text-based mount command: make po_rightmost() work for N options

Sometimes we need to choose the rightmost option among multiple
different mount options.  For example, we want to find the rightmost
of "proto," "tcp," and "udp".  Or, the rightmost of "vers," "nfsvers,"
"v2," and "v3".

Update po_rightmost() to choose among N options instead of just two.

Signed-off-by: Steve Dickson <steved@redhat.com>

diff --git a/utils/mount/parse_opt.c b/utils/mount/parse_opt.c
index f61d0dd6470da10448d7cc3d9df3f0762667c405..493450859f2235714caaca5391496f8eed85a588 100644 (file)
--- a/utils/mount/parse_opt.c
+++ b/utils/mount/parse_opt.c
@@ -421,34 +421,38 @@ po_found_t po_get_numeric(struct mount_options *options, char *keyword, long *va
 #endif /* HAVE_STRTOL */
 
 /**
- * po_rightmost - determine the relative position of two options
+ * po_rightmost - determine the relative position of several options
  * @options: pointer to mount options
- * @key1: pointer to a C string containing an option keyword
- * @key2: pointer to a C string containing another option keyword
+ * @keys: pointer to an array of C strings containing option keywords
+ *
+ * This function can be used to determine which of several similar
+ * options will be the one to take effect.
  *
  * The kernel parses the mount option string from left to right.
  * If an option is specified more than once (for example, "intr"
  * and "nointr", the rightmost option is the last to be parsed,
  * and it therefore takes precedence over previous similar options.
  *
- * This function can be used to determine which of two similar
- * options will be the one to take effect.
+ * This can also distinguish among multiple synonymous options, such
+ * as "proto=," "udp" and "tcp."
+ *
+ * Returns the index into @keys of the option that is rightmost.
+ * If none of the options are present, returns zero.
  */
-po_rightmost_t po_rightmost(struct mount_options *options,
-                           char *key1, char *key2)
+unsigned int po_rightmost(struct mount_options *options, const char *keys[])
 {
        struct mount_option *option;
+       unsigned int i;
 
        if (options) {
                for (option = options->tail; option; option = option->prev) {
-                       if (key2 && strcmp(option->keyword, key2) == 0)
-                               return PO_KEY2_RIGHTMOST;
-                       if (key1 && strcmp(option->keyword, key1) == 0)
-                               return PO_KEY1_RIGHTMOST;
+                       for (i = 0; keys[i] != NULL; i++)
+                               if (strcmp(option->keyword, keys[i]) == 0)
+                                       return i;
                }
        }
 
-       return PO_NEITHER_FOUND;
+       return 0;
 }
 
 /**

diff --git a/utils/mount/parse_opt.h b/utils/mount/parse_opt.h
index 199630f85625b69d8d5074e95450e4ac5cd15a67..e132b1cd979961cb534608d5721cbf38fa21781a 100644 (file)
--- a/utils/mount/parse_opt.h
+++ b/utils/mount/parse_opt.h
@@ -35,12 +35,6 @@ typedef enum {
        PO_BAD_VALUE = 2,
 } po_found_t;
 
-typedef enum {
-       PO_KEY1_RIGHTMOST = -1,
-       PO_NEITHER_FOUND = 0,
-       PO_KEY2_RIGHTMOST = 1,
-} po_rightmost_t;
-
 struct mount_options;
 
 struct mount_options * po_split(char *);
@@ -53,7 +47,8 @@ po_found_t            po_contains(struct mount_options *, char *);
 char *                 po_get(struct mount_options *, char *);
 po_found_t             po_get_numeric(struct mount_options *,
                                        char *, long *);
-po_rightmost_t         po_rightmost(struct mount_options *, char *, char *);
+unsigned int           po_rightmost(struct mount_options *,
+                                       const char *keys[]);
 po_found_t             po_remove_all(struct mount_options *, char *);
 void                   po_destroy(struct mount_options *);
 

diff --git a/utils/mount/stropts.c b/utils/mount/stropts.c
index 43791e615edabc8d21b37a093b61e47f941e9320..bd127ab6bc017e8e9fef2c267666c752571b555c 100644 (file)
--- a/utils/mount/stropts.c
+++ b/utils/mount/stropts.c
@@ -224,9 +224,15 @@ static int nfs_fix_mounthost_option(const sa_family_t family,
  * Returns zero if the "lock" option is in effect, but statd
  * can't be started.  Otherwise, returns 1.
  */
+static const char *nfs_lock_opttbl[] = {
+       "nolock",
+       "lock",
+       NULL,
+};
+
 static int nfs_verify_lock_option(struct mount_options *options)
 {
-       if (po_rightmost(options, "nolock", "lock") == PO_KEY1_RIGHTMOST)
+       if (po_rightmost(options, nfs_lock_opttbl) == 1)
                return 1;
 
        if (!start_statd()) {
@@ -316,6 +322,12 @@ static int nfs_is_permanent_error(int error)
  * Returns a new group of mount options if successful; otherwise
  * NULL is returned if some failure occurred.
  */
+static const char *nfs_transport_opttbl[] = {
+       "udp",
+       "tcp",
+       NULL,
+};
+
 static struct mount_options *nfs_rewrite_mount_options(char *str)
 {
        struct mount_options *options;
@@ -395,12 +407,12 @@ static struct mount_options *nfs_rewrite_mount_options(char *str)
                        po_remove_all(options, "proto");
                }
        }
-       p = po_rightmost(options, "tcp", "udp");
+       p = po_rightmost(options, nfs_transport_opttbl);
        switch (p) {
-       case PO_KEY2_RIGHTMOST:
+       case 1:
                nfs_server.pmap.pm_prot = IPPROTO_UDP;
                break;
-       case PO_KEY1_RIGHTMOST:
+       case 2:
                nfs_server.pmap.pm_prot = IPPROTO_TCP;
                break;
        }
@@ -722,12 +734,18 @@ static int nfsmount_bg(struct nfsmount_info *mi)
  *
  * Returns a valid mount command exit code.
  */
+static const char *nfs_background_opttbl[] = {
+       "bg",
+       "fg",
+       NULL,
+};
+
 static int nfsmount_start(struct nfsmount_info *mi)
 {
        if (!nfs_validate_options(mi))
                return EX_FAIL;
 
-       if (po_rightmost(mi->options, "bg", "fg") == PO_KEY1_RIGHTMOST)
+       if (po_rightmost(mi->options, nfs_background_opttbl) == 1)
                return nfsmount_bg(mi);
        else
                return nfsmount_fg(mi);