]> git.decadent.org.uk Git - nfs-utils.git/blobdiff - utils/mount/stropts.c
text-based mount options: Use new pmap stuffer when rewriting mount options
[nfs-utils.git] / utils / mount / stropts.c
index c11420069d97e363d456eb2c998c8e0054cfd03d..99be0f3844023a35f975f6473aea41085432ba88 100644 (file)
  *
  */
 
-#include <ctype.h>
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <unistd.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdlib.h>
 #include <errno.h>
 #include <netdb.h>
 #include <time.h>
+
 #include <sys/socket.h>
 #include <sys/mount.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
 
 #include "xcommon.h"
 #include "mount.h"
 #include "nls.h"
-#include "nfs_mount.h"
 #include "mount_constants.h"
+#include "stropts.h"
 #include "error.h"
 #include "network.h"
+#include "parse_opt.h"
+#include "version.h"
+#include "parse_dev.h"
 
-#ifdef HAVE_RPCSVC_NFS_PROT_H
-#include <rpcsvc/nfs_prot.h>
-#else
-#include <linux/nfs.h>
-#define nfsstat nfs_stat
+#ifndef NFS_PROGRAM
+#define NFS_PROGRAM    (100003)
 #endif
 
 #ifndef NFS_PORT
-#define NFS_PORT 2049
+#define NFS_PORT       (2049)
+#endif
+
+#ifndef NFS_MAXHOSTNAME
+#define NFS_MAXHOSTNAME                (255)
+#endif
+
+#ifndef NFS_MAXPATHNAME
+#define NFS_MAXPATHNAME                (1024)
+#endif
+
+#ifndef NFS_DEF_FG_TIMEOUT_MINUTES
+#define NFS_DEF_FG_TIMEOUT_MINUTES     (2u)
+#endif
+
+#ifndef NFS_DEF_BG_TIMEOUT_MINUTES
+#define NFS_DEF_BG_TIMEOUT_MINUTES     (10000u)
 #endif
 
 extern int nfs_mount_data_version;
 extern char *progname;
 extern int verbose;
+extern int sloppy;
 
-static int retry_opt = 10000;          /* 10,000 minutes ~= 1 week */
-static int bg_opt = 0;
-static int addr_opt = 0;
-static int ca_opt = 0;
+struct nfsmount_info {
+       const char              *spec,          /* server:/path */
+                               *node,          /* mounted-on dir */
+                               *type;          /* "nfs" or "nfs4" */
+       char                    *hostname;      /* server's hostname */
 
-static int parse_devname(char *hostdir, char **hostname, char **dirname)
-{
-       char *s;
+       struct mount_options    *options;       /* parsed mount options */
+       char                    **extra_opts;   /* string for /etc/mtab */
 
-       if (!(s = strchr(hostdir, ':'))) {
-               nfs_error(_("%s: directory to mount not in host:dir format"),
-                               progname);
-               return -1;
-       }
-       *hostname = hostdir;
-       *dirname = s + 1;
-       *s = '\0';
-       /* Ignore all but first hostname in replicated mounts
-          until they can be fully supported. (mack@sgi.com) */
-       if ((s = strchr(hostdir, ','))) {
-               *s = '\0';
-               nfs_error(_("%s: warning: multiple hostnames not supported"),
-                               progname);
+       int                     flags,          /* MS_ flags */
+                               fake,           /* actually do the mount? */
+                               child;          /* forked bg child? */
+
+       sa_family_t             family;         /* supported address family */
+};
+
+/*
+ * Obtain a retry timeout value based on the value of the "retry=" option.
+ *
+ * Returns a time_t timeout timestamp, in seconds.
+ */
+static time_t nfs_parse_retry_option(struct mount_options *options,
+                                    unsigned int timeout_minutes)
+{
+       long tmp;
+
+       switch (po_get_numeric(options, "retry", &tmp)) {
+       case PO_NOT_FOUND:
+               break;
+       case PO_FOUND:
+               if (tmp >= 0) {
+                       timeout_minutes = tmp;
+                       break;
+               }
+       case PO_BAD_VALUE:
+               if (verbose)
+                       nfs_error(_("%s: invalid retry timeout was specified; "
+                                       "using default timeout"), progname);
+               break;
        }
+
+       return time(NULL) + (time_t)(timeout_minutes * 60);
+}
+
+/*
+ * Convert the passed-in sockaddr-style address to presentation
+ * format, then append an option of the form "keyword=address".
+ *
+ * Returns 1 if the option was appended successfully; otherwise zero.
+ */
+static int nfs_append_generic_address_option(const struct sockaddr *sap,
+                                            const socklen_t salen,
+                                            const char *keyword,
+                                            struct mount_options *options)
+{
+       char address[NI_MAXHOST];
+       char new_option[512];
+
+       if (!nfs_present_sockaddr(sap, salen, address, sizeof(address)))
+               goto out_err;
+
+       if (snprintf(new_option, sizeof(new_option), "%s=%s",
+                                       keyword, address) >= sizeof(new_option))
+               goto out_err;
+
+       if (po_append(options, new_option) != PO_SUCCEEDED)
+               goto out_err;
+
+       return 1;
+
+out_err:
+       nfs_error(_("%s: failed to construct %s option"), progname, keyword);
        return 0;
 }
 
