firmware-utils: bcm4908img: replace size with offset

It's much easier to operate on BCM4908 image data with absolute offset
of each section stored. It doesn't require summing sizes over and over.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>

diff --git a/src/bcm4908img.c b/src/bcm4908img.c
index 536056d42ad32ed7ea7ec0ba7e0efafd708a1bcb..ac76bd1c618649b0a98b9085fdbea1d26e5f5bda 100644 (file)
--- a/src/bcm4908img.c
+++ b/src/bcm4908img.c
@@ -64,11 +64,21 @@ struct bcm4908img_tail {
        uint32_t flags;
 };
 
-/* Info about BCM4908 image */
+/**
+ * struct bcm4908img_info - info about BCM4908 image
+ *
+ * Standard BCM4908 image consists of:
+ * 1. (Optional) vedor header
+ * 2. (Optional) cferom
+ * 3. bootfs  ─┐
+ * 4. padding  ├─ firmware
+ * 5. rootfs  ─┘
+ * 6. BCM4908 tail
+ */
 struct bcm4908img_info {
        size_t file_size;
-       size_t vendor_header_size;      /* Vendor header size */
-       size_t cferom_size;
+       size_t cferom_offset;
+       size_t bootfs_offset;
        uint32_t crc32;                 /* Calculated checksum */
        struct bcm4908img_tail tail;
 };
@@ -200,10 +210,11 @@ static int bcm4908img_calc_crc32(FILE *fp, struct bcm4908img_info *info) {
        size_t length;
        size_t bytes;
 
-       fseek(fp, info->vendor_header_size, SEEK_SET);
+       /* Start with cferom (or bootfs) - skip vendor header */
+       fseek(fp, info->cferom_offset, SEEK_SET);
 
        info->crc32 = 0xffffffff;
-       length = info->file_size - info->vendor_header_size - sizeof(struct bcm4908img_tail);
+       length = info->file_size - info->cferom_offset - sizeof(struct bcm4908img_tail);
        while (length && (bytes = fread(buf, 1, bcm4908img_min(sizeof(buf), length), fp)) > 0) {
                info->crc32 = bcm4908img_crc32(info->crc32, buf, bytes);
                length -= bytes;
@@ -263,14 +274,16 @@ static int bcm4908img_parse(FILE *fp, struct bcm4908img_info *info) {
        }
        chk = (void *)buf;
        if (be32_to_cpu(chk->magic) == 0x2a23245e)
-               info->vendor_header_size = be32_to_cpu(chk->header_len);
+               info->cferom_offset = be32_to_cpu(chk->header_len);
 
-       /* Sizes */
+       /* Offsets */
 
-       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)) {
+       for (info->bootfs_offset = info->cferom_offset;
+            info->bootfs_offset < info->file_size;
+            info->bootfs_offset += 0x20000) {
+               if (fseek(fp, info->bootfs_offset, SEEK_SET)) {
                        err = -errno;
-                       fprintf(stderr, "Failed to fseek to the 0x%zx\n", info->cferom_size);
+                       fprintf(stderr, "Failed to fseek to the 0x%zx\n", info->bootfs_offset);
                        return err;
                }
                if (fread(&tmp16, 1, sizeof(tmp16), fp) != sizeof(tmp16)) {
@@ -280,17 +293,18 @@ static int bcm4908img_parse(FILE *fp, struct bcm4908img_info *info) {
                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");
+       if (info->bootfs_offset >= info->file_size) {
+               fprintf(stderr, "Failed to find bootfs offset\n");
                return -EPROTO;
        }
 
        /* CRC32 */
 
-       fseek(fp, info->vendor_header_size, SEEK_SET);
+       /* Start with cferom (or bootfs) - skip vendor header */
+       fseek(fp, info->cferom_offset, SEEK_SET);
 
        info->crc32 = 0xffffffff;
-       length = info->file_size - info->vendor_header_size - sizeof(*tail);
+       length = info->file_size - info->cferom_offset - sizeof(*tail);
        while (length && (bytes = fread(buf, 1, bcm4908img_min(sizeof(buf), length), fp)) > 0) {
                info->crc32 = bcm4908img_crc32(info->crc32, buf, bytes);
                length -= bytes;
@@ -349,8 +363,9 @@ static int bcm4908img_info(int argc, char **argv) {
                goto err_close;
        }
 
-       printf("Vendor header length:\t%zu\n", info.vendor_header_size);
-       printf("cferom size:\t0x%zx\n", info.cferom_size);
+       if (info.bootfs_offset != info.cferom_offset)
+               printf("cferom offset:\t%zu\n", info.cferom_offset);
+       printf("bootfs offset:\t0x%zx\n", info.bootfs_offset);
        printf("Checksum:\t0x%08x\n", info.crc32);
 
 err_close:
@@ -537,14 +552,14 @@ static int bcm4908img_extract(int argc, char **argv) {
 
        if (!strcmp(type, "cferom")) {
                offset = 0;
-               length = info.cferom_size;
+               length = info.bootfs_offset - offset;
                if (!length) {
                        err = -ENOENT;
                        fprintf(stderr, "This BCM4908 image doesn't contain cferom\n");
                        goto err_close;
                }
        } else if (!strcmp(type, "firmware")) {
-               offset = info.vendor_header_size + info.cferom_size;
+               offset = info.bootfs_offset;
                length = info.file_size - offset - sizeof(struct bcm4908img_tail);
        } else {
                err = -EINVAL;
@@ -648,7 +663,7 @@ static int bcm4908img_bootfs_ls(FILE *fp, struct bcm4908img_info *info) {
        size_t bytes;
        int err = 0;
 
-       for (offset = info->vendor_header_size + info->cferom_size; ; offset += (je32_to_cpu(node.totlen) + 0x03) & ~0x03) {
+       for (offset = info->bootfs_offset; ; offset += (je32_to_cpu(node.totlen) + 0x03) & ~0x03) {
                char name[FILENAME_MAX + 1];
 
                if (fseek(fp, offset, SEEK_SET)) {
@@ -719,7 +734,7 @@ static int bcm4908img_bootfs_mv(FILE *fp, struct bcm4908img_info *info, int argc
                return -EINVAL;
        }
 
-       for (offset = info->vendor_header_size + info->cferom_size; ; offset += (je32_to_cpu(node.totlen) + 0x03) & ~0x03) {
+       for (offset = info->bootfs_offset; ; offset += (je32_to_cpu(node.totlen) + 0x03) & ~0x03) {
                char name[FILENAME_MAX];
                uint32_t crc32;