[PATCH v3] selftest: acct: Add selftest for the acct() syscall

[Abdulrasaq Lawani]

The acct() system call enables or disables process accounting.
If accounting is turned on, records for each terminating process
are appended to a specified filename as it terminates. An argument of NULL
causes accounting to be turned off.

This patch will add a test for the acct() syscall.

Signed-off-by: Abdulrasaq Lawani <abdulrasaqolawani@xxxxxxxxx>
---
Changes in v3:
- Add geteuid to check if test is ran as root.
- Simplify error conditions for acct function.
- Remove unecessary messages.
- Add more informative messages. 
- Update commit message.
- Add error test case for file creation failure.
- Link to v2: https://lore.kernel.org/r/20240630-kselftest-acct-syscall-v2-1-b30bbe2a69cd@xxxxxxxxx

Changes in v2:
Add testcases to test error conditions.
Add kselftest function for reporting results.

- Link to v1: https://lore.kernel.org/r/20240622-kselftest-acct-syscall-v1-1-d270b5be8d37@xxxxxxxxx
---
 tools/testing/selftests/Makefile            |  1 +
 tools/testing/selftests/acct/.gitignore     |  3 ++
 tools/testing/selftests/acct/Makefile       |  4 ++
 tools/testing/selftests/acct/acct_syscall.c | 78 +++++++++++++++++++++++++++++
 4 files changed, 86 insertions(+)

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 9039f3709aff..45a58ef5ad92 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+TARGETS += acct
 TARGETS += alsa
 TARGETS += amd-pstate
 TARGETS += arm64
diff --git a/tools/testing/selftests/acct/.gitignore b/tools/testing/selftests/acct/.gitignore
new file mode 100644
index 000000000000..7e78aac19038
--- /dev/null
+++ b/tools/testing/selftests/acct/.gitignore
@@ -0,0 +1,3 @@
+acct_syscall
+config
+process_log
\ No newline at end of file
diff --git a/tools/testing/selftests/acct/Makefile b/tools/testing/selftests/acct/Makefile
new file mode 100644
index 000000000000..ff3e238c5634
--- /dev/null
+++ b/tools/testing/selftests/acct/Makefile
@@ -0,0 +1,4 @@
+TEST_GEN_PROGS := acct_syscall
+CFLAGS += -Wall
+
+include ../lib.mk
\ No newline at end of file
diff --git a/tools/testing/selftests/acct/acct_syscall.c b/tools/testing/selftests/acct/acct_syscall.c
new file mode 100644
index 000000000000..e44e8fe1f4a3
--- /dev/null
+++ b/tools/testing/selftests/acct/acct_syscall.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* kselftest for acct() system call
+ *  The acct() system call enables or disables process accounting.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
+
+int main(void)
+{
+	char filename[] = "process_log";
+	FILE *fp;
+	pid_t child_pid;
+	int sz;
+
+	// Setting up kselftest framework
+	ksft_print_header();
+	ksft_set_plan(1);
+
+	// Check if test is run a root
+	if (geteuid()) {
+		ksft_test_result_skip("This test needs root to run!\n");
+		return 1;
+	}
+
+	// Create file to log closed processes
+	fp = fopen(filename, "w");
+
+	if (!fp) {
+		ksft_test_result_error("%s.\n", strerror(errno));
+		ksft_finished();
+		return 1;
+	}
+
+	acct(filename);
+
+	// Handle error conditions
+	if (errno) {
+		ksft_test_result_error("%s.\n", strerror(errno));
+		fclose(fp);
+		ksft_finished();
+		return 1;
+	}
+
+	// Create child process and wait for it to terminate.
+
+	child_pid = fork();
+
+	if (child_pid < 0) {
+		ksft_test_result_error("Creating a child process to log failed\n");
+		acct(NULL);
+		return 1;
+	} else if (child_pid > 0) {
+		wait(NULL);
+		fseek(fp, 0L, SEEK_END);
+		sz = ftell(fp);
+
+		acct(NULL);
+
+		if (sz <= 0) {
+			ksft_test_result_fail("Terminated child process not logged\n");
+			ksft_exit_fail();
+			return 1;
+		}
+
+		ksft_test_result_pass("Successfully logged terminated process.\n");
+		fclose(fp);
+		ksft_exit_pass();
+		return 0;
+	}
+
+	return 1;
+}

---
base-commit: 50736169ecc8387247fe6a00932852ce7b057083
change-id: 20240622-kselftest-acct-syscall-2d90f7666b1e

Best regards,
-- 
Abdulrasaq Lawani <abdulrasaqolawani@xxxxxxxxx>