-static int fill_ipv4_sockaddr(const char *hostname, struct sockaddr_in *addr)
+/*
+ * Append the 'addr=' option to the options string to pass a resolved
+ * server address to the kernel.  After a successful mount, this address
+ * is also added to /etc/mtab for use when unmounting.
+ *
+ * If 'addr=' is already present, we strip it out.  This prevents users
+ * from setting a bogus 'addr=' option themselves, and also allows bg
+ * retries to recompute the server's address, in case it has changed.
+ *
+ * Returns 1 if 'addr=' option appended successfully;
+ * otherwise zero.
+ */
+static int nfs_append_addr_option(const struct sockaddr *sap,
+                                 socklen_t salen,
+                                 struct mount_options *options)
+{
+       po_remove_all(options, "addr");
+       return nfs_append_generic_address_option(sap, salen, "addr", options);
+}
+
+/*
+ * Called to discover our address and append an appropriate 'clientaddr='
+ * option to the options string.
+ *
+ * Returns 1 if 'clientaddr=' option created successfully or if
+ * 'clientaddr=' option is already present; otherwise zero.
+ */
+static int nfs_append_clientaddr_option(const struct sockaddr *sap,
+                                       socklen_t salen,
+                                       struct mount_options *options)
 {
-       struct hostent *hp;
-       addr->sin_family = AF_INET;
+       struct sockaddr_storage dummy;
+       struct sockaddr *my_addr = (struct sockaddr *)&dummy;
+       socklen_t my_len = sizeof(dummy);
 
-       if (inet_aton(hostname, &addr->sin_addr))
+       if (po_contains(options, "clientaddr") == PO_FOUND)
                return 1;
-       if ((hp = gethostbyname(hostname)) == NULL) {
-               nfs_error(_("%s: can't get address for %s\n"),
-                               progname, hostname);
+
+       nfs_callback_address(sap, salen, my_addr, &my_len);
+
+       return nfs_append_generic_address_option(my_addr, my_len,
+                                                       "clientaddr", options);
+}
+
+/*
+ * Resolve the 'mounthost=' hostname and append a new option using
+ * the resulting address.
+ */
+static int nfs_fix_mounthost_option(const sa_family_t family,
+                                   struct mount_options *options)
+{
+       struct sockaddr_storage dummy;
+       struct sockaddr *sap = (struct sockaddr *)&dummy;
+       socklen_t salen = sizeof(dummy);
+       char *mounthost;
+
+       mounthost = po_get(options, "mounthost");
+       if (!mounthost)
+               return 1;
+
+       if (!nfs_name_to_address(mounthost, family, sap, &salen)) {
+               nfs_error(_("%s: unable to determine mount server's address"),
+                               progname);
                return 0;
        }
-       if (hp->h_length > sizeof(struct in_addr)) {
-               nfs_error(_("%s: got bad hp->h_length"), progname);
-               hp->h_length = sizeof(struct in_addr);
+
+       return nfs_append_generic_address_option(sap, salen,
+                                                       "mountaddr", options);
+}
+
+/*
+ * 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, nfs_lock_opttbl) == 1)
+               return 1;
+
+       if (!start_statd()) {
+               nfs_error(_("%s: rpc.statd is not running but is "
+                           "required for remote locking."), progname);
+               nfs_error(_("%s: Either use '-o nolock' to keep "
+                           "locks local, or start statd."), progname);
+               return 0;
        }
-       memcpy(&addr->sin_addr, hp->h_addr, hp->h_length);
+
+       return 1;
+}
+
+static int nfs_append_sloppy_option(struct mount_options *options)
+{
+       if (!sloppy || linux_version_code() < MAKE_VERSION(2, 6, 27))
+               return 1;
+
+       if (po_append(options, "sloppy") == PO_FAILED)
+               return 0;
        return 1;
 }
 
