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firmware-utils: bcm4908img: find cferom size

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It's important for modifying / extracting firmware content. cferom is
optional image content at the file beginning.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
This commit is contained in:
Rafał Miłecki 2021-04-02 15:04:46 +02:00
parent 9b9184f178
commit 6af45b842b
1 changed files with 31 additions and 0 deletions
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31
tools/firmware-utils/src/bcm4908img.c
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@ -22,11 +22,19 @@
#define le32_to_cpu(x) bswap_32(x)
#define cpu_to_be32(x) (x)
#define be32_to_cpu(x) (x)
#define cpu_to_le16(x) bswap_16(x)
#define le16_to_cpu(x) bswap_16(x)
#define cpu_to_be16(x) (x)
#define be16_to_cpu(x) (x)
#elif __BYTE_ORDER == __LITTLE_ENDIAN
#define cpu_to_le32(x) (x)
#define le32_to_cpu(x) (x)
#define cpu_to_be32(x) bswap_32(x)
#define be32_to_cpu(x) bswap_32(x)
#define cpu_to_le16(x) (x)
#define le16_to_cpu(x) (x)
#define cpu_to_be16(x) bswap_16(x)
#define be16_to_cpu(x) bswap_16(x)
#else
#error "Unsupported endianness"
#endif
@ -57,6 +65,7 @@ struct bcm4908img_tail {
struct bcm4908img_info {
size_t file_size;
size_t vendor_header_size; /* Vendor header size */
size_t cferom_size;
uint32_t crc32; /* Calculated checksum */
struct bcm4908img_tail tail;
};
@ -203,6 +212,7 @@ static int bcm4908img_parse(FILE *fp, struct bcm4908img_info *info) {
struct chk_header *chk;
struct stat st;
uint8_t buf[1024];
uint16_t tmp16;
size_t length;
size_t bytes;
int err = 0;
@ -229,6 +239,26 @@ static int bcm4908img_parse(FILE *fp, struct bcm4908img_info *info) {
if (be32_to_cpu(chk->magic) == 0x2a23245e)
info->vendor_header_size = be32_to_cpu(chk->header_len);
/* Sizes */
for (; info->vendor_header_size + info->cferom_size <= info->file_size; info->cferom_size += 0x20000) {
if (fseek(fp, info->vendor_header_size + info->cferom_size, SEEK_SET)) {
err = -errno;
fprintf(stderr, "Failed to fseek to the 0x%zx\n", info->cferom_size);
return err;
}
if (fread(&tmp16, 1, sizeof(tmp16), fp) != sizeof(tmp16)) {
fprintf(stderr, "Failed to read while looking for JFFS2\n");
return -EIO;
}
if (be16_to_cpu(tmp16) == 0x8519)
break;
}
if (info->vendor_header_size + info->cferom_size >= info->file_size) {
fprintf(stderr, "Failed to find cferom size (no bootfs found)\n");
return -EPROTO;
}
/* CRC32 */
fseek(fp, info->vendor_header_size, SEEK_SET);
@ -294,6 +324,7 @@ static int bcm4908img_info(int argc, char **argv) {
}
printf("Vendor header length:\t%zu\n", info.vendor_header_size);
printf("cferom size:\t0x%zx\n", info.cferom_size);
printf("Checksum:\t0x%08x\n", info.crc32);
err_close: