412 lines
13 KiB
C
412 lines
13 KiB
C
/*
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* Copyright (c) 2014 Google, Inc.
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*
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* Licensed under the terms of the GNU GPL License version 2
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*
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* Selftests for execveat(2).
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*/
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#define _GNU_SOURCE /* to get O_PATH, AT_EMPTY_PATH */
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#include <sys/sendfile.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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static char longpath[2 * PATH_MAX] = "";
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static char *envp[] = { "IN_TEST=yes", NULL, NULL };
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static char *argv[] = { "execveat", "99", NULL };
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static int execveat_(int fd, const char *path, char **argv, char **envp,
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int flags)
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{
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#ifdef __NR_execveat
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return syscall(__NR_execveat, fd, path, argv, envp, flags);
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#else
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errno = ENOSYS;
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return -1;
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#endif
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}
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#define check_execveat_fail(fd, path, flags, errno) \
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_check_execveat_fail(fd, path, flags, errno, #errno)
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static int _check_execveat_fail(int fd, const char *path, int flags,
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int expected_errno, const char *errno_str)
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{
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int rc;
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errno = 0;
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printf("Check failure of execveat(%d, '%s', %d) with %s... ",
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fd, path?:"(null)", flags, errno_str);
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rc = execveat_(fd, path, argv, envp, flags);
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if (rc > 0) {
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printf("[FAIL] (unexpected success from execveat(2))\n");
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return 1;
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}
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if (errno != expected_errno) {
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printf("[FAIL] (expected errno %d (%s) not %d (%s)\n",
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expected_errno, strerror(expected_errno),
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errno, strerror(errno));
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return 1;
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}
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printf("[OK]\n");
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return 0;
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}
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static int check_execveat_invoked_rc(int fd, const char *path, int flags,
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int expected_rc, int expected_rc2)
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{
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int status;
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int rc;
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pid_t child;
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int pathlen = path ? strlen(path) : 0;
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if (pathlen > 40)
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printf("Check success of execveat(%d, '%.20s...%s', %d)... ",
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fd, path, (path + pathlen - 20), flags);
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else
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printf("Check success of execveat(%d, '%s', %d)... ",
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fd, path?:"(null)", flags);
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child = fork();
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if (child < 0) {
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printf("[FAIL] (fork() failed)\n");
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return 1;
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}
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if (child == 0) {
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/* Child: do execveat(). */
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rc = execveat_(fd, path, argv, envp, flags);
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printf("[FAIL]: execveat() failed, rc=%d errno=%d (%s)\n",
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rc, errno, strerror(errno));
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exit(1); /* should not reach here */
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}
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/* Parent: wait for & check child's exit status. */
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rc = waitpid(child, &status, 0);
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if (rc != child) {
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printf("[FAIL] (waitpid(%d,...) returned %d)\n", child, rc);
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return 1;
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}
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if (!WIFEXITED(status)) {
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printf("[FAIL] (child %d did not exit cleanly, status=%08x)\n",
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child, status);
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return 1;
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}
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if ((WEXITSTATUS(status) != expected_rc) &&
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(WEXITSTATUS(status) != expected_rc2)) {
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printf("[FAIL] (child %d exited with %d not %d nor %d)\n",
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child, WEXITSTATUS(status), expected_rc, expected_rc2);
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return 1;
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}
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printf("[OK]\n");
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return 0;
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}
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static int check_execveat(int fd, const char *path, int flags)
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{
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return check_execveat_invoked_rc(fd, path, flags, 99, 99);
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}
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static char *concat(const char *left, const char *right)
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{
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char *result = malloc(strlen(left) + strlen(right) + 1);
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strcpy(result, left);
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strcat(result, right);
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return result;
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}
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static int open_or_die(const char *filename, int flags)
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{
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int fd = open(filename, flags);
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if (fd < 0) {
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printf("Failed to open '%s'; "
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"check prerequisites are available\n", filename);
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exit(1);
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}
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return fd;
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}
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static void exe_cp(const char *src, const char *dest)
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{
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int in_fd = open_or_die(src, O_RDONLY);
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int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);
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struct stat info;
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fstat(in_fd, &info);
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sendfile(out_fd, in_fd, NULL, info.st_size);
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close(in_fd);
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close(out_fd);
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}
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#define XX_DIR_LEN 200
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static int check_execveat_pathmax(int dot_dfd, const char *src, int is_script)
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{
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int fail = 0;
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int ii, count, len;
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char longname[XX_DIR_LEN + 1];
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int fd;
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if (*longpath == '\0') {
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/* Create a filename close to PATH_MAX in length */
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memset(longname, 'x', XX_DIR_LEN - 1);
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longname[XX_DIR_LEN - 1] = '/';
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longname[XX_DIR_LEN] = '\0';
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count = (PATH_MAX - 3) / XX_DIR_LEN;
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for (ii = 0; ii < count; ii++) {
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strcat(longpath, longname);
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mkdir(longpath, 0755);
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}
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len = (PATH_MAX - 3) - (count * XX_DIR_LEN);
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if (len <= 0)
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len = 1;
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memset(longname, 'y', len);
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longname[len] = '\0';
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strcat(longpath, longname);
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}
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exe_cp(src, longpath);
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/*
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* Execute as a pre-opened file descriptor, which works whether this is
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* a script or not (because the interpreter sees a filename like
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* "/dev/fd/20").
