Replaced some Malloc and all the alloca() calls with __PHYSFS_smallAl…

…loc(), which will stack allocate small (128 or less bytes) blocks and Malloc the rest...naturally these now have to be paired with __PHYSFS_smallFree() calls, so you can't be as lazy as a basic alloca() would let you be. The benefit is both less malloc pressure for those temporary allocations and better stack overflow safety (so if some jerk tries to push a 78 megabyte string through the library as a filename, we won't try to strcpy it to the stack).
icculus · Mar 24, 2007 · 7386320 · 7386320
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commit 7386320
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Showing 9 changed files with 414 additions and 210 deletions.
diff --git a/CHANGELOG.txt b/CHANGELOG.txt
@@ -1,6 +1,18 @@
 /*
  * CHANGELOG.
  */
+
+03222007 - Replaced some Malloc and all the alloca() calls with
+           __PHYSFS_smallAlloc(), which will stack allocate small (128 or
+           less bytes) blocks and Malloc the rest...naturally these now have
+           to be paired with __PHYSFS_smallFree() calls, so you can't be as
+           lazy as a basic alloca() would let you be. The benefit is both less
+           malloc pressure for those temporary allocations and better stack
+           overflow safety (so if some jerk tries to push a 78 megabyte string
+           through the library as a filename, we won't try to strcpy it to
+           the stack). Hopefully some internal interfaces can now get
+           refactored to stop generating heap pointers and let the caller use
+           smallAlloc to further reduce malloc pressure.
 03212007 - Replaced LONGLONGLITERAL with __PHYSFS_UI64/__PHYSFS_SI64 ...
 03202007 - Removed platform/skeleton.c (it was out of date), added
            platform/macosx.c (To further Macify the code and get the #ifdefs

diff --git a/archivers/lzma.c b/archivers/lzma.c
@@ -479,13 +479,14 @@ static void *LZMA_openArchive(const char *name, int forWriting)
 static void doEnumCallback(PHYSFS_EnumFilesCallback cb, void *callbackdata,
                            const char *odir, const char *str, PHYSFS_sint32 ln)
 {
-    char *newstr = alloca(ln + 1);
+    char *newstr = __PHYSFS_smallAlloc(ln + 1);
     if (newstr == NULL)
         return;
 
     memcpy(newstr, str, ln);
     newstr[ln] = '\0';
     cb(callbackdata, odir, newstr);
+    __PHYSFS_smallFree(newstr);
 } /* doEnumCallback */
 
 

diff --git a/archivers/qpak.c b/archivers/qpak.c
@@ -378,13 +378,14 @@ static PHYSFS_sint32 qpak_find_start_of_dir(QPAKinfo *info, const char *path,
 static void doEnumCallback(PHYSFS_EnumFilesCallback cb, void *callbackdata,
                            const char *odir, const char *str, PHYSFS_sint32 ln)
 {
-    char *newstr = alloca(ln + 1);
+    char *newstr = __PHYSFS_smallAlloc(ln + 1);
     if (newstr == NULL)
         return;
 
     memcpy(newstr, str, ln);
     newstr[ln] = '\0';
     cb(callbackdata, odir, newstr);
+    __PHYSFS_smallFree(newstr);
 } /* doEnumCallback */
 
 

diff --git a/archivers/zip.c b/archivers/zip.c
@@ -682,15 +682,15 @@ static int zip_resolve_symlink(void *in, ZIPinfo *info, ZIPentry *entry)
     else  /* symlink target path is compressed... */
     {
         z_stream stream;
-        PHYSFS_uint32 compsize = entry->compressed_size;
-        PHYSFS_uint8 *compressed = (PHYSFS_uint8 *) allocator.Malloc(compsize);
+        PHYSFS_uint32 complen = entry->compressed_size;
+        PHYSFS_uint8 *compressed = (PHYSFS_uint8*) __PHYSFS_smallAlloc(complen);
         if (compressed != NULL)
         {
-            if (__PHYSFS_platformRead(in, compressed, compsize, 1) == 1)
+            if (__PHYSFS_platformRead(in, compressed, complen, 1) == 1)
             {
                 initializeZStream(&stream);
                 stream.next_in = compressed;
-                stream.avail_in = compsize;
+                stream.avail_in = complen;
                 stream.next_out = (unsigned char *) path;
                 stream.avail_out = size;
                 if (zlib_err(inflateInit2(&stream, -MAX_WBITS)) == Z_OK)
@@ -702,7 +702,7 @@ static int zip_resolve_symlink(void *in, ZIPinfo *info, ZIPentry *entry)
                     rc = ((rc == Z_OK) || (rc == Z_STREAM_END));
                 } /* if */
             } /* if */
-            allocator.Free(compressed);
+            __PHYSFS_smallFree(compressed);
         } /* if */
     } /* else */
 
@@ -1177,13 +1177,14 @@ static PHYSFS_sint32 zip_find_start_of_dir(ZIPinfo *info, const char *path,
 static void doEnumCallback(PHYSFS_EnumFilesCallback cb, void *callbackdata,
                            const char *odir, const char *str, PHYSFS_sint32 ln)
 {
-    char *newstr = alloca(ln + 1);
+    char *newstr = __PHYSFS_smallAlloc(ln + 1);
     if (newstr == NULL)
         return;
 
     memcpy(newstr, str, ln);
     newstr[ln] = '\0';
     cb(callbackdata, odir, newstr);
+    __PHYSFS_smallFree(newstr);
 } /* doEnumCallback */