utils: update remount to handle mtab etc

Add a -n option for boot time

diff --git a/Applications/util/remount.c b/Applications/util/remount.c
index bfaf4f8..eba55e5 100644 (file)
--- a/Applications/util/remount.c
+++ b/Applications/util/remount.c
@@ -4,12 +4,42 @@
 #include <sys/mount.h>
 #include <mntent.h>
 
-static char *getdev(char *arg)
+static int quiet;
+
+/* Strip ro and rw from the entry and append the correct one */
+/* Will want extending when we do nosuid */
+static char *modify_opts(char *opts, int flags)
+{
+       static char optbuf[_MAX_MNTLEN];
+       char *op = optbuf;
+       char *p = strtok(opts, ",");
+       while(p) {
+               if (strcmp(p, "ro") != 0 && strcmp(p, "rw") != 0) {
+                       if (op != optbuf)
+                               *op++ = ',';
+                       strcpy(op, p);
+                       op += strlen(p);
+               }
+               p = strtok(NULL,",");
+       }
+       if (flags & MS_RDONLY) {
+               if (op != optbuf)
+                       *op++ = ',';
+               strcpy(op, "ro");
+               op += 2;
+       }
+       if (op == optbuf)
+               return "defaults";
+       *op = 0;
+       return optbuf;
+}
+
+static char *getdev(char *arg, char *p)
 {
        FILE *f;
        struct mntent *mnt;
 
-       f = setmntent("/etc/mtab", "r");
+       f = setmntent(p, "r");
        if (f) {
                while (mnt = getmntent(f)) {
                        if ((strcmp(mnt->mnt_fsname, arg) == 0) || (strcmp(mnt->mnt_dir, arg) == 0)) {
@@ -22,21 +52,60 @@ static char *getdev(char *arg)
        return NULL;
 }
 
-/* FIXME: needs to update mtab entry / support nosuid etc ? */
+static void rewrite_mtab(char *name, flags)
+{
+       FILE *inpf, *outf;
+       struct mntent *mnt;
+
+       if (quiet)
+               return;
+
+       inpf = setmntent("/etc/mtab", "r");
+       if (!inpf) {
+               perror("Can't open /etc/mtab");
+               exit(1);
+       }
+       outf = setmntent("/etc/mtab.new", "w");
+       if (!outf) {
+               perror("Can't create temporary file");
+               exit(1);
+       }
+       /* Correct the options for the remounted entry */
+       while (mnt = getmntent(inpf)) {
+               if (strcmp(name, mnt->mnt_fsname) == 0)
+                       mnt->mnt_opts = modify_opts(mnt->mnt_opts, flags);
+               addmntent(outf, mnt);
+       }
+       endmntent(inpf);
+       endmntent(outf);
+       if (rename("/etc/mtab.new", "/etc/mtab") < 0) {
+               perror("Error installing /etc/mtab");
+               exit(1);
+       }
+}
 
 int main(int argc, char *argv[])
 {
        char *dev;
        unsigned int flags;
-       
+
+       if (argc == 4 && strcmp(argv[1], "-n") == 0) {
+               argc--;
+               argv++;
+               quiet = 1;
+       }
        if (argc != 3) {
                fprintf(stderr, "%s: remount device [ro][rw]\n", argv[0]);
                return 1;
        }
 
-       dev = getdev(argv[1]);
-       if (!dev) dev = argv[1];
-       
+       dev = getdev(argv[1], "/etc/fstab");
+       if (!dev)
+               dev = getdev(argv[1], "/etc/mtab");
+       if (!dev)
+               dev = argv[1];
+
+       /* TODO - nosuid once supported */
        if (strcmp(argv[2], "ro") == 0)
                flags = MS_RDONLY|MS_REMOUNT;
        else if (strcmp(argv[2], "rw") == 0)
@@ -45,10 +114,17 @@ int main(int argc, char *argv[])
                fprintf(stderr, "%s: ro or rw required.\n", argv[0]);
                return 1;
        }
+
+       /* Rewrite first in case we are updating /etc to ro */
+       if (flags & MS_RDONLY)
+               rewrite_mtab(dev, flags);
        
        if (remount(dev, flags)) {
-               perror("umount");
+               perror("remount");
                return 1;
        }
+       /* Otherwise rewrite after in case /etc was ro */
+       if (!(flags & MS_RDONLY))
+               rewrite_mtab(dev, flags);
        return 0;
 }