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lib/procutils: improve proc_is_procfs(), add test 

* add delay between attempts
* zeroize errno and check for EAGAIN (like in other code)
* add small test program
   ./test_procutils --is-procfs [<dir>]

Signed-off-by: Karel Zak <kzak@redhat.com>
This commit is contained in:
Karel Zak 2020-11-20 10:38:01 +01:00
parent 61dc5ae39a
commit 1b54a74e86
1 changed files with 29 additions and 5 deletions
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34
lib/procutils.c
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@ -245,13 +245,17 @@ int proc_is_procfs(int fd)
int ret;
do {
errno = 0;
ret = fstatfs(fd, &st);
} while (ret == -1 && errno == EINTR);
if (ret == 0)
return st.f_type == STATFS_PROC_MAGIC;
else
return 0;
if (ret < 0) {
if (errno != EINTR && errno != EAGAIN)
return 0;
xusleep(250000);
}
} while (ret != 0);
return st.f_type == STATFS_PROC_MAGIC;
}
#ifdef TEST_PROGRAM_PROCUTILS
@ -302,10 +306,28 @@ static int test_processes(int argc, char *argv[])
return EXIT_SUCCESS;
}
static int test_isprocfs(int argc, char *argv[])
{
const char *name = argc > 1 ? argv[1] : "/proc";
int fd = open(name, O_RDONLY);
int is = 0;
if (fd >= 0) {
is = proc_is_procfs(fd);
close(fd);
} else
err(EXIT_FAILURE, "cannot open %s", name);
printf("%s: %s procfs\n", name, is ? "is" : "is NOT");
return is ? EXIT_SUCCESS : EXIT_FAILURE;
}
int main(int argc, char *argv[])
{
if (argc < 2) {
fprintf(stderr, "usage: %1$s --tasks <pid>\n"
" %1$s --is-procfs [<dir>]\n"
" %1$s --processes [---name <name>] [--uid <uid>]\n",
program_invocation_short_name);
return EXIT_FAILURE;
@ -315,6 +337,8 @@ int main(int argc, char *argv[])
return test_tasks(argc - 1, argv + 1);
if (strcmp(argv[1], "--processes") == 0)
return test_processes(argc - 1, argv + 1);
if (strcmp(argv[1], "--is-procfs") == 0)
return test_isprocfs(argc - 1, argv + 1);
return EXIT_FAILURE;
}