__
{
    void *tid;
    int errorAvailable;
    char errorString[80];
    struct __PHYSFS_ERRMSGTYPE__ *next;
} ErrMsg;


/* The various i/o drivers...some of these may not be compiled in. */
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_ZIP;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_ZIP;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_LZMA;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_LZMA;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_GRP;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_GRP;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_QPAK;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_QPAK;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_HOG;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_HOG;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_MVL;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_MVL;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_WAD;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_WAD;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_DIR;
extern const PHYSFS_ArchiveInfo    __PHYSFS_ArchiveInfo_ISO9660;
extern const PHYSFS_Archiver       __PHYSFS_Archiver_ISO9660;


static const PHYSFS_ArchiveInfo *supported_types[] =
{
#if (defined PHYSFS_SUPPORTS_ZIP)
    &__PHYSFS_ArchiveInfo_ZIP,
#endif
#if (defined PHYSFS_SUPPORTS_7Z)
    &__PHYSFS_ArchiveInfo_LZMA,
#endif
#if (defined PHYSFS_SUPPORTS_GRP)
    &__PHYSFS_ArchiveInfo_GRP,
#endif
#if (defined PHYSFS_SUPPORTS_QPAK)
    &__PHYSFS_ArchiveInfo_QPAK,
#endif
#if (defined PHYSFS_SUPPORTS_HOG)
    &__PHYSFS_ArchiveInfo_HOG,
#endif
#if (defined PHYSFS_SUPPORTS_MVL)
    &__PHYSFS_ArchiveInfo_MVL,
#endif
#if (defined PHYSFS_SUPPORTS_WAD)
    &__PHYSFS_ArchiveInfo_WAD,
#endif
#if (defined PHYSFS_SUPPORTS_ISO9660)
    &__PHYSFS_ArchiveInfo_ISO9660,
#endif
    NULL
};

static const PHYSFS_Archiver *archivers[] =
{
#if (defined PHYSFS_SUPPORTS_ZIP)
    &__PHYSFS_Archiver_ZIP,
#endif
#if (defined PHYSFS_SUPPORTS_7Z)
    &__PHYSFS_Archiver_LZMA,
#endif
#if (defined PHYSFS_SUPPORTS_GRP)
    &__PHYSFS_Archiver_GRP,
#endif
#if (defined PHYSFS_SUPPORTS_QPAK)
    &__PHYSFS_Archiver_QPAK,
#endif
#if (defined PHYSFS_SUPPORTS_HOG)
    &__PHYSFS_Archiver_HOG,
#endif
#if (defined PHYSFS_SUPPORTS_MVL)
    &__PHYSFS_Archiver_MVL,
#endif
#if (defined PHYSFS_SUPPORTS_WAD)
    &__PHYSFS_Archiver_WAD,
#endif
#if (defined PHYSFS_SUPPORTS_ISO9660)
    &__PHYSFS_Archiver_ISO9660,
#endif
    NULL
};


/* General PhysicsFS state ... */
static int initialized = 0;
static ErrMsg *errorMessages = NULL;
static DirHandle *searchPath = NULL;
static DirHandle *writeDir = NULL;
static FileHandle *openWriteList = NULL;
static FileHandle *openReadList = NULL;
static char *baseDir = NULL;
static char *userDir = NULL;
static int allowSymLinks = 0;

/* mutexes ... */
static void *errorLock = NULL;     /* protects error message list.        */
static void *stateLock = NULL;     /* protects other PhysFS static state. */

/* allocator ... */
static int externalAllocator = 0;
PHYSFS_Allocator allocator;


/* PHYSFS_Io implementation for i/o to physical filesystem... */

/* !!! FIXME: maybe refcount the paths in a string pool? */
typedef struct __PHYSFS_NativeIoInfo
{
    void *handle;
    const char *path;
    int mode;   /* 'r', 'w', or 'a' */
} NativeIoInfo;

static PHYSFS_sint64 nativeIo_read(PHYSFS_Io *io, void *buf, PHYSFS_uint64 len)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_platformRead(info->handle, buf, len);
} /* nativeIo_read */

static PHYSFS_sint64 nativeIo_write(PHYSFS_Io *io, const void *buffer,
                                    PHYSFS_uint64 len)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_platformWrite(info->handle, buffer, len);
} /* nativeIo_write */

static int nativeIo_seek(PHYSFS_Io *io, PHYSFS_uint64 offset)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_platformSeek(info->handle, offset);
} /* nativeIo_seek */

static PHYSFS_sint64 nativeIo_tell(PHYSFS_Io *io)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_platformTell(info->handle);
} /* nativeIo_tell */

static PHYSFS_sint64 nativeIo_length(PHYSFS_Io *io)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_platformFileLength(info->handle);
} /* nativeIo_length */

static PHYSFS_Io *nativeIo_duplicate(PHYSFS_Io *io)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    return __PHYSFS_createNativeIo(info->path, info->mode);
} /* nativeIo_duplicate */

static int nativeIo_flush(PHYSFS_Io *io)
{
    return __PHYSFS_platformFlush(io->opaque);
} /* nativeIo_flush */

static void nativeIo_destroy(PHYSFS_Io *io)
{
    NativeIoInfo *info = (NativeIoInfo *) io->opaque;
    __PHYSFS_platformClose(info->handle);
    allocator.Free((void *) info->path);
    allocator.Free(info);
    allocator.Free(io);
} /* nativeIo_destroy */

static const PHYSFS_Io __PHYSFS_nativeIoInterface =
{
    nativeIo_read,
    nativeIo_write,
    nativeIo_seek,
    nativeIo_tell,
    nativeIo_length,
    nativeIo_duplicate,
    nativeIo_flush,
    nativeIo_destroy,
    NULL
};

PHYSFS_Io *__PHYSFS_createNativeIo(const char *path, const int mode)
{
    PHYSFS_Io *io = NULL;
    NativeIoInfo *info = NULL;
    void *handle = NULL;
    char *pathdup = NULL;

    assert((mode == 'r') || (mode == 'w') || (mode == 'a'));

    io = (PHYSFS_Io *) allocator.Malloc(sizeof (PHYSFS_Io));
    GOTO_IF_MACRO(io == NULL, ERR_OUT_OF_MEMORY, createNativeIo_failed);
    info = (NativeIoInfo *) allocator.Malloc(sizeof (NativeIoInfo));
    GOTO_IF_MACRO(info == NULL, ERR_OUT_OF_MEMORY, createNativeIo_failed);
    pathdup = (char *) allocator.Malloc(strlen(path) + 1);
    GOTO_IF_MACRO(info == NULL, ERR_OUT_OF_MEMORY, createNativeIo_failed);

    if (mode == 'r')
        handle = __PHYSFS_platformOpenRead(path);
    else if (mode == 'w')
        handle = __PHYSFS_platformOpenWrite(path);
    else if (mode == 'a')
        handle = __PHYSFS_platformOpenAppend(path);

    GOTO_IF_MACRO(handle == NULL, NULL, createNativeIo_failed);

    strcpy(pathdup, path);
    info->handle = handle;
    info->path = pathdup;
    info->mode = mode;
    memcpy(io, &__PHYSFS_nativeIoInterface, sizeof (*io));
    io->opaque = info;
    return io;

createNativeIo_failed:
    if (handle != NULL) __PHYSFS_platformClose(handle);
    if (pathdup != NULL) allocator.Free(pathdup);
    if (info != NULL) allocator.Free(info);
    if (io != NULL) allocator.Free(io);
    return NULL;
} /* __PHYSFS_createNativeIo */


/* functions ... */

typedef struct
{
    char **list;
    PHYSFS_uint32 size;
    const char *errorstr;
} EnumStringListCallbackData;

static void enumStringListCallback(void *data, const char *str)
{
    void *ptr;
    char *newstr;
    EnumStringListCallbackData *pecd = (EnumStringListCallbackData *) data;

    if (pecd->errorstr)
        return;

    ptr = allocator.Realloc(pecd->list, (pecd->size + 2) * sizeof (char *));
    newstr = (char *) allocator.Malloc(strlen(str) + 1);
    if (ptr != NULL)
        pecd->list = (char **) ptr;

    if ((ptr == NULL) || (newstr == NULL))
    {
        pecd->errorstr = ERR_OUT_OF_MEMORY;
        pecd->list[pecd->size] = NULL;
        PHYSFS_freeList(pecd->list);
        return;
    } /* if */

    strcpy(newstr, str);
    pecd->list[pecd->size] = newstr;
    pecd->size++;
} /* enumStringListCallback */


static char **doEnumStringList(void (*func)(PHYSFS_StringCallback, void *))
{
    EnumStringListCallbackData ecd;
    memset(&ecd, '\0', sizeof (ecd));
    ecd.list = (char **) allocator.Malloc(sizeof (char *));
    BAIL_IF_MACRO(ecd.list == NULL, ERR_OUT_OF_MEMORY, NULL);
    func(enumStringListCallback, &ecd);
    BAIL_IF_MACRO(ecd.errorstr != NULL, ecd.errorstr, NULL);
    ecd.list[ecd.size] = NULL;
    return ecd.list;
} /* doEnumStringList */


static void __PHYSFS_bubble_sort(void *a, PHYSFS_uint32 lo, PHYSFS_uint32 hi,
                         int (*cmpfn)(void *, PHYSFS_uint32, PHYSFS_uint32),
                         void (*swapfn)(void *, PHYSFS_uint32, PHYSFS_uint32))
{
    PHYSFS_uint32 i;
    int sorted;

