fixes #292

src/spiffs_hydrogen.c

@@ -479,7 +479,9 @@ s32_t SPIFFS_write(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
   }
 
   if ((fd->flags & SPIFFS_O_APPEND)) {
-    fd->fdoffset = fd->size == SPIFFS_UNDEFINED_LEN ? 0 : fd->size;
+    if (fd->size != SPIFFS_UNDEFINED_LEN && fd->size > fd->fdoffset) {
+      fd->fdoffset = fd->size;
+    }
   }
   offset = fd->fdoffset;
 

src/test/test_bugreports.c

@@ -1231,6 +1231,23 @@ TEST(certain_file_size_fail_165) {
 } TEST_END
 
 
+TEST(multiple_unflushed_writes_fdoffset_tell_292)
+{
+  fs_reset_specific(0, 0, 64*1024, 4096, 4096, 256);
+
+  spiffs_file fh = SPIFFS_open(FS, "test.txt", SPIFFS_O_CREAT | SPIFFS_O_APPEND | SPIFFS_O_WRONLY, 0);
+  SPIFFS_write(FS, fh, "abcdefghij", 5);
+  SPIFFS_write(FS, fh, "abcdefghij", 8);
+  TEST_CHECK_EQ(13, SPIFFS_tell(FS, fh))
+  SPIFFS_write(FS, fh, "abcdefghij", 2);
+  SPIFFS_write(FS, fh, "abcdefghij", 2);
+  TEST_CHECK_EQ(17, SPIFFS_tell(FS, fh))
+  SPIFFS_close(FS, fh);
+  return TEST_RES_OK;
+}
+TEST_END
+
+
 SUITE_TESTS(bug_tests)
   ADD_TEST(nodemcu_full_fs_1)
   ADD_TEST(nodemcu_full_fs_2)
@@ -1253,6 +1270,7 @@ SUITE_TESTS(bug_tests)
   ADD_TEST(fuzzer_found_4)
   ADD_TEST(remove_release_fd_152)
   ADD_TEST(certain_file_size_fail_165)
+  ADD_TEST(multiple_unflushed_writes_fdoffset_tell_292)
   ADD_TEST_NON_DEFAULT(fuzzer_found_single_1)
   ADD_TEST_NON_DEFAULT(log_afl_test)
   ADD_TEST_NON_DEFAULT(afl_test)

src/test/test_hydrogen.c

@@ -2565,4 +2565,3 @@ SUITE_TESTS(hydrogen_tests)
 #endif
 
 SUITE_END(hydrogen_tests)
-