Spiffs filesystem magic, definable in config

Controlled in config by SPIFFS_USE_MAGIC, disabled by default
Initialization tests on all api functions, added functions

SPIFFS_format
SPIFFS_mounted

src/default/spiffs_config.h

@@ -111,14 +111,22 @@
 #define SPIFFS_COPY_BUFFER_STACK        (64)
 #endif
 
+// Enable this to have an identifiable spiffs filesystem. This will look for
+// a magic in all sectors to determine if this is a valid spiffs system or
+// not on mount point. If not, SPIFFS_format must be called prior to mounting
+// again.
+#ifndef SPIFFS_USE_MAGIC
+#define SPIFFS_USE_MAGIC                (0)
+#endif
+
 // SPIFFS_LOCK and SPIFFS_UNLOCK protects spiffs from reentrancy on api level
 // These should be defined on a multithreaded system
 
-// define this to entering a mutex if you're running on a multithreaded system
+// define this to enter a mutex if you're running on a multithreaded system
 #ifndef SPIFFS_LOCK
 #define SPIFFS_LOCK(fs)
 #endif
-// define this to exiting a mutex if you're running on a multithreaded system
+// define this to exit a mutex if you're running on a multithreaded system
 #ifndef SPIFFS_UNLOCK
 #define SPIFFS_UNLOCK(fs)
 #endif

src/spiffs.h

@@ -40,6 +40,13 @@ extern "C" {
 #define SPIFFS_ERR_NOT_WRITABLE         -10021
 #define SPIFFS_ERR_NOT_READABLE         -10022
 #define SPIFFS_ERR_CONFLICTING_NAME     -10023
+#define SPIFFS_ERR_NOT_CONFIGURED       -10024
+
+#define SPIFFS_ERR_NOT_A_FS             -10025
+#define SPIFFS_ERR_MOUNTED              -10026
+#define SPIFFS_ERR_ERASE_FAIL           -10027
+#define SPIFFS_ERR_MAGIC_NOT_POSSIBLE   -10028
+
 
 #define SPIFFS_ERR_INTERNAL             -10050
 
@@ -214,6 +221,11 @@ typedef struct {
 
   // check callback function
   spiffs_check_callback check_cb_f;
+
+  // mounted flag
+  u8_t mounted;
+  // config magic
+  u32_t config_magic;
 } spiffs;
 
 /* spiffs file status struct */
@@ -241,7 +253,10 @@ typedef struct {
 // functions
 
 /**
- * Initializes the file system dynamic parameters and mounts the filesystem
+ * Initializes the file system dynamic parameters and mounts the filesystem.
+ * If SPIFFS_USE_MAGIC is enabled the mounting may fail with SPIFFS_ERR_NOT_A_FS
+ * if the flash does not contain a recognizable file system.
+ * In this case, SPIFFS_format must be called prior to remounting.
  * @param fs            the file system struct
  * @param config        the physical and logical configuration of the file system
  * @param work          a memory work buffer comprising 2*config->log_page_size
@@ -440,6 +455,24 @@ s32_t SPIFFS_check(spiffs *fs);
  */
 s32_t SPIFFS_info(spiffs *fs, u32_t *total, u32_t *used);
 
+/**
+ * Formats the entire file system. All data will be lost.
+ * The filesystem must not be mounted when calling this.
+ *
+ * NB: formatting is awkward. Due to backwards compatibility, SPIFFS_mount
+ * MUST be called prior to formatting in order to configure the filesystem.
+ * If SPIFFS_mount succeeds, SPIFFS_unmount must be called before calling
+ * SPIFFS_format.
+ * If SPIFFS_mount fails, SPIFFS_format can be called directly without calling
+ * SPIFFS_unmount first.
+ */
+s32_t SPIFFS_format(spiffs *fs);
+
+/**
+ * Returns nonzero if spiffs is mounted, or zero if unmounted.
+ */
+u8_t SPIFFS_mounted(spiffs *fs);
+
 #if SPIFFS_TEST_VISUALISATION
 /**
  * Prints out a visualization of the filesystem.

