[Libguestfs] [PATCH 3/3] daemon: lvm-filter: use augeas for setting the filter
Pino Toscano
ptoscano at redhat.com
Tue Aug 26 14:29:11 UTC 2014
The way to set the filter for lvm devices was to open lvm.conf, look
for uncommented "filter =" lines and replace the configuration there.
This had the issue that if there is no uncommented filter line, then the
filter cannot be changed at all; considering newer lvm2 releases ship a
sample configuration with no uncommented filter lines, then the old way
became wrong and not sufficient.
Instead, take a copy of the upstream lvm.aug lens, with a simple change
to allow parsing also negative values in configuration, and install it
in the daemon. When asking to change the lvm filter, use augeas making
sure to use this custom lens for the lvm.conf copy used within the
appliance.
---
appliance/Makefile.am | 6 +-
appliance/guestfs_lvm_conf.aug | 74 +++++++++++++++++
daemon/lvm-filter.c | 183 +++++++++++++++++++++--------------------
3 files changed, 172 insertions(+), 91 deletions(-)
create mode 100644 appliance/guestfs_lvm_conf.aug
diff --git a/appliance/Makefile.am b/appliance/Makefile.am
index 418a6f6..bb0c0e8 100644
--- a/appliance/Makefile.am
+++ b/appliance/Makefile.am
@@ -21,6 +21,7 @@ EXTRA_DIST = \
99-guestfs-serial.rules \
excludefiles.in \
guestfsd.suppressions \
+ guestfs_lvm_conf.aug \
hostfiles.in \
init \
libguestfs-make-fixed-appliance.in \
@@ -74,12 +75,13 @@ packagelist: packagelist.in Makefile
cmp -s $@ $@-t || mv $@-t $@
rm -f $@-t
-supermin.d/daemon.tar.gz: ../daemon/guestfsd guestfsd.suppressions
+supermin.d/daemon.tar.gz: ../daemon/guestfsd guestfsd.suppressions guestfs_lvm_conf.aug
rm -f $@ $@-t
rm -rf tmp-d
- mkdir -p tmp-d$(DAEMON_SUPERMIN_DIR) tmp-d/etc
+ mkdir -p tmp-d$(DAEMON_SUPERMIN_DIR) tmp-d/etc tmp-d/usr/share/guestfs
ln ../daemon/guestfsd tmp-d$(DAEMON_SUPERMIN_DIR)/guestfsd
ln $(srcdir)/guestfsd.suppressions tmp-d/etc/guestfsd.suppressions
+ ln $(srcdir)/guestfs_lvm_conf.aug tmp-d/usr/share/guestfs/guestfs_lvm_conf.aug
( cd tmp-d && tar zcf - * ) > $@-t
rm -r tmp-d
mv $@-t $@
diff --git a/appliance/guestfs_lvm_conf.aug b/appliance/guestfs_lvm_conf.aug
new file mode 100644
index 0000000..ffa5b01
--- /dev/null
+++ b/appliance/guestfs_lvm_conf.aug
@@ -0,0 +1,74 @@
+(*
+Module: LVM
+ Parses LVM metadata.
+
+Author: Gabriel de Perthuis <g2p.code+augeas at gmail.com>
+
+About: License
+ This file is licensed under the LGPL v2+.
+
+About: Configuration files
+ This lens applies to files in /etc/lvm/backup and /etc/lvm/archive.
+
+About: Examples
+ The <Test_LVM> file contains various examples and tests.
+*)
+
+module Guestfs_LVM_conf =
+ autoload xfm
+
+ (* See lvm2/libdm/libdm-config.c for tokenisation;
+ * libdm uses a blacklist but I prefer the safer whitelist approach. *)
+ (* View: identifier
+ * The left hand side of a definition *)
+ let identifier = /[a-zA-Z0-9_-]+/
+
+ (* strings can contain backslash-escaped dquotes, but I don't know
+ * how to get the message across to augeas *)
+ let str = [label "str". Quote.do_dquote (store /([^\"]|\\\\.)*/)]
+ let int = [label "int". store Rx.relinteger]
+ (* View: flat_literal
+ * A literal without structure *)
+ let flat_literal = int|str
+
+ (* allow multiline and mixed int/str, used for raids and stripes *)
+ (* View: list
+ * A list containing flat literals *)
+ let list = [
+ label "list" . counter "list"
+ . del /\[[ \t\n]*/ "["
+ .([seq "list". flat_literal . del /,[ \t\n]*/ ", "]*
+ . [seq "list". flat_literal . del /[ \t\n]*/ ""])?
