feat(stat): stat/mkdir/chmod and mode macros

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2026-09-05 16:35:50 -04:00
parent 87ab610a9b
commit 98f4c3169c
11 changed files with 935 additions and 0 deletions
+384
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/*
* vlibc — stat family test (todo 22).
*
* Exercises sys/stat.h end to end:
*
* 1. stat("/dev/null") reports a character device with a non-zero rdev.
* 2. open+write a temp file, fstat shows S_ISREG with the written size;
* close then stat(path) agrees (and the inode matches).
* 3. umask(0) then mkdir/mkdirat 0755/0700 — stat shows S_ISDIR with the
* exact requested mode; the umask is restored afterwards.
* 4. A symlink created via raw SYS_symlink: lstat reports the link
* itself (S_ISLNK), stat follows it (S_ISREG); fstatat with
* AT_SYMLINK_NOFOLLOW does not follow.
* 5. chmod(file, 0600) / fchmod / fchmodat update the mode.
* 6. chown-family no-ops: fchown(fd, -1, -1) and fchownat(...,-1,-1,0)
* succeed without changing ownership; lchown on the symlink succeeds.
* 7. utimensat(AT_FDCWD, file, NULL, 0) and futimens(fd, NULL) set the
* timestamps to the current time and return 0.
* 8. mkfifo/mkfifoat create FIFOs (S_ISFIFO).
* 9. Level 2: mknod/mknodat create FIFOs via S_IFIFO (no privilege
* needed for a FIFO).
*
* The -f mode runs only the failure scenarios: stat/lstat/fstatat/fstat on
* nonexistent paths/fds, mkdir on an existing directory, mkfifo in a
* missing directory, chmod/fchmod/fchmodat/chown/lchown/fchown/fchownat/
* utimensat/futimens negatives, and (L2) mknod without a type bit
* (EINVAL). Only return values are asserted — errno is never read. The
* negative paths make the LIBRARY write errno (syscall_ret), which under
* a host-linked binary targets glibc's private dtv slot at %fs:0+8, so -f
* exits via raw SYS_exit_group (house pattern, tests/test_malloc.c).
*
* All diagnostics go through raw SYS_write (no stdio): under -Iinclude the
* vlibc public headers shadow GCC's internal ones, so a host header would
* not compile. Not part of the library proper; compiled manually for this
* todo (the tests/ + make check wiring is owned by a later todo).
*/
#include <stddef.h>
#include <sys/stat.h>
#include <unistd.h>
#include "../src/internal/syscall.h"
/* Kernel-UAPI open/at flags, local to this test (include/fcntl.h is todo 21). */
#define T22_AT_FDCWD (-100)
#define T22_AT_SYMLINK_NOFOLLOW 0x100
#define T22_O_RDWR 0x2
#define T22_O_CREAT 0x40
#define T22_O_EXCL 0x80
/* Scratch paths in /tmp (test runs from an arbitrary cwd). */
#define T22_FILE "/tmp/vlibc_stat_t22_file"
#define T22_DIR "/tmp/vlibc_stat_t22_dir"
#define T22_DIR2 "/tmp/vlibc_stat_t22_dir2"
#define T22_LINK "/tmp/vlibc_stat_t22_link"
#define T22_LINK_TARGET "vlibc_stat_t22_file"
#define T22_FIFO "/tmp/vlibc_stat_t22_fifo"
#define T22_FIFO2 "/tmp/vlibc_stat_t22_fifo2"
#define T22_FIFO3 "/tmp/vlibc_stat_t22_fifo3"
#define T22_FIFO4 "/tmp/vlibc_stat_t22_fifo4"
#define T22_FDIR "/tmp/vlibc_stat_t22_fdir"
#define T22_MISSING "/nonexistent-vlibc-zzz"
static int failures;
/* Write a NUL-terminated string to fd via the raw syscall layer. The
* optimize attribute keeps GCC from lowering the length loop into a
* strlen call, which would leave a vlibc-owned symbol undefined in this
* host-linked standalone binary (house idiom, see src/string). */
static __attribute__((optimize("no-tree-loop-distribute-patterns"))) void
say(int fd, const char *s)
{
long n = 0;
while (s[n] != '\0')
{
n++;
}
__syscall3(SYS_write, fd, (long)s, n);
}
/* Write v in decimal to fd. */
static void
say_dec(int fd, unsigned long v) // NOLINT(bugprone-easily-swappable-parameters)
{
char buf[24];
int i = (int)sizeof(buf);
buf[--i] = '\0';
if (v == 0)
{
buf[--i] = '0';
}
while (v > 0 && i > 0)
{
buf[--i] = (char)('0' + v % 10);
v /= 10;
}
say(fd, &buf[i]);
}
static void
check(int ok, const char *msg)
{
if (ok)
{
say(1, "PASS: ");
}
else
{
say(1, "FAIL: ");
failures++;
}
say(1, msg);
say(1, "\n");
}
/*
* Host-TCB slot-1 bracket: the library's errno write on a negative path
* lands at %fs:0+8, glibc's dtv pointer. Save and restore it around each
* such call; only vlibc/raw-syscall code runs in between (task 13
* technique).
