Option to constrain get_next_dir() to directories below global_settings.start_directory.

When enabled, if the user has set "Start File Browser Here" (config.cfg:
start directory) to anything other than root and "Auto-Change Directory"
is set to "Yes" or "Random", the directory returned when an auto change
is required will be constrained to the value of "start directory" or below.

Change-Id: Iaab773868c4cab5a54f6ae67bdb22e84642a9e4b
Reviewed-on: http://gerrit.rockbox.org/182
Reviewed-by: Nick Peskett <rockbox@peskett.co.uk>
Tested-by: Nick Peskett <rockbox@peskett.co.uk>

10 files changed, 157 insertions, 69 deletions

diff --git a/apps/lang/english.lang b/apps/lang/english.lang
index 627fda8b12..d428bee232 100644
--- a/apps/lang/english.lang
+++ b/apps/lang/english.lang
@@ -12993,3 +12993,17 @@
     *: "Restart Sleep Timer On Keypress"
   </voice>
 </phrase>
+<phrase>
+  id: LANG_CONSTRAIN_NEXT_FOLDER
+  desc: in settings_menu. Whether LANG_NEXT_FOLDER should be constrained to directories within LANG_SET_AS_START_DIR
+  user: core
+  <source>
+    *: "Constrain Auto-Change"
+  </source>
+  <dest>
+    *: "Constrain Auto-Change"
+  </dest>
+  <voice>
+    *: "Constrain Auto-Change"
+  </voice>
+</phrase>
diff --git a/apps/menus/playback_menu.c b/apps/menus/playback_menu.c
index d5b20d09f5..17b7e57d32 100644
--- a/apps/menus/playback_menu.c
+++ b/apps/menus/playback_menu.c
@@ -135,6 +135,8 @@ MENUITEM_SETTING(beep, &global_settings.beep ,NULL);
 MENUITEM_SETTING(spdif_enable, &global_settings.spdif_enable, NULL);
 #endif
 MENUITEM_SETTING(next_folder, &global_settings.next_folder, NULL);
+MENUITEM_SETTING(constrain_next_folder,
+                 &global_settings.constrain_next_folder, NULL);
 static int audioscrobbler_callback(int action,const struct menu_item_ex *this_item)
 {
     (void)this_item;
@@ -205,7 +207,7 @@ MAKE_MENU(playback_settings,ID2P(LANG_PLAYBACK),0,
 #ifdef HAVE_SPDIF_POWER
           &spdif_enable,
 #endif
-          &next_folder, &audioscrobbler, &cuesheet
+          &next_folder, &constrain_next_folder, &audioscrobbler, &cuesheet
 #ifdef HAVE_HEADPHONE_DETECTION
          ,&unplug_menu
 #endif
diff --git a/apps/playback.c b/apps/playback.c
index 8fe43eb884..28f664357c 100644
--- a/apps/playback.c
+++ b/apps/playback.c
@@ -2644,8 +2644,17 @@ static void audio_on_skip(void)
     skip_pending = TRACK_SKIP_NONE;
 
     /* Update the playlist current track now */
-    while (playlist_next(playlist_delta) < 0)
+    int pl_retval;
+    while ((pl_retval = playlist_next(playlist_delta)) < 0)
     {
+        if (pl_retval < -1)
+        {
+            /* Some variety of fatal error while updating playlist */
+            filling = STATE_ENDED;
+            audio_stop_playback();
+            return;
+        }
+
         /* Manual skip out of range (because the playlist wasn't updated
            yet by us and so the check in audio_skip returned 'ok') - bring
            back into range */
diff --git a/apps/playlist.c b/apps/playlist.c
index bf55671bf1..5b5f489cde 100644
--- a/apps/playlist.c
+++ b/apps/playlist.c
@@ -175,7 +175,7 @@ static int compare(const void* p1, const void* p2);
 static int get_filename(struct playlist_info* playlist, int index, int seek,
                         bool control_file, char *buf, int buf_length);
 static int get_next_directory(char *dir);
-static int get_next_dir(char *dir, bool is_forward, bool recursion);
+static int get_next_dir(char *dir, bool is_forward);
 static int get_previous_directory(char *dir);
 static int check_subdir_for_music(char *dir, const char *subdir, bool recurse);
 static int format_track_path(char *dest, char *src, int buf_length, int max,
@@ -608,32 +608,33 @@ static int create_and_play_dir(int direction, bool play_last)
     else
       res = get_previous_directory(dir);
 
