lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Message-Id: <1359127752-7125-2-git-send-email-psusi@ubuntu.com> Date: Fri, 25 Jan 2013 10:29:11 -0500 From: Phillip Susi <psusi@...ntu.com> To: tytso@....edu Cc: linux-ext4@...r.kernel.org Subject: [PATCH 2/3] e2image: perform in-place move If given at least one offset and only one file, assume source and dest are the same, and do an in place move. Signed-off-by: Phillip Susi <psusi@...ntu.com> --- misc/e2image.8.in | 3 +++ misc/e2image.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++------- 2 files changed, 53 insertions(+), 7 deletions(-) diff --git a/misc/e2image.8.in b/misc/e2image.8.in index 763f9c7..8ed5d82 100644 --- a/misc/e2image.8.in +++ b/misc/e2image.8.in @@ -227,6 +227,9 @@ MiB for a partition table with: \ \fBe2image -arO 1048576 /dev/sda1 img\fR .br .PP +If you specify at least one offset, and only one file, an in-place +move will be performed, allowing you to safely move the filesystem +from one offset to another. .SH AUTHOR .B e2image was written by Theodore Ts'o (tytso@....edu). diff --git a/misc/e2image.c b/misc/e2image.c index 07e18a1..2830709 100644 --- a/misc/e2image.c +++ b/misc/e2image.c @@ -56,6 +56,7 @@ char all_data; char output_is_blk; /* writing to blk device: don't skip zeroed blocks */ blk64_t source_offset, dest_offset; +char move_mode; static void lseek_error_and_exit(int errnum) { @@ -488,6 +489,9 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd) blk64_t blk; char *buf, *zero_buf; int sparse = 0; + blk64_t start = 0; + blk64_t distance = 0; + blk64_t end = ext2fs_blocks_count(fs->super); retval = ext2fs_get_mem(fs->blocksize, &buf); if (retval) { @@ -499,7 +503,19 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd) com_err(program_name, retval, "while allocating buffer"); exit(1); } - for (blk = 0; blk < ext2fs_blocks_count(fs->super); blk++) { + /* when doing an in place move to the right, you can't start + at the beginning or you will overwrite data, so instead + divide the fs up into distance size chunks and write them + in reverse. */ + if (move_mode && dest_offset > source_offset) { + distance = (dest_offset - source_offset) / fs->blocksize; + if (distance < ext2fs_blocks_count(fs->super)) + start = ext2fs_blocks_count(fs->super) - distance; + } +more_blocks: + if (distance) + ext2fs_llseek (fd, (start * fs->blocksize) + dest_offset, SEEK_SET); + for (blk = start; blk < end; blk++) { if ((blk >= fs->super->s_first_data_block) && ext2fs_test_block_bitmap2(meta_block_map, blk)) { retval = io_channel_read_blk64(fs->io, blk, 1, buf); @@ -528,9 +544,31 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd) } } } + if (distance && start) { + if (start < distance) { + end = start; + start = 0; + } else { + end -= distance; + start -= distance; + if (end < distance) { + /* past overlap, do rest in one go */ + end = start; + start = 0; + } + } + sparse = 0; + goto more_blocks; + } #ifdef HAVE_FTRUNCATE64 if (sparse) { - ext2_loff_t offset = ext2fs_llseek(fd, sparse, SEEK_CUR); + ext2_loff_t offset; + if (distance) + offset = ext2fs_llseek( + fd, + fs->blocksize * ext2fs_blocks_count(fs->super) + dest_offset, + SEEK_SET); + else offset = ext2fs_llseek(fd, sparse, SEEK_CUR); if (offset < 0) lseek_error_and_exit(errno); @@ -538,7 +576,7 @@ static void output_meta_data_blocks(ext2_filsys fs, int fd) write_block(fd, zero_buf, -1, 1, -1); } #else - if (sparse) + if (sparse && !distance) write_block(fd, zero_buf, sparse-1, 1, -1); #endif ext2fs_free_mem(&zero_buf); @@ -1301,10 +1339,15 @@ int main (int argc, char ** argv) default: usage(); } - if (optind != argc - 2 ) + if (optind == argc - 1 && + (source_offset || dest_offset)) + move_mode = 1; + else if (optind != argc - 2 ) usage(); device_name = argv[optind]; - image_fn = argv[optind+1]; + if (move_mode) + image_fn = device_name; + else image_fn = argv[optind+1]; if (flags & E2IMAGE_INSTALL_FLAG) { install_image(device_name, image_fn, img_type); @@ -1334,10 +1377,10 @@ skip_device: if (strcmp(image_fn, "-") == 0) fd = 1; else { - fd = ext2fs_open_file(image_fn, O_CREAT|O_TRUNC|O_WRONLY, 0600); + fd = ext2fs_open_file(image_fn, O_CREAT|O_WRONLY, 0600); if (fd < 0) { com_err(program_name, errno, - _("while trying to open %s"), argv[optind+1]); + _("while trying to open %s"), image_fn); exit(1); } } -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Powered by blists - more mailing lists