[charys117]

Fixes #477.

Since glibc 2.33, fstatat, fstatat64, fstat64 and lstat64 are exported from libc as regular functions (@@GLIBC_2.33), and programs built against a newer glibc call them directly rather than going through __fxstatat, __fxstatat64, __fxstat64 and __lxstat64. libfaketime only intercepts the __*xstat* wrappers for these, so with FAKE_STAT they return real file times while stat() returns faked ones. Python is one common case: os.scandir() / DirEntry.stat() use fstatat, and so does os.stat(..., dir_fd=...).

This PR adds wrappers for the four functions next to the existing stat64() wrapper. They use the same STAT_HANDLER / STAT64_HANDLER macros and the same __GLIBC__ / _TIME_BITS != 64 guards, with the fstatat* pair also under NO_ATFILE. The real functions are looked up with dlsym(RTLD_NEXT, ...) like the others. On glibc < 2.33 these symbols are not exported by libc (programs get them from libc_nonshared.a, which calls the __*xstat* functions), so behaviour there does not change.

It also adds test/stat_entry_points_test.c and test/functests/test_stat_entry_points.sh. The test sets a file's mtime and checks that stat, lstat, fstat and, on glibc, fstatat, stat64, lstat64, fstat64 and fstatat64 all report the faked mtime under FAKETIME=+1d.

Reproducer

The reproducer from #477, extended to the other three functions:

#define _GNU_SOURCE
#include <fcntl.h>
#include <sys/stat.h>
#include <stdio.h>
#include <unistd.h>

int main() {
	struct stat st;
	struct stat64 st64;
	int fd = open("1", O_RDONLY);

	stat("1", &st);
	printf("stat      %ld\n", (long)st.st_mtime);
	fstatat(AT_FDCWD, "1", &st, 0);
	printf("fstatat   %ld\n", (long)st.st_mtime);
	fstatat64(AT_FDCWD, "1", &st64, 0);
	printf("fstatat64 %ld\n", (long)st64.st_mtime);
	fstat64(fd, &st64);
	printf("fstat64   %ld\n", (long)st64.st_mtime);
	lstat64("1", &st64);
	printf("lstat64   %ld\n", (long)st64.st_mtime);
	return 0;
}

With touch -d '2020-01-01 00:00:00 UTC' 1 and FAKETIME=-1d LD_PRELOAD=src/libfaketime.so.1:

              master        this PR
stat      1577750400     1577750400
fstatat   1577836800     1577750400
fstatat64 1577836800     1577750400
fstat64   1577836800     1577750400
lstat64   1577836800     1577750400

Python:

$ FAKETIME=-1d LD_PRELOAD=src/libfaketime.so.1 python3 -c '...'
master   stat 1577750400  scandir 1577836800  dir_fd 1577836800
this PR  stat 1577750400  scandir 1577750400  dir_fd 1577750400

Testing

• make test passes on Ubuntu 24.04 (glibc 2.39) and Debian 13 (glibc 2.41), on both x86_64 and aarch64. The new test fails against master's library on all four, for fstatat, lstat64, fstat64 and fstatat64.
• test/docker_baseline.sh alpine:3.20 (musl) passes. The glibc-only checks are skipped there.
• glibc 2.31 (Ubuntu 20.04, aarch64): the library and the new test built by hand, since master's Makefile needs a newer make there. master and this PR give the same, already faked, results.
• test/release_check.sh and test/compile_abi_variants.sh (gcc and clang) pass, a clang build passes the new test, and the macOS build (Makefile.OSX) still compiles.