-    if (!res)
+    if (res < 0)
+        /* return the error encountered */
+        return res;
+
+    if (playlist_create(dir, NULL) != -1)
     {
-        if (playlist_create(dir, NULL) != -1)
-        {
-            ft_build_playlist(tree_get_context(), 0);
+        ft_build_playlist(tree_get_context(), 0);
 
-            if (global_settings.playlist_shuffle)
-                 playlist_shuffle(current_tick, -1);
+        if (global_settings.playlist_shuffle)
+             playlist_shuffle(current_tick, -1);
 
-            if (play_last && direction <= 0)
-                index = current_playlist.amount - 1;
-            else
-                index = 0;
+        if (play_last && direction <= 0)
+            index = current_playlist.amount - 1;
+        else
+            index = 0;
 
 #if (CONFIG_CODEC == SWCODEC)
-            current_playlist.started = true;
+        current_playlist.started = true;
 #else
-            playlist_start(index, 0);
+        playlist_start(index, 0);
 #endif
-        }
-
-        /* we've overwritten the dircache when getting the next/previous dir,
-           so the tree browser context will need to be reloaded */
-        reload_directory();
     }
 
+    /* we've overwritten the dircache when getting the next/previous dir,
+       so the tree browser context will need to be reloaded */
+    reload_directory();
+
     return index;
 }
 
@@ -1435,18 +1436,18 @@ static int get_filename(struct playlist_info* playlist, int index, int seek,
 }
 
 static int get_next_directory(char *dir){
-  return get_next_dir(dir,true,false);
+    return get_next_dir(dir, true);
 }
 
 static int get_previous_directory(char *dir){
-  return get_next_dir(dir,false,false);
+    return get_next_dir(dir, false);
 }
 
 /*
  * search through all the directories (starting with the current) to find
  * one that has tracks to play
  */
-static int get_next_dir(char *dir, bool is_forward, bool recursion)
+static int get_next_dir(char *dir, bool is_forward)
 {
     struct playlist_info* playlist = &current_playlist;
     int result = -1;
@@ -1454,6 +1455,27 @@ static int get_next_dir(char *dir, bool is_forward, bool recursion)
     bool exit = false;
     struct tree_context* tc = tree_get_context();
     int saved_dirfilter = *(tc->dirfilter);
+    unsigned int base_len;
+
+    if (global_settings.constrain_next_folder)
+    {
+        /* constrain results to directories below user's start directory */
+        strcpy(dir, global_settings.start_directory);
+        base_len = strlen(dir);
+
+        /* strip any trailing slash from base directory */
+        if (base_len > 0 && dir[base_len - 1] == '/')
+        {
+            base_len--;
+            dir[base_len] = '\0';
+        }
+    }
+    else
+    {
+        /* start from root directory */
+        dir[0] = '\0';
+        base_len = 0;
+    }
 
     /* process random folder advance */
     if (global_settings.next_folder == FOLDER_ADVANCE_RANDOM)
@@ -1461,43 +1483,46 @@ static int get_next_dir(char *dir, bool is_forward, bool recursion)
         int fd = open(ROCKBOX_DIR "/folder_advance_list.dat", O_RDONLY);
         if (fd >= 0)
         {
-            char buffer[MAX_PATH];
             int folder_count = 0;
-            srand(current_tick);
-            *(tc->dirfilter) = SHOW_MUSIC;
-            tc->sort_dir = global_settings.sort_dir;
             read(fd,&folder_count,sizeof(int));
-            if (!folder_count)
-                exit = true;
-            while (!exit)
+            if (folder_count)
             {
-                int i = rand()%folder_count;
-                lseek(fd,sizeof(int) + (MAX_PATH*i),SEEK_SET);
-                read(fd,buffer,MAX_PATH);
-                if (check_subdir_for_music(buffer, "", false) ==0)
-                    exit = true;
+                char buffer[MAX_PATH];
+                /* give up looking for a directory after we've had four
+                   times as many tries as there are directories. */
+                unsigned long allowed_tries = folder_count * 4;
+                int i;
+                srand(current_tick);
+                *(tc->dirfilter) = SHOW_MUSIC;
+                tc->sort_dir = global_settings.sort_dir;
+                while (!exit && allowed_tries--)
+                {
+                    i = rand() % folder_count;
+                    lseek(fd, sizeof(int) + (MAX_PATH * i), SEEK_SET);
+                    read(fd, buffer, MAX_PATH);
+                    /* is the current dir within our base dir and has music? */
+                    if ((base_len == 0 || !strncmp(buffer, dir, base_len))
+                        && check_subdir_for_music(buffer, "", false) == 0)
+                            exit = true;
+                }
+                close(fd);
+                *(tc->dirfilter) = saved_dirfilter;
+                tc->sort_dir = global_settings.sort_dir;
+                reload_directory();
+                if (exit)
+                {
+                    strcpy(dir,buffer);
+                    return 0;
+                }
             }
-            if (folder_count)
-                strcpy(dir,buffer);
-            close(fd);
-            *(tc->dirfilter) = saved_dirfilter;
-            tc->sort_dir = global_settings.sort_dir;
-            reload_directory();
-            return 0;
+            else
+                close(fd);
         }
     }
 
