12:49 p.m.
Introduce unescape_device_mapper_lvm() for turning
/dev/mapper/VG-LV
key IDs into
/dev/VG/LV
ones, unescaping doubled hyphens to single hyphens in both VG and LV in
the process. Libguestfs uses the /dev/VG/LV format internally, for
identifying devices, but the user might want to specify the
/dev/mapper/VG-LV ID format with the "--key ID:..." options.
Call unescape_device_mapper_lvm() from key_store_import_key(). That is,
translate the ID as soon as the "--key" option is processed -- let the
keystore only know about the usual /dev/VG/LV format, for later matching.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2168506
Signed-off-by: Laszlo Ersek <lersek(a)redhat.com>
---
Notes:
regcomp() must definitely allocate memory dynamically, and we
(intentionally) never free that -- we never call regfree(). I assume
valgrind will catch this as a leak, so we might have to extend
"valgrind-suppressions" in each dependent superproject. However, I'm
unable to run "make check-valgrind" successfully in e.g. virt-v2v even
before these patches; see also
<https://listman.redhat.com/archives/libguestfs/2023-May/031496.html>;.
options/keys.c | 86 ++++++++++++++++++++
1 file changed, 86 insertions(+)
diff --git a/options/keys.c b/options/keys.c
index bc7459749276..f0164a6ed987 100644
--- a/options/keys.c
+++ b/options/keys.c
@@ -27,6 +27,7 @@
#include <errno.h>
#include <error.h>
#include <assert.h>
+#include <regex.h>
#include "guestfs.h"
@@ -260,6 +261,90 @@ key_store_add_from_selector (struct key_store *ks, const char
*selector)
return key_store_import_key (ks, &key);
}
+/* A /dev/mapper/ escaped character is:
+ * - either any character except a slash or a hyphen,
+ * - or a double hyphen.
+ *
+ * Note that parens are deliberately not included here -- they will be included
+ * in the full pattern, for making them more easily countable.
+ *
+ * Also note that the bracket expression below does not contain a range
+ * expression, therefore it should not be locale-sensitive.
+ */
+#define ESC_CH "[^-/]|--"
+
+/* Turn /dev/mapper/VG-LV into /dev/VG/LV. */
+static void
+unescape_device_mapper_lvm (char *id)
+{
+ static bool compiled;
+ int rc;
+ static regex_t regex;
+ regmatch_t match[5];
+ char *output;
+ const char *vg_start, *vg_end, *lv_start, *lv_end;
+ const char *input;
+
+ if (!compiled) {
+ /* Recognize /dev/mapper/VG-LV pathnames, where VG and LV don't contain
+ * slashes, plus any original hyphens in them are doubled for escaping.
+ */
+ static const char pattern[] = "^/dev/("
+ "mapper/"
+ "((" ESC_CH ")+)"
+ "-"
+ "((" ESC_CH ")+)"
+ ")$";
+
+ rc = regcomp (®ex, pattern, REG_EXTENDED);
+ if (rc != 0) {
+ char errbuf[256];
+
+ /* When regcomp() fails, the contents of "regex" are undefined, so we
+ * cannot pass "regex" to regerror().
+ */
+ (void)regerror (rc, NULL, errbuf, sizeof errbuf);
+ error (EXIT_FAILURE, 0,
+ _("%s: Failed to compile pattern (%s). Please report a bug for "
+ "libguestfs -- refer to guestfs(3) section BUGS."),
+ __func__, errbuf);
+ }
+ compiled = true;
+ }
+
+ rc = regexec (®ex, id, 5, match, 0);
+
+ /* If there's no match, just leave "id" alone. */
+ if (rc != 0)
+ return;
+
+ /* Start outputting after "/dev/". */
+ output = id + match[1].rm_so;
+ vg_start = id + match[2].rm_so;
+ vg_end = id + match[2].rm_eo;
+ lv_start = id + match[4].rm_so;
+ lv_end = id + match[4].rm_eo;
+
+ /* Each of the following two loops produces at most as many bytes as it
+ * consumes, so we unescape "id" in-place.
+ */
+ input = vg_start;
+ while (input < vg_end)
+ if ((*output++ = *input++) == '-')
+ input++;
+
+ *output++ = '/';
+
+ input = lv_start;
+ while (input < lv_end)
+ if ((*output++ = *input++) == '-')
+ input++;
+
+ *output++ = '\0';
+}
+
+#undef ESC_CH
+
struct key_store *
key_store_import_key (struct key_store *ks, struct key_store_key *key)
{
@@ -278,6 +363,7 @@ key_store_import_key (struct key_store *ks, struct key_store_key
*key)
error (EXIT_FAILURE, errno, "realloc");
ks->keys = new_keys;
+ unescape_device_mapper_lvm (key->id);
ks->keys[ks->nr_keys] = *key;
++ks->nr_keys;