src/spiffs_gc.c

@@ -8,31 +8,11 @@ static s32_t spiffs_gc_erase_block(
     spiffs *fs,
     spiffs_block_ix bix) {
   s32_t res;
-  u32_t addr = SPIFFS_BLOCK_TO_PADDR(fs, bix);
-  s32_t size = SPIFFS_CFG_LOG_BLOCK_SZ(fs);
 
   SPIFFS_GC_DBG("gc: erase block %i\n", bix);
-
+  res = spiffs_erase_block(fs, bix);
-  // here we ignore res, just try erasing the block
-  while (size > 0) {
-    SPIFFS_GC_DBG("gc: erase %08x:%08x\n", addr,  SPIFFS_CFG_PHYS_ERASE_SZ(fs));
-    (void)fs->cfg.hal_erase_f(addr, SPIFFS_CFG_PHYS_ERASE_SZ(fs));
-    addr += SPIFFS_CFG_PHYS_ERASE_SZ(fs);
-    size -= SPIFFS_CFG_PHYS_ERASE_SZ(fs);
-  }
-  fs->free_blocks++;
-
-  // register erase count for this block
-  res = _spiffs_wr(fs, SPIFFS_OP_C_WRTHRU | SPIFFS_OP_T_OBJ_LU2, 0,
-      SPIFFS_ERASE_COUNT_PADDR(fs, bix),
-      sizeof(spiffs_obj_id), (u8_t *)&fs->max_erase_count);
   SPIFFS_CHECK_RES(res);
 
-  fs->max_erase_count++;
-  if (fs->max_erase_count == SPIFFS_OBJ_ID_IX_FLAG) {
-    fs->max_erase_count = 0;
-  }
-
 #if SPIFFS_CACHE
   {
     u32_t i;

src/spiffs_hydrogen.c

@@ -21,6 +21,36 @@ u32_t SPIFFS_buffer_bytes_for_cache(spiffs *fs, u32_t num_pages) {
 #endif
 #endif
 
+u8_t SPIFFS_mounted(spiffs *fs) {
+  return SPIFFS_CHECK_MOUNT(fs);
+}
+
+s32_t SPIFFS_format(spiffs *fs) {
+  SPIFFS_API_CHECK_CFG(fs);
+  if (SPIFFS_CHECK_MOUNT(fs)) {
+    fs->err_code = SPIFFS_ERR_MOUNTED;
+    return -1;
+  }
+
+  s32_t res;
+  SPIFFS_LOCK(fs);
+
+  spiffs_block_ix bix = 0;
+  while (bix < fs->block_count) {
+    fs->max_erase_count = 0;
+    res = spiffs_erase_block(fs, bix);
+    if (res != SPIFFS_OK) {
+      res = SPIFFS_ERR_ERASE_FAIL;
+    }
+    SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
+    bix++;
+  }
+
+  SPIFFS_UNLOCK(fs);
+
+  return 0;
+}
+
 s32_t SPIFFS_mount(spiffs *fs, spiffs_config *config, u8_t *work,
     u8_t *fd_space, u32_t fd_space_size,
     void *cache, u32_t cache_size,
@@ -65,7 +95,16 @@ s32_t SPIFFS_mount(spiffs *fs, spiffs_config *config, u8_t *work,
   spiffs_cache_init(fs);
 #endif
 
-  s32_t res = spiffs_obj_lu_scan(fs);
+  s32_t res;
+
+#if SPIFFS_USE_MAGIC
+  res = SPIFFS_CHECK_MAGIC_POSSIBLE(fs) ? SPIFFS_OK : SPIFFS_ERR_MAGIC_NOT_POSSIBLE;
+  SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
+#endif
+
+  fs->config_magic = SPIFFS_CONFIG_MAGIC;
+
+  res = spiffs_obj_lu_scan(fs);
   SPIFFS_API_CHECK_RES_UNLOCK(fs, res);
 
