Add new function to filter fstab options

This fixes parsing of options in shared/generator.c. Existing code
had some issues:

- it would treate whitespace and semicolons as seperators. fstab(5)
  is pretty clear that only commas matter. And the syntax does
  not allow for spaces to be inserted in the field in fstab.
  Whitespace might be escaped, but then it should not seperate
  options. Treat whitespace and semicolons as any other character.
- it assumed that x-systemd.device-timeout would always be followed
  by "=". But this is not guaranteed, hasmntopt will return this
  option even if there's no value. Uninitialized memory could be read.
- some error paths would log, and inconsistently, some would just
  return an error code.

Filtering is split out to a separate function and tests are added.

Similar code paths in other places are adjusted to use the new function.

1 files changed, 145 insertions, 0 deletions

diff --git a/src/shared/fstab-util.c b/src/shared/fstab-util.c
new file mode 100644
index 0000000000..546c81b80f
--- /dev/null
+++ b/src/shared/fstab-util.c
@@ -0,0 +1,145 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  This file is part of systemd.
+
+  Copyright 2015 Zbigniew Jędrzejewski-Szmek
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd 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
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include "fstab-util.h"
+#include "strv.h"
+#include "util.h"
+
+int fstab_filter_options(const char *opts, const char *names,
+                         const char **namefound, char **value, char **filtered) {
+        const char *name, *n = NULL, *x;
+        _cleanup_strv_free_ char **stor = NULL;
+        _cleanup_free_ char *v = NULL, **strv = NULL;
+
+        assert(names && *names);
+
+        if (!opts)
+                goto answer;
+
+        /* If !value and !filtered, this function is not allowed to fail. */
+
+        if (!filtered) {
+                const char *word, *state;
+                size_t l;
+
+                FOREACH_WORD_SEPARATOR(word, l, opts, ",", state)
+                        NULSTR_FOREACH(name, names) {
+                                if (l < strlen(name))
+                                        continue;
+                                if (!strneq(word, name, strlen(name)))
+                                        continue;
+
+                                /* we know that the string is NUL
+                                 * terminated, so *x is valid */
+                                x = word + strlen(name);
+                                if (IN_SET(*x, '\0', '=', ',')) {
+                                        n = name;
+                                        if (value) {
+                                                free(v);
+                                                if (IN_SET(*x, '\0', ','))
+                                                        v = NULL;
+                                                else {
+                                                        assert(*x == '=');
+                                                        x++;
+                                                        v = strndup(x, l - strlen(name) - 1);
+                                                        if (!v)
+                                                                return -ENOMEM;
+                                                }
+                                        }
+                                }
+                        }
+        } else {
+                char **t, **s;
+
+                stor = strv_split(opts, ",");
+                if (!stor)
+                        return -ENOMEM;
+                strv = memdup(stor, sizeof(char*) * (strv_length(stor) + 1));
+                if (!strv)
+                        return -ENOMEM;
+
+                for (s = t = strv; *s; s++) {
+                        NULSTR_FOREACH(name, names) {
+                                x = startswith(*s, name);
+                                if (x && IN_SET(*x, '\0', '='))
+                                        goto found;
+                        }
+
+                        *t = *s;
+                        t++;
+                        continue;
+                found:
+                        /* Keep the last occurence found */
+                        n = name;
+                        if (value) {
+                                free(v);
+                                if (*x == '\0')
+                                        v = NULL;
+                                else {
+                                        assert(*x == '=');
+                                        x++;
+                                        v = strdup(x);
+                                        if (!v)
+                                                return -ENOMEM;
+                                }
+                        }
+                }
+                *t = NULL;
+        }
+
+answer:
+        if (namefound)
+                *namefound = n;
+        if (filtered) {
+                char *f;
+
+                f = strv_join(strv, ",");
+                if (!f)
+                        return -ENOMEM;
+
+                *filtered = f;
+        }
+        if (value) {
+                *value = v;
+                v = NULL;
+        }
+
+        return !!n;
+}
+
+int fstab_find_pri(const char *options, int *ret) {
+        _cleanup_free_ char *opt = NULL;
+        int r;
+        unsigned pri;
+
+        assert(ret);
+
+        r = fstab_filter_options(options, "pri\0", NULL, &opt, NULL);
+        if (r <= 0)
+                return r;
+
+        r = safe_atou(opt, &pri);
+        if (r < 0)
+                return r;
+
+        *ret = (int) r;
+        return 1;
+}