+ . Util.del_str "]"]
+
+ (* View: val
+ * Any value that appears on the right hand side of an assignment *)
+ let val = flat_literal | list
+
+ (* View: nondef
+ * A line that doesn't contain a statement *)
+ let nondef =
+ Util.empty
+ | Util.comment
+
+ (* Build.block couldn't be reused, because of recursion and
+ * a different philosophy of whitespace handling. *)
+ (* View: def
+ * An assignment, or a block containing definitions *)
+ let rec def = [
+ Util.indent . key identifier . (
+ del /[ \t]*\{\n/ " {\n"
+ .[label "dict".(nondef | def)*]
+ . Util.indent . Util.del_str "}\n"
+ |Sep.space_equal . val . Util.comment_or_eol)]
+
+ (* View: lns
+ * The main lens *)
+ let lns = (nondef | def)*
+
+ let filter =
+ incl "/etc/lvm/archive/*.vg"
+ . incl "/etc/lvm/backup/*"
+ . Util.stdexcl
+
+ let xfm = transform lns filter
diff --git a/daemon/lvm-filter.c b/daemon/lvm-filter.c
index 6976bab..3bab9bf 100644
--- a/daemon/lvm-filter.c
+++ b/daemon/lvm-filter.c
@@ -25,12 +25,30 @@
#include <unistd.h>
#include <sys/stat.h>
+#include <augeas.h>
+
#include "c-ctype.h"
#include "ignore-value.h"
#include "daemon.h"
#include "actions.h"
+#ifdef HAVE_ATTRIBUTE_CLEANUP
+#define CLEANUP_AUG_CLOSE __attribute__((cleanup(cleanup_aug_close)))
+
+static void
+cleanup_aug_close (void *ptr)
+{
+ augeas *aug = * (augeas **) ptr;
+
+ if (aug != NULL)
+ aug_close (aug);
+}
+
+#else
+#define CLEANUP_AUG_CLOSE
+#endif
+
GUESTFSD_EXT_CMD(str_lvm, lvm);
GUESTFSD_EXT_CMD(str_cp, cp);
GUESTFSD_EXT_CMD(str_rm, rm);
@@ -107,87 +125,76 @@ rm_lvm_system_dir (void)
ignore_value (system (cmd));
}
-/* Does the current line match the regexp /^\s*filter\s*=/ */
+/* Rewrite the 'filter = [ ... ]' line in lvm.conf. */
static int
-is_filter_line (const char *line)
+set_filter (char *const *filters)
{
- while (*line && c_isspace (*line))
- line++;
- if (!*line)
- return 0;
-
- if (! STRPREFIX (line, "filter"))
- return 0;
- line += 6;
-
- while (*line && c_isspace (*line))
- line++;
- if (!*line)
- return 0;
-
- if (*line != '=')
- return 0;
+ CLEANUP_AUG_CLOSE augeas *aug = NULL;
+ int r;
+ int count;
- return 1;
-}
+ /* Small optimization: do not load the files at init time,
+ * but do that only after having applied the transformation.
+ */
+ const int flags = AUG_NO_ERR_CLOSE | AUG_NO_LOAD;
+ aug = aug_init (lvm_system_dir, "/usr/share/guestfs/", flags);
+ if (!aug) {
+ reply_with_error ("augeas initialization failed");
+ return -1;
+ }
-/* Rewrite the 'filter = [ ... ]' line in lvm.conf. */
-static int
-set_filter (const char *filter)
-{
- char lvm_conf[64];
- snprintf (lvm_conf, sizeof lvm_conf, "%s/lvm/lvm.conf", lvm_system_dir);
+ if (aug_error (aug) != AUG_NOERROR) {
+ AUGEAS_ERROR ("aug_init");
+ return -1;
+ }
- char lvm_conf_new[64];
- snprintf (lvm_conf_new, sizeof lvm_conf, "%s/lvm/lvm.conf.new",
- lvm_system_dir);
+ r = aug_transform (aug, "guestfs_lvm_conf", "/lvm/lvm.conf",
+ 0 /* = included */);
+ if (r == -1) {
+ AUGEAS_ERROR ("aug_transform");
+ return -1;
+ }
- FILE *ifp = fopen (lvm_conf, "r");
- if (ifp == NULL) {
- reply_with_perror ("open: %s", lvm_conf);
+ if (aug_load (aug) == -1) {
+ AUGEAS_ERROR ("aug_load");
return -1;
}
- FILE *ofp = fopen (lvm_conf_new, "w");
- if (ofp == NULL) {
- reply_with_perror ("open: %s", lvm_conf_new);
- fclose (ifp);
+
+ /* Remove all the old filters ... */
+ r = aug_rm (aug, "/files/lvm/lvm.conf/devices/dict/filter/list/*");
+ if (r == -1) {
+ AUGEAS_ERROR ("aug_rm");
return -1;
}
- CLEANUP_FREE char *line = NULL;
- size_t allocsize = 0;
- while (getline (&line, &allocsize, ifp) != -1) {
- int r;
- if (is_filter_line (line)) {
- r = fprintf (ofp, " filter = [ %s ]\n", filter);
- } else {
- r = fprintf (ofp, "%s", line);
- }
