[pseudo] [PATCH v2 0/4] Add open_tree() wrapper

[pseudo] [PATCH v2 0/4] Add open_tree() wrapper

[frezidok1]

From: Dmitry Sakhonchik <frezidok1@gmail.com>

v2:
- Handle relative paths correctly in the open_tree wrapper
- Add fallback to SYS_open_tree when libc function is absent
- Add tests coverage with relative paths (dirfd != AT_FDCWD)
- Add support and tests for syscall(SYS_open_tree, ...)

Dmitry Sakhonchik (4):
  ports/linux/guts: Add open_tree wrapper
  test: Add open_tree test
  ports/linux/pseudo_wrappers.c: Add syscall support for open_tree()
    wrapper
  test: Add open_tree syscall test

 ports/linux/guts/open_tree.c   |  46 ++++++++++
 ports/linux/portdefs.h         |   9 ++
 ports/linux/pseudo_wrappers.c  |  14 +++
 ports/linux/wrapfuncs.in       |   1 +
 test/test-open_tree-syscall.c  | 152 +++++++++++++++++++++++++++++++++
 test/test-open_tree-syscall.sh |   5 ++
 test/test-open_tree.c          | 139 ++++++++++++++++++++++++++++++
 test/test-open_tree.sh         |   5 ++
 8 files changed, 371 insertions(+)
 create mode 100644 ports/linux/guts/open_tree.c
 create mode 100644 test/test-open_tree-syscall.c
 create mode 100755 test/test-open_tree-syscall.sh
 create mode 100644 test/test-open_tree.c
 create mode 100755 test/test-open_tree.sh

[pseudo] [PATCH v2 1/4] ports/linux/guts: Add open_tree wrapper

[frezidok1]

From: Dmitry Sakhonchik <frezidok1@gmail.com>

[YOCTO #16379]

OPEN_TREE_CLONE is not handled since it requires CAP_SYS_ADMIN and is outside the common pseudo use case.

Signed-off-by: Dmitry Sakhonchik <frezidok1@gmail.com>
---
 ports/linux/guts/open_tree.c | 46 ++++++++++++++++++++++++++++++++++++
 ports/linux/portdefs.h       |  9 +++++++
 ports/linux/wrapfuncs.in     |  1 +
 3 files changed, 56 insertions(+)
 create mode 100644 ports/linux/guts/open_tree.c

diff --git a/ports/linux/guts/open_tree.c b/ports/linux/guts/open_tree.c
new file mode 100644
index 0000000..6c2aad9
--- /dev/null
+++ b/ports/linux/guts/open_tree.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2026 Yocto Project
+ * guts/COPYRIGHT for information.
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ * int open_tree(int dirfd, const char *path, unsigned int flags)
+ *	int rc = -1;
+ */
+
+	struct stat64 buf;
+	int save_errno;
+	char *pseudo_path;
+
+	if (real_open_tree) {
+		pseudo_debug(PDBGF_SYSCALL, "open_tree, calling open_tree.\n");
+		rc = real_open_tree(dirfd, path, flags);
+	} else {
+		pseudo_debug(PDBGF_SYSCALL, "open_tree, calling syscall.\n");
+		rc = real_syscall(SYS_open_tree, dirfd, path, flags);
+	}
+
+	pseudo_path = pseudo_root_path(__func__, __LINE__, dirfd, path, 0);
+
+	if (rc != -1) {
+		save_errno = errno;
+		int stat_rc;
+
+		stat_rc = real___fxstatat64(_STAT_VER, dirfd, pseudo_path, &buf, (flags & AT_SYMLINK_NOFOLLOW) ? AT_SYMLINK_NOFOLLOW : 0);
+
+		pseudo_debug(PDBGF_FILE, "open_tree(path %s), flags %o, stat rc %d, stat mode %o\n",
+			pseudo_path, flags, stat_rc, buf.st_mode);
+
+		if (stat_rc != -1) {
+			pseudo_client_op(OP_OPEN, 0, rc, dirfd, pseudo_path, &buf);
+		} else {
+			pseudo_debug(PDBGF_FILE, "open_tree(fd %d, path %d/%s, flags %d) succeeded, but stat failed (%s).\n",
+				rc, dirfd, pseudo_path, flags, strerror(errno));
+			pseudo_client_op(OP_OPEN, 0, rc, dirfd, pseudo_path, 0);
+		}
+		errno = save_errno;
+	}
+
+/*	return rc;
+ * }
+ */
diff --git a/ports/linux/portdefs.h b/ports/linux/portdefs.h
index 1f1a41a..565fed9 100644
--- a/ports/linux/portdefs.h
+++ b/ports/linux/portdefs.h
@@ -82,3 +82,12 @@ extern int unshare(int flags);
 