 /*
- * XXX: This should really use the technique neil recently added
- * to get the address off the local end of a socket connected to
- * the server -- to get the right address to use on multi-homed
- * clients
+ * Set up mandatory NFS mount options.
+ *
+ * Returns 1 if successful; otherwise zero.
  */
-static int get_my_ipv4addr(char *ip_addr, int len)
+static int nfs_validate_options(struct nfsmount_info *mi)
 {
-       char myname[1024];
-       struct sockaddr_in myaddr;
+       struct sockaddr_storage dummy;
+       struct sockaddr *sap = (struct sockaddr *)&dummy;
+       socklen_t salen = sizeof(dummy);
 
-       if (gethostname(myname, sizeof(myname))) {
-               nfs_error(_("%s: can't determine client address\n"),
-                               progname);
+       if (!nfs_parse_devname(mi->spec, &mi->hostname, NULL))
                return 0;
+
+       if (!nfs_name_to_address(mi->hostname, mi->family, sap, &salen))
+               return 0;
+
+       if (strncmp(mi->type, "nfs4", 4) == 0) {
+               if (!nfs_append_clientaddr_option(sap, salen, mi->options))
+                       return 0;
+       } else {
+               if (!nfs_fix_mounthost_option(mi->family, mi->options))
+                       return 0;
+               if (!mi->fake && !nfs_verify_lock_option(mi->options))
+                       return 0;
        }
-       if (!fill_ipv4_sockaddr(myname, &myaddr))
+
+       if (!nfs_append_sloppy_option(mi->options))
                return 0;
 
-       snprintf(ip_addr, len, "%s", inet_ntoa(myaddr.sin_addr));
-       ip_addr[len - 1] = '\0';
+       return nfs_append_addr_option(sap, salen, mi->options);
+}
 
-       return 1;
+/*
+ * Distinguish between permanent and temporary errors.
+ *
+ * Returns 0 if the passed-in error is temporary, thus the
+ * mount system call should be retried; returns one if the
+ * passed-in error is permanent, thus the mount system call
+ * should not be retried.
+ */
+static int nfs_is_permanent_error(int error)
+{
+       switch (error) {
+       case ESTALE:
+       case ETIMEDOUT:
+       case ECONNREFUSED:
+               return 0;       /* temporary */
+       default:
+               return 1;       /* permanent */
+       }
 }
 
