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| author | Theodore Ts'o <tytso@mit.edu> | 2006-08-30 01:57:00 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2006-08-30 01:57:00 -0400 |
| commit | 69022e029f3273b3b860bf701219cd3fe615f76b (patch) | |
| tree | 81ecd1b770fe3a4d8e0c325ce78bc6f0c17c927b /ext2ed/init.c | |
| parent | a3e025c7493b58ec88b775f26a41e4205a6a2c9f (diff) | |
| download | e2fsprogs-69022e029f3273b3b860bf701219cd3fe615f76b.tar.gz | |
Fix potential 2**32-1 overflow problems by ext2fs_div_ceil()
Add a new function, ext2fs_div_ceil(), which correctly calculates a division
of two unsigned integer where the result is always rounded up the next
largest integer. This is used everywhere where we might have
previously caused an overflow when the number of blocks
or inodes is too close to 2**32-1.
Based on patches from Eric Sandeen, but generalized to use this new function
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Eric Sandeen <esandeen@redhat.com>
Diffstat (limited to 'ext2ed/init.c')
| -rw-r--r-- | ext2ed/init.c | 11 |
1 files changed, 9 insertions, 2 deletions
diff --git a/ext2ed/init.c b/ext2ed/init.c index f89d8934..7ab2e28c 100644 --- a/ext2ed/init.c +++ b/ext2ed/init.c @@ -370,6 +370,13 @@ void add_user_command (struct struct_commands *ptr,char *name,char *description, ptr->callback [num]=callback; } +static unsigned int div_ceil(unsigned int a, unsigned int b) +{ + if (!a) + return 0; + return ((a - 1) / b) + 1; +} + int set_file_system_info (void) { @@ -415,8 +422,8 @@ int set_file_system_info (void) file_system_info.first_group_desc_offset=2*EXT2_MIN_BLOCK_SIZE; else file_system_info.first_group_desc_offset=file_system_info.block_size; - file_system_info.groups_count=( sb->s_blocks_count-sb->s_first_data_block+sb->s_blocks_per_group-1) / - sb->s_blocks_per_group; + file_system_info.groups_count = div_ceil(sb->s_blocks_count, + sb->s_blocks_per_group); file_system_info.inodes_per_block=file_system_info.block_size/sizeof (struct ext2_inode); file_system_info.blocks_per_group=sb->s_inodes_per_group/file_system_info.inodes_per_block; |