mtd: support -c (datasize) option for fixseama command

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

package/system/mtd/src/mtd.c

@@ -674,7 +674,7 @@ resume:
 			break;
 		case MTD_IMAGE_FORMAT_SEAMA:
 			if (mtd_fixseama)
-				mtd_fixseama(mtd, 0);
+				mtd_fixseama(mtd, 0, 0);
 			break;
 		default:
 			break;
@@ -737,8 +737,10 @@ static void usage(void)
 	if (mtd_fixtrx) {
 	    fprintf(stderr,
 	"        -o offset               offset of the image header in the partition(for fixtrx)\n");
+	}
+	if (mtd_fixtrx || mtd_fixseama) {
 		fprintf(stderr,
-	"        -c datasize             amount of data to be used for checksum calculation (for fixtrx)\n");
+	"        -c datasize             amount of data to be used for checksum calculation (for fixtrx / fixseama)\n");
 	}
 	fprintf(stderr,
 #ifdef FIS_SUPPORT
@@ -987,7 +989,7 @@ int main (int argc, char **argv)
 			break;
 		case CMD_FIXSEAMA:
 			if (mtd_fixseama)
-				mtd_fixseama(device, 0);
+				mtd_fixseama(device, 0, data_size);
 			break;
 	}
 

package/system/mtd/src/mtd.h

@@ -26,6 +26,6 @@ extern void mtd_parse_jffs2data(const char *buf, const char *dir);
 extern int trx_fixup(int fd, const char *name)  __attribute__ ((weak));
 extern int trx_check(int imagefd, const char *mtd, char *buf, int *len) __attribute__ ((weak));
 extern int mtd_fixtrx(const char *mtd, size_t offset, size_t data_size) __attribute__ ((weak));
-extern int mtd_fixseama(const char *mtd, size_t offset) __attribute__ ((weak));
+extern int mtd_fixseama(const char *mtd, size_t offset, size_t data_size) __attribute__ ((weak));
 extern int mtd_resetbc(const char *mtd) __attribute__ ((weak));
 #endif /* __mtd_h */

package/system/mtd/src/seama.c

@@ -104,14 +104,13 @@ err_out:
 }
 
 int
-mtd_fixseama(const char *mtd, size_t offset)
+mtd_fixseama(const char *mtd, size_t offset, size_t data_size)
 {
 	int fd;
 	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)
@@ -155,7 +154,8 @@ mtd_fixseama(const char *mtd, size_t offset)
 	}
 
 	data_offset = offset + sizeof(struct seama_entity_header) + ntohs(shdr->metasize);
-	data_size = mtdsize - data_offset;
+	if (!data_size)
+		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))