 /*
- * Walk through our mount options string, and indicate the presence
- * of 'bg', 'retry=', and 'clientaddr='.
+ * Reconstruct the mount option string based on a portmapper probe
+ * of the server.  Returns one if the server's portmapper returned
+ * something we can use, otherwise zero.
+ *
+ * To handle version and transport protocol fallback properly, we
+ * need to parse some of the mount options in order to set up a
+ * portmap probe.  Mount options that nfs_rewrite_mount_options()
+ * doesn't recognize are left alone.
+ *
+ * Returns a new group of mount options if successful; otherwise
+ * NULL is returned if some failure occurred.
  */
-static void extract_interesting_options(char *opts)
+static struct mount_options *nfs_rewrite_mount_options(char *str)
 {
-       char *opt, *opteq;
-       int val;
-
-       opts = xstrdup(opts);
-
-       for (opt = strtok(opts, ","); opt; opt = strtok(NULL, ",")) {
-               if ((opteq = strchr(opt, '='))) {
-                       val = atoi(opteq + 1);
-                       *opteq = '\0';
-                       if (strcmp(opt, "bg") == 0)
-                               bg_opt++;
-                       else if (strcmp(opt, "retry") == 0)
-                               retry_opt = val;
-                       else if (strcmp(opt, "addr") == 0)
-                               addr_opt++;
-                       else if (strcmp(opt, "clientaddr") == 0)
-                               ca_opt++;
-               } else {
-                       if (strcmp(opt, "bg") == 0)
-                               bg_opt++;
-               }
+       struct mount_options *options;
+       char *option, new_option[64];
+       clnt_addr_t mnt_server = { };
+       clnt_addr_t nfs_server = { };
+
+       options = po_split(str);
+       if (!options) {
+               errno = EFAULT;
+               return NULL;
+       }
+
+       errno = EINVAL;
+       option = po_get(options, "addr");
+       if (option) {
+               nfs_server.saddr.sin_family = AF_INET;
+               if (!inet_aton((const char *)option, &nfs_server.saddr.sin_addr))
+                       goto err;
+       } else
+               goto err;
+
+       option = po_get(options, "mountaddr");
+       if (option) {
+               mnt_server.saddr.sin_family = AF_INET;
+               if (!inet_aton((const char *)option, &mnt_server.saddr.sin_addr))
+                       goto err;
+       } else
+               memcpy(&mnt_server.saddr, &nfs_server.saddr,
+                               sizeof(mnt_server.saddr));
+
+       nfs_options2pmap(options, &nfs_server.pmap, &mnt_server.pmap);
+
+       /* The kernel NFS client doesn't support changing the RPC program
+        * number for these services, so reset these fields before probing
+        * the server's ports.  */
+       nfs_server.pmap.pm_prog = NFS_PROGRAM;
+       mnt_server.pmap.pm_prog = MOUNTPROG;
+
+       if (!probe_bothports(&mnt_server, &nfs_server)) {
+               errno = ESPIPE;
+               goto err;
+       }
+
+       snprintf(new_option, sizeof(new_option) - 1,
+                "nfsvers=%lu", nfs_server.pmap.pm_vers);
+       if (po_append(options, new_option) == PO_FAILED)
+               goto err;
+
+       if (nfs_server.pmap.pm_prot == IPPROTO_TCP)
+               snprintf(new_option, sizeof(new_option) - 1,
+                        "proto=tcp");
+       else
+               snprintf(new_option, sizeof(new_option) - 1,
+                        "proto=udp");
+       if (po_append(options, new_option) == PO_FAILED)
+               goto err;
+
+       if (nfs_server.pmap.pm_port != NFS_PORT) {
+               snprintf(new_option, sizeof(new_option) - 1,
+                        "port=%lu", nfs_server.pmap.pm_port);
+               if (po_append(options, new_option) == PO_FAILED)
+                       goto err;
+
        }
 
-       free(opts);
+       if (mnt_server.pmap.pm_prot == IPPROTO_TCP)
+               snprintf(new_option, sizeof(new_option) - 1,
+                        "mountproto=tcp");
+       else
+               snprintf(new_option, sizeof(new_option) - 1,
+                        "mountproto=udp");
+       if (po_append(options, new_option) == PO_FAILED)
+               goto err;
+
+       snprintf(new_option, sizeof(new_option) - 1,
+                "mountport=%lu", mnt_server.pmap.pm_port);
+       if (po_append(options, new_option) == PO_FAILED)
+               goto err;
+
+       errno = 0;
+       return options;
+
+err:
+       po_destroy(options);
+       return NULL;
 }
 
 /*
- * Append the "addr=" option to the options string.
+ * Do the mount(2) system call.
  *
- * We always add our own addr= to the end of the options string.
+ * Returns 1 if successful, otherwise zero.
+ * "errno" is set to reflect the individual error.
  */
-static int append_addr_opt(const char *spec, char **extra_opts)
+static int nfs_sys_mount(const struct nfsmount_info *mi, const char *type,
+                        const char *options)
 {
-       static char hostdir[1024], new_opts[1024], ip_addr[255];
-       char *hostname, *dirname, *s, *old_opts;
-       struct sockaddr_in addr;
+       int result;
+
+       result = mount(mi->spec, mi->node, type,
+                               mi->flags & ~(MS_USER|MS_USERS), options);
+       if (verbose && result) {
+               int save = errno;
+               nfs_error(_("%s: mount(2): %s"), progname, strerror(save));
+               errno = save;
+       }
+       return !result;
+}
 
