[hurd] 11/64: Always canonicalize fstab entries with realpath

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit 36f340ae47a0f643be6d59a8190600cdd34eef0c
Author: Samuel Thibault <address@hidden>
Date:   Fri Nov 21 04:08:57 2014 +0100

    Always canonicalize fstab entries with realpath
    
    To avoid spurious ./, /, symlinks, etc.
    
    * sutils/fstab.c (fs_set_mntent): Try to call realpath on mnt_fsname and 
mnt_dir
    field of `mntent'.
    (fstab_find_mount): Try to call realpath on `name' parameter.
    (fstab_find): Do not try to call realpath.
    (fstab_read): Reset errno to zero before calling getmntent.
    * utils/umount.c (main): Do not warn about missing fstab entries for
    active translators.
---
 sutils/fstab.c | 103 ++++++++++++++++++++++++++++++++++-----------------------
 utils/umount.c |   4 +--
 2 files changed, 63 insertions(+), 44 deletions(-)

diff --git a/sutils/fstab.c b/sutils/fstab.c
index ed59151..e13f15b 100644
--- a/sutils/fstab.c
+++ b/sutils/fstab.c
@@ -240,16 +240,32 @@ fstypes_find_program (struct fstypes *types, const char 
*program,
 
 /* Copy MNTENT into FS, copying component strings as well.  */
 error_t
-fs_set_mntent (struct fs *fs, const struct mntent *mntent)
+fs_set_mntent (struct fs *fs, const struct mntent *provided_mntent)
 {
   char *end;
   size_t needed = 0;
+  struct mntent mntent = *provided_mntent;
+  char *real_fsname = NULL;
+  char *real_dir = NULL;
 
   if (fs->storage)
     free (fs->storage);
 
+  if (mntent.mnt_fsname)
+    {
+      real_fsname = realpath (mntent.mnt_fsname, NULL);
+      if (real_fsname)
+       mntent.mnt_fsname = real_fsname;
+    }
+  if (mntent.mnt_dir)
+    {
+      real_dir = realpath (mntent.mnt_dir, NULL);
+      if (real_dir)
+       mntent.mnt_dir = real_dir;
+    }
+
   /* Allocate space for all string mntent fields in FS.  */
-#define COUNT(field) if (mntent->field) needed += strlen (mntent->field) + 1;
+#define COUNT(field) if (mntent.field) needed += strlen (mntent.field) + 1;
   COUNT (mnt_fsname);
   COUNT (mnt_dir);
   COUNT (mnt_type);
@@ -258,10 +274,14 @@ fs_set_mntent (struct fs *fs, const struct mntent *mntent)
 
   fs->storage = malloc (needed);
   if (! fs->storage)
-    return ENOMEM;
+    {
+      free (real_fsname);
+      free (real_dir);
+      return ENOMEM;
+    }
 
-  if (!fs->mntent.mnt_dir || !mntent->mnt_dir
-      || strcmp (fs->mntent.mnt_dir, mntent->mnt_dir) != 0)
+  if (!fs->mntent.mnt_dir || !mntent.mnt_dir
+      || strcmp (fs->mntent.mnt_dir, mntent.mnt_dir) != 0)
     {
       fs->mounted = fs->readonly = -1;
       if (fs->fsys != MACH_PORT_NULL)
@@ -270,15 +290,15 @@ fs_set_mntent (struct fs *fs, const struct mntent *mntent)
     }
 
   /* Copy MNTENT into FS; string-valued fields will be fixed up next.  */
-  fs->mntent = *mntent;
+  fs->mntent = mntent;
 
   /* Copy each mntent field from MNTENT into FS's version.  */
   end = fs->storage;
 #define STORE(field) \
-  if (mntent->field)                           \
+  if (mntent.field)                            \
     {                                          \
       fs->mntent.field = end;                  \
-      end = stpcpy (end, mntent->field) + 1;   \
+      end = stpcpy (end, mntent.field) + 1;    \
     }                                          \
   else                                         \
     fs->mntent.field = 0;
@@ -289,10 +309,13 @@ fs_set_mntent (struct fs *fs, const struct mntent *mntent)
 #undef STORE
 
   if (fs->type
-      && (!mntent->mnt_type
-         || strcasecmp (fs->type->name, mntent->mnt_type) != 0))
+      && (!mntent.mnt_type
+         || strcasecmp (fs->type->name, mntent.mnt_type) != 0))
     fs->type = 0;              /* Type is different.  */
 
