Add lstat test

tests/Makefile

@@ -108,6 +108,7 @@ EXPECT_NAMES=\
 	string/stpcpy \
 	string/stpncpy \
 	strings \
+	sys_stat/lstat \
 	sys_stat/fstatat \
 	sys_syslog/syslog \
 	time/asctime \

tests/sys_stat/lstat.c

@@ -0,0 +1,101 @@
+#include <assert.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <sys/stat.h>
+
+int main(void) {
+    int status = EXIT_FAILURE;
+
+    char tempdir_path[] = "/tmp/lstat_test.XXXXXX";
+    if (!mkdtemp(tempdir_path)) {
+        perror("mkdtemp");
+        goto bye;
+    }
+    int tempdir = open(tempdir_path, O_DIRECTORY);
+    if (tempdir == -1) {
+        perror("open (tempdir)");
+        goto rmtemp;
+    }
+
+    // Source
+    const char src_name[] = "kerouac";
+    char src_buf[PATH_MAX] = {0};
+    strcpy(src_buf, tempdir_path);
+    strcat(src_buf, "/");
+    strcat(src_buf, src_name);
+    // TODO: Use openat
+    int source = open(src_buf, O_CREAT);
+    if (source == -1) {
+        perror("open");
+        goto close_dir;
+    }
+
+    // Dest (link)
+    const char dst_name[] = "on_the_road";
+    char dst_buf[PATH_MAX] = {0};
+    strcpy(dst_buf, tempdir_path);
+    strcat(dst_buf, "/");
+    strcat(dst_buf, dst_name);
+    if (symlink(src_buf, dst_buf) == -1) {
+        perror("symlink");
+        goto rm_source;
+    }
+
+    struct stat src_stat = {0};
+    if (fstatat(tempdir, dst_name, &src_stat, 0) == -1) {
+        perror("fstatat");
+        goto rm_dest;
+    }
+    // Quick consistency check
+    uid_t uid = getuid();
+    gid_t gid = getgid();
+    if (src_stat.st_uid != uid) {
+        fprintf(
+            stderr,
+            "uid:\n\tExpected %ld\n\tActual: %ld\n",
+            (intmax_t) uid,
+            (intmax_t) gid
+        );
+        goto rm_dest;
+    }
+    if (src_stat.st_nlink != 1) {
+        fputs("nlink: Expected one hard link\n", stderr);
+        goto rm_dest;
+    }
+    if ((src_stat.st_mode & S_IFMT) != S_IFREG) {
+        fputs("mode: Expected a normal file\n", stderr);
+        goto rm_dest;
+    }
+
+    struct stat dst_stat = {0};
+    if (lstat(dst_buf, &dst_stat) == -1) {
+        perror("lstat");
+        goto rm_dest;
+    }
+    if (memcmp(&src_stat, &dst_stat, sizeof(struct stat)) == 0) {
+        fputs("lstat incorrectly followed the symlink\n", stderr);
+        goto rm_dest;
+    }
+    if ((dst_stat.st_mode & S_IFMT) != S_IFLNK) {
+        fputs("lstat did not stat a link\n", stderr);
+        goto rm_dest;
+    }
+
+    status = EXIT_SUCCESS;
+rm_dest:
+    unlink(dst_buf);
+rm_source:
+    unlink(src_buf);
+close_dir:
+    close(tempdir);
+rmtemp:
+    rmdir(tempdir_path);
+bye:
+    return status;
+}