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authorRob Landley <rob@landley.net>2007-01-31 10:50:56 -0500
committerRob Landley <rob@landley.net>2007-01-31 10:50:56 -0500
commit15406bbe98556a2109f983f1bccc0ac90632d0e0 (patch)
tree663ec23dbbd4cee7f80d50bf241d2736062de724 /toys
parent9568d5afcfea1b5a5019c23e25bba33283970f30 (diff)
downloadtoybox-15406bbe98556a2109f983f1bccc0ac90632d0e0.tar.gz
This creates an almost valid empty ext2 filesystem, except for a few superblock
fields (blank free_blocks and free_inodes), and no root directory. (And technically, no lost+found either.)
Diffstat (limited to 'toys')
-rw-r--r--toys/mke2fs.c44
1 files changed, 25 insertions, 19 deletions
diff --git a/toys/mke2fs.c b/toys/mke2fs.c
index 28aea87a..bf019567 100644
--- a/toys/mke2fs.c
+++ b/toys/mke2fs.c
@@ -28,6 +28,7 @@
// E - extended options (stride=stripe-size blocks)
// O - none,dir_index,filetype,has_journal,journal_dev,sparse_super
+#define INODES_RESERVED 10
// According to http://www.opengroup.org/onlinepubs/9629399/apdxa.htm
// we should generate a uuid structure by reading a clock with 100 nanosecond
@@ -74,7 +75,7 @@ static void init_superblock(struct ext2_superblock *sb)
temp = (TT.blocks * (uint64_t)TT.reserved_percent) /100;
sb->r_blocks_count = SWAP_LE32(temp);
- sb->first_data_block = TT.blocksize == SWAP_LE32(1024 ? 1 : 0);
+ sb->first_data_block = SWAP_LE32(TT.blocksize == 1024 ? 1 : 0);
// Set blocks_per_group and frags_per_group, which is the size of an
// allocation bitmap that fits in one block (I.E. how many bits per block)?
@@ -98,7 +99,7 @@ static void init_superblock(struct ext2_superblock *sb)
// How many blocks of inodes total, rounded up
temp = TT.inodes / (TT.blocksize/sizeof(struct ext2_inode));
- if (TT.inodes & (TT.blocksize-1)) temp++;
+ if (temp * (TT.blocksize/sizeof(struct ext2_inode)) != TT.inodes) temp++;
// How many blocks of inodes per group, again rounded up
TT.inodes = temp / TT.groups;
if (temp & (TT.groups-1)) TT.inodes++;
@@ -116,7 +117,7 @@ static void init_superblock(struct ext2_superblock *sb)
sb->state = sb->errors = SWAP_LE16(1);
sb->rev_level = SWAP_LE32(1);
- sb->first_ino = SWAP_LE32(11); // First 10 reserved for special uses.
+ sb->first_ino = SWAP_LE32(INODES_RESERVED+1);
sb->inode_size = SWAP_LE16(sizeof(struct ext2_inode));
sb->feature_incompat = SWAP_LE32(EXT2_FEATURE_INCOMPAT_FILETYPE);
sb->feature_ro_compat = SWAP_LE32(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER);
@@ -165,9 +166,11 @@ static void bits_set(char *array, int start, int len)
if ((start&7) || len<8) {
array[start/8]|=(1<<(start&7));
start++;
+ len--;
} else {
array[start/8]=255;
start+=8;
+ len-=8;
}
}
}
@@ -214,9 +217,16 @@ int mke2fs_main(void)
for (i=0; i<TT.groups; i++) {
struct ext2_inode *in = (struct ext2_inode *)toybuf;
- uint32_t start;
+ uint32_t start, itable, used, end;
int j, slot;
+ // Where does this group end?
+ end = blockbits;
+ if ((i+1)*blockbits > TT.blocks) end = TT.blocks & (blockbits-1);
+
+ // Blocks used by inode table
+ itable = ((TT.inodes/TT.groups)*sizeof(struct ext2_inode))/TT.blocksize;
+
// If a superblock goes here, write it out.
start = group_superblock_used(i);
if (start) {
@@ -233,7 +243,6 @@ int mke2fs_main(void)
// Loop through groups to write group descriptor table.
for(j=0; j<TT.groups; j++) {
- uint32_t used;
// Figure out what sector this group starts in.
used = group_superblock_used(j);
@@ -249,6 +258,7 @@ int mke2fs_main(void)
// is uint16_t. Add in endianness conversion and this little
// dance is called for.
temp = SWAP_LE32(TT.sb.inodes_per_group);
+ if (!i) temp -= INODES_RESERVED;
bg[slot].free_inodes_count = SWAP_LE16(temp);
// How many blocks will the inode table use?
@@ -256,7 +266,7 @@ int mke2fs_main(void)
temp /= TT.blocksize;
// How many does that leave? (TODO: fill it up)
- temp = blockbits-used-temp;
+ temp = end-used-temp;
bg[slot].free_blocks_count = SWAP_LE32(temp);
// Fill out rest of group structure (TODO: gene2fs allocation)
@@ -273,24 +283,15 @@ int mke2fs_main(void)
// Write block usage bitmap (TODO: fill it)
- // Blocks used by inode table
- temp = (TT.inodes/TT.groups)*sizeof(struct ext2_inode);
- temp += TT.blocksize-1;
- temp /= TT.blocksize;
-
memset(toybuf, 0, TT.blocksize);
- bits_set(toybuf, 0, start+temp);
- if ((i+1)*TT.blocksize*8 > TT.blocks) {
- temp = TT.blocks & (blockbits-1);
- bits_set(toybuf, temp, blockbits-temp);
- }
+ bits_set(toybuf, 0, start+itable);
+ if (end!=blockbits) bits_set(toybuf, end, blockbits-end);
xwrite(TT.fsfd, toybuf, TT.blocksize);
- temp = TT.inodes/TT.groups;
-
// Write inode bitmap (TODO)
+ temp = TT.inodes/TT.groups;
memset(toybuf, 0, TT.blocksize);
- if (!i) bits_set(toybuf,0,10);
+ if (!i) bits_set(toybuf, 0, INODES_RESERVED);
bits_set(toybuf, temp, blockbits-temp);
xwrite(TT.fsfd, toybuf, TT.blocksize);
@@ -303,6 +304,11 @@ int mke2fs_main(void)
}
}
xwrite(TT.fsfd, in, TT.blocksize);
+
+ // Write empty data blocks
+ memset(toybuf, 0, TT.blocksize);
+ for (j = start; j < end; j++)
+ xwrite(TT.fsfd, toybuf, TT.blocksize);
}
return 0;