+  free (real_fsname);
+  free (real_dir);
+
   return 0;
 }
 
@@ -470,11 +493,21 @@ fstab_find_device (const struct fstab *fstab, const char 
*name)
   if (strcmp (name, "none") == 0)
     return NULL;
 
+  char *real_name = realpath (name, NULL);
+  const char *lookup_name;
+
+  if (real_name)
+    lookup_name = real_name;
+  else
+    lookup_name = name;
+
   struct fs *fs;
   for (fs = fstab->entries; fs; fs = fs->next)
-    if (strcmp (fs->mntent.mnt_fsname, name) == 0)
-      return fs;
-  return 0;
+    if (strcmp (fs->mntent.mnt_fsname, lookup_name) == 0)
+      break;
+
+  free (real_name);
+  return fs;
 }
 
 /* Returns the FS entry in FSTAB with the mount point NAME (there can only
@@ -482,8 +515,6 @@ fstab_find_device (const struct fstab *fstab, const char 
*name)
 inline struct fs *
 fstab_find_mount (const struct fstab *fstab, const char *name)
 {
-  struct fs *fs;
-
   /* Don't count "none" or "-" as matching any other mount point.
      It is canonical to use "none" for swap partitions, and multiple
      such do not in fact conflict with each other.  Likewise, the
@@ -494,10 +525,21 @@ fstab_find_mount (const struct fstab *fstab, const char 
*name)
       || !strcmp (name, "ignore"))
     return 0;
 
+  char *real_name = realpath (name, NULL);
+  const char *lookup_name;
+
+  if (real_name)
+    lookup_name = real_name;
+  else
+    lookup_name = name;
+
+  struct fs *fs;
   for (fs = fstab->entries; fs; fs = fs->next)
-    if (strcmp (fs->mntent.mnt_dir, name) == 0)
-      return fs;
-  return 0;
+    if (strcmp (fs->mntent.mnt_dir, lookup_name) == 0)
+      break;
+
+  free (real_name);
+  return fs;
 }
 
 /* Returns the FS entry in FSTAB with the device or mount point NAME (there
@@ -505,29 +547,7 @@ fstab_find_mount (const struct fstab *fstab, const char 
*name)
 inline struct fs *
 fstab_find (const struct fstab *fstab, const char *name)
 {
-  struct fs *ret;
-  char *real_name;
-
-  ret = fstab_find_device (fstab, name);
-  if (ret)
-    return ret;
-
-  ret = fstab_find_mount (fstab, name);
-  if (ret)
-    return ret;
-
-  real_name = realpath (name, NULL);
-
-  ret = fstab_find_device (fstab, real_name);
-  if (ret) {
-    free (real_name);
-    return ret;
-  }
-
-  ret = fstab_find_mount (fstab, real_name);
-  free (real_name);
-
-  return ret;
+  return fstab_find_device (fstab, name) ?: fstab_find_mount (fstab, name);
 }
 
 /* Cons FS onto the beginning of FSTAB's entry list.  */
@@ -690,6 +710,7 @@ fstab_read (struct fstab *fstab, const char *name)
     {
       while (!err && !feof (stream))
        {
+         errno = 0;
          struct mntent *mntent = getmntent (stream);
 
          if (! mntent)
diff --git a/utils/umount.c b/utils/umount.c
index cf6be22..4005029 100644
--- a/utils/umount.c
+++ b/utils/umount.c
@@ -292,8 +292,6 @@ main (int argc, char **argv)
            fs = fstab_find_device (fstab, t);
            if (! fs)
              {
-               error (0, 0, "could not find entry for: %s", t);
-
                /* As last resort, just assume it is the mountpoint.  */
                struct mntent m =
                  {
@@ -307,7 +305,7 @@ main (int argc, char **argv)
 
                err = fstab_add_mntent (fstab, &m, &fs);
                if (err)
-                 error (2, err, "%s", t);
+                 error (2, err, "could not find entry for: %s", t);
              }
          }
 

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