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debugfs: optionally create undo file 

Provide the user with an option to create an undo file so that they
can roll back a failed debugfs expedition.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
debian
Darrick J. Wong 2015-05-05 10:41:52 -04:00 committed by Theodore Ts'o
parent 2d291b3c6b
commit 491cc33ac6
2 changed files with 113 additions and 8 deletions
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16
debugfs/debugfs.8.in
View File

@ -31,6 +31,10 @@ request
data_source_device
]
[
.B \-z
.I undo_file
]
[
device
]
.SH DESCRIPTION
@ -130,6 +134,16 @@ and then exit.
print the version number of
.B debugfs
and exit.
.TP
.BI \-z " undo_file"
Before overwriting a file system block, write the old contents of the block to
an undo file. This undo file can be used with e2undo(8) to restore the old
contents of the file system should something go wrong. If the empty string is
passed as the undo_file argument, the undo file will be written to a file named
resize2fs-\fIdevice\fR.e2undo in the directory specified via the
\fIE2FSPROGS_UNDO_DIR\fR environment variable.
WARNING: The undo file cannot be used to recover from a power or system crash.
.SH SPECIFYING FILES
Many
.B debugfs
@ -535,7 +549,7 @@ to those inodes. The
flag will enable checking the file type information in the directory
entry to make sure it matches the inode's type.
.TP
.BI open " [-weficD] [-b blocksize] [-s superblock] device"
.BI open " [-weficD] [-b blocksize] [-s superblock] [-z undo_file] device"
Open a filesystem for editing. The
.I -f
flag forces the filesystem to be opened even if there are some unknown

105
debugfs/debugfs.c
View File

@ -15,6 +15,7 @@
#include <ctype.h>
#include <string.h>
#include <time.h>
#include <libgen.h>
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#else
@ -48,12 +49,88 @@ ext2_filsys current_fs;
quota_ctx_t current_qctx;
ext2_ino_t root, cwd;
static int debugfs_setup_tdb(const char *device_name, char *undo_file,
io_manager *io_ptr)
{
errcode_t retval = ENOMEM;
char *tdb_dir = NULL, *tdb_file = NULL;
char *dev_name, *tmp_name;
int free_tdb_dir = 0;
/* (re)open a specific undo file */
if (undo_file && undo_file[0] != 0) {
set_undo_io_backing_manager(*io_ptr);
*io_ptr = undo_io_manager;
retval = set_undo_io_backup_file(undo_file);
if (retval)
goto err;
printf("Overwriting existing filesystem; this can be undone "
"using the command:\n"
" e2undo %s %s\n\n",
undo_file, device_name);
return 0;
}
/*
* Configuration via a conf file would be
* nice
*/
tdb_dir = getenv("E2FSPROGS_UNDO_DIR");
if (tdb_dir == NULL || !strcmp(tdb_dir, "none") || (tdb_dir[0] == 0) ||
access(tdb_dir, W_OK)) {
if (free_tdb_dir)
free(tdb_dir);
return 0;
}
tmp_name = strdup(device_name);
if (!tmp_name)
goto errout;
dev_name = basename(tmp_name);
tdb_file = malloc(strlen(tdb_dir) + 8 + strlen(dev_name) + 7 + 1);
if (!tdb_file) {
free(tmp_name);
goto errout;
}
sprintf(tdb_file, "%s/debugfs-%s.e2undo", tdb_dir, dev_name);
free(tmp_name);
if ((unlink(tdb_file) < 0) && (errno != ENOENT)) {
retval = errno;
goto errout;
}
set_undo_io_backing_manager(*io_ptr);
*io_ptr = undo_io_manager;
retval = set_undo_io_backup_file(tdb_file);
if (retval)
goto errout;
printf("Overwriting existing filesystem; this can be undone "
"using the command:\n"
" e2undo %s %s\n\n", tdb_file, device_name);
if (free_tdb_dir)
free(tdb_dir);
free(tdb_file);
return 0;
errout:
if (free_tdb_dir)
free(tdb_dir);
free(tdb_file);
err:
com_err("debugfs", retval, "while trying to setup undo file\n");
return retval;
}
static void open_filesystem(char *device, int open_flags, blk64_t superblock,
blk64_t blocksize, int catastrophic,
char *data_filename)
char *data_filename, char *undo_file)
{
int retval;
io_channel data_io = 0;
io_manager io_ptr = unix_io_manager;
if (superblock != 0 && blocksize == 0) {
com_err(device, 0, "if you specify the superblock, you must also specify the block size");
@ -84,8 +161,14 @@ static void open_filesystem(char *device, int open_flags, blk64_t superblock,
if (catastrophic)
open_flags |= EXT2_FLAG_SKIP_MMP;
if (undo_file) {
retval = debugfs_setup_tdb(device, undo_file, &io_ptr);
if (retval)
exit(1);
}
retval = ext2fs_open(device, open_flags, superblock, blocksize,
unix_io_manager, &current_fs);
io_ptr, &current_fs);
if (retval) {
com_err(device, retval, "while opening filesystem");
if (retval == EXT2_ET_BAD_MAGIC)
@ -136,9 +219,10 @@ void do_open_filesys(int argc, char **argv)
blk64_t blocksize = 0;
int open_flags = EXT2_FLAG_SOFTSUPP_FEATURES | EXT2_FLAG_64BITS;
char *data_filename = 0;
char *undo_file = NULL;
reset_getopt();
while ((c = getopt (argc, argv, "iwfecb:s:d:D")) != EOF) {
while ((c = getopt(argc, argv, "iwfecb:s:d:Dz:")) != EOF) {
switch (c) {
case 'i':
open_flags |= EXT2_FLAG_IMAGE_FILE;
@ -177,6 +261,9 @@ void do_open_filesys(int argc, char **argv)
if (err)
return;
break;
case 'z':
undo_file = optarg;
break;
default:
goto print_usage;
}
@ -188,7 +275,7 @@ void do_open_filesys(int argc, char **argv)
return;
open_filesystem(argv[optind], open_flags,
superblock, blocksize, catastrophic,
data_filename);
data_filename, undo_file);
return;
print_usage:
@ -2219,7 +2306,7 @@ int main(int argc, char **argv)
"Usage: %s [-b blocksize] [-s superblock] [-f cmd_file] "
"[-R request] [-V] ["
#ifndef READ_ONLY
"[-w] "
"[-w] [-z undo_file] "
#endif
"[-c] device]";
int c;
@ -2234,7 +2321,8 @@ int main(int argc, char **argv)
#ifdef READ_ONLY
const char *opt_string = "nicR:f:b:s:Vd:D";
#else
const char *opt_string = "niwcR:f:b:s:Vd:D";
const char *opt_string = "niwcR:f:b:s:Vd:Dz:";
char *undo_file = NULL;
#endif
if (debug_prog_name == 0)
@ -2291,6 +2379,9 @@ int main(int argc, char **argv)
fprintf(stderr, "\tUsing %s\n",
error_message(EXT2_ET_BASE));
exit(0);
case 'z':
undo_file = optarg;
break;
default:
com_err(argv[0], 0, usage, debug_prog_name);
return 1;
@ -2299,7 +2390,7 @@ int main(int argc, char **argv)
if (optind < argc)
open_filesystem(argv[optind], open_flags,
superblock, blocksize, catastrophic,
data_filename);
data_filename, undo_file);
sci_idx = ss_create_invocation(debug_prog_name, "0.0", (char *) NULL,
&debug_cmds, &retval);