    do
    {
        sorted = 1;
        for (i = lo; i < hi; i++)
        {
            if (cmpfn(a, i, i + 1) > 0)
            {
                swapfn(a, i, i + 1);
                sorted = 0;
            } /* if */
        } /* for */
    } while (!sorted);
} /* __PHYSFS_bubble_sort */


static void __PHYSFS_quick_sort(void *a, PHYSFS_uint32 lo, PHYSFS_uint32 hi,
                         int (*cmpfn)(void *, PHYSFS_uint32, PHYSFS_uint32),
                         void (*swapfn)(void *, PHYSFS_uint32, PHYSFS_uint32))
{
    PHYSFS_uint32 i;
    PHYSFS_uint32 j;
    PHYSFS_uint32 v;

    if ((hi - lo) <= PHYSFS_QUICKSORT_THRESHOLD)
        __PHYSFS_bubble_sort(a, lo, hi, cmpfn, swapfn);
    else
    {
        i = (hi + lo) / 2;

        if (cmpfn(a, lo, i) > 0) swapfn(a, lo, i);
        if (cmpfn(a, lo, hi) > 0) swapfn(a, lo, hi);
        if (cmpfn(a, i, hi) > 0) swapfn(a, i, hi);

        j = hi - 1;
        swapfn(a, i, j);
        i = lo;
        v = j;
        while (1)
        {
            while(cmpfn(a, ++i, v) < 0) { /* do nothing */ }
            while(cmpfn(a, --j, v) > 0) { /* do nothing */ }
            if (j < i)
                break;
            swapfn(a, i, j);
        } /* while */
        if (i != (hi-1))
            swapfn(a, i, hi-1);
        __PHYSFS_quick_sort(a, lo, j, cmpfn, swapfn);
        __PHYSFS_quick_sort(a, i+1, hi, cmpfn, swapfn);
    } /* else */
} /* __PHYSFS_quick_sort */


void __PHYSFS_sort(void *entries, PHYSFS_uint32 max,
                   int (*cmpfn)(void *, PHYSFS_uint32, PHYSFS_uint32),
                   void (*swapfn)(void *, PHYSFS_uint32, PHYSFS_uint32))
{
    /*
     * Quicksort w/ Bubblesort fallback algorithm inspired by code from here:
     *   http://www.cs.ubc.ca/spider/harrison/Java/sorting-demo.html
     */
    __PHYSFS_quick_sort(entries, 0, max - 1, cmpfn, swapfn);
} /* __PHYSFS_sort */


static ErrMsg *findErrorForCurrentThread(void)
{
    ErrMsg *i;
    void *tid;

    if (errorLock != NULL)
        __PHYSFS_platformGrabMutex(errorLock);

    if (errorMessages != NULL)
    {
        tid = __PHYSFS_platformGetThreadID();

        for (i = errorMessages; i != NULL; i = i->next)
        {
            if (i->tid == tid)
            {
                if (errorLock != NULL)
                    __PHYSFS_platformReleaseMutex(errorLock);
                return i;
            } /* if */
        } /* for */
    } /* if */

    if (errorLock != NULL)
        __PHYSFS_platformReleaseMutex(errorLock);

    return NULL;   /* no error available. */
} /* findErrorForCurrentThread */


void __PHYSFS_setError(const char *str)
{
    ErrMsg *err;

    if (str == NULL)
        return;

    err = findErrorForCurrentThread();

    if (err == NULL)
    {
        err = (ErrMsg *) allocator.Malloc(sizeof (ErrMsg));
        if (err == NULL)
            return;   /* uhh...? */

        memset((void *) err, '\0', sizeof (ErrMsg));
        err->tid = __PHYSFS_platformGetThreadID();

        if (errorLock != NULL)
            __PHYSFS_platformGrabMutex(errorLock);

        err->next = errorMessages;
        errorMessages = err;

        if (errorLock != NULL)
            __PHYSFS_platformReleaseMutex(errorLock);
    } /* if */

    err->errorAvailable = 1;
    strncpy(err->errorString, str, sizeof (err->errorString));
    err->errorString[sizeof (err->errorString) - 1] = '\0';
} /* __PHYSFS_setError */


const char *PHYSFS_getLastError(void)
{
    ErrMsg *err = findErrorForCurrentThread();

    if ((err == NULL) || (!err->errorAvailable))
        return NULL;

    err->errorAvailable = 0;
    return err->errorString;
} /* PHYSFS_getLastError */


/* MAKE SURE that errorLock is held before calling this! */
static void freeErrorMessages(void)
{
    ErrMsg *i;
    ErrMsg *next;

    for (i = errorMessages; i != NULL; i = next)
    {
        next = i->next;
        allocator.Free(i);
    } /* for */

    errorMessages = NULL;
} /* freeErrorMessages */


void PHYSFS_getLinkedVersion(PHYSFS_Version *ver)
{
    if (ver != NULL)
    {
        ver->major = PHYSFS_VER_MAJOR;
        ver->minor = PHYSFS_VER_MINOR;
        ver->patch = PHYSFS_VER_PATCH;
    } /* if */
} /* PHYSFS_getLinkedVersion */


static const char *find_filename_extension(const char *fname)
{
    const char *retval = NULL;
    if (fname != NULL)
    {
        retval = strchr(fname, '.');
        const char *p = retval;

        while (p != NULL)
        {
            p = strchr(p + 1, '.');
            if (p != NULL)
                retval = p;
        } /* while */

        if (retval != NULL)
            retval++;  /* skip '.' */
    } /* if */

    return retval;
} /* find_filename_extension */


static DirHandle *tryOpenDir(PHYSFS_Io *io, const PHYSFS_Archiver *funcs,
                             const char *d, int forWriting)
{
    DirHandle *retval = NULL;
    void *opaque = NULL;

    if (io != NULL)
        BAIL_IF_MACRO(!io->seek(io, 0), NULL, NULL);

    opaque = funcs->openArchive(io, d, forWriting);
    if (opaque != NULL)
    {
        retval = (DirHandle *) allocator.Malloc(sizeof (DirHandle));
        if (retval == NULL)
            funcs->dirClose(opaque);
        else
        {
            memset(retval, '\0', sizeof (DirHandle));
            retval->mountPoint = NULL;
            retval->funcs = funcs;
            retval->opaque = opaque;
        } /* else */
    } /* if */

    return retval;
} /* tryOpenDir */


static DirHandle *openDirectory(PHYSFS_Io *io, const char *d, int forWriting)
{
    DirHandle *retval = NULL;
    const PHYSFS_Archiver **i;
    const char *ext;

    assert((io != NULL) || (d != NULL));

    if (io == NULL)
    {
        BAIL_IF_MACRO(!__PHYSFS_platformExists(d), ERR_NO_SUCH_FILE, NULL);

        /* DIR gets first shot (unlike the rest, it doesn't deal with files). */
        retval = tryOpenDir(io, &__PHYSFS_Archiver_DIR, d, forWriting);
        if (retval != NULL)
            return retval;

        io = __PHYSFS_createNativeIo(d, forWriting ? 'w' : 'r');
        BAIL_IF_MACRO_MUTEX(io == NULL, NULL, stateLock, 0);
    } /* if */

    ext = find_filename_extension(d);
    if (ext != NULL)
    {
        /* Look for archivers with matching file extensions first... */
        for (i = archivers; (*i != NULL) && (retval == NULL); i++)
        {
            if (__PHYSFS_stricmpASCII(ext, (*i)->info->extension) == 0)
                retval = tryOpenDir(io, *i, d, forWriting);
        } /* for */

        /* failing an exact file extension match, try all the others... */
        for (i = archivers; (*i != NULL) && (retval == NULL); i++)
        {
            if (__PHYSFS_stricmpASCII(ext, (*i)->info->extension) != 0)
                retval = tryOpenDir(io, *i, d, forWriting);
        } /* for */
    } /* if */

    else  /* no extension? Try them all. */
    {
        for (i = archivers; (*i != NULL) && (retval == NULL); i++)
            retval = tryOpenDir(io, *i, d, forWriting);
    } /* else */

    BAIL_IF_MACRO(retval == NULL, ERR_UNSUPPORTED_ARCHIVE, NULL);
    return retval;
} /* openDirectory */


/*
 * Make a platform-independent path string sane. Doesn't actually check the
 *  file hierarchy, it just cleans up the string.
 *  (dst) must be a buffer at least as big as (src), as this is where the
 *  cleaned up string is deposited.
 * If there are illegal bits in the path (".." entries, etc) then we
 *  return zero and (dst) is undefined. Non-zero if the path was sanitized.
 */
static int sanitizePlatformIndependentPath(const char *src, char *dst)
{
    char *prev;
    char ch;

    while (*src == '/')  /* skip initial '/' chars... */
        src++;

    prev = dst;
    do
    {
        ch = *(src++);

        if ((ch == ':') || (ch == '\\'))  /* illegal chars in a physfs path. */
            BAIL_MACRO(ERR_INSECURE_FNAME, 0);

        if (ch == '/')   /* path separator. */
        {
            *dst = '\0';  /* "." and ".." are illegal pathnames. */
            if ((strcmp(prev, ".") == 0) || (strcmp(prev, "..") == 0))
                BAIL_MACRO(ERR_INSECURE_FNAME, 0);

            while (*src == '/')   /* chop out doubles... */
                src++;

            if (*src == '\0') /* ends with a pathsep? */
                break;  /* we're done, don't add final pathsep to dst. */

            prev = dst + 1;
        } /* if */

        *(dst++) = ch;
    } while (ch != '\0');

    return 1;
} /* sanitizePlatformIndependentPath */


/*
 * Figure out if (fname) is part of (h)'s mountpoint. (fname) must be an
 *  output from sanitizePlatformIndependentPath(), so that it is in a known
 *  state.
 *
 * This only finds legitimate segments of a mountpoint. If the mountpoint is
 *  "/a/b/c" and (fname) is "/a/b/c", "/", or "/a/b/c/d", then the results are
 *  all zero. "/a/b" will succeed, though.
 */
static int partOfMountPoint(DirHandle *h, char *fname)
{
    /* !!! FIXME: This code feels gross. */
    int rc;
    size_t len, mntpntlen;

    if (h->mountPoint == NULL)
        return 0;
    else if (*fname == '\0')
        return 1;

    len = strlen(fname);
    mntpntlen = strlen(h->mountPoint);
    if (len > mntpntlen)  /* can't be a subset of mountpoint. */
        return 0;