-       if (strlen(spec) >= sizeof(hostdir)) {
-               nfs_error(_("%s: excessively long host:dir argument\n"),
-                               progname);
+/*
+ * Retry an NFS mount that failed because the requested service isn't
+ * available on the server.
+ *
+ * Returns 1 if successful.  Otherwise, returns zero.
+ * "errno" is set to reflect the individual error.
+ *
+ * Side effect: If the retry is successful, both 'options' and
+ * 'extra_opts' are updated to reflect the mount options that worked.
+ * If the retry fails, 'options' and 'extra_opts' are left unchanged.
+ */
+static int nfs_retry_nfs23mount(struct nfsmount_info *mi)
+{
+       struct mount_options *retry_options;
+       char *retry_str = NULL;
+       char **extra_opts = mi->extra_opts;
+
+       retry_options = nfs_rewrite_mount_options(*extra_opts);
+       if (!retry_options)
                return 0;
-       }
-       strcpy(hostdir, spec);
-       if (parse_devname(hostdir, &hostname, &dirname)) {
-               nfs_error(_("%s: parsing host:dir argument failed\n"),
-                               progname);
+
+       if (po_join(retry_options, &retry_str) == PO_FAILED) {
+               po_destroy(retry_options);
+               errno = EIO;
                return 0;
        }
 
-       if (!fill_ipv4_sockaddr(hostname, &addr))
-               return 0;
-       if (!get_my_ipv4addr(ip_addr, sizeof(ip_addr)))
-               return 0;
+       if (verbose)
+               printf(_("%s: text-based options (retry): '%s'\n"),
+                       progname, retry_str);
 
-       /* add IP address to mtab options for use when unmounting */
-       s = inet_ntoa(addr.sin_addr);
-       old_opts = *extra_opts;
-       if (!old_opts)
-               old_opts = "";
-       if (strlen(old_opts) + strlen(s) + 10 >= sizeof(new_opts)) {
-               nfs_error(_("%s: excessively long option argument\n"),
-                               progname);
+       if (!nfs_sys_mount(mi, "nfs", retry_str)) {
+               po_destroy(retry_options);
+               free(retry_str);
                return 0;
        }
-       snprintf(new_opts, sizeof(new_opts), "%s%saddr=%s",
-                old_opts, *old_opts ? "," : "", s);
-       *extra_opts = xstrdup(new_opts);
 
+       free(*extra_opts);
+       *extra_opts = retry_str;
+       po_replace(mi->options, retry_options);
        return 1;
 }
 
 /*
- * Append the "clientaddr=" option to the options string.
+ * Attempt an NFSv2/3 mount via a mount(2) system call.  If the kernel
+ * claims the requested service isn't supported on the server, probe
+ * the server to see what's supported, rewrite the mount options,
+ * and retry the request.
  *
- * Returns 1 if clientaddr option created successfully;
- * otherwise zero.
+ * Returns 1 if successful.  Otherwise, returns zero.
+ * "errno" is set to reflect the individual error.
+ *
+ * Side effect: If the retry is successful, both 'options' and
+ * 'extra_opts' are updated to reflect the mount options that worked.
+ * If the retry fails, 'options' and 'extra_opts' are left unchanged.
  */
-static int append_clientaddr_opt(const char *spec, char **extra_opts)
+static int nfs_try_nfs23mount(struct nfsmount_info *mi)
 {
-       static char new_opts[1024], cbuf[1024];
-       static char ip_addr[16] = "127.0.0.1";
+       char **extra_opts = mi->extra_opts;
 
-       if (!get_my_ipv4addr(ip_addr, sizeof(ip_addr)))
+       if (po_join(mi->options, extra_opts) == PO_FAILED) {
+               errno = EIO;
                return 0;
+       }
 
-       /* Ensure we have enough padding for the following strcat()s */
-       if (strlen(*extra_opts) + strlen(ip_addr) + 10 >= sizeof(new_opts)) {
-               nfs_error(_("%s: excessively long option argument"),
-                               progname);
+       if (verbose)
+               printf(_("%s: text-based options: '%s'\n"),
+                       progname, *extra_opts);
+
+       if (mi->fake)
+               return 1;
+
+       if (nfs_sys_mount(mi, "nfs", *extra_opts))
+               return 1;
+
+       /*
+        * The kernel returns EOPNOTSUPP if the RPC bind failed,
+        * and EPROTONOSUPPORT if the version isn't supported.
+        */
+       if (errno != EOPNOTSUPP && errno != EPROTONOSUPPORT)
+               return 0;
+
+       return nfs_retry_nfs23mount(mi);
+}
+
+/*
+ * Attempt an NFS v4 mount via a mount(2) system call.
+ *
+ * Returns 1 if successful.  Otherwise, returns zero.
+ * "errno" is set to reflect the individual error.
+ */
+static int nfs_try_nfs4mount(struct nfsmount_info *mi)
+{
+       char **extra_opts = mi->extra_opts;
+
+       if (po_join(mi->options, extra_opts) == PO_FAILED) {
+               errno = EIO;
                return 0;
        }
 
