Re: [Libguestfs] [libguestfs-common PATCH 2/2] options/keys: introduce unescape_device_mapper_lvm()

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&gt; --- 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 (&regex, 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 (&regex, 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; _______________________________________________ Libguestfs mailing list Libguestfs(a)redhat.com https://listman.redhat.com/mailman/listinfo/libguestfs