    /* if true, must be not a match or a complete match, but not a subset. */
    if ((len + 1) == mntpntlen)
        return 0;

    rc = strncmp(fname, h->mountPoint, len); /* !!! FIXME: case insensitive? */
    if (rc != 0)
        return 0;  /* not a match. */

    /* make sure /a/b matches /a/b/ and not /a/bc ... */
    return h->mountPoint[len] == '/';
} /* partOfMountPoint */


static DirHandle *createDirHandle(PHYSFS_Io *io, const char *newDir,
                                  const char *mountPoint, int forWriting)
{
    DirHandle *dirHandle = NULL;
    char *tmpmntpnt = NULL;

    if (mountPoint != NULL)
    {
        const size_t len = strlen(mountPoint) + 1;
        tmpmntpnt = (char *) __PHYSFS_smallAlloc(len);
        GOTO_IF_MACRO(!tmpmntpnt, ERR_OUT_OF_MEMORY, badDirHandle);
        if (!sanitizePlatformIndependentPath(mountPoint, tmpmntpnt))
            goto badDirHandle;
        mountPoint = tmpmntpnt;  /* sanitized version. */
    } /* if */

    dirHandle = openDirectory(io, newDir, forWriting);
    GOTO_IF_MACRO(!dirHandle, NULL, badDirHandle);

    if (newDir == NULL)
        dirHandle->dirName = NULL;
    else
    {
        dirHandle->dirName = (char *) allocator.Malloc(strlen(newDir) + 1);
        GOTO_IF_MACRO(!dirHandle->dirName, ERR_OUT_OF_MEMORY, badDirHandle);
        strcpy(dirHandle->dirName, newDir);
    } /* else */

    if ((mountPoint != NULL) && (*mountPoint != '\0'))
    {
        dirHandle->mountPoint = (char *)allocator.Malloc(strlen(mountPoint)+2);
        GOTO_IF_MACRO(!dirHandle->mountPoint, ERR_OUT_OF_MEMORY, badDirHandle);
        strcpy(dirHandle->mountPoint, mountPoint);
        strcat(dirHandle->mountPoint, "/");
    } /* if */

    __PHYSFS_smallFree(tmpmntpnt);
    return dirHandle;

badDirHandle:
    if (dirHandle != NULL)
    {
        dirHandle->funcs->dirClose(dirHandle->opaque);
        allocator.Free(dirHandle->dirName);
        allocator.Free(dirHandle->mountPoint);
        allocator.Free(dirHandle);
    } /* if */

    __PHYSFS_smallFree(tmpmntpnt);
    return NULL;
} /* createDirHandle */


/* MAKE SURE you've got the stateLock held before calling this! */
static int freeDirHandle(DirHandle *dh, FileHandle *openList)
{
    FileHandle *i;

    if (dh == NULL)
        return 1;

    for (i = openList; i != NULL; i = i->next)
        BAIL_IF_MACRO(i->dirHandle == dh, ERR_FILES_STILL_OPEN, 0);

    dh->funcs->dirClose(dh->opaque);
    allocator.Free(dh->dirName);
    allocator.Free(dh->mountPoint);
    allocator.Free(dh);
    return 1;
} /* freeDirHandle */


static char *calculateUserDir(void)
{
    char *retval = __PHYSFS_platformGetUserDir();
    if (retval != NULL)
    {
        /* make sure it really exists and is normalized. */
        char *ptr = __PHYSFS_platformRealPath(retval);
        allocator.Free(retval);
        retval = ptr;
    } /* if */

    if (retval == NULL)
    {
        const char *dirsep = PHYSFS_getDirSeparator();
        const char *uname = __PHYSFS_platformGetUserName();
        const char *str = (uname != NULL) ? uname : "default";

        retval = (char *) allocator.Malloc(strlen(baseDir) + strlen(str) +
                                           strlen(dirsep) + 6);

        if (retval == NULL)
            __PHYSFS_setError(ERR_OUT_OF_MEMORY);
        else
            sprintf(retval, "%susers%s%s", baseDir, dirsep, str);

        allocator.Free((void *) uname);
    } /* else */

    return retval;
} /* calculateUserDir */


static int appendDirSep(char **dir)
{
    const char *dirsep = PHYSFS_getDirSeparator();
    char *ptr;

    if (strcmp((*dir + strlen(*dir)) - strlen(dirsep), dirsep) == 0)
        return 1;

    ptr = (char *) allocator.Realloc(*dir, strlen(*dir) + strlen(dirsep) + 1);
    if (!ptr)
    {
        allocator.Free(*dir);
        return 0;
    } /* if */

    strcat(ptr, dirsep);
    *dir = ptr;
    return 1;
} /* appendDirSep */


static char *calculateBaseDir(const char *argv0)
{
    char *retval = NULL;
    const char *dirsep = NULL;
    char *ptr = NULL;

    /* Give the platform layer first shot at this. */
    retval = __PHYSFS_platformCalcBaseDir(argv0);
    if (retval != NULL)
        return retval;

    /* We need argv0 to go on. */
    BAIL_IF_MACRO(argv0 == NULL, ERR_ARGV0_IS_NULL, NULL);

    dirsep = PHYSFS_getDirSeparator();
    if (strlen(dirsep) == 1)  /* fast path. */
        ptr = strrchr(argv0, *dirsep);
    else
    {
        ptr = strstr(argv0, dirsep);
        if (ptr != NULL)
        {
            char *p = ptr;
            while (p != NULL)
            {
                ptr = p;
                p = strstr(p + 1, dirsep);
            } /* while */
        } /* if */
    } /* else */

    if (ptr != NULL)
    {
        size_t size = (size_t) (ptr - argv0);
        retval = (char *) allocator.Malloc(size + 1);
        BAIL_IF_MACRO(retval == NULL, ERR_OUT_OF_MEMORY, NULL);
        memcpy(retval, argv0, size);
        retval[size] = '\0';
        return retval;
    } /* if */

    /* argv0 wasn't helpful. */
    BAIL_MACRO(ERR_INVALID_ARGUMENT, NULL);
} /* calculateBaseDir */


static int initializeMutexes(void)
{
    errorLock = __PHYSFS_platformCreateMutex();
    if (errorLock == NULL)
        goto initializeMutexes_failed;

    stateLock = __PHYSFS_platformCreateMutex();
    if (stateLock == NULL)
        goto initializeMutexes_failed;

    return 1;  /* success. */

initializeMutexes_failed:
    if (errorLock != NULL)
        __PHYSFS_platformDestroyMutex(errorLock);

    if (stateLock != NULL)
        __PHYSFS_platformDestroyMutex(stateLock);

    errorLock = stateLock = NULL;
    return 0;  /* failed. */
} /* initializeMutexes */


static void setDefaultAllocator(void);

int PHYSFS_init(const char *argv0)
{
    char *ptr;

    BAIL_IF_MACRO(initialized, ERR_IS_INITIALIZED, 0);

    if (!externalAllocator)
        setDefaultAllocator();

    if (allocator.Init != NULL)
        BAIL_IF_MACRO(!allocator.Init(), NULL, 0);

    BAIL_IF_MACRO(!__PHYSFS_platformInit(), NULL, 0);

    BAIL_IF_MACRO(!initializeMutexes(), NULL, 0);

    baseDir = calculateBaseDir(argv0);
    BAIL_IF_MACRO(baseDir == NULL, NULL, 0);

    /* !!! FIXME: only call this if we got this from argv0 (unreliable). */
    ptr = __PHYSFS_platformRealPath(baseDir);
    allocator.Free(baseDir);
    BAIL_IF_MACRO(ptr == NULL, NULL, 0);
    baseDir = ptr;

    BAIL_IF_MACRO(!appendDirSep(&baseDir), NULL, 0);

    userDir = calculateUserDir();
    if ((userDir == NULL) || (!appendDirSep(&userDir)))
    {
        allocator.Free(baseDir);
        baseDir = NULL;
        return 0;
    } /* if */

    initialized = 1;