-       strcat(new_opts, *extra_opts);
+       if (verbose)
+               printf(_("%s: text-based options: '%s'\n"),
+                       progname, *extra_opts);
 
-       snprintf(cbuf, sizeof(cbuf) - 1, "%sclientaddr=%s",
-                       *extra_opts ? "," : "", ip_addr);
-       strcat(new_opts, cbuf);
+       if (mi->fake)
+               return 1;
 
-       *extra_opts = xstrdup(new_opts);
+       return nfs_sys_mount(mi, "nfs4", *extra_opts);
+}
 
-       return 1;
+/*
+ * Perform either an NFSv2/3 mount, or an NFSv4 mount system call.
+ *
+ * Returns 1 if successful.  Otherwise, returns zero.
+ * "errno" is set to reflect the individual error.
+ */
+static int nfs_try_mount(struct nfsmount_info *mi)
+{
+       if (strncmp(mi->type, "nfs4", 4) == 0)
+               return nfs_try_nfs4mount(mi);
+       else
+               return nfs_try_nfs23mount(mi);
 }
 
 /*
- * nfsmount_s - Mount an NFSv2 or v3 file system using C string options
+ * Handle "foreground" NFS mounts.
  *
- * @spec:      C string hostname:path specifying remoteshare to mount
- * @node:      C string pathname of local mounted on directory
- * @flags:     MS_ style flags
- * @extra_opts:        pointer to C string containing fs-specific mount options
- *             (possibly also a return argument)
- * @fake:      flag indicating whether to carry out the whole operation
- * @bg:                one if this is a backgrounded mount attempt
+ * Retry the mount request for as long as the 'retry=' option says.
  *
- * XXX: need to handle bg, fg, and retry options.
+ * Returns a valid mount command exit code.
  */
-int nfsmount_s(const char *spec, const char *node, int flags,
-               char **extra_opts, int fake, int bg)
+static int nfsmount_fg(struct nfsmount_info *mi)
 {
-       int retval = EX_FAIL;
+       unsigned int secs = 1;
+       time_t timeout;
 
+       timeout = nfs_parse_retry_option(mi->options,
+                                        NFS_DEF_FG_TIMEOUT_MINUTES);
        if (verbose)
-               printf(_("%s: using C string mount system call interface\n"),
-                       progname);
-
-       extract_interesting_options(*extra_opts);
+               printf(_("%s: timeout set for %s"),
+                       progname, ctime(&timeout));
 
-       if (!addr_opt && !append_addr_opt(spec, extra_opts))
-               goto fail;
+       for (;;) {
+               if (nfs_try_mount(mi))
+                       return EX_SUCCESS;
 
-       if (verbose)
-               printf(_("%s: option string is '%s'\n"),
-                       progname, *extra_opts);
+               if (nfs_is_permanent_error(errno))
+                       break;
 
-       if (!fake) {
-               if (mount(spec, node, "nfs",
-                               flags & ~(MS_USER|MS_USERS), *extra_opts)) {
-                       mount_error(spec, node, errno);
-                       goto fail;
+               if (time(NULL) > timeout) {
+                       errno = ETIMEDOUT;
+                       break;
                }
-       }
 
-       return 0;
+               if (errno != ETIMEDOUT) {
+                       if (sleep(secs))
+                               break;
+                       secs <<= 1;
+                       if (secs > 10)
+                               secs = 10;
+               }
+       };
 
-fail:
-       return retval;
+       mount_error(mi->spec, mi->node, errno);
+       return EX_FAIL;
 }
 