-    /* not random folder advance (or random folder advance unavailable) */
-    if (recursion)
-    {
-       /* start with root */
-       dir[0] = '\0';
-    }
-    else
-    {
-        /* start with current directory */
+    /* if the current file is within our base dir, use its dir instead */
+    if (base_len == 0 || !strncmp(playlist->filename, dir, base_len))
         strlcpy(dir, playlist->filename, playlist->dirlen);
-    }
 
     /* use the tree browser dircache to load files */
     *(tc->dirfilter) = SHOW_ALL;
@@ -1546,7 +1571,7 @@ static int get_next_dir(char *dir, bool is_forward, bool recursion)
                 exit = true;
                 break;
             }
-            
+
             if (files[i].attr & ATTR_DIRECTORY)
             {
                 if (!start_dir)
@@ -1566,16 +1591,30 @@ static int get_next_dir(char *dir, bool is_forward, bool recursion)
 
         if (!exit)
         {
-            /* move down to parent directory.  current directory name is
-               stored as the starting point for the search in parent */
-            start_dir = strrchr(dir, '/');
-            if (start_dir)
+            /* we've already descended to the base dir with nothing found,
+               check whether that contains music */
+            if (strlen(dir) <= base_len)
             {
-                *start_dir = '\0';
-                start_dir++;
+                result = check_subdir_for_music(dir, "", true);
+                if (result == -1)
+                    /* there's no music files in the base directory,
+                       treat as a fatal error */
+                    result = -2;
+                break;
             }
             else
-                break;
+            {
+                /* move down to parent directory.  current directory name is
+                   stored as the starting point for the search in parent */
+                start_dir = strrchr(dir, '/');
+                if (start_dir)
+                {
+                    *start_dir = '\0';
+                    start_dir++;
+                }
+                else
+                    break;
+            }
         }
     }
 
@@ -1583,11 +1622,6 @@ static int get_next_dir(char *dir, bool is_forward, bool recursion)
     *(tc->dirfilter) = saved_dirfilter;
     tc->sort_dir = global_settings.sort_dir;
 
-    /* special case if nothing found: try start searching again from root */
-    if (result == -1 && !recursion){
-        result = get_next_dir(dir, is_forward, true);
-    }
-
     return result;
 }
 
@@ -1606,7 +1640,12 @@ static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
     bool has_subdir = false;
     struct tree_context* tc = tree_get_context();
 
-    snprintf(dir+dirlen, MAX_PATH-dirlen, "/%s", subdir);
+    snprintf(
+        dir + dirlen, MAX_PATH - dirlen,
+        /* only add a trailing slash if we need one */
+        dirlen && dir[dirlen - 1] == '/' ? "%s" : "/%s",
+        subdir
+    );
     
     if (ft_load(tc, dir) < 0)
     {
diff --git a/apps/plugins/random_folder_advance_config.c b/apps/plugins/random_folder_advance_config.c
index f459aa0776..7f6018df4e 100644
--- a/apps/plugins/random_folder_advance_config.c
+++ b/apps/plugins/random_folder_advance_config.c
@@ -65,8 +65,15 @@ static void traversedir(char* location, char* name)
     bool check = false;
     int i;
 