    /* This makes sure that the error subsystem is initialized. */
    __PHYSFS_setError(PHYSFS_getLastError());

    return 1;
} /* PHYSFS_init */


/* MAKE SURE you hold stateLock before calling this! */
static int closeFileHandleList(FileHandle **list)
{
    FileHandle *i;
    FileHandle *next = NULL;

    for (i = *list; i != NULL; i = next)
    {
        PHYSFS_Io *io = i->io;
        next = i->next;

        if (!io->flush(io))
        {
            *list = i;
            return 0;
        } /* if */

        io->destroy(io);
        allocator.Free(i);
    } /* for */

    *list = NULL;
    return 1;
} /* closeFileHandleList */


/* MAKE SURE you hold the stateLock before calling this! */
static void freeSearchPath(void)
{
    DirHandle *i;
    DirHandle *next = NULL;

    closeFileHandleList(&openReadList);

    if (searchPath != NULL)
    {
        for (i = searchPath; i != NULL; i = next)
        {
            next = i->next;
            freeDirHandle(i, openReadList);
        } /* for */
        searchPath = NULL;
    } /* if */
} /* freeSearchPath */


int PHYSFS_deinit(void)
{
    BAIL_IF_MACRO(!initialized, ERR_NOT_INITIALIZED, 0);
    BAIL_IF_MACRO(!__PHYSFS_platformDeinit(), NULL, 0);

    closeFileHandleList(&openWriteList);
    BAIL_IF_MACRO(!PHYSFS_setWriteDir(NULL), ERR_FILES_STILL_OPEN, 0);

    freeSearchPath();
    freeErrorMessages();

    if (baseDir != NULL)
    {
        allocator.Free(baseDir);
        baseDir = NULL;
    } /* if */

    if (userDir != NULL)
    {
        allocator.Free(userDir);
        userDir = NULL;
    } /* if */

    allowSymLinks = 0;
    initialized = 0;

    __PHYSFS_platformDestroyMutex(errorLock);
    __PHYSFS_platformDestroyMutex(stateLock);

    if (allocator.Deinit != NULL)
        allocator.Deinit();

    errorLock = stateLock = NULL;
    return 1;
} /* PHYSFS_deinit */


int PHYSFS_isInit(void)
{
    return initialized;
} /* PHYSFS_isInit */


const PHYSFS_ArchiveInfo **PHYSFS_supportedArchiveTypes(void)
{
    return supported_types;
} /* PHYSFS_supportedArchiveTypes */


void PHYSFS_freeList(void *list)
{
    void **i;
    if (list != NULL)
    {
        for (i = (void **) list; *i != NULL; i++)
            allocator.Free(*i);

        allocator.Free(list);
    } /* if */
} /* PHYSFS_freeList */


const char *PHYSFS_getDirSeparator(void)
{
    return __PHYSFS_platformDirSeparator;
} /* PHYSFS_getDirSeparator */


char **PHYSFS_getCdRomDirs(void)
{
    return doEnumStringList(__PHYSFS_platformDetectAvailableCDs);
} /* PHYSFS_getCdRomDirs */


void PHYSFS_getCdRomDirsCallback(PHYSFS_StringCallback callback, void *data)
{
    __PHYSFS_platformDetectAvailableCDs(callback, data);
} /* PHYSFS_getCdRomDirsCallback */


const char *PHYSFS_getBaseDir(void)
{
    return baseDir;   /* this is calculated in PHYSFS_init()... */
} /* PHYSFS_getBaseDir */


const char *PHYSFS_getUserDir(void)
{
    return userDir;   /* this is calculated in PHYSFS_init()... */
} /* PHYSFS_getUserDir */


const char *PHYSFS_getWriteDir(void)
{
    const char *retval = NULL;

    __PHYSFS_platformGrabMutex(stateLock);
    if (writeDir != NULL)
        retval = writeDir->dirName;
    __PHYSFS_platformReleaseMutex(stateLock);

    return retval;
} /* PHYSFS_getWriteDir */


int PHYSFS_setWriteDir(const char *newDir)
{
    int retval = 1;

    __PHYSFS_platformGrabMutex(stateLock);

    if (writeDir != NULL)
    {
        BAIL_IF_MACRO_MUTEX(!freeDirHandle(writeDir, openWriteList), NULL,
                            stateLock, 0);
        writeDir = NULL;
    } /* if */

    if (newDir != NULL)
    {
        /* !!! FIXME: PHYSFS_Io shouldn't be NULL */
        writeDir = createDirHandle(NULL, newDir, NULL, 1);
        retval = (writeDir != NULL);
    } /* if */

    __PHYSFS_platformReleaseMutex(stateLock);

    return retval;
} /* PHYSFS_setWriteDir */


int PHYSFS_mount(const char *newDir, const char *mountPoint, int appendToPath)
{
    DirHandle *dh;
    DirHandle *prev = NULL;
    DirHandle *i;

    BAIL_IF_MACRO(newDir == NULL, ERR_INVALID_ARGUMENT, 0);

    if (mountPoint == NULL)
        mountPoint = "/";

    __PHYSFS_platformGrabMutex(stateLock);

    for (i = searchPath; i != NULL; i = i->next)
    {
        /* already in search path? */
        BAIL_IF_MACRO_MUTEX(strcmp(newDir, i->dirName)==0, NULL, stateLock, 1);
        prev = i;
    } /* for */

    dh = createDirHandle(NULL, newDir, mountPoint, 0);
    BAIL_IF_MACRO_MUTEX(dh == NULL, NULL, stateLock, 0);

    if (appendToPath)
    {
        if (prev == NULL)
            searchPath = dh;
        else
            prev->next = dh;
    } /* if */
    else
    {
        dh->next = searchPath;
        searchPath = dh;
    } /* else */

    __PHYSFS_platformReleaseMutex(stateLock);
    return 1;
} /* PHYSFS_mount */


int PHYSFS_addToSearchPath(const char *newDir, int appendToPath)
{
    return PHYSFS_mount(newDir, NULL, appendToPath);
} /* PHYSFS_addToSearchPath */


int PHYSFS_removeFromSearchPath(const char *oldDir)
{
    return PHYSFS_unmount(oldDir);
} /* PHYSFS_removeFromSearchPath */


int PHYSFS_unmount(const char *oldDir)
{
    DirHandle *i;
    DirHandle *prev = NULL;
    DirHandle *next = NULL;

    BAIL_IF_MACRO(oldDir == NULL, ERR_INVALID_ARGUMENT, 0);

    __PHYSFS_platformGrabMutex(stateLock);
    for (i = searchPath; i != NULL; i = i->next)
    {
        if (strcmp(i->dirName, oldDir) == 0)
        {
            next = i->next;
            BAIL_IF_MACRO_MUTEX(!freeDirHandle(i, openReadList), NULL,
                                stateLock, 0);

            if (prev == NULL)
                searchPath = next;
            else
                prev->next = next;

            BAIL_MACRO_MUTEX(NULL, stateLock, 1);
        } /* if */
        prev = i;
    } /* for */

    BAIL_MACRO_MUTEX(ERR_NOT_IN_SEARCH_PATH, stateLock, 0);
} /* PHYSFS_unmount */


char **PHYSFS_getSearchPath(void)
{
    return doEnumStringList(PHYSFS_getSearchPathCallback);
} /* PHYSFS_getSearchPath */


const char *PHYSFS_getMountPoint(const char *dir)
{
    DirHandle *i;
    __PHYSFS_platformGrabMutex(stateLock);
    for (i = searchPath; i != NULL; i = i->next)
    {
        if (strcmp(i->dirName, dir) == 0)
        {
            const char *retval = ((i->mountPoint) ? i->mountPoint : "/");
            __PHYSFS_platformReleaseMutex(stateLock);
            return retval;
        } /* if */
    } /* for */
    __PHYSFS_platformReleaseMutex(stateLock);

    BAIL_MACRO(ERR_NOT_IN_SEARCH_PATH, NULL);
} /* PHYSFS_getMountPoint */


void PHYSFS_getSearchPathCallback(PHYSFS_StringCallback callback, void *data)
{
    DirHandle *i;

    __PHYSFS_platformGrabMutex(stateLock);

    for (i = searchPath; i != NULL; i = i->next)
        callback(data, i->dirName);

    __PHYSFS_platformReleaseMutex(stateLock);
} /* PHYSFS_getSearchPathCallback */


/* Split out to avoid stack allocation in a loop. */
static void setSaneCfgAddPath(const char *i, const size_t l, const char *dirsep,
                              int archivesFirst)
{
    const char *d = PHYSFS_getRealDir(i);
    const size_t allocsize = strlen(d) + strlen(dirsep) + l + 1;
    char *str = (char *) __PHYSFS_smallAlloc(allocsize);
    if (str != NULL)
    {
        sprintf(str, "%s%s%s", d, dirsep, i);
        PHYSFS_mount(str, NULL, archivesFirst == 0);
        __PHYSFS_smallFree(str);
    } /* if */
} /* setSaneCfgAddPath */


int PHYSFS_setSaneConfig(const char *organization, const char *appName,
                         const char *archiveExt, int includeCdRoms,
                         int archivesFirst)
{
    const char *basedir = PHYSFS_getBaseDir();
    const char *userdir = PHYSFS_getUserDir();
    const char *dirsep = PHYSFS_getDirSeparator();
    PHYSFS_uint64 len = 0;
    char *str = NULL;

    BAIL_IF_MACRO(!initialized, ERR_NOT_INITIALIZED, 0);

    /* set write dir... */
    len = (strlen(userdir) + (strlen(organization) * 2) +
            (strlen(appName) * 2) + (strlen(dirsep) * 3) + 2);

    str = (char *) __PHYSFS_smallAlloc(len);

    BAIL_IF_MACRO(str == NULL, ERR_OUT_OF_MEMORY, 0);
    sprintf(str, "%s.%s%s%s", userdir, organization, dirsep, appName);

    if (!PHYSFS_setWriteDir(str))
    {
        int no_write = 0;
        sprintf(str, ".%s/%s", organization, appName);
        if ( (PHYSFS_setWriteDir(userdir)) &&
             (PHYSFS_mkdir(str)) )
        {
            sprintf(str, "%s.%s%s%s", userdir, organization, dirsep, appName);
            if (!PHYSFS_setWriteDir(str))
                no_write = 1;
        } /* if */
        else
        {
            no_write = 1;
        } /* else */

        if (no_write)
        {
            PHYSFS_setWriteDir(NULL);   /* just in case. */
            __PHYSFS_smallFree(str);
            BAIL_MACRO(ERR_CANT_SET_WRITE_DIR, 0);
        } /* if */
    } /* if */

