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@ubuntu.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/misc/e2image.8.in b/misc/e2image.8.in
index ba97ef8..f04dda2 100644 (file)
--- a/misc/e2image.8.in
+++ b/misc/e2image.8.in
@@ -237,6 +237,9 @@ 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@mit.edu).

diff --git a/misc/e2image.c b/misc/e2image.c
index 2f80eff..bf5033a 100644 (file)
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -56,6 +56,7 @@ static char all_data;
 static 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)
 {
@@ -492,6 +493,9 @@ 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) {
@@ -503,7 +507,19 @@ 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);
@@ -532,9 +548,31 @@ 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);
@@ -542,7 +580,7 @@ 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);
@@ -1312,7 +1350,10 @@ 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();
 
        if (all_data && !img_type) {
@@ -1325,8 +1366,20 @@ int main (int argc, char ** argv)
                        "Offsets are only allowed with raw images.");
                exit(1);
        }
+       if (move_mode && img_type != E2IMAGE_RAW) {
+               com_err(program_name, 0,
+                       "Move mode is only allowed with raw images.");
+               exit(1);
+       }
+       if (move_mode && !all_data) {
+               com_err(program_name, 0,
+                       "Move mode requires all data mode.");
+               exit(1);
+       }
        device_name = argv[optind];
-       image_fn = argv[optind+1];
+       if (move_mode)
+               image_fn = device_name;
+       else image_fn = argv[optind+1];
 
        retval = ext2fs_check_if_mounted(device_name, &mount_flags);
        if (retval) {
@@ -1373,10 +1426,14 @@ skip_device:
        if (strcmp(image_fn, "-") == 0)
                fd = 1;
        else {
-               fd = ext2fs_open_file(image_fn, O_CREAT|O_TRUNC|O_WRONLY, 0600);
+               int o_flags = O_CREAT|O_WRONLY;
+
+               if (img_type != E2IMAGE_RAW)
+                       o_flags |= O_TRUNC;
+               fd = ext2fs_open_file(image_fn, o_flags, 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);
                }
        }

diff --git a/tests/i_e2image/script b/tests/i_e2image/script
index 0315ae2..adf59a4 100644 (file)
--- a/tests/i_e2image/script
+++ b/tests/i_e2image/script
@@ -20,6 +20,7 @@ for i in $ORIG_IMAGES; do
        bunzip2 < $SRCDIR/$ORIG_IMG.bz2 > $i
        md5sum $i >> $MD5_TMP
 
+       rm -f $RAW_IMG
        echo "e2image -r $ORIG_IMG $RAW_IMG"
        $E2IMAGE      -r $i $RAW_IMG
        md5sum $RAW_IMG >> $MD5_TMP
@@ -28,6 +29,7 @@ for i in $ORIG_IMAGES; do
        $E2IMAGE      -Q $i $QCOW2_IMG
        md5sum $QCOW2_IMG >> $MD5_TMP
 
+       rm -f $QCOW2_TO_RAW
        echo "e2image -r $QCOW2_IMG $QCOW2_TO_RAW"
        $E2IMAGE      -r $i $QCOW2_TO_RAW
        md5sum $QCOW2_TO_RAW >> $MD5_TMP