 #define SYS_openat2 __NR_openat2
 #endif
+
+#ifndef SYS_open_tree
+
+#ifndef __NR_open_tree
+#define __NR_open_tree 428
+#endif
+
+#define SYS_open_tree __NR_open_tree
+#endif
diff --git a/ports/linux/wrapfuncs.in b/ports/linux/wrapfuncs.in
index 3cea20a..a51e9a0 100644
--- a/ports/linux/wrapfuncs.in
+++ b/ports/linux/wrapfuncs.in
@@ -10,6 +10,7 @@ int lchown(const char *path, uid_t owner, gid_t group); /* flags=AT_SYMLINK_NOFO
 int __fxstatat(int ver, int dirfd, const char *path, struct stat *buf, int flags);
 int openat(int dirfd, const char *path, int flags, ...{mode_t mode}); /* flags=((flags&O_NOFOLLOW)||((flags&(O_CREAT|O_EXCL))==(O_CREAT|O_EXCL))), noignore_path=1 */
 int __openat_2(int dirfd, const char *path, int flags); /* flags=((flags&O_NOFOLLOW)||((flags&(O_CREAT|O_EXCL))==(O_CREAT|O_EXCL))), noignore_path=1 */
+int open_tree(int dirfd, const char *path, unsigned int flags); /* noignore_path=1 */
 int mknod(const char *path, mode_t mode, dev_t dev); /* real_func=pseudo_mknod */
 int mknodat(int dirfd, const char *path, mode_t mode, dev_t dev); /* real_func=pseudo_mknodat */
 int __xmknod(int ver, const char *path, mode_t mode, dev_t *dev); /* flags=AT_SYMLINK_NOFOLLOW */

[pseudo] [PATCH v2 2/4] test: Add open_tree test

[frezidok1]

From: Dmitry Sakhonchik <frezidok1@gmail.com>

[YOCTO #16379]

Covers basic open_tree wrapper functionality and the AT_EMPTY_PATH case.

Signed-off-by: Dmitry Sakhonchik <frezidok1@gmail.com>
---
 test/test-open_tree.c  | 139 +++++++++++++++++++++++++++++++++++++++++
 test/test-open_tree.sh |   5 ++
 2 files changed, 144 insertions(+)
 create mode 100644 test/test-open_tree.c
 create mode 100755 test/test-open_tree.sh

diff --git a/test/test-open_tree.c b/test/test-open_tree.c
new file mode 100644
index 0000000..0fc02f4
--- /dev/null
+++ b/test/test-open_tree.c
@@ -0,0 +1,139 @@
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/mount.h>
+
+#define TEST_DIR "test-open-tree-dir"
+#define TEST_FILE "test-open-tree-file"
+
+static int test_no_flags(void) {
+    int treefd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    treefd = open_tree(AT_FDCWD, TEST_DIR, 0);
+    if (treefd == -1) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+out:
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static int test_relative_dirfd(void) {
+    int basefd = -1;
+    int treefd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    basefd = open(".", O_PATH | O_DIRECTORY);
+    if (basefd < 0) {
+        perror("open");
+        goto out;
+    }
+
+    treefd = open_tree(basefd, TEST_DIR, 0);
+    if (treefd < 0) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+out:
+    if (basefd != -1) {
+        close(basefd);
+    }
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static int test_at_empty_path(void) {
+    int treefd = -1;
+    int dirfd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    dirfd = open(TEST_DIR, O_PATH | O_DIRECTORY);
+    if (dirfd < 0) {
+        perror("open");
+        goto out;
+    }
+
+    treefd = open_tree(dirfd, "", AT_EMPTY_PATH);
+    if (treefd == -1) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+out:
+    if (dirfd != -1) {
+        close(dirfd);
+    }
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static void cleanup(void) {
+    if (unlink(TEST_DIR "/" TEST_FILE) == -1 && errno != ENOENT) {
+        perror("unlink");
+    }
+    if (rmdir(TEST_DIR) == -1 && errno != ENOENT) {
+        perror("rmdir");
+    }
+}
+
+int main(void) {
+    cleanup();
+
+    if (mkdir(TEST_DIR, 0777) == -1) {
+        perror("mkdir");
+        return 1;
+    }
+
+    int rc = test_no_flags() || test_at_empty_path() || test_relative_dirfd();
+
+    cleanup();
+
+    return rc;
+}
diff --git a/test/test-open_tree.sh b/test/test-open_tree.sh
new file mode 100755
index 0000000..1654a0b
--- /dev/null
+++ b/test/test-open_tree.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+./test/test-open_tree
+
+PSEUDO_IGNORE_PATHS=/ ./test/test-open_tree
\ No newline at end of file

[pseudo] [PATCH v2 3/4] ports/linux/pseudo_wrappers.c: Add syscall support for open_tree() wrapper

[frezidok1]

From: Dmitry Sakhonchik <frezidok1@gmail.com>

[YOCTO #16379]

Signed-off-by: Dmitry Sakhonchik <frezidok1@gmail.com>
---
 ports/linux/pseudo_wrappers.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/ports/linux/pseudo_wrappers.c b/ports/linux/pseudo_wrappers.c
index b920cb2..33cba2d 100644
--- a/ports/linux/pseudo_wrappers.c
+++ b/ports/linux/pseudo_wrappers.c
@@ -102,6 +102,20 @@ syscall(long number, ...) {
 #error SYS_openat2 not defined
 #endif
 
