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Add support for reversed CRCs in elfpatching

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This commit is contained in:
Mario Hüttel 2023-01-15 21:21:00 +01:00
parent 6f40e37e81
commit cf7d0c22f7
1 changed files with 11 additions and 5 deletions
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16
src/elfpatch.c
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@ -489,14 +489,14 @@ int elf_patch_check_for_section(elfpatch_handle_t *ep, const char *section)
return ret; return ret;
} }
static size_t translate_index(size_t index, enum granularity granularity, bool little_endian) static size_t translate_index(size_t index, enum granularity granularity, bool little_endian, bool reversed)
{ {
size_t word_idx; size_t word_idx;
size_t part_idx; size_t part_idx;
size_t d_index; size_t d_index;
size_t gran_in_bytes; size_t gran_in_bytes;
if (!little_endian || granularity == GRANULARITY_BYTE) if ((!little_endian && !reversed) || (little_endian && reversed) || granularity == GRANULARITY_BYTE)
return index; return index;
gran_in_bytes = (size_t)granularity / 8u; gran_in_bytes = (size_t)granularity / 8u;
@ -546,8 +546,9 @@ int elf_patch_compute_crc_over_section(elfpatch_handle_t *ep, const char *sectio
return -2; return -2;
} }
/* If big endian or granularity is byte, simply compute CRC. No reordering is necessary */ /* If big endian for non reversed / little endian for reversed or granularity is byte, simply compute CRC. No reordering is necessary */
if (!little_endian || granularity == GRANULARITY_BYTE) { if ((!little_endian && !crc->settings.rev) || (little_endian && crc->settings.rev) ||
granularity == GRANULARITY_BYTE) {
crc_push_bytes(crc, data->d_buf, data->d_size); crc_push_bytes(crc, data->d_buf, data->d_size);
} else { } else {
/* Little endian case with > byte sized chunks */ /* Little endian case with > byte sized chunks */
@ -560,7 +561,12 @@ int elf_patch_compute_crc_over_section(elfpatch_handle_t *ep, const char *sectio
} }
for (idx = 0; idx < data->d_size; idx++) for (idx = 0; idx < data->d_size; idx++)
crc_push_byte(crc, ((char *)data->d_buf)[translate_index(idx, granularity, little_endian)]); crc_push_byte(crc,
((char *)data->d_buf)[
translate_index(idx, granularity,
little_endian,
crc->settings.rev)
]);
/* Pad with zeroes */ /* Pad with zeroes */
for (idx = 0; idx < padding_count; idx++) for (idx = 0; idx < padding_count; idx++)