implement byte-order swaps

littlekernel · Aug 20, 2021 · 4ff130e · 4ff130e
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commit 4ff130e
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Showing 4 changed files with 21 additions and 52 deletions.
diff --git a/lib/fs/ext2/dir.c b/lib/fs/ext2/dir.c
@@ -21,6 +21,7 @@ struct dircookie {
     uint cursor;
 };
 
+// TODO, move to ext2.c
 static void ext2_dump_inode(struct ext2_inode *inode) {
 #if LOCAL_TRACE
   printf("mode:   %d\n", inode->i_mode);
@@ -232,43 +233,6 @@ status_t ext2_opendir(fscookie *cookie, const char *name, dircookie **dcookie) {
 
     *dcookie = dir;
 
-#if 0
-    buf = malloc(EXT2_BLOCK_SIZE(ext2->sb));
-
-    file_blocknum = 0;
-    for (;;) {
-        /* read in the offset */
-        err = ext2_read_inode(ext2, &dir_inode, buf, file_blocknum * EXT2_BLOCK_SIZE(ext2->sb), EXT2_BLOCK_SIZE(ext2->sb));
-        if (err <= 0) {
-            free(buf);
-            return -1;
-        }
-
-        /* walk through the directory entries, looking for the one that matches */
-        struct ext2_dir_entry_2 *ent;
-        uint pos = 0;
-        while (pos < EXT2_BLOCK_SIZE(ext2->sb)) {
-            ent = (struct ext2_dir_entry_2 *)&buf[pos];
-
-            LTRACEF("ent %d:%d: inode 0x%x, reclen %d, namelen %d\n",
-                    file_blocknum, pos, LE32(ent->inode), LE16(ent->rec_len), ent->name_len/* , ent->name*/);
-
-            /* sanity check the record length */
-            if (LE16(ent->rec_len) == 0)
-                break;
-
-            pos += ROUNDUP(LE16(ent->rec_len), 4);
-        }
-
-        file_blocknum++;
-
-        /* sanity check the directory. 4MB should be enough */
-        if (file_blocknum > 1024) {
-            free(buf);
-            return -1;
-        }
-    }
-#endif
     return 0;
 }
 status_t ext2_readdir(dircookie *cookie, struct dirent *ent_out) {

diff --git a/lib/fs/ext2/ext2_fs.h b/lib/fs/ext2/ext2_fs.h
@@ -99,6 +99,7 @@ struct ext2_group_desc {
 
 /*
  * Structure of an inode on the disk
+ * endian_swap_inode and ext2_load_inode deal with byte-order
  */
 struct ext2_inode {
     uint16_t    i_mode;     /* File mode */

diff --git a/lib/fs/ext2/ext4_fs.h b/lib/fs/ext2/ext4_fs.h
@@ -5,6 +5,8 @@
 #define RO_COMPAT_EXTRA_ISIZE   0x040
 #define RO_COMPAT_METADATA_CSUM 0x400
 
+// all fields in little-endian, LE16 and LE32 must be used
+// TODO? add a variant of endian_swap_inode
 typedef struct {
   uint16_t eh_magic;
   uint16_t eh_entries;
@@ -13,6 +15,8 @@ typedef struct {
   uint32_t eh_generation;
 } ext4_extent_header;
 
+// all fields in little-endian, LE16 and LE32 must be used
+// TODO? add a variant of endian_swap_inode
 typedef struct {
   uint32_t ee_block;
   uint16_t ee_len;

diff --git a/lib/fs/ext2/io.c b/lib/fs/ext2/io.c
@@ -131,32 +131,32 @@ static blocknum_t file_block_to_fs_block(ext2_t *ext2, struct ext2_inode *inode,
     if (inode->i_flags & 0x80000) { // inode is stored using extents
         ext4_extent_header *eh = (ext4_extent_header*)&inode->i_block;
         //printf("its an extent based object\n");
-        //printf("eh_magic:      0x%x\n", eh->eh_magic);
-        //printf("eh_entries:    %d\n", eh->eh_entries);
-        //printf("eh_max:        %d\n", eh->eh_max);
-        //printf("eh_depth:      %d\n", eh->eh_depth);
-        //printf("eh_generation: %d\n", eh->eh_generation);
-        if (eh->eh_magic != 0xf30a) {
+        //printf("eh_magic:      0x%x\n", LE16(eh->eh_magic));
+        //printf("eh_entries:    %d\n", LE16(eh->eh_entries));
+        //printf("eh_max:        %d\n", LE16(eh->eh_max));
+        //printf("eh_depth:      %d\n", LE16(eh->eh_depth));
+        //printf("eh_generation: %d\n", LE32(eh->eh_generation));
+        if (LE16(eh->eh_magic) != 0xf30a) {
           puts("extent header magic invalid");
           return 0;
         }
         block = 0; // TODO
-        if (eh->eh_depth == 0) {
+        if (LE16(eh->eh_depth) == 0) {
           ext4_extent *extents = (ext4_extent*)( ((uint32_t)&inode->i_block) + 12);
-          for (int i=0; i<eh->eh_entries; i++) {
+          for (int i=0; i < LE16(eh->eh_entries); i++) {
 #if 0
             printf("extent %d\n", i);
-            printf("  ee_block:    %d\n", extents[i].ee_block);
-            printf("  ee_len:      %d\n", extents[i].ee_len);
-            printf("  ee_start_hi: %d\n", extents[i].ee_start_hi);
-            printf("  ee_start_lo: %d\n", extents[i].ee_start_lo);
+            printf("  ee_block:    %d\n", LE32(extents[i].ee_block));
+            printf("  ee_len:      %d\n", LE16(extents[i].ee_len));
+            printf("  ee_start_hi: %d\n", LE16(extents[i].ee_start_hi));
+            printf("  ee_start_lo: %d\n", LE32(extents[i].ee_start_lo));
 #endif
-            if ((fileblock >= extents[i].ee_block) && (fileblock < (extents[i].ee_block + extents[i].ee_len))) {
-              if (extents[i].ee_start_hi != 0) {
+            if ((fileblock >= LE32(extents[i].ee_block)) && (fileblock < (LE32(extents[i].ee_block) + LE16(extents[i].ee_len)))) {
+              if (LE16(extents[i].ee_start_hi) != 0) {
                 puts("unsupported >32bit blocknr");
                 return 0;
               }
-              block = extents[i].ee_start_lo + (fileblock - extents[i].ee_block);
+              block = LE32(extents[i].ee_start_lo) + (fileblock - LE32(extents[i].ee_block));
             }
           }
         }