Fix returning inode numbers from readdir() in offset==0 mode. (#584)

- Test added for all passthrough examples.
- passthrough.c uses offset==0 mode. The others don't.
- passthrough.c changed to set FUSE_FILL_DIR_PLUS to make the test pass.
- This fixes #583.

ChangeLog.rst

@@ -4,6 +4,7 @@ Unreleased Changes
 * Allow "nonempty" as a mount option, for backwards compatibility with
   fusermount 2. The option has no effect since mounting over non-empty
   directories is allowed by default.
+* Fix returning inode numbers from readdir() in offset==0 mode.
 
 libfuse 3.10.1 (2020-12-07)
 ===========================

example/passthrough.c

@@ -132,7 +132,7 @@ static int xmp_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
 		memset(&st, 0, sizeof(st));
 		st.st_ino = de->d_ino;
 		st.st_mode = de->d_type << 12;
-		if (filler(buf, de->d_name, &st, 0, 0))
+		if (filler(buf, de->d_name, &st, 0, FUSE_FILL_DIR_PLUS))
 			break;
 	}
 

lib/fuse.c

@@ -3566,7 +3566,7 @@ static int fill_dir_plus(void *dh_, const char *name, const struct stat *statp,
 		return 1;
 	}
 
-	if (off && statp && (flags & FUSE_FILL_DIR_PLUS)) {
+	if (statp && (flags & FUSE_FILL_DIR_PLUS)) {
 		e.attr = *statp;
 
 		if (!is_dot_or_dotdot(name)) {

test/meson.build

@@ -10,6 +10,9 @@ endforeach
 td += executable('test_syscalls', 'test_syscalls.c',
                  include_directories: include_dirs,
                  install: false)
+td += executable('readdir_inode', 'readdir_inode.c',
+                 include_directories: include_dirs,
+                 install: false)
 
 test_scripts = [ 'conftest.py', 'pytest.ini', 'test_examples.py',
                  'util.py', 'test_ctests.py' ]

test/readdir_inode.c

@@ -0,0 +1,45 @@
+/*
+ * Prints each directory entry and its inode as returned by 'readdir'.
+ * Skips '.' and '..' because readdir is not required to return them and
+ * some of our examples don't.
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <errno.h>
+
+int main(int argc, char* argv[])
+{
+    DIR* dirp;
+    struct dirent* dent;
+
+    if (argc != 2) {
+        fprintf(stderr, "Usage: readdir_inode dir\n");
+        return 1;
+    }
+
+    dirp = opendir(argv[1]);
+    if (dirp == NULL) {
+        perror("failed to open directory");
+        return 2;
+    }
+
+    errno = 0;
+    dent = readdir(dirp);
+    while (dent != NULL) {
+        if (strcmp(dent->d_name, ".") != 0 && strcmp(dent->d_name, "..") != 0) {
+            printf("%llu %s\n", (unsigned long long)dent->d_ino, dent->d_name);
+        }
+        dent = readdir(dirp);
+    }
+    if (errno != 0) {
+        perror("failed to read directory entry");
+        return 3;
+    }
+
+    closedir(dirp);
+
+    return 0;
+}

test/test_examples.py

@@ -72,6 +72,15 @@ class raii_tmpdir:
 def short_tmpdir():
     return raii_tmpdir()
 
+def readdir_inode(dir):
+    cmd = base_cmdline + [ pjoin(basename, 'test', 'readdir_inode'), dir ]
+    with subprocess.Popen(cmd, stdout=subprocess.PIPE,
+                          universal_newlines=True) as proc:
+        lines = proc.communicate()[0].splitlines()
+    lines.sort()
+    return lines
+
+
 @pytest.mark.parametrize("cmdline_builder", (invoke_directly, invoke_mount_fuse,
                                              invoke_mount_fuse_drop_privileges))
 @pytest.mark.parametrize("options", powerset(options))
@@ -602,6 +611,10 @@ def tst_readdir(src_dir, mnt_dir):
     listdir_should.sort()
     assert listdir_is == listdir_should
 
+    inodes_is = readdir_inode(mnt_newdir)
+    inodes_should = readdir_inode(src_newdir)
+    assert inodes_is == inodes_should
+
     os.unlink(file_)
     os.unlink(subfile)
     os.rmdir(subdir)
@@ -623,6 +636,10 @@ def tst_readdir_big(src_dir, mnt_dir):
     listdir_should = sorted(os.listdir(src_dir))
     assert listdir_is == listdir_should
 
+    inodes_is = readdir_inode(mnt_dir)
+    inodes_should = readdir_inode(src_dir)
+    assert inodes_is == inodes_should
+
     for fname in fnames:
         stat_src = os.stat(pjoin(src_dir, fname))
         stat_mnt = os.stat(pjoin(mnt_dir, fname))
@@ -631,7 +648,7 @@ def tst_readdir_big(src_dir, mnt_dir):
         assert stat_src.st_ctime == stat_mnt.st_ctime
         assert stat_src.st_size == stat_mnt.st_size
         os.unlink(pjoin(src_dir, fname))
-    
+
 def tst_truncate_path(mnt_dir):
     assert len(TEST_DATA) > 1024