 /*
- * nfs4mount_s - Mount an NFSv4 file system using C string options
+ * Handle "background" NFS mount [first try]
  *
- * @spec:      C string hostname:path specifying remoteshare to mount
- * @node:      C string pathname of local mounted on directory
- * @flags:     MS_ style flags
- * @extra_opts:        pointer to C string containing fs-specific mount options
- *             (possibly also a return argument)
- * @fake:      flag indicating whether to carry out the whole operation
- * @bg:                one if this is a backgrounded mount attempt
+ * Returns a valid mount command exit code.
  *
- * XXX: need to handle bg, fg, and retry options.
+ * EX_BG should cause the caller to fork and invoke nfsmount_child.
+ */
+static int nfsmount_parent(struct nfsmount_info *mi)
+{
+       if (nfs_try_mount(mi))
+               return EX_SUCCESS;
+
+       if (nfs_is_permanent_error(errno)) {
+               mount_error(mi->spec, mi->node, errno);
+               return EX_FAIL;
+       }
+
+       sys_mount_errors(mi->hostname, errno, 1, 1);
+       return EX_BG;
+}
+
+/*
+ * Handle "background" NFS mount [retry daemon]
  *
+ * Returns a valid mount command exit code: EX_SUCCESS if successful,
+ * EX_FAIL if a failure occurred.  There's nothing to catch the
+ * error return, though, so we use sys_mount_errors to log the
+ * failure.
  */
-int nfs4mount_s(const char *spec, const char *node, int flags,
-               char **extra_opts, int fake)
+static int nfsmount_child(struct nfsmount_info *mi)
 {
-       int retval = EX_FAIL;
+       unsigned int secs = 1;
+       time_t timeout;
 
-       if (verbose)
-               printf(_("%s: using C string mount system call interface\n"),
-                       progname);
+       timeout = nfs_parse_retry_option(mi->options,
+                                        NFS_DEF_BG_TIMEOUT_MINUTES);
 
-       extract_interesting_options(*extra_opts);
+       for (;;) {
+               if (sleep(secs))
+                       break;
+               secs <<= 1;
+               if (secs > 120)
+                       secs = 120;
 
-       if (!addr_opt && !append_addr_opt(spec, extra_opts))
-               goto fail;
+               if (nfs_try_mount(mi))
+                       return EX_SUCCESS;
 
-       if (!ca_opt && !append_clientaddr_opt(spec, extra_opts))
-               goto fail;
+               if (nfs_is_permanent_error(errno))
+                       break;
 
-       if (verbose)
-               printf(_("%s: option string is '%s'\n"),
-                       progname, *extra_opts);
+               if (time(NULL) > timeout)
+                       break;
 
-       if (!fake) {
-               if (mount(spec, node, "nfs4",
-                               flags & ~(MS_USER|MS_USERS), *extra_opts)) {
-                       mount_error(spec, node, errno);
-                       goto fail;
-               }
-       }
+               sys_mount_errors(mi->hostname, errno, 1, 1);
+       };
 
-       return 0;
+       sys_mount_errors(mi->hostname, errno, 1, 0);
+       return EX_FAIL;
+}
+
+/*
+ * Handle "background" NFS mount
+ *
+ * Returns a valid mount command exit code.
+ */
+static int nfsmount_bg(struct nfsmount_info *mi)
+{
+       if (!mi->child)
+               return nfsmount_parent(mi);
+       else
+               return nfsmount_child(mi);
+}
+
+/*
+ * Process mount options and try a mount system call.
+ *
+ * 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, nfs_background_opttbl) == 1)
+               return nfsmount_bg(mi);
+       else
+               return nfsmount_fg(mi);
+}
+
+/**
+ * nfsmount_string - Mount an NFS file system using C string options
+ * @spec: C string specifying remote share to mount ("hostname:path")
+ * @node: C string pathname of local mounted-on directory
+ * @type: C string that represents file system type ("nfs" or "nfs4")
+ * @flags: MS_ style mount flags
+ * @extra_opts:        pointer to C string containing fs-specific mount options
+ *             (input and output argument)
+ * @fake: flag indicating whether to carry out the whole operation
+ * @child: one if this is a mount daemon (bg)
+ */
+int nfsmount_string(const char *spec, const char *node, const char *type,
+                   int flags, char **extra_opts, int fake, int child)
+{
+       struct nfsmount_info mi = {
+               .spec           = spec,
+               .node           = node,
+               .type           = type,
+               .extra_opts     = extra_opts,
+               .flags          = flags,
+               .fake           = fake,
+               .child          = child,
+#ifdef IPV6_SUPPORTED
+               .family         = AF_UNSPEC,    /* either IPv4 or v6 */
+#else
+               .family         = AF_INET,      /* only IPv4 */
+#endif
+       };
+       int retval = EX_FAIL;
+
+       mi.options = po_split(*extra_opts);
+       if (mi.options) {
+               retval = nfsmount_start(&mi);
+               po_destroy(mi.options);
+       } else
+               nfs_error(_("%s: internal option parsing error"), progname);
 
-fail:
+       free(mi.hostname);
        return retval;
 }