Fix track formatting problems in playlist.c

Some changes in behavior were made with filesystem code commit
for the sake of compatibility that changed expected behavior.

* Restore substitution of drive spec in fully-qualified DOS paths
with the playlists's volume spec (or root on univolume targets).
Drive-relative paths of the form "c:foo" (no separator after
':') will be treated as purely relative.

* Restore old behavior of preserving leading whitespace in the
source path and trimming only trailing tabs and spaces.

* Multivolume: Volume substition on fully-qualified UNIX/RB paths
has NOT been reintroduced (and perhaps wasn't intended in the
first place). They will not be modified because there is no
ambiguity to resolve. Doing so would prevent a playlist on
external storage from referencing a file on main storage without
qualifying it with "/<0>...".

* Plain relative paths are and always have been interpreted as
relative to the location of the playlist.

Change-Id: Ic0800cea79c59563b7bac20f8b08abb5051906c7

apps/playlist.c

@@ -1712,23 +1712,59 @@ static int check_subdir_for_music(char *dir, const char *subdir, bool recurse)
 static ssize_t format_track_path(char *dest, char *src, int buf_length,
                                  const char *dir)
 {
-    size_t len;
+    size_t len = 0;
+
+    /* Look for the end of the string */
+    while (1)
+    {
+        int c = src[len];
+        if (c == '\n' || c == '\r' || c == '\0')
+            break;
+        len++;
+    }
+
+    /* Now work back killing white space */
+    while (len > 0)
+    {
+        int c = src[len - 1];
+        if (c != '\t' && c != ' ')
+            break;
+        len--;
+    }
 
-    /* strip whitespace at beginning and end */
-    len = path_trim_whitespace(src, (const char **)&src);
     src[len] = '\0';
 
-    /* replace backslashes with forward slashes */
+    /* Replace backslashes with forward slashes */
     path_correct_separators(src, src);
 
-    /* handle DOS style drive letter and parse non-greedily so that:
-     * 1) "c:/foo" becomes "/foo" and the result is absolute
-     * 2) "c:foo becomes "foo" and the result is relative
-     * This is how Windows seems to handle it except drive letters are of no
-     * meaning here. */
-    path_strip_drive(src, (const char **)&src, false);
+    /* Drive letters have no meaning here; handle DOS style drive letter
+     * and parse greedily so that:
+     *
+     * 1) "c:/foo" is fully qualified, use directory volume only
+     * 2) "c:foo" is relative to current directory on C, use directory path
+     *
+     * Assume any volume on the beginning of the directory path is actually
+     * the volume on which it resides. This may not be the case if the dir
+     * param contains a path such as "/<1>/foo/../../<0>/bar", which refers
+     * to "/<0>/bar" (aka "/bar" at this time). *fingers crossed*
+     *
+     * If any stripped drive spec was absolute, prepend the playlist
+     * directory's volume spec, or root if none. Relative paths remain
+     * relative and the playlist's directory fully qualifies them. Absolute
+     * UNIX-style paths remain unaltered.
+     */
+    if (path_strip_drive(src, (const char **)&src, true) >= 0 &&
+        src[-1] == PATH_SEPCH)
+    {
+    #ifdef HAVE_MULTIVOLUME
+        const char *p;
+        path_strip_volume(dir, &p, false);
+        dir = strmemdupa(dir, p - dir); /* empty if no volspec on dir */
+    #else
+        dir = "";                       /* only volume is root */
+    #endif
+    }
 
-    /* prepends directory only if src is relative */
     len = path_append(dest, *dir ? dir : PATH_ROOTSTR, src, buf_length);
     if (len >= (size_t)buf_length)
         return -1; /* buffer too small */

firmware/common/pathfuncs.c

@@ -197,35 +197,6 @@ int path_strip_drive(const char *name, const char **nameptr, bool greedy)
     return -1;
 }
 
-/* Strips leading and trailing whitespace from a path
- * "  a/b \txyz"  *nameptr->a, len=3: "a/b"
- */
-size_t path_trim_whitespace(const char *name, const char **nameptr)
-{
-    /* NOTE: this won't currently treat DEL (0x7f) as non-printable */
-    const unsigned char *p = name;
-    int c;
-
-    while ((c = *p) <= ' ' && c)
-        ++p;
-
-    const unsigned char *first = p;
-    const unsigned char *last = p;
-
-    while (1)
-    {
-        if (c < ' ')
-        {
-            *nameptr = first;
-            return last - first;
-        }
-
-        while ((c = *++p) > ' ');
-        last = p;
-        while (c == ' ') c = *++p;
-    }
-}
-
 /* Strips directory components from the path
  * ""      *nameptr->NUL,   len=0: ""
  * "/"     *nameptr->/,     len=1: "/"

firmware/export/pathfuncs.h

@@ -78,7 +78,6 @@ int get_volume_name(int volume, char *name);
 #endif
 
 int path_strip_drive(const char *name, const char **nameptr, bool greedy);
-size_t path_trim_whitespace(const char *name, const char **nameptr);
 size_t path_basename(const char *name, const char **nameptr);
 size_t path_dirname(const char *name, const char **nameptr);
 size_t path_strip_trailing_separators(const char *name, const char **nameptr);