    /* Put write dir first in search path... */
    PHYSFS_mount(str, NULL, 0);
    __PHYSFS_smallFree(str);

        /* Put base path on search path... */
    PHYSFS_mount(basedir, NULL, 1);

        /* handle CD-ROMs... */
    if (includeCdRoms)
    {
        char **cds = PHYSFS_getCdRomDirs();
        char **i;
        for (i = cds; *i != NULL; i++)
            PHYSFS_mount(*i, NULL, 1);

        PHYSFS_freeList(cds);
    } /* if */

        /* Root out archives, and add them to search path... */
    if (archiveExt != NULL)
    {
        char **rc = PHYSFS_enumerateFiles("/");
        char **i;
        size_t extlen = strlen(archiveExt);
        char *ext;

        for (i = rc; *i != NULL; i++)
        {
            size_t l = strlen(*i);
            if ((l > extlen) && ((*i)[l - extlen - 1] == '.'))
            {
                ext = (*i) + (l - extlen);
                if (__PHYSFS_stricmpASCII(ext, archiveExt) == 0)
                    setSaneCfgAddPath(*i, l, dirsep, archivesFirst);
            } /* if */
        } /* for */

        PHYSFS_freeList(rc);
    } /* if */

    return 1;
} /* PHYSFS_setSaneConfig */


void PHYSFS_permitSymbolicLinks(int allow)
{
    allowSymLinks = allow;
} /* PHYSFS_permitSymbolicLinks */


int PHYSFS_symbolicLinksPermitted(void)
{
    return allowSymLinks;
} /* PHYSFS_symbolicLinksPermitted */


/* string manipulation in C makes my ass itch. */
char *__PHYSFS_convertToDependent(const char *prepend,
                                  const char *dirName,
                                  const char *append)
{
    const char *dirsep = __PHYSFS_platformDirSeparator;
    size_t sepsize = strlen(dirsep);
    char *str;
    char *i1;
    char *i2;
    size_t allocSize;

    while (*dirName == '/')  /* !!! FIXME: pass through sanitize function. */
        dirName++;

    allocSize = strlen(dirName) + 1;
    if (prepend != NULL)
        allocSize += strlen(prepend) + sepsize;
    if (append != NULL)
        allocSize += strlen(append) + sepsize;

    /* make sure there's enough space if the dir separator is bigger. */
    if (sepsize > 1)
    {
        str = (char *) dirName;
        do
        {
            str = strchr(str, '/');
            if (str != NULL)
            {
                allocSize += (sepsize - 1);
                str++;
            } /* if */
        } while (str != NULL);
    } /* if */

    str = (char *) allocator.Malloc(allocSize);
    BAIL_IF_MACRO(str == NULL, ERR_OUT_OF_MEMORY, NULL);

    if (prepend == NULL)
        *str = '\0';
    else
    {
        strcpy(str, prepend);
        strcat(str, dirsep);
    } /* else */

    for (i1 = (char *) dirName, i2 = str + strlen(str); *i1; i1++, i2++)
    {
        if (*i1 == '/')
        {
            strcpy(i2, dirsep);
            i2 += sepsize;
        } /* if */
        else
        {
            *i2 = *i1;
        } /* else */
    } /* for */
    *i2 = '\0';

    if (append)
    {
        strcat(str, dirsep);
        strcat(str, append);
    } /* if */

    return str;
} /* __PHYSFS_convertToDependent */


/*
 * Verify that (fname) (in platform-independent notation), in relation
 *  to (h) is secure. That means that each element of fname is checked
 *  for symlinks (if they aren't permitted). This also allows for quick
 *  rejection of files that exist outside an archive's mountpoint.
 *
 * With some exceptions (like PHYSFS_mkdir(), which builds multiple subdirs
 *  at a time), you should always pass zero for "allowMissing" for efficiency.
 *
 * (fname) must point to an output from sanitizePlatformIndependentPath(),
 *  since it will make sure that path names are in the right format for
 *  passing certain checks. It will also do checks for "insecure" pathnames
 *  like ".." which should be done once instead of once per archive. This also
 *  gives us license to treat (fname) as scratch space in this function.
 *
 * Returns non-zero if string is safe, zero if there's a security issue.
 *  PHYSFS_getLastError() will specify what was wrong. (*fname) will be
 *  updated to point past any mount point elements so it is prepared to
 *  be used with the archiver directly.
 */
static int verifyPath(DirHandle *h, char **_fname, int allowMissing)
{
    char *fname = *_fname;
    int retval = 1;
    char *start;
    char *end;

    if (*fname == '\0')  /* quick rejection. */
        return 1;

    /* !!! FIXME: This codeblock sucks. */
    if (h->mountPoint != NULL)  /* NULL mountpoint means "/". */
    {
        size_t mntpntlen = strlen(h->mountPoint);
        size_t len = strlen(fname);
        assert(mntpntlen > 1); /* root mount points should be NULL. */
        /* not under the mountpoint, so skip this archive. */
        BAIL_IF_MACRO(len < mntpntlen-1, ERR_NO_SUCH_PATH, 0);
        /* !!! FIXME: Case insensitive? */
        retval = strncmp(h->mountPoint, fname, mntpntlen-1);
        BAIL_IF_MACRO(retval != 0, ERR_NO_SUCH_PATH, 0);
        if (len > mntpntlen-1)  /* corner case... */
            BAIL_IF_MACRO(fname[mntpntlen-1] != '/', ERR_NO_SUCH_PATH, 0);
        fname += mntpntlen-1;  /* move to start of actual archive path. */
        if (*fname == '/')
            fname++;
        *_fname = fname;  /* skip mountpoint for later use. */
        retval = 1;  /* may be reset, below. */
    } /* if */

    start = fname;
    if (!allowSymLinks)
    {
        while (1)
        {
            int rc = 0;
            end = strchr(start, '/');

            if (end != NULL) *end = '\0';
            rc = h->funcs->isSymLink(h->opaque, fname, &retval);
            if (end != NULL) *end = '/';

            BAIL_IF_MACRO(rc, ERR_SYMLINK_DISALLOWED, 0);   /* insecure. */

            /* break out early if path element is missing. */
            if (!retval)
            {
                /*
                 * We need to clear it if it's the last element of the path,
                 *  since this might be a non-existant file we're opening
                 *  for writing...
                 */
                if ((end == NULL) || (allowMissing))
                    retval = 1;
                break;
            } /* if */

            if (end == NULL)
                break;

            start = end + 1;
        } /* while */
    } /* if */

    return retval;
} /* verifyPath */


static int doMkdir(const char *_dname, char *dname)
{
    DirHandle *h;
    char *start;
    char *end;
    int retval = 0;
    int exists = 1;  /* force existance check on first path element. */

    BAIL_IF_MACRO(!sanitizePlatformIndependentPath(_dname, dname), NULL, 0);

    __PHYSFS_platformGrabMutex(stateLock);
    BAIL_IF_MACRO_MUTEX(writeDir == NULL, ERR_NO_WRITE_DIR, stateLock, 0);
    h = writeDir;
    BAIL_IF_MACRO_MUTEX(!verifyPath(h, &dname, 1), NULL, stateLock, 0);

    start = dname;
    while (1)
    {
        end = strchr(start, '/');
        if (end != NULL)
            *end = '\0';

        /* only check for existance if all parent dirs existed, too... */
        if (exists)
            retval = h->funcs->isDirectory(h->opaque, dname, &exists);

        if (!exists)
            retval = h->funcs->mkdir(h->opaque, dname);

        if (!retval)
            break;

        if (end == NULL)
            break;

        *end = '/';
        start = end + 1;
    } /* while */

    __PHYSFS_platformReleaseMutex(stateLock);
    return retval;
} /* doMkdir */


int PHYSFS_mkdir(const char *_dname)
{
    int retval = 0;
    char *dname;
    size_t len;

    BAIL_IF_MACRO(_dname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_dname) + 1;
    dname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(dname == NULL, ERR_OUT_OF_MEMORY, 0);
    retval = doMkdir(_dname, dname);
    __PHYSFS_smallFree(dname);
    return retval;
} /* PHYSFS_mkdir */


static int doDelete(const char *_fname, char *fname)
{
    int retval;
    DirHandle *h;
    BAIL_IF_MACRO(!sanitizePlatformIndependentPath(_fname, fname), NULL, 0);

    __PHYSFS_platformGrabMutex(stateLock);

    BAIL_IF_MACRO_MUTEX(writeDir == NULL, ERR_NO_WRITE_DIR, stateLock, 0);
    h = writeDir;
    BAIL_IF_MACRO_MUTEX(!verifyPath(h, &fname, 0), NULL, stateLock, 0);
    retval = h->funcs->remove(h->opaque, fname);

    __PHYSFS_platformReleaseMutex(stateLock);
    return retval;
} /* doDelete */


int PHYSFS_delete(const char *_fname)
{
    int retval;
    char *fname;
    size_t len;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, 0);
    retval = doDelete(_fname, fname);
    __PHYSFS_smallFree(fname);
    return retval;
} /* PHYSFS_delete */


const char *PHYSFS_getRealDir(const char *_fname)
{
    const char *retval = NULL;
    char *fname = NULL;
    size_t len;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, NULL);
    len = strlen(_fname) + 1;
    fname = __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, NULL);
    if (sanitizePlatformIndependentPath(_fname, fname))
    {
        DirHandle *i;
        __PHYSFS_platformGrabMutex(stateLock);
        for (i = searchPath; ((i != NULL) && (retval == NULL)); i = i->next)
        {
            char *arcfname = fname;
            if (partOfMountPoint(i, arcfname))
                retval = i->dirName;
            else if (verifyPath(i, &arcfname, 0))
            {
                if (i->funcs->exists(i->opaque, arcfname))
                    retval = i->dirName;
            } /* if */
        } /* for */
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* if */