*/
static unsigned long
tcb_slot1(void)
{
return *(unsigned long *)((char *)__builtin_thread_pointer() + 8);
}
static void
tcb_slot1_set(unsigned long value)
{
*(unsigned long *)((char *)__builtin_thread_pointer() + 8) = value;
}
/* 1. /dev/null is a character device. */
static void
dev_null_scenario(void)
{
struct stat st = {0};
check(sizeof(struct stat) == 144, "sizeof(struct stat) is 144");
check(stat("/dev/null", &st) == 0, "stat(/dev/null) returns 0");
check(S_ISCHR(st.st_mode), "st_mode classifies /dev/null as S_ISCHR");
check(st.st_rdev != 0, "st_rdev of /dev/null is non-zero");
check(fstatat(T22_AT_FDCWD, "/dev/null", &st, 0) == 0,
"fstatat(AT_FDCWD, /dev/null) returns 0");
check(S_ISCHR(st.st_mode), "fstatat st_mode classifies /dev/null as S_ISCHR");
check(!S_ISREG(st.st_mode) && !S_ISDIR(st.st_mode) && !S_ISFIFO(st.st_mode),
"/dev/null is not reg/dir/fifo");
}
/* 2 + 5 + 6 + 7: the temp file lifecycle. */
static void
file_scenario(void)
{
static const char payload[] = "hello from vlibc stat\n";
struct stat st = {0};
struct stat st2 = {0};
unsigned long saved;
ssize_t wrote;
int fd;
fd = open(T22_FILE, T22_O_RDWR | T22_O_CREAT | T22_O_EXCL, 0644);
check(fd >= 0, "open O_RDWR|O_CREAT|O_EXCL 0644 returns a descriptor");
if (fd < 0)
{
return;
}
wrote = write(fd, payload, sizeof(payload) - 1);
check(wrote == (ssize_t)(sizeof(payload) - 1), "write of 22 bytes returns 22");
check(fstat(fd, &st) == 0, "fstat(fd) returns 0");
check(S_ISREG(st.st_mode), "fstat st_mode classifies the file as S_ISREG");
check(st.st_size == (off_t)(sizeof(payload) - 1), "fstat st_size equals the written bytes");
check((st.st_mode & 0777) == 0644, "fstat st_mode permission bits are 0644 (umask(0))");
check(st.st_nlink == 1, "fstat st_nlink is 1");
check(st.st_atime > 0 && st.st_mtime > 0 && st.st_ctime > 0,
"st_atime/st_mtime/st_ctime macros expose positive times");
check(stat(T22_FILE, &st2) == 0, "stat(path) returns 0");
check(st2.st_size == st.st_size, "stat(path) st_size matches fstat");
check(st2.st_ino == st.st_ino, "stat(path) st_ino matches fstat");
/* 5. chmod family. */
check(chmod(T22_FILE, 0600) == 0, "chmod(file, 0600) returns 0");
saved = tcb_slot1();
check(stat(T22_FILE, &st2) == 0, "stat after chmod returns 0");
tcb_slot1_set(saved);
check((st2.st_mode & 0777) == 0600, "mode is 0600 after chmod");
check(fchmod(fd, 0640) == 0, "fchmod(fd, 0640) returns 0");
check(fchmodat(T22_AT_FDCWD, T22_FILE, 0644, 0) == 0,
"fchmodat(AT_FDCWD, file, 0644) returns 0");
saved = tcb_slot1();
check(stat(T22_FILE, &st2) == 0, "stat after fchmodat returns 0");
tcb_slot1_set(saved);
check((st2.st_mode & 0777) == 0644, "mode is 0644 after fchmodat");
/* 6. chown-family no-ops (-1 = leave unchanged). */
check(fchown(fd, (uid_t)-1, (gid_t)-1) == 0, "fchown(fd, -1, -1) returns 0");
check(fchownat(T22_AT_FDCWD, T22_FILE, (uid_t)-1, (gid_t)-1, 0) == 0,
"fchownat(AT_FDCWD, file, -1, -1, 0) returns 0");
/* 7. utimensat/futimens with NULL times (set to current time). */
check(utimensat(T22_AT_FDCWD, T22_FILE, 0, 0) == 0,
"utimensat(AT_FDCWD, file, NULL, 0) returns 0");
check(futimens(fd, 0) == 0, "futimens(fd, NULL) returns 0");
