Avoid segmentation fault with NOTMUCH_CONFIG=/new/config/file notmuch setup

Since commit f41a35e2923b0b3ef2f66e91cd30e20b4c1a336a running a command
such as:

	NOTMUCH_CONFIG=/new/config/file notmuch setup

would result in a segmentation fault.

The purpose of that commit was to ensure that an attempt to manipulate
a non-standard database would not inadvertently manipulate the default
database only due to a typo in the NOTMUCH_CONFIG environment
variable. That is, a command like:

	NOTMUCH_CONFIG=mistyped-config-filename notmuch tag -new tag:new

shouldn't modify the database at ${HOME}/mail, but should instead
simply report that the mistype configuration filename does not exist.

We fix both cases simultaneously by reporting the error message
whenever the function calling notmuch_config_open is not explicitly
prepared for a default configuration file.

diff --git a/notmuch-config.c b/notmuch-config.c
index 58f83b0d299c8d4b6213758448bf1db69302b6b3..cf306039466b552f8196b3095ca3058616f801d2 100644 (file)
--- a/notmuch-config.c
+++ b/notmuch-config.c
@@ -151,26 +151,33 @@ get_username_from_passwd_file (void *ctx)
  * etc.), this function will print a message to stderr and return
  * NULL.
  *
- * Note: It is *not* an error if the specified configuration file does
- * not exist. In this case, a default configuration will be created
- * and returned. Subsequently calling notmuch_config_save will cause
- * the configuration to be written to the filename specified at the
- * time of notmuch_config_open.
+ * FILE NOT FOUND: When the specified configuration file (whether from
+ * 'filename' or the $NOTMUCH_CONFIG environment variable) does not
+ * exist, the behavior of this function depends on the 'is_new_ret'
+ * variable.
  *
- * The default configuration settings are determined as follows:
+ *     If is_new_ret is NULL, then a "file not found" message will be
+ *     printed to stderr and NULL will be returned.
+
+ *     If is_new_ret is non-NULL then a default configuration will be
+ *     returned and *is_new_ret will be set to 1 on return so that
+ *     the caller can recognize this case.
+ *
+ *     These default configuration settings are determined as
+ *     follows:
  *
- *     database_path:          $HOME/mail
+ *             database_path:          $HOME/mail
  *
- *     user_name:              From /etc/passwd
+ *             user_name:              From /etc/passwd
  *
- *     user_primary_mail:      $EMAIL variable if set, otherwise
- *                             constructed from the username and
- *                             hostname of the current machine.
+ *             user_primary_mail:      $EMAIL variable if set, otherwise
+ *                                     constructed from the username and
+ *                                     hostname of the current machine.
  *
- *     user_other_email:       Not set.
+ *             user_other_email:       Not set.
  *
- * The default configuration also contains comments to guide the user
- * in editing the file directly.
+ *     The default configuration also contains comments to guide the
+ *     user in editing the file directly.
  */
 notmuch_config_t *
 notmuch_config_open (void *ctx,
@@ -220,14 +227,19 @@ notmuch_config_open (void *ctx,
                                     G_KEY_FILE_KEEP_COMMENTS,
                                     &error))
     {
-       /* We are capable of dealing with a non-existent configuration
-        * file, so be silent about that (unless the user had set a
-        * non-default configuration file with the NOTMUCH_CONFIG
-        * variable)
+       /* If the caller passed a non-NULL value for is_new_ret, then
+        * the caller is prepared for a default configuration file in
+        * the case of FILE NOT FOUND. Otherwise, any read failure is
+        * an error.
         */
-       if (notmuch_config_env ||
-           !(error->domain == G_FILE_ERROR &&
-             error->code == G_FILE_ERROR_NOENT))
+       if (is_new_ret &&
+           error->domain == G_FILE_ERROR &&
+           error->code == G_FILE_ERROR_NOENT)
+       {
+           g_error_free (error);
+           is_new = 1;
+       }
+       else
        {
            fprintf (stderr, "Error reading configuration file %s: %s\n",
                     config->filename, error->message);
@@ -235,9 +247,6 @@ notmuch_config_open (void *ctx,
            g_error_free (error);
            return NULL;
        }
-
-       g_error_free (error);
-       is_new = 1;
     }
 
     /* Whenever we know of configuration sections that don't appear in