    __PHYSFS_smallFree(fname);
    return retval;
} /* PHYSFS_getRealDir */


static int locateInStringList(const char *str,
                              char **list,
                              PHYSFS_uint32 *pos)
{
    PHYSFS_uint32 len = *pos;
    PHYSFS_uint32 half_len;
    PHYSFS_uint32 lo = 0;
    PHYSFS_uint32 middle;
    int cmp;

    while (len > 0)
    {
        half_len = len >> 1;
        middle = lo + half_len;
        cmp = strcmp(list[middle], str);

        if (cmp == 0)  /* it's in the list already. */
            return 1;
        else if (cmp > 0)
            len = half_len;
        else
        {
            lo = middle + 1;
            len -= half_len + 1;
        } /* else */
    } /* while */

    *pos = lo;
    return 0;
} /* locateInStringList */


static void enumFilesCallback(void *data, const char *origdir, const char *str)
{
    PHYSFS_uint32 pos;
    void *ptr;
    char *newstr;
    EnumStringListCallbackData *pecd = (EnumStringListCallbackData *) data;

    /*
     * See if file is in the list already, and if not, insert it in there
     *  alphabetically...
     */
    pos = pecd->size;
    if (locateInStringList(str, pecd->list, &pos))
        return;  /* already in the list. */

    ptr = allocator.Realloc(pecd->list, (pecd->size + 2) * sizeof (char *));
    newstr = (char *) allocator.Malloc(strlen(str) + 1);
    if (ptr != NULL)
        pecd->list = (char **) ptr;

    if ((ptr == NULL) || (newstr == NULL))
        return;  /* better luck next time. */

    strcpy(newstr, str);

    if (pos != pecd->size)
    {
        memmove(&pecd->list[pos+1], &pecd->list[pos],
                 sizeof (char *) * ((pecd->size) - pos));
    } /* if */

    pecd->list[pos] = newstr;
    pecd->size++;
} /* enumFilesCallback */


char **PHYSFS_enumerateFiles(const char *path)
{
    EnumStringListCallbackData ecd;
    memset(&ecd, '\0', sizeof (ecd));
    ecd.list = (char **) allocator.Malloc(sizeof (char *));
    BAIL_IF_MACRO(ecd.list == NULL, ERR_OUT_OF_MEMORY, NULL);
    PHYSFS_enumerateFilesCallback(path, enumFilesCallback, &ecd);
    ecd.list[ecd.size] = NULL;
    return ecd.list;
} /* PHYSFS_enumerateFiles */


/*
 * Broke out to seperate function so we can use stack allocation gratuitously.
 */
static void enumerateFromMountPoint(DirHandle *i, const char *arcfname,
                                    PHYSFS_EnumFilesCallback callback,
                                    const char *_fname, void *data)
{
    const size_t len = strlen(arcfname);
    char *ptr = NULL;
    char *end = NULL;
    const size_t slen = strlen(i->mountPoint) + 1;
    char *mountPoint = (char *) __PHYSFS_smallAlloc(slen);

    if (mountPoint == NULL)
        return;  /* oh well. */

    strcpy(mountPoint, i->mountPoint);
    ptr = mountPoint + ((len) ? len + 1 : 0);
    end = strchr(ptr, '/');
    assert(end);  /* should always find a terminating '/'. */
    *end = '\0';
    callback(data, _fname, ptr);
    __PHYSFS_smallFree(mountPoint);
} /* enumerateFromMountPoint */


/* !!! FIXME: this should report error conditions. */
void PHYSFS_enumerateFilesCallback(const char *_fname,
                                   PHYSFS_EnumFilesCallback callback,
                                   void *data)
{
    size_t len;
    char *fname;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, ) /*0*/;
    BAIL_IF_MACRO(callback == NULL, ERR_INVALID_ARGUMENT, ) /*0*/;

    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, ) /*0*/;

    if (sanitizePlatformIndependentPath(_fname, fname))
    {
        DirHandle *i;
        int noSyms;

        __PHYSFS_platformGrabMutex(stateLock);
        noSyms = !allowSymLinks;
        for (i = searchPath; i != NULL; i = i->next)
        {
            char *arcfname = fname;
            if (partOfMountPoint(i, arcfname))
                enumerateFromMountPoint(i, arcfname, callback, _fname, data);

            else if (verifyPath(i, &arcfname, 0))
            {
                i->funcs->enumerateFiles(i->opaque, arcfname, noSyms,
                                         callback, _fname, data);
            } /* else if */
        } /* for */
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* if */

    __PHYSFS_smallFree(fname);
} /* PHYSFS_enumerateFilesCallback */


int PHYSFS_exists(const char *fname)
{
    return (PHYSFS_getRealDir(fname) != NULL);
} /* PHYSFS_exists */


PHYSFS_sint64 PHYSFS_getLastModTime(const char *fname)
{
    PHYSFS_Stat statbuf;
    BAIL_IF_MACRO(!PHYSFS_stat(fname, &statbuf), NULL, -1);
    return statbuf.modtime;
} /* PHYSFS_getLastModTime */


int PHYSFS_isDirectory(const char *_fname)
{
    int retval = 0;
    size_t len;
    char *fname;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, 0);

    if (!sanitizePlatformIndependentPath(_fname, fname))
        retval = 0;

    else if (*fname == '\0')
        retval = 1;  /* Root is always a dir.  :) */

    else
    {
        DirHandle *i;
        int exists = 0;

        __PHYSFS_platformGrabMutex(stateLock);
        for (i = searchPath; ((i != NULL) && (!exists)); i = i->next)
        {
            char *arcfname = fname;
            if ((exists = partOfMountPoint(i, arcfname)) != 0)
                retval = 1;
            else if (verifyPath(i, &arcfname, 0))
                retval = i->funcs->isDirectory(i->opaque, arcfname, &exists);
        } /* for */
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* else */

    __PHYSFS_smallFree(fname);
    return retval;
} /* PHYSFS_isDirectory */


int PHYSFS_isSymbolicLink(const char *_fname)
{
    int retval = 0;
    size_t len;
    char *fname;

    BAIL_IF_MACRO(!allowSymLinks, ERR_SYMLINK_DISALLOWED, 0);

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, 0);

    if (!sanitizePlatformIndependentPath(_fname, fname))
        retval = 0;

    else if (*fname == '\0')
        retval = 1;  /* Root is never a symlink. */

    else
    {
        DirHandle *i;
        int fileExists = 0;

        __PHYSFS_platformGrabMutex(stateLock);
        for (i = searchPath; ((i != NULL) && (!fileExists)); i = i->next)
        {
            char *arcfname = fname;
            if ((fileExists = partOfMountPoint(i, arcfname)) != 0)
                retval = 0;  /* virtual dir...not a symlink. */
            else if (verifyPath(i, &arcfname, 0))
                retval = i->funcs->isSymLink(i->opaque, arcfname, &fileExists);
        } /* for */
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* else */

    __PHYSFS_smallFree(fname);
    return retval;
} /* PHYSFS_isSymbolicLink */


static PHYSFS_File *doOpenWrite(const char *_fname, int appending)
{
    FileHandle *fh = NULL;
    size_t len;
    char *fname;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, 0);

    if (sanitizePlatformIndependentPath(_fname, fname))
    {
        PHYSFS_Io *io = NULL;
        DirHandle *h = NULL;
        const PHYSFS_Archiver *f;

        __PHYSFS_platformGrabMutex(stateLock);

        GOTO_IF_MACRO(!writeDir, ERR_NO_WRITE_DIR, doOpenWriteEnd);

        h = writeDir;
        GOTO_IF_MACRO(!verifyPath(h, &fname, 0), NULL, doOpenWriteEnd);

        f = h->funcs;
        if (appending)
            io = f->openAppend(h->opaque, fname);
        else
            io = f->openWrite(h->opaque, fname);

        GOTO_IF_MACRO(io == NULL, NULL, doOpenWriteEnd);

        fh = (FileHandle *) allocator.Malloc(sizeof (FileHandle));
        if (fh == NULL)
        {
            io->destroy(io);
            GOTO_MACRO(ERR_OUT_OF_MEMORY, doOpenWriteEnd);
        } /* if */
        else
        {
            memset(fh, '\0', sizeof (FileHandle));
            fh->io = io;
            fh->dirHandle = h;
            fh->next = openWriteList;
            openWriteList = fh;
        } /* else */

        doOpenWriteEnd:
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* if */

    __PHYSFS_smallFree(fname);
    return ((PHYSFS_File *) fh);
} /* doOpenWrite */


PHYSFS_File *PHYSFS_openWrite(const char *filename)
{
    return doOpenWrite(filename, 0);
} /* PHYSFS_openWrite */


PHYSFS_File *PHYSFS_openAppend(const char *filename)
{
    return doOpenWrite(filename, 1);
} /* PHYSFS_openAppend */


PHYSFS_File *PHYSFS_openRead(const char *_fname)
{
    FileHandle *fh = NULL;
    char *fname;
    size_t len;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, 0);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, 0);

    if (sanitizePlatformIndependentPath(_fname, fname))
    {
        int fileExists = 0;
        DirHandle *i = NULL;
        PHYSFS_Io *io = NULL;

