[PATCH 3/4] mount: implement -O, --test-opts

[Justus Winter]

--test-opts in combination with --all mounts only those filesystems
with options matching the given set of options.

Note that the semantic of the inverting "no" prefix differs from
--types: While --types=nonfs,ufs means neither nfs nor ufs,
--test-opts=nofoo,bar means not foo, but bar.

* utils/mount.c (test_opts): New variable.
(test_opts_len): Likewise.
(parse_opt): Handle -O, --test-opts.
(match_options): New function.
(main): Use match_options as filter.
---
 utils/mount.c |   62 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 60 insertions(+), 2 deletions(-)

diff --git a/utils/mount.c b/utils/mount.c
index f8928f1..07077a5 100644
--- a/utils/mount.c
+++ b/utils/mount.c
@@ -39,6 +39,8 @@ static int fake;
 static char *options;
 static size_t options_len;
 static mach_msg_timeout_t timeout;
+static char *test_opts;
+static size_t test_opts_len;
 
 static enum { mount, query } mode;
 static enum { qf_standard, qf_fstab, qf_translator } query_format;
@@ -57,6 +59,8 @@ static const struct argp_option argp_opts[] =
   {"remount", 0, 0, OPTION_ALIAS},
   {"verbose", 'v', 0, 0, "Give more detailed information"},
   {"no-mtab", 'n', 0, 0, "Do not update /etc/mtab"},
+  {"test-opts", 'O', "OPTIONS", 0,
+   "Only mount fstab entries matching the given set of options"},
   {"fake", 'f', 0, 0, "Do not actually mount, just pretend"},
   {0, 0}
 };
@@ -122,6 +126,12 @@ parse_opt (int key, char *arg, struct argp_state *state)
       fake = 1;
       break;
 
+    case 'O':
+      err = argz_create_sep (arg, ',', &test_opts, &test_opts_len);
+      if (err)
+       argp_failure (state, 100, ENOMEM, "%s", arg);
+      break;
+
     case ARGP_KEY_ARG:
       if (mountpoint == 0)     /* One arg: mountpoint */
        mountpoint = arg;
@@ -192,6 +202,49 @@ static const struct argp_child argp_kids[] =
   { 0 } };
 static struct argp argp = { argp_opts, parse_opt, args_doc, doc, argp_kids };
 
+/* Check whether the given mount entry matches the given set of
+   options.
+
+   Returns 0 if foo is in the options vector but nofoo is in test_opts.
+   Returns 0 if foo is in test_opts but foo is not in the options vector. */
+int
+match_options (struct mntent *mntent)
+{
+  char *opts;
+  size_t opts_len;
+
+  error_t err = argz_create_sep (mntent->mnt_opts, ',', &opts, &opts_len);
+  if (err)
+    error (3, err, "parsing mount options failed");
+
+  for (char *test = test_opts;
+       test; test = argz_next (test_opts, test_opts_len, test))
+    {
+      char *needle = test;
+      int inverse = strncmp("no", needle, 2) == 0;
+      if (inverse)
+        needle += 2;
+
+      int match = 0;
+      for (char *opt = opts; opt; opt = argz_next (opts, opts_len, opt))
+        {
+          if (strcmp (opt, needle) == 0) {
+            if (inverse)
+              return 0; /* foo in opts, nofoo in test_opts. */
+
+            /* foo in opts, foo in test_opts, record match. */
+            match = 1;
+          }
+        }
+
+      if (! inverse && ! match)
+        return 0; /* No foo in opts, but foo in test_opts. */
+    }
+
+  /* If no conflicting test_opt was encountered, return success. */
+  return 1;
+}
+
 /* Mount one filesystem.  */
 static error_t
 do_mount (struct fs *fs, int remount)
@@ -615,8 +668,13 @@ main (int argc, char **argv)
       case mount:
        for (fs = fstab->entries; fs; fs = fs->next)
          {
-           if (fstab_params.do_all && hasmntopt (&fs->mntent, MNTOPT_NOAUTO))
-             continue;
+           if (fstab_params.do_all) {
+              if (hasmntopt (&fs->mntent, MNTOPT_NOAUTO))
+                continue;
+
+              if (! match_options (&fs->mntent))
+                continue;
+            }
            err |= do_mount (fs, remount);
          }
        break;
-- 
1.7.10.4