- if (r < 0) {
- /* NB. fprintf doesn't set errno on error. */
- reply_with_error ("%s: write failed", lvm_conf_new);
- fclose (ifp);
- fclose (ofp);
- unlink (lvm_conf_new);
+ /* ... and add the new ones. */
+ for (count = 0; filters[count] != NULL; ++count) {
+ char buf[128];
+
+ snprintf (buf, sizeof buf,
+ "/files/lvm/lvm.conf/devices/dict/filter/list/%d/str",
+ count + 1);
+
+ if (aug_set (aug, buf, filters[count]) == -1) {
+ AUGEAS_ERROR ("aug_set: %d: %s", count, filters[count]);
return -1;
}
}
- if (fclose (ifp) == EOF) {
- reply_with_perror ("close: %s", lvm_conf);
- unlink (lvm_conf_new);
- fclose (ofp);
+ /* Safety check for the written filter nodes. */
+ r = aug_match (aug, "/files/lvm/lvm.conf/devices/dict/filter/list/*/str",
+ NULL);
+ if (r == -1) {
+ AUGEAS_ERROR ("aug_match");
return -1;
}
- if (fclose (ofp) == EOF) {
- reply_with_perror ("close: %s", lvm_conf_new);
- unlink (lvm_conf_new);
+ if (r != count) {
+ reply_with_error ("filters# vs matches mismatch: %d vs %d", count, r);
return -1;
}
- if (rename (lvm_conf_new, lvm_conf) == -1) {
- reply_with_perror ("rename: %s", lvm_conf);
- unlink (lvm_conf_new);
+ if (aug_save (aug) == -1) {
+ AUGEAS_ERROR ("aug_save");
return -1;
}
@@ -240,25 +247,16 @@ rescan (void)
return 0;
}
-/* Construct the new, specific filter string. We can assume that
+/* Construct the new, specific filter strings. We can assume that
* the 'devices' array does not contain any regexp metachars,
* because it's already been checked by the stub code.
*/
-static char *
-make_filter_string (char *const *devices)
+static char **
+make_filter_strings (char *const *devices)
{
size_t i;
- size_t len = 64;
- for (i = 0; devices[i] != NULL; ++i)
- len += 2 * strlen (devices[i]) + 64;
-
- char *filter = malloc (len);
- if (filter == NULL) {
- reply_with_perror ("malloc");
- return NULL;
- }
+ DECLARE_STRINGSBUF (ret);
- char *p = filter;
for (i = 0; devices[i] != NULL; ++i) {
/* Because of the way matching works in LVM (yes, they wrote their
* own regular expression engine!), each match clause should be either:
@@ -269,33 +267,38 @@ make_filter_string (char *const *devices)
* "a|^/dev/sda$|", "a|^/dev/sda[0-9]|",
*/
size_t slen = strlen (devices[i]);
- char str[2*slen+64];
- if (c_isdigit (devices[i][slen-1])) /* single partition */
- snprintf (str, 2*slen+64, "\"a|^%s$|\", ", devices[i]);
- else /* whole block device */
- snprintf (str, 2*slen+64, "\"a|^%s$|\", \"a|^%s[0-9]|\", ",
- devices[i], devices[i]);
+ if (add_sprintf (&ret, "a|^%s$|", devices[i]) == -1)
+ goto error;
- strcpy (p, str);
- p += strlen (str);
+ if (!c_isdigit (devices[i][slen-1])) {
+ /* whole block device */
+ if (add_sprintf (&ret, "a|^%s[0-9]|", devices[i]) == -1)
+ goto error;
+ }
}
- strcpy (p, "\"r|.*|\"");
-
- return filter; /* Caller must free. */
+ if (add_string (&ret, "r|.*|") == -1)
+ goto error;
+
+ end_stringsbuf (&ret);
+ return ret.argv;
+error:
+ if (ret.argv)
+ free_stringslen (ret.argv, ret.size);
+ return NULL;
}
int
do_lvm_set_filter (char *const *devices)
{
- CLEANUP_FREE char *filter = make_filter_string (devices);
- if (filter == NULL)
+ CLEANUP_FREE_STRING_LIST char **filters = make_filter_strings (devices);
+ if (filters == NULL)
return -1;
if (deactivate () == -1)
return -1;
- int r = set_filter (filter);
+ int r = set_filter (filters);
if (r == -1)
return -1;
@@ -308,10 +311,12 @@ do_lvm_set_filter (char *const *devices)
int
do_lvm_clear_filter (void)
{
+ const char *const filters[2] = { "a/.*/", NULL };
+
if (deactivate () == -1)
return -1;
- if (set_filter ("\"a/.*/\"") == -1)
+ if (set_filter ((char *const *) filters) == -1)
return -1;
if (rescan () == -1)
--
1.9.3
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