        __PHYSFS_platformGrabMutex(stateLock);

        GOTO_IF_MACRO(!searchPath, ERR_NO_SUCH_PATH, openReadEnd);

        /* !!! FIXME: Why aren't we using a for loop here? */
        i = searchPath;

        do
        {
            char *arcfname = fname;
            if (verifyPath(i, &arcfname, 0))
            {
                io = i->funcs->openRead(i->opaque, arcfname, &fileExists);
                if (io)
                    break;
            } /* if */
            i = i->next;
        } while ((i != NULL) && (!fileExists));

        /* !!! FIXME: may not set an error if openRead didn't fail. */
        GOTO_IF_MACRO(io == NULL, NULL, openReadEnd);

        fh = (FileHandle *) allocator.Malloc(sizeof (FileHandle));
        if (fh == NULL)
        {
            io->destroy(io);
            GOTO_MACRO(ERR_OUT_OF_MEMORY, openReadEnd);
        } /* if */

        memset(fh, '\0', sizeof (FileHandle));
        fh->io = io;
        fh->forReading = 1;
        fh->dirHandle = i;
        fh->next = openReadList;
        openReadList = fh;

        openReadEnd:
        __PHYSFS_platformReleaseMutex(stateLock);
    } /* if */

    __PHYSFS_smallFree(fname);
    return ((PHYSFS_File *) fh);
} /* PHYSFS_openRead */


static int closeHandleInOpenList(FileHandle **list, FileHandle *handle)
{
    FileHandle *prev = NULL;
    FileHandle *i;
    int rc = 1;

    for (i = *list; i != NULL; i = i->next)
    {
        if (i == handle)  /* handle is in this list? */
        {
            PHYSFS_Io *io = handle->io;
            PHYSFS_uint8 *tmp = handle->buffer;
            rc = PHYSFS_flush((PHYSFS_File *) handle);
            if (!rc)
                return -1;
            io->destroy(io);

            if (tmp != NULL)  /* free any associated buffer. */
                allocator.Free(tmp);

            if (prev == NULL)
                *list = handle->next;
            else
                prev->next = handle->next;

            allocator.Free(handle);
            return 1;
        } /* if */
        prev = i;
    } /* for */

    return 0;
} /* closeHandleInOpenList */


int PHYSFS_close(PHYSFS_File *_handle)
{
    FileHandle *handle = (FileHandle *) _handle;
    int rc;

    __PHYSFS_platformGrabMutex(stateLock);

    /* -1 == close failure. 0 == not found. 1 == success. */
    rc = closeHandleInOpenList(&openReadList, handle);
    BAIL_IF_MACRO_MUTEX(rc == -1, NULL, stateLock, 0);
    if (!rc)
    {
        rc = closeHandleInOpenList(&openWriteList, handle);
        BAIL_IF_MACRO_MUTEX(rc == -1, NULL, stateLock, 0);
    } /* if */

    __PHYSFS_platformReleaseMutex(stateLock);
    BAIL_IF_MACRO(!rc, ERR_NOT_A_HANDLE, 0);
    return 1;
} /* PHYSFS_close */


static PHYSFS_sint64 doBufferedRead(FileHandle *fh, void *buffer,
                                    PHYSFS_uint64 len)
{
    PHYSFS_Io *io = NULL;
    PHYSFS_sint64 retval = 0;
    PHYSFS_uint32 buffered = 0;
    PHYSFS_sint64 rc = 0;

    if (len == 0)
        return 0;

    buffered = fh->buffill - fh->bufpos;
    if (buffered >= len)  /* totally in the buffer, just copy and return! */
    {
        memcpy(buffer, fh->buffer + fh->bufpos, (size_t) len);
        fh->bufpos += (PHYSFS_uint32) len;
        return (PHYSFS_sint64) len;
    } /* else if */

    if (buffered > 0) /* partially in the buffer... */
    {
        memcpy(buffer, fh->buffer + fh->bufpos, (size_t) buffered);
        buffer = ((PHYSFS_uint8 *) buffer) + buffered;
        len -= buffered;
        retval = buffered;
        buffered = fh->buffill = fh->bufpos = 0;
    } /* if */

    /* if you got here, the buffer is drained and we still need bytes. */
    assert(buffered == 0);
    assert(len > 0);

    io = fh->io;
    if (len >= fh->bufsize)  /* need more than the buffer takes. */
    {
        /* leave buffer empty, go right to output instead. */
        rc = io->read(io, buffer, len);
        if (rc < 0)
            return ((retval == 0) ? rc : retval);
        return retval + rc;
    } /* if */

    /* need less than buffer can take. Fill buffer. */
    rc = io->read(io, fh->buffer, fh->bufsize);
    if (rc < 0)
        return ((retval == 0) ? rc : retval);

    assert(fh->bufpos == 0);
    fh->buffill = (PHYSFS_uint32) rc;
    rc = doBufferedRead(fh, buffer, len);  /* go from the start, again. */
    if (rc < 0)
        return ((retval == 0) ? rc : retval);

    return retval + rc;
} /* doBufferedRead */


PHYSFS_sint64 PHYSFS_read(PHYSFS_File *handle, void *buffer,
                          PHYSFS_uint32 size, PHYSFS_uint32 count)
{
    const PHYSFS_uint64 len = ((PHYSFS_uint64) size) * ((PHYSFS_uint64) count);
    const PHYSFS_sint64 retval = PHYSFS_readBytes(handle, buffer, len);
    return ( (retval <= 0) ? retval : (retval / ((PHYSFS_sint64) count)) );
} /* PHYSFS_read */


PHYSFS_sint64 PHYSFS_readBytes(PHYSFS_File *handle, void *buffer,
                               PHYSFS_uint64 len)
{
    FileHandle *fh = (FileHandle *) handle;

#ifdef PHYSFS_NO_64BIT_SUPPORT
    const PHYSFS_uint64 maxlen = __PHYSFS_UI64(0x7FFFFFFF);
#else
    const PHYSFS_uint64 maxlen = __PHYSFS_UI64(0x7FFFFFFFFFFFFFFF);
#endif

    BAIL_IF_MACRO(!__PHYSFS_ui64FitsAddressSpace(len),ERR_INVALID_ARGUMENT,-1);
    BAIL_IF_MACRO(len > maxlen, ERR_INVALID_ARGUMENT, -1);
    BAIL_IF_MACRO(!fh->forReading, ERR_FILE_ALREADY_OPEN_W, -1);
    BAIL_IF_MACRO(len == 0, NULL, 0);
    if (fh->buffer != NULL)
        return doBufferedRead(fh, buffer, len);

    return fh->io->read(fh->io, buffer, len);
} /* PHYSFS_readBytes */


static PHYSFS_sint64 doBufferedWrite(PHYSFS_File *handle, const void *buffer,
                                     PHYSFS_uint64 len)
{
    FileHandle *fh = (FileHandle *) handle;

    /* whole thing fits in the buffer? */
    if ( (((PHYSFS_uint64) fh->buffill) + len) < fh->bufsize )
    {
        memcpy(fh->buffer + fh->buffill, buffer, (size_t) len);
        fh->buffill += (PHYSFS_uint32) len;
        return (PHYSFS_sint64) len;
    } /* if */

    /* would overflow buffer. Flush and then write the new objects, too. */
    BAIL_IF_MACRO(!PHYSFS_flush(handle), NULL, -1);
    return fh->io->write(fh->io, buffer, len);
} /* doBufferedWrite */


PHYSFS_sint64 PHYSFS_write(PHYSFS_File *handle, const void *buffer,
                           PHYSFS_uint32 size, PHYSFS_uint32 count)
{
    const PHYSFS_uint64 len = ((PHYSFS_uint64) size) * ((PHYSFS_uint64) count);
    const PHYSFS_sint64 retval = PHYSFS_writeBytes(handle, buffer, len);
    return ( (retval <= 0) ? retval : (retval / ((PHYSFS_sint64) count)) );
} /* PHYSFS_write */


PHYSFS_sint64 PHYSFS_writeBytes(PHYSFS_File *handle, const void *buffer,
                                PHYSFS_uint64 len)
{
    FileHandle *fh = (FileHandle *) handle;

#ifdef PHYSFS_NO_64BIT_SUPPORT
    const PHYSFS_uint64 maxlen = __PHYSFS_UI64(0x7FFFFFFF);
#else
    const PHYSFS_uint64 maxlen = __PHYSFS_UI64(0x7FFFFFFFFFFFFFFF);
#endif

    BAIL_IF_MACRO(!__PHYSFS_ui64FitsAddressSpace(len),ERR_INVALID_ARGUMENT,-1);
    BAIL_IF_MACRO(len > maxlen, ERR_INVALID_ARGUMENT, -1);
    BAIL_IF_MACRO(fh->forReading, ERR_FILE_ALREADY_OPEN_R, -1);
    BAIL_IF_MACRO(len == 0, NULL, 0);
    if (fh->buffer != NULL)
        return doBufferedWrite(handle, buffer, len);

    return fh->io->write(fh->io, buffer, len);
} /* PHYSFS_write */


int PHYSFS_eof(PHYSFS_File *handle)
{
    FileHandle *fh = (FileHandle *) handle;

    if (!fh->forReading)  /* never EOF on files opened for write/append. */
        return 0;

