[LTP] [PATCH 2/2] syscalls/fanotify21: add new test checking the returned pidfd from fanotify in FAN_REPORT_PIDFD mode

[Amir Goldstein]

On Wed, Oct 27, 2021 at 12:45 PM Matthew Bobrowski <repnop@google.com> wrote:
>
> A new test that performs verification on the values returned within the
> struct fanotify_event_info_pidfd record when notification group intialized
> in FAN_REPORT_PIDFD mode.
>
> Signed-off-by: Matthew Bobrowski <repnop@google.com>
> ---
>  testcases/kernel/syscalls/fanotify/.gitignore |   1 +
>  .../kernel/syscalls/fanotify/fanotify21.c     | 363 ++++++++++++++++++
>  2 files changed, 364 insertions(+)
>  create mode 100644 testcases/kernel/syscalls/fanotify/fanotify21.c
>
> diff --git a/testcases/kernel/syscalls/fanotify/.gitignore b/testcases/kernel/syscalls/fanotify/.gitignore
> index c99e6fff7..35e73b91e 100644
> --- a/testcases/kernel/syscalls/fanotify/.gitignore
> +++ b/testcases/kernel/syscalls/fanotify/.gitignore
> @@ -18,4 +18,5 @@
>  /fanotify18
>  /fanotify19
>  /fanotify20
> +/fanotify21
>  /fanotify_child
> diff --git a/testcases/kernel/syscalls/fanotify/fanotify21.c b/testcases/kernel/syscalls/fanotify/fanotify21.c
> new file mode 100644
> index 000000000..f64f8fef4
> --- /dev/null
> +++ b/testcases/kernel/syscalls/fanotify/fanotify21.c
> @@ -0,0 +1,363 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2021 Google. All Rights Reserved.
> + *
> + * Started by Matthew Bobrowski <repnop@google.com>
> + */
> +
> +/*\
> + * [Description]
> + *
> + * A test which verifies whether the returned struct
> + * fanotify_event_info_pidfd in FAN_REPORT_PIDFD mode contains the
> + * expected set of information.
> + */
> +
> +#define _GNU_SOURCE
> +#include <stdio.h>
> +#include <ctype.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include "tst_test.h"
> +#include "tst_safe_stdio.h"
> +#include "lapi/pidfd_open.h"
> +
> +#ifdef HAVE_SYS_FANOTIFY_H
> +#include "fanotify.h"
> +
> +#define BUF_SZ         4096
> +#define MOUNT_PATH     "fs_mnt"
> +#define TEST_FILE      MOUNT_PATH "/testfile"
> +
> +struct pidfd_fdinfo_t {
> +       int pos;
> +       int flags;
> +       int mnt_id;
> +       int pid;
> +       int ns_pid;
> +};
> +
> +struct test_case_t {
> +       char *name;
> +       int fork;
> +       int want_pidfd_err;
> +} test_cases[] = {
> +       {
> +               "return a valid pidfd for event created by self",
> +               0,
> +               0,
> +       },
> +       {
> +               "return invalid pidfd for event created by terminated child",
> +               1,
> +               FAN_NOPIDFD,
> +       },
> +};
> +
> +static int fanotify_fd;
> +static char event_buf[BUF_SZ];
> +static struct pidfd_fdinfo_t *self_pidfd_fdinfo = NULL;
> +
> +static char *trim(char *line)
> +{
> +       char *start = line;
> +       char *end = line + strlen(line);
> +
> +       while(*start && isspace(*start))
> +               start++;
> +
> +       while(end > start && isspace(*(end - 1)))
> +               end--;
> +
> +       *end = '\0';
> +       return start;
> +}
> +
> +static int parse_pidfd_fdinfo_line(char *line,
> +                                  struct pidfd_fdinfo_t *pidfd_fdinfo)
> +{
> +       char *ptr, *key, *value;
> +
> +       ptr = strchr(line, ':');
> +       if (ptr == NULL)
> +               return -1;
> +
> +       *ptr++ = '\0';
> +       key = trim(line);
> +       value = trim(ptr);
> +
> +       /*
> +        * Ensure to cover all keys of interest that may be found within the
> +        * pidfd fdinfo. If we encounter an unexpected key, skip it.
> +        */
> +       if (strcmp(key, "pos") == 0)
> +               pidfd_fdinfo->pos = atoi(value);
> +       else if (strcmp(key, "flags") == 0)
> +               pidfd_fdinfo->flags = (int)strtol(value, NULL, 16);
> +       else if (strcmp(key, "mnt_id") == 0)
> +               pidfd_fdinfo->mnt_id = atoi(value);
> +       else if (strcmp(key, "Pid") == 0)
> +               pidfd_fdinfo->pid = atoi(value);
> +       else if (strcmp(key, "NSpid") == 0)
> +               pidfd_fdinfo->ns_pid = atoi(value);
> +
> +       return 0;
> +}

Please use existing LTP parsing utilities.
It's never a good idea to re-implement these sort of things.
With a quick grep I found:

SAFE_FILE_LINES_SCANF("/proc/meminfo", "SwapCached: %ld",

Otherwise, test looks fine to me.

Thanks,
Amir.