fatelf-replace.c
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/**
* FatELF; support multiple ELF binaries in one file.
*
* Please see the file LICENSE.txt in the source's root directory.
*
* This file written by Ryan C. Gordon.
*/
#define FATELF_UTILS 1
#include "fatelf-utils.h"
static int xfind_fatelf_record_by_elf(const char *fname, const int fd,
const char *fatfname,
const FATELF_header *header)
{
FATELF_record record;
int i;
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xread_elf_header(fname, fd, 0, &record);
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for (i = 0; i < ((int)header->num_records); i++)
{
if (fatelf_record_matches(&header->records[i], &record))
return i;
} // for
xfail("No record matches '%s' in FatELF file '%s'", fname, fatfname);
return -1;
} // xfind_fatelf_record_by_elf
static int fatelf_replace(const char *out, const char *fname,
const char *newobj)
{
const int fd = xopen(fname, O_RDONLY, 0755);
const int newfd = xopen(newobj, O_RDONLY, 0755);
FATELF_header *header = xread_fatelf_header(fname, fd);
const int idx = xfind_fatelf_record_by_elf(newobj, newfd, fname, header);
const int outfd = xopen(out, O_WRONLY | O_CREAT | O_TRUNC, 0755);
uint64_t offset = FATELF_DISK_FORMAT_SIZE(((int)header->num_records));
int i;
unlink_on_xfail = out;
// pad out some bytes for the header we'll write at the end...
xwrite_zeros(out, outfd, (size_t) offset);
for (i = 0; i < ((int) header->num_records); i++)
{
const uint64_t binary_offset = align_to_page(offset);
FATELF_record *rec = &header->records[i];
// append this binary to the final file, padded to page alignment.
xwrite_zeros(out, outfd, (size_t) (binary_offset - offset));
if (i == idx) // the thing we're replacing...
rec->size = xcopyfile(newobj, newfd, out, outfd);
else
xcopyfile_range(fname, fd, out, outfd, binary_offset, rec->size);
rec->offset = binary_offset;
offset = binary_offset + rec->size;
} // for
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xappend_junk(fname, fd, out, outfd, header);
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// Write the actual FatELF header now...
xwrite_fatelf_header(out, outfd, header);
xclose(out, outfd);
xclose(newobj, newfd);
xclose(fname, fd);
free(header);
unlink_on_xfail = NULL;
return 0; // success.
} // fatelf_replace
int main(int argc, const char **argv)
{
xfatelf_init(argc, argv);
if (argc != 4) // this could stand to use getopt(), later.
xfail("USAGE: %s <out> <in> <newelf>", argv[0]);
return fatelf_replace(argv[1], argv[2], argv[3]);
} // main
// end of fatelf-replace.c ...