Improve ff_write - save large blocks in chunks

mongoose.c

@@ -495,10 +495,6 @@ bool mg_file_printf(struct mg_fs *fs, const char *path, const char *fmt, ...) {
 #if MG_ENABLE_FATFS
 #include <ff.h>
 
-#if !defined(MG_FATFS_ROOT)
-#define MG_FATFS_ROOT "/"
-#endif
-
 static int ff_stat(const char *path, size_t *size, time_t *mtime) {
   FILINFO fi;
   if (path[0] == '\0' || strcmp(path, MG_FATFS_ROOT) == 0) {
@@ -554,9 +550,14 @@ static size_t ff_read(void *fp, void *buf, size_t len) {
 }
 
 static size_t ff_write(void *fp, const void *buf, size_t len) {
-  unsigned n = 0;
-  f_write((FIL *) fp, buf, len, &n);
-  return n;
+  unsigned n, sum = 0, bs = MG_FATFS_BSIZE;
+  while ((size_t) sum < len &&
+         f_write((FIL *) fp, (char *) buf + sum,
+                 sum + bs > len ? len - sum : bs, &n) == FR_OK &&
+         n > 0) {
+    sum += n;
+  }
+  return sum;
 }
 
 static size_t ff_seek(void *fp, size_t offset) {
@@ -1865,9 +1866,9 @@ int mg_http_upload(struct mg_connection *c, struct mg_http_message *hm,
       mg_http_reply(c, 400, "", "open(%s): %d", path, errno);
       return -2;
     } else {
-      fs->write(fd->fd, hm->body.ptr, hm->body.len);
+      int written = (int) fs->write(fd->fd, hm->body.ptr, hm->body.len);
       mg_fs_close(fd);
-      mg_http_reply(c, 200, "", "");
+      mg_http_reply(c, 200, "", "%d", written);
       return (int) hm->body.len;
     }
   }