check(close(fd) == 0, "close of the temp file returns 0");
}
/* 3. mkdir/mkdirat with a cleared umask. */
static void
mkdir_scenario(void)
{
struct stat st = {0};
mode_t old;
old = umask(0);
check(mkdir(T22_DIR, 0755) == 0, "mkdir(dir, 0755) returns 0");
check(mkdirat(T22_AT_FDCWD, T22_DIR2, 0700) == 0, "mkdirat(AT_FDCWD, dir2, 0700) returns 0");
umask(old);
check(stat(T22_DIR, &st) == 0, "stat(dir) returns 0");
check(S_ISDIR(st.st_mode), "st_mode classifies dir as S_ISDIR");
check((st.st_mode & 0777) == 0755, "dir mode is exactly 0755 (umask(0))");
check(stat(T22_DIR2, &st) == 0, "stat(dir2) returns 0");
check(S_ISDIR(st.st_mode) && (st.st_mode & 0777) == 0700, "dir2 mode is exactly 0700");
}
/* 4. symlink: lstat reports the link, stat follows. */
static void
symlink_scenario(void)
{
struct stat st = {0};
check(__syscall2(SYS_symlink, (long)T22_LINK_TARGET, (long)T22_LINK) == 0,
"raw SYS_symlink creates the link");
check(lstat(T22_LINK, &st) == 0, "lstat(link) returns 0");
check(S_ISLNK(st.st_mode), "lstat st_mode classifies the link as S_ISLNK");
check(!S_ISREG(st.st_mode), "lstat does not follow the link");
check(stat(T22_LINK, &st) == 0, "stat(link) returns 0");
check(S_ISREG(st.st_mode), "stat follows the link to S_ISREG");
check(fstatat(T22_AT_FDCWD, T22_LINK, &st, T22_AT_SYMLINK_NOFOLLOW) == 0,
"fstatat(link, AT_SYMLINK_NOFOLLOW) returns 0");
check(S_ISLNK(st.st_mode), "fstatat with AT_SYMLINK_NOFOLLOW reports S_ISLNK");
check(lchown(T22_LINK, (uid_t)-1, (gid_t)-1) == 0, "lchown(link, -1, -1) returns 0");
}
/* 8. mkfifo/mkfifoat create FIFOs. */
static void
mkfifo_scenario(void)
{
struct stat st = {0};
check(mkfifo(T22_FIFO, 0644) == 0, "mkfifo(fifo, 0644) returns 0");
check(mkfifoat(T22_AT_FDCWD, T22_FIFO2, 0600) == 0,
"mkfifoat(AT_FDCWD, fifo2, 0600) returns 0");
check(stat(T22_FIFO, &st) == 0, "stat(fifo) returns 0");
check(S_ISFIFO(st.st_mode), "st_mode classifies fifo as S_ISFIFO");
check(stat(T22_FIFO2, &st) == 0, "stat(fifo2) returns 0");
check(S_ISFIFO(st.st_mode), "st_mode classifies fifo2 as S_ISFIFO");
}
#if VLIBC_LEVEL_GE(2)
/* 9. mknod/mknodat create FIFOs (no privilege needed for S_IFIFO). */
static void
mknod_scenario(void)
{
struct stat st = {0};
check(mknod(T22_FIFO3, S_IFIFO | 0640, 0) == 0, "mknod(fifo3, S_IFIFO|0640, 0) returns 0");
check(mknodat(T22_AT_FDCWD, T22_FIFO4, S_IFIFO | 0600, 0) == 0,
"mknodat(AT_FDCWD, fifo4, S_IFIFO|0600, 0) returns 0");
check(stat(T22_FIFO3, &st) == 0, "stat(fifo3) returns 0");
check(S_ISFIFO(st.st_mode) && (st.st_mode & 0777) == 0640,
"mknod fifo3 is S_ISFIFO with mode 0640");
check(stat(T22_FIFO4, &st) == 0, "stat(fifo4) returns 0");
check(S_ISFIFO(st.st_mode) && (st.st_mode & 0777) == 0600,
"mknodat fifo4 is S_ISFIFO with mode 0600");
}
#endif /* VLIBC_LEVEL_GE(2) */
/* Clean up every scratch path; failures here are reported, not fatal. */
static void
cleanup_scenario(void)
{
long r;
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_LINK, 0);
check(r == 0, "raw unlinkat removes the link");
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_FILE, 0);
check(r == 0, "raw unlinkat removes the temp file");
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_FIFO, 0);