+#ifdef SYS_open_tree
+	if (number == SYS_open_tree) {
+		pseudo_debug(PDBGF_SYSCALL, "syscall, faking open_tree.\n");
+		va_start(ap, number);
+		int dirfd = va_arg(ap, int);
+		const char *path = va_arg(ap, const char*);
+		unsigned int flags = va_arg(ap, unsigned int);
+
+		return wrap_open_tree(dirfd, path, flags);
+	}
+#else
+#error SYS_open_tree not defined
+#endif
+
 #ifdef SYS_renameat2
         /* Call out wrapper, expanding the variable arguments first */
 	if (number == SYS_renameat2) {

[pseudo] [PATCH v2 4/4] test: Add open_tree syscall test

[frezidok1]

From: Dmitry Sakhonchik <frezidok1@gmail.com>

[YOCTO #16379]

Covers basic wrapper functionality when using syscall(SYS_open_tree, ...), also tests AT_EMPTY_PATH flag and related paths using dirfd != AT_FDCWD.

Signed-off-by: Dmitry Sakhonchik <frezidok1@gmail.com>
---
 test/test-open_tree-syscall.c  | 152 +++++++++++++++++++++++++++++++++
 test/test-open_tree-syscall.sh |   5 ++
 2 files changed, 157 insertions(+)
 create mode 100644 test/test-open_tree-syscall.c
 create mode 100755 test/test-open_tree-syscall.sh

diff --git a/test/test-open_tree-syscall.c b/test/test-open_tree-syscall.c
new file mode 100644
index 0000000..03f5618
--- /dev/null
+++ b/test/test-open_tree-syscall.c
@@ -0,0 +1,152 @@
+#define _GNU_SOURCE
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <sys/stat.h>
+
+#define TEST_DIR "test-open-tree-dir"
+#define TEST_FILE "test-open-tree-file"
+
+static int do_open_tree_syscall(int dirfd, const char *path,
+                unsigned int flags)
+{
+#ifdef SYS_open_tree
+    return syscall(SYS_open_tree, dirfd, path, flags);
+#elif defined(__NR_open_tree)
+    return syscall(__NR_open_tree, dirfd, path, flags);
+#else
+    errno = ENOSYS;
+    return -1;
+#endif
+}
+
+static int test_no_flags(void) {
+    int treefd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    treefd = do_open_tree_syscall(AT_FDCWD, TEST_DIR, 0);
+    if (treefd == -1) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+out:
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static int test_relative_dirfd(void) {
+    int basefd = -1;
+    int treefd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    basefd = open(".", O_PATH | O_DIRECTORY);
+    if (basefd < 0) {
+        perror("open");
+        goto out;
+    }
+
+    treefd = do_open_tree_syscall(basefd, TEST_DIR, 0);
+    if (treefd < 0) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+    out:
+        if (basefd != -1) {
+            close(basefd);
+        }
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static int test_at_empty_path(void) {
+    int treefd = -1;
+    int dirfd = -1;
+    int fd = -1;
+    int rc = 1;
+
+    dirfd = open(TEST_DIR, O_PATH | O_DIRECTORY);
+    if (dirfd < 0) {
+        perror("open");
+        goto out;
+    }
+
+    treefd = do_open_tree_syscall(dirfd, "", AT_EMPTY_PATH);
+    if (treefd == -1) {
+        perror("open_tree");
+        goto out;
+    }
+
+    fd = openat(treefd, TEST_FILE, O_CREAT | O_RDWR, 0666);
+    if (fd < 0) {
+        perror("openat");
+        goto out;
+    }
+
+    rc = 0;
+out:
+    if (dirfd != -1) {
+        close(dirfd);
+    }
+    if (treefd != -1) {
+        close(treefd);
+    }
+    if (fd != -1) {
+        close(fd);
+    }
+    return rc;
+}
+
+static void cleanup(void) {
+    if (unlink(TEST_DIR "/" TEST_FILE) == -1 && errno != ENOENT) {
+        perror("unlink");
+    }
+    if (rmdir(TEST_DIR) == -1 && errno != ENOENT) {
+        perror("rmdir");
+    }
+}
+
+int main(void) {
+    cleanup();
+
+    if (mkdir(TEST_DIR, 0777) == -1) {
+        perror("mkdir");
+        return 1;
+    }
+
+    int rc = test_no_flags() || test_at_empty_path() || test_relative_dirfd();
+
+    cleanup();
+
+    return rc;
+}
diff --git a/test/test-open_tree-syscall.sh b/test/test-open_tree-syscall.sh
new file mode 100755
index 0000000..3cb4d96
--- /dev/null
+++ b/test/test-open_tree-syscall.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+./test/test-open_tree-syscall
+
+PSEUDO_IGNORE_PATHS=/ ./test/test-open_tree-syscall
\ No newline at end of file