   SPIFFS_DBG("page index byte len:         %i\n", SPIFFS_CFG_LOG_PAGE_SZ(fs));
@@ -79,13 +118,15 @@ s32_t SPIFFS_mount(spiffs *fs, spiffs_config *config, u8_t *work,
 
   fs->check_cb_f = check_cb_f;
 
+  fs->mounted = 1;
+
   SPIFFS_UNLOCK(fs);
 
   return 0;
 }
 
 void SPIFFS_unmount(spiffs *fs) {
-  if (!SPIFFS_CHECK_MOUNT(fs)) return;
+  if (!SPIFFS_CHECK_CFG(fs) || !SPIFFS_CHECK_MOUNT(fs)) return;
   SPIFFS_LOCK(fs);
   u32_t i;
   spiffs_fd *fds = (spiffs_fd *)fs->fd_space;
@@ -98,7 +139,8 @@ void SPIFFS_unmount(spiffs *fs) {
       spiffs_fd_return(fs, cur_fd->file_nbr);
     }
   }
-  fs->block_count = 0;
+  fs->mounted = 0;
+
   SPIFFS_UNLOCK(fs);
 }
 
@@ -112,6 +154,7 @@ void SPIFFS_clearerr(spiffs *fs) {
 
 s32_t SPIFFS_creat(spiffs *fs, char *path, spiffs_mode mode) {
   (void)mode;
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
   spiffs_obj_id obj_id;
@@ -127,6 +170,7 @@ s32_t SPIFFS_creat(spiffs *fs, char *path, spiffs_mode mode) {
 
 spiffs_file SPIFFS_open(spiffs *fs, char *path, spiffs_flags flags, spiffs_mode mode) {
   (void)mode;
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -185,6 +229,7 @@ spiffs_file SPIFFS_open(spiffs *fs, char *path, spiffs_flags flags, spiffs_mode
 }
 
 spiffs_file SPIFFS_open_by_dirent(spiffs *fs, struct spiffs_dirent *e, spiffs_flags flags, spiffs_mode mode) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -214,6 +259,7 @@ spiffs_file SPIFFS_open_by_dirent(spiffs *fs, struct spiffs_dirent *e, spiffs_fl
 }
 
 s32_t SPIFFS_read(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -282,6 +328,7 @@ static s32_t spiffs_hydro_write(spiffs *fs, spiffs_fd *fd, void *buf, u32_t offs
 }
 
 s32_t SPIFFS_write(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -400,6 +447,7 @@ s32_t SPIFFS_write(spiffs *fs, spiffs_file fh, void *buf, s32_t len) {
 }
 
 s32_t SPIFFS_lseek(spiffs *fs, spiffs_file fh, s32_t offs, int whence) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -444,6 +492,7 @@ s32_t SPIFFS_lseek(spiffs *fs, spiffs_file fh, s32_t offs, int whence) {
 }
 
 s32_t SPIFFS_remove(spiffs *fs, char *path) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -477,6 +526,7 @@ s32_t SPIFFS_remove(spiffs *fs, char *path) {
 }
 
 s32_t SPIFFS_fremove(spiffs *fs, spiffs_file fh) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -525,6 +575,7 @@ static s32_t spiffs_stat_pix(spiffs *fs, spiffs_page_ix pix, spiffs_file fh, spi
 }
 
 s32_t SPIFFS_stat(spiffs *fs, char *path, spiffs_stat *s) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -542,6 +593,7 @@ s32_t SPIFFS_stat(spiffs *fs, char *path, spiffs_stat *s) {
 }
 
 s32_t SPIFFS_fstat(spiffs *fs, spiffs_file fh, spiffs_stat *s) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -595,6 +647,7 @@ static s32_t spiffs_fflush_cache(spiffs *fs, spiffs_file fh) {
 }
 
