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mtd: seama: fix image data handling

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1) Put sanity checks in one place
2) Respect provided offset
3) Read only as much data as needed for MD5 calculation

Thanks to the last change this is a great speedup and memory saver. On
devices with NAND flash we were allocating & reading about 128 MiB while
something about 8 MiB is enough.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
This commit is contained in:
rmilecki 2016-05-09 12:53:39 +00:00 committed by Rafał Miłecki
parent 30edc32888
commit 06a3241c27
1 changed files with 18 additions and 28 deletions
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46
package/system/mtd/src/seama.c
View file

@ -51,49 +51,30 @@ ssize_t pread(int fd, void *buf, size_t count, off_t offset);
ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
int
seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block_offset)
seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t data_offset, size_t data_size)
{
char *buf;
char *data;
ssize_t res;
size_t msize;
size_t isize;
MD5_CTX ctx;
unsigned char digest[16];
int i;
int err = 0;
if (len < sizeof(struct seama_entity_header))
return -1;
buf = malloc(len);
buf = malloc(data_size);
if (!buf) {
err = -ENOMEM;
goto err_out;
}
res = pread(fd, buf, len, block_offset);
if (res != len) {
res = pread(fd, buf, data_size, data_offset);
if (res != data_size) {
perror("pread");
err = -EIO;
goto err_free;
}
isize = ntohl(shdr->size);
msize = ntohs(shdr->metasize);
if (isize == 0) {
/* the image contains no checksum */
return -1;
}
len -= sizeof(struct seama_entity_header) + msize;
if (isize > len)
isize = len;
data = buf + sizeof(struct seama_entity_header) + msize;
MD5_Init(&ctx);
MD5_Update(&ctx, data, isize);
MD5_Update(&ctx, buf, data_size);
MD5_Final(digest, &ctx);
if (!memcmp(digest, shdr->md5, sizeof(digest))) {
@ -103,7 +84,7 @@ seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block
}
if (quiet < 2) {
fprintf(stderr, "new size:%u, new MD5: ", isize);
fprintf(stderr, "new size:%u, new MD5: ", data_size);
for (i = 0; i < sizeof(digest); i++)
fprintf(stderr, "%02x", digest[i]);
@ -111,7 +92,7 @@ seama_fix_md5(struct seama_entity_header *shdr, int fd, size_t len, size_t block
}
/* update the size in the image */
shdr->size = htonl(isize);
shdr->size = htonl(data_size);
/* update the checksum in the image */
memcpy(shdr->md5, digest, sizeof(digest));
@ -129,6 +110,8 @@ mtd_fixseama(const char *mtd, size_t offset)
char *first_block;
ssize_t res;
size_t block_offset;
size_t data_offset;
size_t data_size;
struct seama_entity_header *shdr;
if (quiet < 2)
@ -162,13 +145,20 @@ mtd_fixseama(const char *mtd, size_t offset)
exit(1);
}
shdr = (struct seama_entity_header *)first_block;
shdr = (struct seama_entity_header *)(first_block + offset);
if (shdr->magic != htonl(SEAMA_MAGIC)) {
fprintf(stderr, "No SEAMA header found\n");
return -1;
} else if (!ntohl(shdr->size)) {
fprintf(stderr, "Seama entity with empty image\n");
exit(1);
}
if (seama_fix_md5(shdr, fd, mtdsize, block_offset))
data_offset = offset + sizeof(struct seama_entity_header) + ntohs(shdr->metasize);
data_size = mtdsize - data_offset;
if (data_size > ntohl(shdr->size))
data_size = ntohl(shdr->size);
if (seama_fix_md5(shdr, fd, data_offset, data_size))
goto out;
if (mtd_erase_block(fd, block_offset)) {