Merge pull request #805 from littlefs-project/fix-dir-seek-end

Fix issue where seeking to end-of-directory return LFS_ERR_INVAL

lfs.c

@@ -2712,11 +2712,6 @@ static int lfs_dir_rawseek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
     dir->id = (off > 0 && lfs_pair_cmp(dir->head, lfs->root) == 0);
 
     while (off > 0) {
-        int diff = lfs_min(dir->m.count - dir->id, off);
-        dir->id += diff;
-        dir->pos += diff;
-        off -= diff;
-
         if (dir->id == dir->m.count) {
             if (!dir->m.split) {
                 return LFS_ERR_INVAL;
@@ -2729,6 +2724,11 @@ static int lfs_dir_rawseek(lfs_t *lfs, lfs_dir_t *dir, lfs_off_t off) {
 
             dir->id = 0;
         }
+
+        int diff = lfs_min(dir->m.count - dir->id, off);
+        dir->id += diff;
+        dir->pos += diff;
+        off -= diff;
     }
 
     return 0;

tests/test_dirs.toml

@@ -810,7 +810,8 @@ code = '''
     }
     lfs_unmount(&lfs) => 0;
 
-    for (int j = 2; j < COUNT; j++) {
+    // try seeking to each dir entry
+    for (int j = 0; j < COUNT; j++) {
         lfs_mount(&lfs, cfg) => 0;
         lfs_dir_t dir;
         lfs_dir_open(&lfs, &dir, "hello") => 0;
@@ -822,16 +823,15 @@ code = '''
         assert(strcmp(info.name, "..") == 0);
         assert(info.type == LFS_TYPE_DIR);
 
-        lfs_soff_t pos;
         for (int i = 0; i < j; i++) {
             char path[1024];
             sprintf(path, "kitty%03d", i);
             lfs_dir_read(&lfs, &dir, &info) => 1;
             assert(strcmp(info.name, path) == 0);
             assert(info.type == LFS_TYPE_DIR);
-            pos = lfs_dir_tell(&lfs, &dir);
-            assert(pos >= 0);
         }
+        lfs_soff_t pos = lfs_dir_tell(&lfs, &dir);
+        assert(pos >= 0);
 
         lfs_dir_seek(&lfs, &dir, pos) => 0;
         char path[1024];
@@ -861,6 +861,52 @@ code = '''
         lfs_dir_close(&lfs, &dir) => 0;
         lfs_unmount(&lfs) => 0;
     }
+
+    // try seeking to end of dir
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "hello") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+
+    for (int i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "kitty%03d", i);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        assert(strcmp(info.name, path) == 0);
+        assert(info.type == LFS_TYPE_DIR);
+    }
+    lfs_soff_t pos = lfs_dir_tell(&lfs, &dir);
+    assert(pos >= 0);
+
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_seek(&lfs, &dir, pos) => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_rewind(&lfs, &dir) => 0;
+    char path[1024];
+    sprintf(path, "kitty%03d", 0);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, path) == 0);
+    assert(info.type == LFS_TYPE_DIR);
+
+    lfs_dir_seek(&lfs, &dir, pos) => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_close(&lfs, &dir) => 0;
+    lfs_unmount(&lfs) => 0;
 '''
 
 [cases.test_dirs_toot_seek]
@@ -877,7 +923,7 @@ code = '''
     }
     lfs_unmount(&lfs) => 0;
 
-    for (int j = 2; j < COUNT; j++) {
+    for (int j = 0; j < COUNT; j++) {
         lfs_mount(&lfs, cfg) => 0;
         lfs_dir_t dir;
         lfs_dir_open(&lfs, &dir, "/") => 0;
@@ -889,16 +935,15 @@ code = '''
         assert(strcmp(info.name, "..") == 0);
         assert(info.type == LFS_TYPE_DIR);
 
-        lfs_soff_t pos;
         for (int i = 0; i < j; i++) {
             char path[1024];
             sprintf(path, "hi%03d", i);
             lfs_dir_read(&lfs, &dir, &info) => 1;
             assert(strcmp(info.name, path) == 0);
             assert(info.type == LFS_TYPE_DIR);
-            pos = lfs_dir_tell(&lfs, &dir);
-            assert(pos >= 0);
         }
+        lfs_soff_t pos = lfs_dir_tell(&lfs, &dir);
+        assert(pos >= 0);
 
         lfs_dir_seek(&lfs, &dir, pos) => 0;
         char path[1024];
@@ -928,5 +973,51 @@ code = '''
         lfs_dir_close(&lfs, &dir) => 0;
         lfs_unmount(&lfs) => 0;
     }
+
+    // try seeking to end of dir
+    lfs_mount(&lfs, cfg) => 0;
+    lfs_dir_t dir;
+    lfs_dir_open(&lfs, &dir, "/") => 0;
+    struct lfs_info info;
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+
+    for (int i = 0; i < COUNT; i++) {
+        char path[1024];
+        sprintf(path, "hi%03d", i);
+        lfs_dir_read(&lfs, &dir, &info) => 1;
+        assert(strcmp(info.name, path) == 0);
+        assert(info.type == LFS_TYPE_DIR);
+    }
+    lfs_soff_t pos = lfs_dir_tell(&lfs, &dir);
+    assert(pos >= 0);
+
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_seek(&lfs, &dir, pos) => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_rewind(&lfs, &dir) => 0;
+    char path[1024];
+    sprintf(path, "hi%03d", 0);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, ".") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, "..") == 0);
+    assert(info.type == LFS_TYPE_DIR);
+    lfs_dir_read(&lfs, &dir, &info) => 1;
+    assert(strcmp(info.name, path) == 0);
+    assert(info.type == LFS_TYPE_DIR);
+
+    lfs_dir_seek(&lfs, &dir, pos) => 0;
+    lfs_dir_read(&lfs, &dir, &info) => 0;
+
+    lfs_dir_close(&lfs, &dir) => 0;
+    lfs_unmount(&lfs) => 0;
 '''