Added implementation for "rename" on FAT file system

libraries/fs/fat/FATFileSystem.cpp

@@ -108,6 +108,15 @@ int FATFileSystem::remove(const char *filename) {
     return 0;
 }
 
+int FATFileSystem::rename(const char *oldname, const char *newname) {
+    FRESULT res = f_rename(oldname, newname);
+    if (res) {
+        debug_if(FFS_DBG, "f_rename() failed: %d\n", res);
+        return -1;
+    }
+    return 0;
+}
+
 int FATFileSystem::format() {
     FRESULT res = f_mkfs(_fsid, 0, 512); // Logical drive number, Partitioning rule, Allocation unit size (bytes per cluster)
     if (res) {

libraries/fs/fat/FATFileSystem.h

@@ -41,6 +41,7 @@ public:
 
     virtual FileHandle *open(const char* name, int flags);
     virtual int remove(const char *filename);
+    virtual int rename(const char *oldname, const char *newname);
     virtual int format();
     virtual DirHandle *opendir(const char *name);
     virtual int mkdir(const char *name, mode_t mode);

libraries/mbed/common/retarget.cpp

@@ -323,7 +323,15 @@ extern "C" int remove(const char *path) {
 }
 
 extern "C" int rename(const char *oldname, const char *newname) {
-    return -1;
+    FilePath fpOld(oldname);
+    FilePath fpNew(newname);
+    FileSystemLike *fsOld = fpOld.fileSystem();
+    FileSystemLike *fsNew = fpNew.fileSystem();
+
+    /* rename only if both files are on the same FS */
+    if (fsOld != fsNew || fsOld == NULL) return -1;
+
+    return fsOld->rename(fpOld.fileName(), fpNew.fileName());
 }
 
 extern "C" char *tmpnam(char *s) {