check(r == 0, "raw unlinkat removes fifo");
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_FIFO2, 0);
check(r == 0, "raw unlinkat removes fifo2");
#if VLIBC_LEVEL_GE(2)
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_FIFO3, 0);
check(r == 0, "raw unlinkat removes fifo3");
r = __syscall3(SYS_unlinkat, T22_AT_FDCWD, (long)T22_FIFO4, 0);
check(r == 0, "raw unlinkat removes fifo4");
#endif /* VLIBC_LEVEL_GE(2) */
r = __syscall1(SYS_rmdir, (long)T22_DIR);
check(r == 0, "raw rmdir removes dir");
r = __syscall1(SYS_rmdir, (long)T22_DIR2);
check(r == 0, "raw rmdir removes dir2");
}
/* The failure scenarios. Exit via raw SYS_exit_group: the library's errno
* writes on these paths corrupt glibc's private dtv slot at %fs:0+8, so
* host cleanup must never run (house pattern). */
static void
failure_scenarios(void)
{
struct stat st = {0};
check(stat(T22_MISSING, &st) == -1, "stat(nonexistent) returns -1");
check(lstat(T22_MISSING, &st) == -1, "lstat(nonexistent) returns -1");
check(fstatat(T22_AT_FDCWD, T22_MISSING, &st, 0) == -1,
"fstatat(AT_FDCWD, nonexistent) returns -1");
check(fstat(-1, &st) == -1, "fstat(-1) returns -1");
check(mkdir(T22_FDIR, 0755) == 0, "mkdir(fdir) succeeds for the negative");
check(mkdir(T22_FDIR, 0755) == -1, "mkdir(existing dir) returns -1");
check(mkfifo("/nonexistent-vlibc-zzz/x", 0644) == -1, "mkfifo in missing dir returns -1");
check(chmod(T22_MISSING, 0600) == -1, "chmod(nonexistent) returns -1");
check(fchmod(-1, 0600) == -1, "fchmod(-1) returns -1");
check(fchmodat(T22_AT_FDCWD, T22_MISSING, 0600, 0) == -1, "fchmodat(nonexistent) returns -1");
check(chown(T22_MISSING, (uid_t)-1, (gid_t)-1) == -1, "chown(nonexistent) returns -1");
check(lchown(T22_MISSING, (uid_t)-1, (gid_t)-1) == -1, "lchown(nonexistent) returns -1");
check(fchown(-1, (uid_t)-1, (gid_t)-1) == -1, "fchown(-1) returns -1");
check(fchownat(T22_AT_FDCWD, T22_MISSING, (uid_t)-1, (gid_t)-1, 0) == -1,
"fchownat(nonexistent) returns -1");
check(utimensat(T22_AT_FDCWD, T22_MISSING, 0, 0) == -1, "utimensat(nonexistent) returns -1");
check(futimens(-1, 0) == -1, "futimens(-1) returns -1");
#if VLIBC_LEVEL_GE(2)
check(mknod(T22_FDIR, 0644, 0) == -1, "mknod without a type bit returns -1");
check(mknodat(T22_AT_FDCWD, T22_FDIR, 0644, 0) == -1, "mknodat without a type bit returns -1");
check(mknod("/nonexistent-vlibc-zzz/x", S_IFIFO | 0644, 0) == -1,
"mknod in missing dir returns -1");
#endif /* VLIBC_LEVEL_GE(2) */
__syscall1(SYS_rmdir, (long)T22_FDIR);
if (failures == 0)
{
say(1, "all stat failure scenarios passed\n");
}
else
{
say(1, "FAILURES: ");
say_dec(1, (unsigned long)failures);
say(1, "\n");
}
__syscall1(SYS_exit_group, failures == 0 ? 0 : 1);
}
int
main(int argc, char **argv)
{
if (argc > 1 && argv[1][0] == '-' && argv[1][1] == 'f' && argv[1][2] == '\0')
{
failure_scenarios();
}
dev_null_scenario();
file_scenario();
mkdir_scenario();
symlink_scenario();
mkfifo_scenario();
#if VLIBC_LEVEL_GE(2)
mknod_scenario();
#endif /* VLIBC_LEVEL_GE(2) */
cleanup_scenario();
if (failures == 0)
{
say(1, "all stat tests passed\n");
}
else
{
say(1, "FAILURES: ");
say_dec(1, (unsigned long)failures);
say(1, "\n");
}
return failures == 0 ? 0 : 1;
}