 s32_t SPIFFS_fflush(spiffs *fs, spiffs_file fh) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   s32_t res = SPIFFS_OK;
 #if SPIFFS_CACHE_WR
@@ -608,6 +661,7 @@ s32_t SPIFFS_fflush(spiffs *fs, spiffs_file fh) {
 }
 
 void SPIFFS_close(spiffs *fs, spiffs_file fh) {
+  SPIFFS_API_CHECK_CFG(fs);
   if (!SPIFFS_CHECK_MOUNT(fs)) {
     fs->err_code = SPIFFS_ERR_NOT_MOUNTED;
     return;
@@ -623,6 +677,7 @@ void SPIFFS_close(spiffs *fs, spiffs_file fh) {
 }
 
 s32_t SPIFFS_rename(spiffs *fs, char *old, char *new) {
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -664,6 +719,7 @@ s32_t SPIFFS_rename(spiffs *fs, char *old, char *new) {
 
 spiffs_DIR *SPIFFS_opendir(spiffs *fs, char *name, spiffs_DIR *d) {
   (void)name;
+  SPIFFS_API_CHECK_CFG(fs);
   if (!SPIFFS_CHECK_MOUNT(fs)) {
     fs->err_code = SPIFFS_ERR_NOT_MOUNTED;
     return 0;
@@ -743,12 +799,14 @@ struct spiffs_dirent *SPIFFS_readdir(spiffs_DIR *d, struct spiffs_dirent *e) {
 }
 
 s32_t SPIFFS_closedir(spiffs_DIR *d) {
+  SPIFFS_API_CHECK_CFG(d->fs);
   SPIFFS_API_CHECK_MOUNT(d->fs);
   return 0;
 }
 
 s32_t SPIFFS_check(spiffs *fs) {
   s32_t res;
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -766,6 +824,7 @@ s32_t SPIFFS_check(spiffs *fs) {
 
 s32_t SPIFFS_info(spiffs *fs, u32_t *total, u32_t *used) {
   s32_t res = SPIFFS_OK;
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 
@@ -790,6 +849,7 @@ s32_t SPIFFS_info(spiffs *fs, u32_t *total, u32_t *used) {
 #if SPIFFS_TEST_VISUALISATION
 s32_t SPIFFS_vis(spiffs *fs) {
   s32_t res = SPIFFS_OK;
+  SPIFFS_API_CHECK_CFG(fs);
   SPIFFS_API_CHECK_MOUNT(fs);
   SPIFFS_LOCK(fs);
 

src/spiffs_nucleus.c

@@ -213,6 +213,45 @@ s32_t spiffs_obj_lu_find_entry_visitor(
   return SPIFFS_VIS_END;
 }
 
+s32_t spiffs_erase_block(
+    spiffs *fs,
+    spiffs_block_ix bix) {
+  s32_t res;
+  u32_t addr = SPIFFS_BLOCK_TO_PADDR(fs, bix);
+  s32_t size = SPIFFS_CFG_LOG_BLOCK_SZ(fs);
+
+  // here we ignore res, just try erasing the block
+  while (size > 0) {
+    SPIFFS_DBG("erase %08x:%08x\n", addr,  SPIFFS_CFG_PHYS_ERASE_SZ(fs));
+    (void)fs->cfg.hal_erase_f(addr, SPIFFS_CFG_PHYS_ERASE_SZ(fs));
+    addr += SPIFFS_CFG_PHYS_ERASE_SZ(fs);
+    size -= SPIFFS_CFG_PHYS_ERASE_SZ(fs);
+  }
+  fs->free_blocks++;
+
+  // register erase count for this block
+  res = _spiffs_wr(fs, SPIFFS_OP_C_WRTHRU | SPIFFS_OP_T_OBJ_LU2, 0,
+      SPIFFS_ERASE_COUNT_PADDR(fs, bix),
+      sizeof(spiffs_obj_id), (u8_t *)&fs->max_erase_count);
+  SPIFFS_CHECK_RES(res);
+
+#if SPIFFS_USE_MAGIC
+  // finally, write magic
+  spiffs_obj_id magic = SPIFFS_MAGIC(fs);
+  res = _spiffs_wr(fs, SPIFFS_OP_C_WRTHRU | SPIFFS_OP_T_OBJ_LU2, 0,
+      SPIFFS_MAGIC_PADDR(fs, bix),
+      sizeof(spiffs_obj_id), (u8_t *)&magic);
+  SPIFFS_CHECK_RES(res);
+#endif
+
+  fs->max_erase_count++;
+  if (fs->max_erase_count == SPIFFS_OBJ_ID_IX_FLAG) {
+    fs->max_erase_count = 0;
+  }
+
+  return res;
+}
+
 
