update: added options which control symlink behaviour

The configuration options "follow_outside_symlinks" and
"follow_inside_symlinks" let the user control whether MPD should
follow symbolic links in the music directory.

[mk: converted variables to "bool"; moved configuration to
update_global_init()]

doc/mpd.conf.5

@@ -35,6 +35,17 @@ This specifies the directory where music is located.
 .B playlist_directory <directory>
 This specifies the directory where saved playlists are stored.
 .TP
+.B follow_outside_symlinks <yes or no>
+Control if MPD will follow symbolic links pointing outside the music dir.
+You must recreate the database after changing this option.
+The default is "no".
+.TP
+.B follow_inside_symlinks <yes or no>
+Control if MPD will follow symbolic links pointing outside the music dir, potentially
+adding duplicates to the database.
+You must recreate the database after changing this option.
+The default is "yes".
+.TP
 .B db_file <file>
 This specifies where the db file will be stored.
 .TP

doc/mpdconf.example

@@ -7,6 +7,8 @@ playlist_directory              "~/.mpd/playlists"
 db_file                         "~/.mpd/mpd.db"
 log_file                        "~/.mpd/mpd.log"
 error_file                      "~/.mpd/mpd.error"
+#follow_outside_symlinks         "no"
+#follow_inside_symlinks          "yes"
 ################################################################
 
 

src/conf.c

@@ -145,6 +145,8 @@ void initConf(void)
 	/* registerConfigParam(name,                   repeatable, block); */
 	registerConfigParam(CONF_MUSIC_DIR,                     0,     0);
 	registerConfigParam(CONF_PLAYLIST_DIR,                  0,     0);
+	registerConfigParam(CONF_FOLLOW_INSIDE_SYMLINKS,        0,     0);
+	registerConfigParam(CONF_FOLLOW_OUTSIDE_SYMLINKS,       0,     0);
 	registerConfigParam(CONF_DB_FILE,                       0,     0);
 	registerConfigParam(CONF_LOG_FILE,                      0,     0);
 	registerConfigParam(CONF_ERROR_FILE,                    0,     0);

src/conf.h

@@ -23,6 +23,8 @@
 
 #define CONF_MUSIC_DIR                  "music_directory"
 #define CONF_PLAYLIST_DIR               "playlist_directory"
+#define CONF_FOLLOW_INSIDE_SYMLINKS     "follow_inside_symlinks"
+#define CONF_FOLLOW_OUTSIDE_SYMLINKS    "follow_outside_symlinks"
 #define CONF_DB_FILE                    "db_file"
 #define CONF_LOG_FILE                   "log_file"
 #define CONF_ERROR_FILE                 "error_file"

src/update.c

@@ -31,6 +31,7 @@
 #include "condition.h"
 #include "update.h"
 #include "idle.h"
+#include "conf.h"
 
 #include <glib.h>
 
@@ -56,6 +57,14 @@ static struct song *delete;
 
 static struct condition delete_cond;
 
+enum {
+	DEFAULT_FOLLOW_INSIDE_SYMLINKS = true,
+	DEFAULT_FOLLOW_OUTSIDE_SYMLINKS = false,
+};
+
+static bool follow_inside_symlinks;
+static bool follow_outside_symlinks;
+
 unsigned
 isUpdatingDB(void)
 {
@@ -337,19 +346,28 @@ skip_symlink(const struct directory *directory, const char *utf8_name)
 		/* don't skip if this is not a symlink */
 		return errno != EINVAL;
 
-	if (buffer[0] == '/')
+	if (!follow_inside_symlinks && !follow_outside_symlinks) {
+		/* ignore all symlinks */
+		return true;
+	} else if (follow_inside_symlinks && follow_outside_symlinks) {
+		/* consider all symlinks */
 		return false;
+	}
+
+	if (buffer[0] == '/')
+		return !follow_outside_symlinks;
 
 	p = buffer;
 	while (*p == '.') {
 		if (p[1] == '.' && p[2] == '/') {
 			/* "../" moves to parent directory */
 			directory = directory->parent;
-			if (directory == NULL)
+			if (directory == NULL) {
 				/* we have moved outside the music
-				   directory - don't skip this
+				   directory - skip this symlink
-				   symlink */
+				   if such symlinks are not allowed */
-				return false;
+				return !follow_outside_symlinks;
+			}
 			p += 3;
 		} else if (p[1] == '/')
 			/* eliminate "./" */
@@ -359,8 +377,9 @@ skip_symlink(const struct directory *directory, const char *utf8_name)
 	}
 
 	/* we are still in the music directory, so this symlink points
-	   to a song which is already in the database - skip it */
+	   to a song which is already in the database - skip according
-	return true;
+	   to the follow_inside_symlinks param*/
+	return !follow_inside_symlinks;
 }
 
 static bool
@@ -583,6 +602,13 @@ void reap_update_task(void)
 
 void update_global_init(void)
 {
+	follow_inside_symlinks =
+		config_get_bool(CONF_FOLLOW_INSIDE_SYMLINKS,
+				DEFAULT_FOLLOW_INSIDE_SYMLINKS);
+
+	follow_outside_symlinks =
+		config_get_bool(CONF_FOLLOW_OUTSIDE_SYMLINKS,
+				DEFAULT_FOLLOW_OUTSIDE_SYMLINKS);
 }
 
 void update_global_finish(void)