fuse2fs: support "fuse2fs -o offset=<bytes>"

This works the same way that mount -o offset=<bytes> works, and can be
used to mount particular partitions from a whole disk image.

Signed-off-by: Matt Stark <msta@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/misc/fuse2fs.c b/misc/fuse2fs.c
index 6d4bcf4fdfd4edb6cdd4eb256f949dc4eda3a7d4..0dc77eadc53c3b22aea3a0a5ed1923d67ea96633 100644 (file)
--- a/misc/fuse2fs.c
+++ b/misc/fuse2fs.c
@@ -325,6 +325,7 @@ struct fuse2fs {
        int fakeroot;
        int alloc_all_blocks;
        int norecovery;
+       unsigned long offset;
        FILE *err_fp;
        unsigned int next_generation;
 };
@@ -3660,6 +3661,7 @@ static struct fuse_opt fuse2fs_opts[] = {
        FUSE2FS_OPT("fuse2fs_debug",    debug,                  1),
        FUSE2FS_OPT("no_default_opts",  no_default_opts,        1),
        FUSE2FS_OPT("norecovery",       norecovery,             1),
+       FUSE2FS_OPT("offset=%lu",       offset,         0),
 
        FUSE_OPT_KEY("-V",             FUSE2FS_VERSION),
        FUSE_OPT_KEY("--version",      FUSE2FS_VERSION),
@@ -3698,6 +3700,7 @@ static int fuse2fs_opt_proc(void *data, const char *arg,
        "    -o minixdf             minix-style df\n"
        "    -o fakeroot            pretend to be root for permission checks\n"
        "    -o no_default_opts     do not include default fuse options\n"
+       "    -o offset=<bytes>      similar to mount -o offset=<bytes>, mount the partition starting at <bytes>\n"
        "    -o norecovery          don't replay the journal (implies ro)\n"
        "    -o fuse2fs_debug       enable fuse2fs debugging\n"
        "\n",
@@ -3777,7 +3780,9 @@ int main(int argc, char *argv[])
        ret = 2;
        if (!fctx.ro)
                flags |= EXT2_FLAG_RW;
-       err = ext2fs_open2(fctx.device, NULL, flags, 0, 0, unix_io_manager,
+       char options[50];
+       sprintf(options, "offset=%lu", fctx.offset);
+       err = ext2fs_open2(fctx.device, options, flags, 0, 0, unix_io_manager,
                           &global_fs);
        if (err) {
                printf(_("%s: %s.\n"), fctx.device, error_message(err));