mtd: check for Seama magic early when fixing MD5
This avoid long (and unneeded) process of reading all data in case of running on MTD not containig Seama entity. Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
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		@@ -53,7 +53,7 @@ ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
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int
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					int
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seama_fix_md5(char *buf, size_t len)
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					seama_fix_md5(char *buf, size_t len)
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{
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					{
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	struct seama_hdr *shdr;
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						struct seama_hdr *shdr = (struct seama_hdr *) buf;
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	char *data;
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						char *data;
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	size_t msize;
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						size_t msize;
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	size_t isize;
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						size_t isize;
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@@ -64,12 +64,6 @@ seama_fix_md5(char *buf, size_t len)
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	if (len < sizeof(struct seama_hdr))
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						if (len < sizeof(struct seama_hdr))
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		return -1;
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							return -1;
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	shdr = (struct seama_hdr *) buf;
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	if (shdr->magic != htonl(SEAMA_MAGIC)) {
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		fprintf(stderr, "no SEAMA header found\n");
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		return -1;
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	}
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	isize = ntohl(shdr->size);
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						isize = ntohl(shdr->size);
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	msize = ntohs(shdr->metasize);
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						msize = ntohs(shdr->metasize);
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	if (isize == 0) {
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						if (isize == 0) {
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@@ -115,9 +109,11 @@ int
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mtd_fixseama(const char *mtd, size_t offset)
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					mtd_fixseama(const char *mtd, size_t offset)
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{
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					{
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	int fd;
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						int fd;
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						char *first_block;
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	char *buf;
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						char *buf;
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	ssize_t res;
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						ssize_t res;
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	size_t block_offset;
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						size_t block_offset;
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						struct seama_hdr *shdr;
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	if (quiet < 2)
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						if (quiet < 2)
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		fprintf(stderr, "Trying to fix SEAMA header in %s at 0x%x...\n",
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							fprintf(stderr, "Trying to fix SEAMA header in %s at 0x%x...\n",
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@@ -138,6 +134,24 @@ mtd_fixseama(const char *mtd, size_t offset)
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		exit(1);
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							exit(1);
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	}
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						}
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						first_block = malloc(erasesize);
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						if (!first_block) {
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							perror("malloc");
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							exit(1);
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						}
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						res = pread(fd, first_block, erasesize, block_offset);
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						if (res != erasesize) {
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							perror("pread");
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							exit(1);
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						}
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						shdr = (struct seama_hdr *)first_block;
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						if (shdr->magic != htonl(SEAMA_MAGIC)) {
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							fprintf(stderr, "No SEAMA header found\n");
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							return -1;
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						}
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	buf = malloc(mtdsize);
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						buf = malloc(mtdsize);
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	if (!buf) {
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						if (!buf) {
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		perror("malloc");
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							perror("malloc");
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