From 4086b915ebf7bc1a4ad4cec202ffb63682d1bfd0 Mon Sep 17 00:00:00 2001
From: David Zeuthen <davidz@redhat.com>
Date: Thu, 11 Aug 2011 17:17:50 -0400
Subject: [PATCH] Preserve mode_t of /etc/fstab and /etc/crypttab when updating

Signed-off-by: David Zeuthen <davidz@redhat.com>
---
 src/udiskslinuxblock.c | 140 ++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 126 insertions(+), 14 deletions(-)

diff --git a/src/udiskslinuxblock.c b/src/udiskslinuxblock.c
index cd9dc21..abc3a48 100644
--- a/src/udiskslinuxblock.c
+++ b/src/udiskslinuxblock.c
@@ -22,6 +22,10 @@
 #include <glib/gi18n-lib.h>
 
 #include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
 #include <pwd.h>
 #include <grp.h>
 #include <mntent.h>
@@ -485,6 +489,113 @@ out:
   return dest;
 }
 
+/* ---------------------------------------------------------------------------------------------------- */
+
+/* TODO: maybe move to GLib */
+static gboolean
+_g_file_set_contents_full (const gchar  *filename,
+                           const gchar  *contents,
+                           gssize        contents_len,
+                           gint          mode_for_new_file,
+                           GError      **error)
+{
+  gboolean ret;
+  struct stat statbuf;
+  gint mode;
+  gchar *tmpl;
+  gint fd;
+  FILE *f;
+
+  ret = FALSE;
+  tmpl = NULL;
+
+  if (stat (filename, &statbuf) != 0)
+    {
+      if (errno == ENOENT)
+        {
+          mode = mode_for_new_file;
+        }
+      else
+        {
+          g_set_error (error,
+                       G_IO_ERROR,
+                       g_io_error_from_errno (errno),
+                       "Error stat(2)'ing %s: %m",
+                       filename);
+          goto out;
+        }
+    }
+  else
+    {
+      mode = statbuf.st_mode;
+    }
+
+  tmpl = g_strdup_printf ("%s.XXXXXX", filename);
+  fd = g_mkstemp_full (tmpl, O_RDWR, mode);
+  if (fd == -1)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   g_io_error_from_errno (errno),
+                   "Error creating temporary file: %m");
+      goto out;
+    }
+
+  f = fdopen (fd, "w");
+  if (f == NULL)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   g_io_error_from_errno (errno),
+                   "Error calling fdopen: %m");
+      g_unlink (tmpl);
+      goto out;
+    }
+
+  if (contents_len < 0 )
+    contents_len = strlen (contents);
+  if (fwrite (contents, 1, contents_len, f) != contents_len)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   g_io_error_from_errno (errno),
+                   "Error calling fwrite on temp file: %m");
+      fclose (f);
+      g_unlink (tmpl);
+      goto out;
+    }
+
+  if (fsync (fileno (f)) != 0)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   g_io_error_from_errno (errno),
+                   "Error calling fsync on temp file: %m");
+      fclose (f);
+      g_unlink (tmpl);
+      goto out;
+    }
+  fclose (f);
+
+  if (rename (tmpl, filename) != 0)
+    {
+      g_set_error (error,
+                   G_IO_ERROR,
+                   g_io_error_from_errno (errno),
+                   "Error renaming temp file to final file: %m");
+      g_unlink (tmpl);
+      goto out;
+    }
+
+  ret = TRUE;
+
+ out:
+  g_free (tmpl);
+  return ret;
+}
+
+/* ---------------------------------------------------------------------------------------------------- */
+
 static gboolean
 add_remove_fstab_entry (GVariant  *remove,
                         GVariant  *add,
@@ -626,10 +737,11 @@ add_remove_fstab_entry (GVariant  *remove,
       g_free (escaped_opts);
     }
 
-  if (!g_file_set_contents ("/etc/fstab",
-                            str->str,
-                            -1,
-                            error) != 0)
+  if (!_g_file_set_contents_full ("/etc/fstab",
+                                  str->str,
+                                  -1,
+                                  0644, /* mode to use if non-existant */
+                                  error) != 0)
     goto out;
 
   ret = TRUE;
@@ -851,11 +963,11 @@ add_remove_crypttab_entry (GVariant  *remove,
                   goto out;
             }
 
-          /* TODO: XXX: would like to use mode 0600 here - umask(3) at start-up? */
-          if (!g_file_set_contents (filename,
-                                    add_passphrase_contents,
-                                    -1,
-                                    error))
+          if (!_g_file_set_contents_full (filename,
+                                          add_passphrase_contents,
+                                          -1,
+                                          0600, /* mode to use if non-existant */
+                                          error))
             {
               g_free (filename);
               goto out;
@@ -869,11 +981,11 @@ add_remove_crypttab_entry (GVariant  *remove,
                               add_options);
     }
 
-  /* TODO: XXX: ugh, the mode is wrong.. umask(3) at start-up? */
-  if (!g_file_set_contents ("/etc/crypttab",
-                            str->str,
-                            -1,
-                            error) != 0)
+  if (!_g_file_set_contents_full ("/etc/crypttab",
+                                  str->str,
+                                  -1,
+                                  0600, /* mode to use if non-existant */
+                                  error) != 0)
     goto out;
 
   ret = TRUE;
-- 
2.7.4