 static s32_t spiffs_obj_lu_scan_v(
     spiffs *fs,
@@ -238,40 +277,44 @@ static s32_t spiffs_obj_lu_scan_v(
   return SPIFFS_VIS_COUNTINUE;
 }
 
+
 // Scans thru all obj lu and counts free, deleted and used pages
 // Find the maximum block erase count
+// Checks magic if enabled
 s32_t spiffs_obj_lu_scan(
     spiffs *fs) {
   s32_t res;
   spiffs_block_ix bix;
   int entry;
+#if SPIFFS_USE_MAGIC
+  spiffs_block_ix unerased_bix = (spiffs_block_ix)-1;
+#endif
 
-  fs->free_blocks = 0;
+  // find out erase count
-  fs->stats_p_allocated = 0;
+  // if enabled, check magic
-  fs->stats_p_deleted = 0;
-
-  res = spiffs_obj_lu_find_entry_visitor(fs,
-      0,
-      0,
-      0,
-      0,
-      spiffs_obj_lu_scan_v,
-      0,
-      0,
-      &bix,
-      &entry);
-
-  if (res == SPIFFS_VIS_END) {
-    res = SPIFFS_OK;
-  }
-
-  SPIFFS_CHECK_RES(res);
-
   bix = 0;
   spiffs_obj_id erase_count_final;
   spiffs_obj_id erase_count_min = SPIFFS_OBJ_ID_FREE;
   spiffs_obj_id erase_count_max = 0;
   while (bix < fs->block_count) {
+#if SPIFFS_USE_MAGIC
+    spiffs_obj_id magic;
+    res = _spiffs_rd(fs,
+        SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ,
+        0, SPIFFS_MAGIC_PADDR(fs, bix) ,
+        sizeof(spiffs_obj_id), (u8_t *)&magic);
+
+    SPIFFS_CHECK_RES(res);
+    if (magic != SPIFFS_MAGIC(fs)) {
+      if (unerased_bix == (spiffs_block_ix)-1) {
+        // allow one unerased block as it might be powered down during an erase
+        unerased_bix = bix;
+      } else {
+        // more than one unerased block, bail out
+        SPIFFS_CHECK_RES(SPIFFS_ERR_NOT_A_FS);
+      }
+    }
+#endif
     spiffs_obj_id erase_count;
     res = _spiffs_rd(fs,
         SPIFFS_OP_T_OBJ_LU2 | SPIFFS_OP_C_READ,
@@ -297,6 +340,38 @@ s32_t spiffs_obj_lu_scan(
 
   fs->max_erase_count = erase_count_final;
 
