Hi Zhangjin,
On Wed, Jun 28, 2023 at 09:51:57PM +0800, Zhangjin Wu wrote:
Three mmap/munmap related test cases are added:
mmap_bad: the length argument must be greater than 0, otherwise, fail with -EINVAL.
munmap_bad: invalid (void *)-1 address fail with -EINVAL.
mmap_munmap_good: mmap() a file with good offset and then munmap().
Note, it is not easy to find a unique file for mmap() in different scenes, so, a file list is used to search the right one:
/proc/1/exe, for 'run' and 'run-user' target 'run-user' can not find '/proc/self/exe'
/proc/self/exe, for 'libc-test' target normal program 'libc-test' has no permission to access '/proc/1/exe'
Strictly speaking, if your executable is not readable (e.g. chmod 111 due to a restrictive umask) it will also fail that one.
ok.
- the others, for kernel without procfs let it pass even with 'worst case' kernel configs
You should include /dev/zero, which is commonly used to allocate anonymous memory and is more likely present and readable than any of the other files. And another file of choice is obviously argv[0] ;-) In this case you don't need any of the other extra ones. Thus I could suggest that you try in this order:
/dev/zero, /proc/self/exe, /proc/1/exe, argv[0]and be done with it. That doesn't prevent one from extending the list if really needed later, but I doubt it would be needed. Also, it's already arranged in a read-write, then read-only fallbacks mode, so if we later need to add more complex tests involving writes, the writable /dev/zero will have precedence.
Cool, both /dev/zero and argv[0] are very good candidates ;-)
Just verified both of them, works perfectly.
- /dev/zero
we need to mknod it in prepare() and also, in test_mmap_munmap(), stat() return a zero size of /dev/zero, in this case, we should assign a non-zero file_size ourselves.
- file_size = stat_buf.st_size; + /* file size of the special /dev/zero is 0, let's assign one manually */ + if (i == 0) + file_size = 3*page_size - 1; + else + file_size = stat_buf.st_size;
- argv[0]
since nolibc has no realpath() currently, we can simply support the current path and the absolute path like this:
nolibc-test.c:
/* assigned as argv[0] in main(), will be used by some tests */ static char exe[PATH_MAX + 1];
main():
/* get absolute path of myself, nolibc has no realpath() currently */ #ifndef NOLIBC realpath(argv[0], exe); #else /* assume absolute path has no "./" */ if (strncmp(argv[0], "./", 2) != 0) strncat(exe, argv[0], strlen(argv[0]) + 1); else { pwd = getenv("PWD"); /* skip the ending '\0' */ strncat(exe, getenv("PWD"), strlen(pwd)); /* skip the first '.' */ strncat(exe, argv[0] + 1, strlen(argv[0])); } #endif
A full functional realpath() is a little complex, such as '../' support and even symlink support, let's delay its requirement at current stage ;-)
one or both of them may also help the other test cases:
- chroot_exe (used '/init' before)
CASE_TEST(chroot_exe); EXPECT_SYSER(1, chroot(proc ? "/proc/self/exe" : exe), -1, ENOTDIR); break;
- chmod_exe (replace the one: chmod_tmpdir in another patchset)
CASE_TEST(chmod_exe); EXPECT_SYSZR(1, chmod(proc ? "/proc/self/exe" : exe, 0555)); break;
It should be safe enough to only remove the writable attribute for the test program.
- stat_timestamps (used '/init' before)
if (stat("/proc/self/", &st) && stat(exe, &st) && stat("/dev/zero", &st) && stat("/", &st))
Will update the related patches with them.
Thanks, Zhangjin
Willy