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Message-Id: <1381247792-22508-2-git-send-email-psusi@ubuntu.com>
Date: Tue, 8 Oct 2013 11:56:29 -0400
From: Phillip Susi <psusi@...ntu.com>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org
Subject: [PATCH 1/4] e2image: add offset switches
Add -o and -O switches to specify the offset where the source
and destination filesystems start. This is useful if you have
an image of a partitioned disk or wish to create one.
Signed-off-by: Phillip Susi <psusi@...ntu.com>
---
misc/e2image.8.in | 36 ++++++++++++++++++++++++++++++++++++
misc/e2image.c | 24 +++++++++++++++++++-----
2 files changed, 55 insertions(+), 5 deletions(-)
diff --git a/misc/e2image.8.in b/misc/e2image.8.in
index 84b9729..86d3dfc 100644
--- a/misc/e2image.8.in
+++ b/misc/e2image.8.in
@@ -10,6 +10,14 @@ e2image \- Save critical ext2/ext3/ext4 filesystem metadata to a file
[
.B \-rsIQa
]
+[
+.B \-o
+.I source_offset
+]
+[
+.B \-O
+.I dest_offset
+]
.I device
.I image-file
.SH DESCRIPTION
@@ -191,6 +199,34 @@ give an image that is suitable to use to clone the entire FS or
for backup purposes. Note that this option only works with the
raw or QCOW2 formats.
.PP
+.SH OFFSETS
+Normally a filesystem starts at the beginning of a partition, and
+.B e2image
+is run on the partition. When working with image files, you don't
+have the option of using the partition device, so you can specify
+the offset where the filesystem starts directly with the
+.B \-o
+option. Similarly the
+.B \-O
+option specifies the offset that should be seeked to in the destination
+before writing the filesystem.
+.PP
+For example, if you have a
+.B dd
+image of a whole hard drive that contains an ext2 fs in a partition
+starting at 1 MiB, you can clone that fs with:
+.PP
+.br
+\ \fBe2image \-aro 1048576 img /dev/sda1\fR
+.br
+.PP
+Or you can clone a fs into an image file, leaving room in the first
+MiB for a partition table with:
+.PP
+.br
+\ \fBe2image -arO 1048576 /dev/sda1 img\fR
+.br
+.PP
.SH AUTHOR
.B e2image
was written by Theodore Ts'o (tytso@....edu).
diff --git a/misc/e2image.c b/misc/e2image.c
index 885a794..cf486c0 100644
--- a/misc/e2image.c
+++ b/misc/e2image.c
@@ -55,6 +55,7 @@ char * device_name = NULL;
char all_data;
char output_is_blk;
/* writing to blk device: don't skip zeroed blocks */
+blk64_t source_offset, dest_offset;
static void lseek_error_and_exit(int errnum)
{
@@ -87,7 +88,7 @@ static int get_bits_from_size(size_t size)
static void usage(void)
{
- fprintf(stderr, _("Usage: %s [-rsIQa] device image_file\n"),
+ fprintf(stderr, _("Usage: %s [-rsIQa] [-o source_offset] [-O dest_offset] device image_file\n"),
program_name);
exit (1);
}
@@ -1269,7 +1270,7 @@ int main (int argc, char ** argv)
if (argc && *argv)
program_name = *argv;
add_error_table(&et_ext2_error_table);
- while ((c = getopt(argc, argv, "rsIQa")) != EOF)
+ while ((c = getopt(argc, argv, "rsIQao:O:")) != EOF)
switch (c) {
case 'I':
flags |= E2IMAGE_INSTALL_FLAG;
@@ -1290,6 +1291,12 @@ int main (int argc, char ** argv)
case 'a':
all_data = 1;
break;
+ case 'o':
+ source_offset = strtoull(optarg, NULL, 0);
+ break;
+ case 'O':
+ dest_offset = strtoull(optarg, NULL, 0);
+ break;
default:
usage();
}
@@ -1317,9 +1324,11 @@ int main (int argc, char ** argv)
goto skip_device;
}
}
-
- retval = ext2fs_open (device_name, open_flag, 0, 0,
- unix_io_manager, &fs);
+ char *options;
+ asprintf (&options, "offset=%llu", source_offset);
+ retval = ext2fs_open2 (device_name, options, open_flag, 0, 0,
+ unix_io_manager, &fs);
+ free (options);
if (retval) {
com_err (program_name, retval, _("while trying to open %s"),
device_name);
@@ -1338,6 +1347,11 @@ skip_device:
exit(1);
}
}
+ if (dest_offset)
+ if (ext2fs_llseek (fd, dest_offset, SEEK_SET) < 0) {
+ perror("ext2fs_llseek");
+ exit(1);
+ }
if ((img_type & E2IMAGE_QCOW2) && (fd == 1)) {
com_err(program_name, 0, "QCOW2 image can not be written to "
--
1.8.1.2
--
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