+#if SPIFFS_USE_MAGIC
+  if (unerased_bix != (spiffs_block_ix)-1) {
+    // found one unerased block, remedy
+    SPIFFS_DBG("mount: erase block %i\n", bix);
+    res = spiffs_erase_block(fs, unerased_bix);
+    SPIFFS_CHECK_RES(res);
+  }
+#endif
+
+  // count blocks
+
+  fs->free_blocks = 0;
+  fs->stats_p_allocated = 0;
+  fs->stats_p_deleted = 0;
+
+  res = spiffs_obj_lu_find_entry_visitor(fs,
+      0,
+      0,
+      0,
+      0,
+      spiffs_obj_lu_scan_v,
+      0,
+      0,
+      &bix,
+      &entry);
+
+  if (res == SPIFFS_VIS_END) {
+    res = SPIFFS_OK;
+  }
+
+  SPIFFS_CHECK_RES(res);
+
   return res;
 }
 

src/spiffs_nucleus.h

@@ -131,6 +131,10 @@
 #define SPIFFS_OBJ_ID_DELETED           ((spiffs_obj_id)0)
 #define SPIFFS_OBJ_ID_FREE              ((spiffs_obj_id)-1)
 
+#define SPIFFS_MAGIC(fs)                ((spiffs_obj_id)(0x20140529 ^ SPIFFS_CFG_LOG_PAGE_SZ(fs)))
+
+#define SPIFFS_CONFIG_MAGIC             (0x20090315)
+
 #if SPIFFS_SINGLETON == 0
 #define SPIFFS_CFG_LOG_PAGE_SZ(fs) \
   ((fs)->cfg.log_page_size)
@@ -189,9 +193,18 @@
 // returns data size in a data page
 #define SPIFFS_DATA_PAGE_SIZE(fs) \
     ( SPIFFS_CFG_LOG_PAGE_SZ(fs) - sizeof(spiffs_page_header) )
-// returns physical address for block's erase count
+// returns physical address for block's erase count,
+// always in the physical last entry of the last object lookup page
 #define SPIFFS_ERASE_COUNT_PADDR(fs, bix) \
   ( SPIFFS_BLOCK_TO_PADDR(fs, bix) + SPIFFS_OBJ_LOOKUP_PAGES(fs) * SPIFFS_CFG_LOG_PAGE_SZ(fs) - sizeof(spiffs_obj_id) )
+// returns physical address for block's magic,
+// always in the physical second last entry of the last object lookup page
+#define SPIFFS_MAGIC_PADDR(fs, bix) \
+  ( SPIFFS_BLOCK_TO_PADDR(fs, bix) + SPIFFS_OBJ_LOOKUP_PAGES(fs) * SPIFFS_CFG_LOG_PAGE_SZ(fs) - sizeof(spiffs_obj_id)*2 )
+// checks if there is any room for magic in the object luts
+#define SPIFFS_CHECK_MAGIC_POSSIBLE(fs) \
+  ( (SPIFFS_OBJ_LOOKUP_MAX_ENTRIES(fs) % (SPIFFS_CFG_LOG_PAGE_SZ(fs)/sizeof(spiffs_obj_id))) * sizeof(spiffs_obj_id) \
+    <= (SPIFFS_CFG_LOG_PAGE_SZ(fs)-sizeof(spiffs_obj_id)*2) )
 
 // define helpers object
 
@@ -238,7 +251,10 @@
 
 
 #define SPIFFS_CHECK_MOUNT(fs) \
-  ((fs)->block_count > 0)
+  ((fs)->mounted != 0)
+
+#define SPIFFS_CHECK_CFG(fs) \
+  ((fs)->config_magic == SPIFFS_CONFIG_MAGIC)
 
 #define SPIFFS_CHECK_RES(res) \
   do { \
@@ -251,6 +267,12 @@
     return -1; \
   }
 
+#define SPIFFS_API_CHECK_CFG(fs) \
+  if (!SPIFFS_CHECK_CFG((fs))) { \
+    (fs)->err_code = SPIFFS_ERR_NOT_CONFIGURED; \
+    return -1; \
+  }
+
 #define SPIFFS_API_CHECK_RES(fs, res) \
   if ((res) < SPIFFS_OK) { \
     (fs)->err_code = (res); \
@@ -484,6 +506,10 @@ s32_t spiffs_obj_lu_find_entry_visitor(
     spiffs_block_ix *block_ix,
     int *lu_entry);
 