    /* can't be eof if buffer isn't empty */
    if (fh->bufpos == fh->buffill)
    {
        /* check the Io. */
        PHYSFS_Io *io = fh->io;
        const PHYSFS_sint64 pos = io->tell(io);
        const PHYSFS_sint64 len = io->length(io);
        if ((pos < 0) || (len < 0))
            return 0;  /* beats me. */
        return (pos >= len);
    } /* if */

    return 0;
} /* PHYSFS_eof */


PHYSFS_sint64 PHYSFS_tell(PHYSFS_File *handle)
{
    FileHandle *fh = (FileHandle *) handle;
    const PHYSFS_sint64 pos = fh->io->tell(fh->io);
    const PHYSFS_sint64 retval = fh->forReading ?
                                 (pos - fh->buffill) + fh->bufpos :
                                 (pos + fh->buffill);
    return retval;
} /* PHYSFS_tell */


int PHYSFS_seek(PHYSFS_File *handle, PHYSFS_uint64 pos)
{
    FileHandle *fh = (FileHandle *) handle;
    BAIL_IF_MACRO(!PHYSFS_flush(handle), NULL, 0);

    if (fh->buffer && fh->forReading)
    {
        /* avoid throwing away our precious buffer if seeking within it. */
        PHYSFS_sint64 offset = pos - PHYSFS_tell(handle);
        if ( /* seeking within the already-buffered range? */
            ((offset >= 0) && (offset <= fh->buffill - fh->bufpos)) /* fwd */
            || ((offset < 0) && (-offset <= fh->bufpos)) /* backward */ )
        {
            fh->bufpos += (PHYSFS_uint32) offset;
            return 1; /* successful seek */
        } /* if */
    } /* if */

    /* we have to fall back to a 'raw' seek. */
    fh->buffill = fh->bufpos = 0;
    return fh->io->seek(fh->io, pos);
} /* PHYSFS_seek */


PHYSFS_sint64 PHYSFS_fileLength(PHYSFS_File *handle)
{
    PHYSFS_Io *io = ((FileHandle *) handle)->io;
    return io->length(io);
} /* PHYSFS_filelength */


int PHYSFS_setBuffer(PHYSFS_File *handle, PHYSFS_uint64 _bufsize)
{
    FileHandle *fh = (FileHandle *) handle;
    PHYSFS_uint32 bufsize;

    /* !!! FIXME: Unlocalized string. */
    /* !!! FIXME: actually, why use 32 bits here? */
    BAIL_IF_MACRO(_bufsize > 0xFFFFFFFF, "buffer must fit in 32-bits", 0);
    bufsize = (PHYSFS_uint32) _bufsize;

    BAIL_IF_MACRO(!PHYSFS_flush(handle), NULL, 0);

    /*
     * For reads, we need to move the file pointer to where it would be
     *  if we weren't buffering, so that the next read will get the
     *  right chunk of stuff from the file. PHYSFS_flush() handles writes.
     */
    if ((fh->forReading) && (fh->buffill != fh->bufpos))
    {
        PHYSFS_uint64 pos;
        const PHYSFS_sint64 curpos = fh->io->tell(fh->io);
        BAIL_IF_MACRO(curpos == -1, NULL, 0);
        pos = ((curpos - fh->buffill) + fh->bufpos);
        BAIL_IF_MACRO(!fh->io->seek(fh->io, pos), NULL, 0);
    } /* if */

    if (bufsize == 0)  /* delete existing buffer. */
    {
        if (fh->buffer != NULL)
        {
            allocator.Free(fh->buffer);
            fh->buffer = NULL;
        } /* if */
    } /* if */

    else
    {
        PHYSFS_uint8 *newbuf;
        newbuf = (PHYSFS_uint8 *) allocator.Realloc(fh->buffer, bufsize);
        BAIL_IF_MACRO(newbuf == NULL, ERR_OUT_OF_MEMORY, 0);
        fh->buffer = newbuf;
    } /* else */

    fh->bufsize = bufsize;
    fh->buffill = fh->bufpos = 0;
    return 1;
} /* PHYSFS_setBuffer */


int PHYSFS_flush(PHYSFS_File *handle)
{
    FileHandle *fh = (FileHandle *) handle;
    PHYSFS_Io *io;
    PHYSFS_sint64 rc;

    if ((fh->forReading) || (fh->bufpos == fh->buffill))
        return 1;  /* open for read or buffer empty are successful no-ops. */

    /* dump buffer to disk. */
    io = fh->io;
    rc = io->write(io, fh->buffer + fh->bufpos, fh->buffill - fh->bufpos);
    BAIL_IF_MACRO(rc <= 0, NULL, 0);
    fh->bufpos = fh->buffill = 0;
    return io->flush(io);
} /* PHYSFS_flush */


int PHYSFS_stat(const char *_fname, PHYSFS_Stat *stat)
{
    int retval = 0;
    char *fname;
    size_t len;

    BAIL_IF_MACRO(_fname == NULL, ERR_INVALID_ARGUMENT, -1);
    BAIL_IF_MACRO(stat == NULL, ERR_INVALID_ARGUMENT, -1);
    len = strlen(_fname) + 1;
    fname = (char *) __PHYSFS_smallAlloc(len);
    BAIL_IF_MACRO(fname == NULL, ERR_OUT_OF_MEMORY, -1);

    /* set some sane defaults... */
    stat->filesize = -1;
    stat->modtime = -1;
    stat->createtime = -1;
    stat->accesstime = -1;
    stat->filetype = PHYSFS_FILETYPE_OTHER;
    stat->readonly = 1;  /* !!! FIXME */

    if (sanitizePlatformIndependentPath(_fname, fname))
    {
        if (*fname == '\0')
        {
            stat->filetype = PHYSFS_FILETYPE_DIRECTORY;
            stat->readonly = !writeDir; /* Writeable if we have a writeDir */
            retval = 1;
        } /* if */
        else
        {
            DirHandle *i;
            int exists = 0;
            __PHYSFS_platformGrabMutex(stateLock);
            for (i = searchPath; ((i != NULL) && (!exists)); i = i->next)
            {
                char *arcfname = fname;
                exists = partOfMountPoint(i, arcfname);
                if (exists)
                {
                    stat->filetype = PHYSFS_FILETYPE_DIRECTORY;
                    stat->readonly = 1;  /* !!! FIXME */
                    retval = 1;
                } /* if */
                else if (verifyPath(i, &arcfname, 0))
                {
                    /* !!! FIXME: this test is wrong and should be elsewhere. */
                    stat->readonly = !(writeDir &&
                                 (strcmp(writeDir->dirName, i->dirName) == 0));
                    retval = i->funcs->stat(i->opaque, arcfname, &exists, stat);
                } /* else if */
            } /* for */
            __PHYSFS_platformReleaseMutex(stateLock);
        } /* else */
    } /* if */

    __PHYSFS_smallFree(fname);
    return retval;
} /* PHYSFS_stat */


int PHYSFS_setAllocator(const PHYSFS_Allocator *a)
{
    BAIL_IF_MACRO(initialized, ERR_IS_INITIALIZED, 0);
    externalAllocator = (a != NULL);
    if (externalAllocator)
        memcpy(&allocator, a, sizeof (PHYSFS_Allocator));

    return 1;
} /* PHYSFS_setAllocator */


const PHYSFS_Allocator *PHYSFS_getAllocator(void)
{
    BAIL_IF_MACRO(!initialized, ERR_NOT_INITIALIZED, NULL);
    return &allocator;
} /* PHYSFS_getAllocator */


static void *mallocAllocatorMalloc(PHYSFS_uint64 s)
{
    BAIL_IF_MACRO(!__PHYSFS_ui64FitsAddressSpace(s), ERR_OUT_OF_MEMORY, NULL);
    #undef malloc
    return malloc((size_t) s);
} /* mallocAllocatorMalloc */


static void *mallocAllocatorRealloc(void *ptr, PHYSFS_uint64 s)
{
    BAIL_IF_MACRO(!__PHYSFS_ui64FitsAddressSpace(s), ERR_OUT_OF_MEMORY, NULL);
    #undef realloc
    return realloc(ptr, (size_t) s);
} /* mallocAllocatorRealloc */


static void mallocAllocatorFree(void *ptr)
{
    #undef free
    free(ptr);
} /* mallocAllocatorFree */


static void setDefaultAllocator(void)
{
    assert(!externalAllocator);
    if (!__PHYSFS_platformSetDefaultAllocator(&allocator))
    {
        allocator.Init = NULL;
        allocator.Deinit = NULL;
        allocator.Malloc = mallocAllocatorMalloc;
        allocator.Realloc = mallocAllocatorRealloc;
        allocator.Free = mallocAllocatorFree;
    } /* if */
} /* setDefaultAllocator */


void *__PHYSFS_initSmallAlloc(void *ptr, PHYSFS_uint64 len)
{
    const char useHeap = ((ptr == NULL) ? 1 : 0);
    if (useHeap)  /* too large for stack allocation or alloca() failed. */
        ptr = allocator.Malloc(len+1);

    if (ptr != NULL)
    {
        char *retval = (char *) ptr;
        /*printf("%s alloc'd (%d) bytes at (%p).\n",
                useHeap ? "heap" : "stack", (int) len, ptr);*/
        *retval = useHeap;
        return (retval + 1);
    } /* if */

    return NULL;  /* allocation failed. */
} /* __PHYSFS_initSmallAlloc */


void __PHYSFS_smallFree(void *ptr)
{
    if (ptr != NULL)
    {
        char *block = ((char *) ptr) - 1;
        const char useHeap = *block;
        if (useHeap)
            allocator.Free(block);
        /*printf("%s free'd (%p).\n", useHeap ? "heap" : "stack", block);*/
    } /* if */
} /* __PHYSFS_smallFree */

/* end of physfs.c ... */