Richard W.M. Jones
2010-Jul-28 22:24 UTC
[Libguestfs] [PATCH] New APIs: findfs-label and findfs-uuid
These APIs are needed for ease of inspection of /etc/fstab from C. (Actually the way we are doing it currently in Perl is incredibly convoluted .. we should have just used findfs). Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones New in Fedora 11: Fedora Windows cross-compiler. Compile Windows programs, test, and build Windows installers. Over 70 libraries supprt'd http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw -------------- next part -------------->From c10cdec2418dbcf2fed9605365402d4cfc75eff3 Mon Sep 17 00:00:00 2001From: Richard Jones <rjones at redhat.com> Date: Wed, 28 Jul 2010 23:11:38 +0100 Subject: [PATCH] New APIs: findfs-label and findfs-uuid These two calls wrap up the /sbin/findfs command, allowing you to find a filesystem by only knowing its label or UUID. This is especially useful when resolving LABEL=... or UUID=... entries in /etc/fstab. Sample guestfish session:><fs> vfs-uuid /dev/vda1277dd61c-bf34-4253-a8dc-df500a05e7df><fs> findfs-uuid 277dd61c-bf34-4253-a8dc-df500a05e7df/dev/vda1><fs> vfs-label /dev/vda1/boot><fs> findfs-label /boot/dev/vda1><fs> vfs-uuid /dev/VolGroup00/LogVol0040ce7c36-82ce-4a12-a99d-48f5e054162c><fs> findfs-uuid 40ce7c36-82ce-4a12-a99d-48f5e054162c/dev/mapper/VolGroup00-LogVol00><fs> findfs-uuid 12345678libguestfs: error: findfs_uuid: findfs: unable to resolve 'UUID=12345678' --- daemon/Makefile.am | 1 + daemon/findfs.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++ po/POTFILES.in | 1 + src/MAX_PROC_NR | 2 +- src/generator.ml | 28 ++++++++++++++++++- 5 files changed, 101 insertions(+), 3 deletions(-) create mode 100644 daemon/findfs.c diff --git a/daemon/Makefile.am b/daemon/Makefile.am index 27fca2a..0c8be08 100644 --- a/daemon/Makefile.am +++ b/daemon/Makefile.am @@ -84,6 +84,7 @@ guestfsd_SOURCES = \ ext2.c \ fallocate.c \ file.c \ + findfs.c \ fill.c \ find.c \ fsck.c \ diff --git a/daemon/findfs.c b/daemon/findfs.c new file mode 100644 index 0000000..cdce4a0 --- /dev/null +++ b/daemon/findfs.c @@ -0,0 +1,72 @@ +/* libguestfs - the guestfsd daemon + * Copyright (C) 2009 Red Hat Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#include <config.h> + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "daemon.h" +#include "actions.h" + +static char * +findfs (const char *tag, const char *label_or_uuid) +{ + /* Kill the cache file, forcing blkid to reread values from the + * original filesystems. In blkid there is a '-p' option which is + * supposed to do this, but (a) it doesn't work and (b) that option + * is not supported in RHEL 5. + */ + unlink ("/etc/blkid/blkid.tab"); + + size_t len = strlen (tag) + strlen (label_or_uuid) + 2; + char arg[len]; + snprintf (arg, len, "%s=%s", tag, label_or_uuid); + + char *out, *err; + int r = command (&out, &err, "findfs", arg, NULL); + if (r == -1) { + reply_with_error ("%s", err); + free (out); + free (err); + return NULL; + } + + free (err); + + /* Trim trailing \n if present. */ + len = strlen (out); + if (len > 0 && out[len-1] == '\n') + out[len-1] = '\0'; + + return out; /* caller frees */ +} + +char * +do_findfs_uuid (const char *uuid) +{ + return findfs ("UUID", uuid); +} + +char * +do_findfs_label (const char *label) +{ + return findfs ("LABEL", label); +} diff --git a/po/POTFILES.in b/po/POTFILES.in index bf066ea..8ce5c97 100644 --- a/po/POTFILES.in +++ b/po/POTFILES.in @@ -21,6 +21,7 @@ daemon/fallocate.c daemon/file.c daemon/fill.c daemon/find.c +daemon/findfs.c daemon/fsck.c daemon/glob.c daemon/grep.c diff --git a/src/MAX_PROC_NR b/src/MAX_PROC_NR index 175b6c5..2b930fc 100644 --- a/src/MAX_PROC_NR +++ b/src/MAX_PROC_NR @@ -1 +1 @@ -263 +265 diff --git a/src/generator.ml b/src/generator.ml index 04a675a..66453e0 100755 --- a/src/generator.ml +++ b/src/generator.ml @@ -4952,7 +4952,9 @@ a file in the host and attach it as a device."); This returns the filesystem label of the filesystem on C<device>. -If the filesystem is unlabeled, this returns the empty string."); +If the filesystem is unlabeled, this returns the empty string. + +To find a filesystem from the label, use C<guestfs_findfs_label>."); ("vfs_uuid", (RString "uuid", [Device "device"]), 254, [], (let uuid = uuidgen () in @@ -4964,7 +4966,9 @@ If the filesystem is unlabeled, this returns the empty string."); This returns the filesystem UUID of the filesystem on C<device>. -If the filesystem does not have a UUID, this returns the empty string."); +If the filesystem does not have a UUID, this returns the empty string. + +To find a filesystem from the UUID, use C<guestfs_findfs_uuid>."); ("lvm_set_filter", (RErr, [DeviceList "devices"]), 255, [Optional "lvm2"], (* Can't be tested with the current framework because @@ -5081,6 +5085,26 @@ This command deletes the key in key slot C<keyslot> from the encrypted LUKS device C<device>. C<key> must be one of the I<other> keys."); + ("findfs_uuid", (RString "device", [String "uuid"]), 264, [], + [], + "find a filesystem by UUID", + "\ +This command searches the filesystems and returns the one +which has the given UUID. An error is returned if no such +filesystem can be found. + +To find the UUID of a filesystem, use C<guestfs_vfs_uuid>."); + + ("findfs_label", (RString "device", [String "label"]), 265, [], + [], + "find a filesystem by label", + "\ +This command searches the filesystems and returns the one +which has the given label. An error is returned if no such +filesystem can be found. + +To find the label of a filesystem, use C<guestfs_vfs_label>."); + ] let all_functions = non_daemon_functions @ daemon_functions -- 1.7.1
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