+s32_t spiffs_erase_block(
+    spiffs *fs,
+    spiffs_block_ix bix);
+
 // ---------------
 
 s32_t spiffs_obj_lu_scan(

src/test/params_test.h

@@ -15,6 +15,9 @@
 // spiffs file system offset in emulated spi flash
 #define SPIFFS_PHYS_ADDR      (4*1024*1024)
 
+// test using filesystem magic
+//#define SPIFFS_USE_MAGIC    1
+
 #define SECTOR_SIZE         65536
 #define LOG_BLOCK           (SECTOR_SIZE*2)
 #define LOG_PAGE            (SECTOR_SIZE/256)

src/test/test_bugreports.c

@@ -157,4 +157,19 @@ TEST(nodemcu_full_fs_2) {
 
 } TEST_END(nodemcu_full_fs_2)
 
+TEST(magic_test) {
+  // one obj lu page, not full
+  fs_reset_specific(0, 4096*16, 4096, 4096*1, 128);
+  TEST_CHECK(SPIFFS_CHECK_MAGIC_POSSIBLE(FS));
+  // one obj lu page, full
+  fs_reset_specific(0, 4096*16, 4096, 4096*2, 128);
+  TEST_CHECK(!SPIFFS_CHECK_MAGIC_POSSIBLE(FS));
+  // two obj lu pages, not full
+  fs_reset_specific(0, 4096*16, 4096, 4096*4, 128);
+  TEST_CHECK(SPIFFS_CHECK_MAGIC_POSSIBLE(FS));
+
+  return TEST_RES_OK;
+
+} TEST_END(magic_test)
+
 SUITE_END(bug_tests)

src/test/test_spiffs.c

@@ -318,6 +318,7 @@ void fs_reset_specific(u32_t phys_addr, u32_t phys_size,
     u32_t log_block_size, u32_t log_page_size) {
   memset(area, 0xcc, sizeof(area));
   memset(&area[phys_addr], 0xff, phys_size);
+  memset(&__fs, 0, sizeof(__fs));
 
   spiffs_config c;
   c.hal_erase_f = _erase;
@@ -332,7 +333,20 @@ void fs_reset_specific(u32_t phys_addr, u32_t phys_size,
   memset(erases,0,sizeof(erases));
   memset(_cache,0,sizeof(_cache));
 
-  SPIFFS_mount(&__fs, &c, _work, _fds, sizeof(_fds), _cache, sizeof(_cache), spiffs_check_cb_f);
+  s32_t res = SPIFFS_mount(&__fs, &c, _work, _fds, sizeof(_fds), _cache, sizeof(_cache), spiffs_check_cb_f);
+#if SPIFFS_USE_MAGIC
+  if (res == SPIFFS_OK) {
+    SPIFFS_unmount(&__fs);
+  }
+  res = SPIFFS_format(&__fs);
+  if (res != SPIFFS_OK) {
+    printf("format failed, %i\n", SPIFFS_errno(&__fs));
+  }
+  res = SPIFFS_mount(&__fs, &c, _work, _fds, sizeof(_fds), _cache, sizeof(_cache), spiffs_check_cb_f);
+  if (res != SPIFFS_OK) {
+    printf("mount failed, %i\n", SPIFFS_errno(&__fs));
+  }
+#endif
 
   clear_flash_ops_log();
   log_flash_ops = 1;
@@ -574,6 +588,8 @@ void _teardown() {
   printf("  cache hits      : %i (sum %i)\n", (FS)->cache_hits, chits_tot);
   printf("  cache misses    : %i (sum %i)\n", (FS)->cache_misses, cmiss_tot);
   printf("  cache utiliz    : %f\n", ((float)chits_tot/(float)(chits_tot + cmiss_tot)));
+  chits_tot = 0;
+  cmiss_tot = 0;
 #endif
 #endif
   dump_flash_access_stats();