tools/testing/selftests/pidfd/pidfd_file_handle_test.c

File Facts

System

Linux kernel

Corpus path

tools/testing/selftests/pidfd/pidfd_file_handle_test.c

Extension

.c

Size

14457 bytes

Lines

564

Domain

Support Tooling And Documentation

Bucket

tools

Inferred role

Support Tooling And Documentation: implementation source

Status

source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

• Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.
• Defines or uses C structs; map object ownership, embedded links, reference counts, and lock ownership.

Dependency Surface

• errno.h
• fcntl.h
• limits.h
• linux/types.h
• poll.h
• sched.h
• signal.h
• stdio.h
• stdlib.h
• string.h
• syscall.h
• sys/prctl.h
• sys/wait.h
• unistd.h
• sys/socket.h
• linux/kcmp.h
• sys/stat.h
• pidfd.h
• kselftest_harness.h

Detected Declarations

• function ASSERT_LT

Annotated Snippet

if (pidfd >= 0) {
			TH_LOG("Managed to open pidfd outside of the caller's pid namespace hierarchy");
			_exit(1);
		}
		_exit(0);
	}

	ASSERT_EQ(wait_for_pid(pid), 0);

	free(fh);
}

/*
 * Test that we can decode a pidfs file handle of a process that has
 * exited but not been reaped.
 */
TEST_F(file_handle, pid_has_exited)
{
	int mnt_id, pidfd, child_pidfd3;
	struct file_handle *fh;
	struct stat st1, st2;

	fh = malloc(sizeof(struct file_handle) + MAX_HANDLE_SZ);
	ASSERT_NE(fh, NULL);
	memset(fh, 0, sizeof(struct file_handle) + MAX_HANDLE_SZ);
	fh->handle_bytes = MAX_HANDLE_SZ;

	ASSERT_EQ(name_to_handle_at(self->child_pidfd3, "", fh, &mnt_id, AT_EMPTY_PATH), 0);

	ASSERT_EQ(fstat(self->child_pidfd3, &st1), 0);

	pidfd = open_by_handle_at(self->pidfd, fh, 0);
	ASSERT_GE(pidfd, 0);

	ASSERT_EQ(fstat(pidfd, &st2), 0);
	ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);

	ASSERT_EQ(close(pidfd), 0);

	child_pidfd3 = self->child_pidfd3;
	self->child_pidfd3 = -EBADF;
	EXPECT_EQ(sys_pidfd_send_signal(child_pidfd3, SIGKILL, NULL, 0), 0);
	EXPECT_EQ(close(child_pidfd3), 0);
	EXPECT_EQ(sys_waitid(P_PID, self->child_pid3, NULL, WEXITED | WNOWAIT), 0);

	pidfd = open_by_handle_at(self->pidfd, fh, 0);
	ASSERT_GE(pidfd, 0);

	EXPECT_EQ(sys_waitid(P_PID, self->child_pid3, NULL, WEXITED), 0);
}

/*
 * Test that we fail to decode a pidfs file handle of a process that has
 * already been reaped.
 */
TEST_F(file_handle, pid_has_been_reaped)
{
	int mnt_id, pidfd, child_pidfd3;
	struct file_handle *fh;
	struct stat st1, st2;

	fh = malloc(sizeof(struct file_handle) + MAX_HANDLE_SZ);
	ASSERT_NE(fh, NULL);
	memset(fh, 0, sizeof(struct file_handle) + MAX_HANDLE_SZ);
	fh->handle_bytes = MAX_HANDLE_SZ;

	ASSERT_EQ(name_to_handle_at(self->child_pidfd3, "", fh, &mnt_id, AT_EMPTY_PATH), 0);

	ASSERT_EQ(fstat(self->child_pidfd3, &st1), 0);

	pidfd = open_by_handle_at(self->pidfd, fh, 0);
	ASSERT_GE(pidfd, 0);

	ASSERT_EQ(fstat(pidfd, &st2), 0);
	ASSERT_TRUE(st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino);

	ASSERT_EQ(close(pidfd), 0);

	child_pidfd3 = self->child_pidfd3;
	self->child_pidfd3 = -EBADF;
	EXPECT_EQ(sys_pidfd_send_signal(child_pidfd3, SIGKILL, NULL, 0), 0);
	EXPECT_EQ(close(child_pidfd3), 0);
	EXPECT_EQ(sys_waitid(P_PID, self->child_pid3, NULL, WEXITED), 0);

	pidfd = open_by_handle_at(self->pidfd, fh, 0);
	ASSERT_LT(pidfd, 0);
}

/*
 * Test valid flags to open a pidfd file handle. Note, that

Annotation

• Immediate include surface: `errno.h`, `fcntl.h`, `limits.h`, `linux/types.h`, `poll.h`, `sched.h`, `signal.h`, `stdio.h`.
• Detected declarations: `function ASSERT_LT`.
• Atlas domain: Support Tooling And Documentation / tools.
• Implementation status: source implementation candidate.

Implementation Notes

• This generated page is the file-by-file coverage layer; curated subsystem chapters should link here when they synthesize a multi-file control flow.
• Core OS pages should be promoted from atlas-only to deep-reviewed when they explain data structures, invariants, locking, lifecycle, and C implementation snippets.
• Driver-family pages are intentionally pattern-oriented unless they are part of the selected PCIe/NVMe representative device path.