-    rb->snprintf(fullpath, sizeof(fullpath), "%s/%s", location, name);
-    dir = rb->opendir(fullpath);
+    /* behave differently if we're at root to avoid
+       duplication of the initial slash later on */
+    if (location[0] == '\0' && name[0] == '\0') {
+        rb->strcpy(fullpath, "");
+        dir = rb->opendir("/");
+    } else {
+        rb->snprintf(fullpath, sizeof(fullpath), "%s/%s", location, name);
+        dir = rb->opendir(fullpath);
+    }
     if (dir) {
         entry = rb->readdir(dir);
         while (entry) {
diff --git a/apps/settings.h b/apps/settings.h
index 012e289d0c..777c7dbefe 100644
--- a/apps/settings.h
+++ b/apps/settings.h
@@ -590,6 +590,8 @@ struct user_settings
     /* playlist/playback settings */
     int  repeat_mode; /* 0=off 1=repeat all 2=repeat one 3=shuffle 4=ab */
     int  next_folder; /* move to next folder */
+    bool constrain_next_folder; /* whether next_folder is constrained to
+                                   directories within start_directory */
     int  recursive_dir_insert; /* should directories be inserted recursively */
     bool fade_on_stop; /* fade on pause/unpause/stop */
     bool playlist_shuffle;
diff --git a/apps/settings_list.c b/apps/settings_list.c
index 2258582a78..5acebef2a5 100644
--- a/apps/settings_list.c
+++ b/apps/settings_list.c
@@ -1328,6 +1328,9 @@ const struct settings_list settings[] = {
                    "folder navigation", "off,on,random",NULL ,3,
                    ID2P(LANG_SET_BOOL_NO), ID2P(LANG_SET_BOOL_YES),
                    ID2P(LANG_RANDOM)),
+    BOOL_SETTING(0, constrain_next_folder, LANG_CONSTRAIN_NEXT_FOLDER, false,
+                 "constrain next folder", off_on,
+                 LANG_SET_BOOL_YES, LANG_SET_BOOL_NO, NULL),
 
 #ifdef HAVE_TAGCACHE
 #if CONFIG_CODEC == SWCODEC 
diff --git a/manual/appendix/config_file_options.tex b/manual/appendix/config_file_options.tex
index 3db416ecfa..59148e15cc 100644
--- a/manual/appendix/config_file_options.tex
+++ b/manual/appendix/config_file_options.tex
@@ -145,6 +145,7 @@
     cuesheet support
                     & on, off           & N/A\\
     folder navigation & off, on, random & N/A\\
+    constrain next folder & off, on     & N/A\\
     gather runtime data & off, on       & N/A\\
     \opt{usb_charging_enable}{
       usb charging  & on, off, force    & N/A\\
diff --git a/manual/configure_rockbox/playback_options.tex b/manual/configure_rockbox/playback_options.tex
index b3a5c82ee6..bfc2f5c87a 100644
--- a/manual/configure_rockbox/playback_options.tex
+++ b/manual/configure_rockbox/playback_options.tex
@@ -221,8 +221,15 @@ you to configure settings related to audio playback.
 
   \note{This feature only works when songs have been played from the file
     browser.  Using it with the database may cause unexpected behaviour.}
+  %
 
+\section{\label{ref:ConstrainAutoChange}Constrain Auto-Change}
+  If enabled and you have set \setting{Start File Browser Here} to a directory
+  other than root, \setting{Auto-Change Directory} will be constrained to the
+  directory you have chosen and those below it.
+  See \reference{ref:StartFileBrowserHere}.
   %
+
 \opt{headphone_detection}{
 \section{Pause on Headphone Unplug}
   Enables and disables automatic pausing of 
diff --git a/manual/rockbox_interface/browsing_and_playing.tex b/manual/rockbox_interface/browsing_and_playing.tex
index d0144c261d..37d8cb01ca 100644
--- a/manual/rockbox_interface/browsing_and_playing.tex
+++ b/manual/rockbox_interface/browsing_and_playing.tex
@@ -188,9 +188,13 @@ each option pertains both to files and directories):
   \item [Set As Recording Directory.]
     Save recordings in the selected directory.
 }
-\item [Start File Browser Here.]
+\item [\label{ref:StartFileBrowserHere}Start File Browser Here.]
   This option allows users to set the currently selected directory as the default
   start directory for the file browser. This option is not available for files.
+  \note{If you have \setting{Auto-Change Directory} and
+  \setting{Constrain Auto-Change} enabled, the directories returned will
+  be constrained to the directory you have chosen here and those below it.
+  See \reference{ref:ConstrainAutoChange}}
 \item [Add to Shortcuts.]
   Adds a link to the selected item in the \fname{shortcuts.link} file.
   If the file does not already exist it will be created in the root directory.