Prevent possible buffer overflow when locating album art.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16231 a1c6a512-1295-4272-9138-f99709370657

apps/misc.c

@@ -1125,17 +1125,31 @@ bool dir_exists(const char *path)
  * removes the extension of filename (if it doesn't start with a .)
  * puts the result in buffer
  */
-char *strip_extension(const char *filename, char *buffer)
+char *strip_extension(char* buffer, int buffer_size, const char *filename)
 {
-    int dotpos;
     char *dot = strrchr(filename, '.');
+    int len;
+    
+    if (buffer_size <= 0)
+    {
+        return NULL;
+    }
+
+    buffer_size--;  /* Make room for end nil */
+
     if (dot != 0 && filename[0] != '.')
     {
-        dotpos = dot - filename;
-        strncpy(buffer, filename, dotpos);
-        buffer[dotpos] = '\0';
+        len = dot - filename;
+        len = MIN(len, buffer_size);
+        strncpy(buffer, filename, len);
     }
     else
-        strcpy(buffer, filename);
+    {
+        len = buffer_size;
+        strncpy(buffer, filename, buffer_size);
+    }
+
+    buffer[len] = 0;
+
     return buffer;
 }

apps/misc.h

@@ -122,6 +122,6 @@ bool dir_exists(const char *path);
  * removes the extension of filename (if it doesn't start with a .)
  * puts the result in buffer
  */
-char *strip_extension(const char *filename, char *buffer);
+char *strip_extension(char* buffer, int buffer_size, const char *filename);
 
 #endif /* MISC_H */

apps/recorder/albumart.c

@@ -124,7 +124,7 @@ bool search_albumart_files(const struct mp3entry *id3, const char *size_string,
     albumlen = id3->album ? strlen(id3->album) : 0;
 
     /* the first file we look for is one specific to the track playing */
-    strip_extension(trackname, path);
+    strip_extension(path, sizeof(path) - strlen(size_string) - 4, trackname);
     strcat(path, size_string);
     strcat(path, ".bmp");
     found = file_exists(path);

apps/tree.c

@@ -163,7 +163,7 @@ static char * tree_get_filename(int selected_item, void * data, char *buffer)
 
     if(stripit)
     {
-        return(strip_extension(name, buffer));
+        return(strip_extension(buffer, MAX_PATH, name));
     }
     return(name);
 }