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*/
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fd = open(longpath, O_RDONLY);
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if (fd > 0) {
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printf("Invoke copy of '%s' via filename of length %zu:\n",
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src, strlen(longpath));
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fail += check_execveat(fd, "", AT_EMPTY_PATH);
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} else {
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printf("Failed to open length %zu filename, errno=%d (%s)\n",
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strlen(longpath), errno, strerror(errno));
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fail++;
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}
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/*
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* Execute as a long pathname relative to ".". If this is a script,
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* the interpreter will launch but fail to open the script because its
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* name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
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*
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* The failure code is usually 127 (POSIX: "If a command is not found,
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* the exit status shall be 127."), but some systems give 126 (POSIX:
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* "If the command name is found, but it is not an executable utility,
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* the exit status shall be 126."), so allow either.
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*/
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if (is_script)
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fail += check_execveat_invoked_rc(dot_dfd, longpath, 0,
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127, 126);
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else
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fail += check_execveat(dot_dfd, longpath, 0);
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return fail;
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}
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static int run_tests(void)
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{
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int fail = 0;
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char *fullname = realpath("execveat", NULL);
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char *fullname_script = realpath("script", NULL);
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char *fullname_symlink = concat(fullname, ".symlink");
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int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);
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int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",
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O_DIRECTORY|O_RDONLY);
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int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);
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int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);
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int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);
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int fd = open_or_die("execveat", O_RDONLY);
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int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);
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int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);
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int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);
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int fd_denatured_path = open_or_die("execveat.denatured",
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O_RDONLY|O_PATH);
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int fd_script = open_or_die("script", O_RDONLY);
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int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);
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int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",
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O_RDONLY|O_PATH);
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int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);
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int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
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int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
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/* Check if we have execveat at all, and bail early if not */
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errno = 0;
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execveat_(-1, NULL, NULL, NULL, 0);
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if (errno == ENOSYS) {
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printf("[FAIL] ENOSYS calling execveat - no kernel support?\n");
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return 1;
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}
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/* Change file position to confirm it doesn't affect anything */
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lseek(fd, 10, SEEK_SET);
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/* Normal executable file: */
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/* dfd + path */
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fail += check_execveat(subdir_dfd, "../execveat", 0);
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fail += check_execveat(dot_dfd, "execveat", 0);
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fail += check_execveat(dot_dfd_path, "execveat", 0);
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/* absolute path */
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fail += check_execveat(AT_FDCWD, fullname, 0);
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/* absolute path with nonsense dfd */
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fail += check_execveat(99, fullname, 0);
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/* fd + no path */
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fail += check_execveat(fd, "", AT_EMPTY_PATH);
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/* O_CLOEXEC fd + no path */
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fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);
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/* O_PATH fd */
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fail += check_execveat(fd_path, "", AT_EMPTY_PATH);
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/* Mess with executable file that's already open: */
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/* fd + no path to a file that's been renamed */
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rename("execveat.ephemeral", "execveat.moved");
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fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
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/* fd + no path to a file that's been deleted */
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unlink("execveat.moved"); /* remove the file now fd open */
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fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
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/* Mess with executable file that's already open with O_PATH */
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/* fd + no path to a file that's been deleted */
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unlink("execveat.path.ephemeral");
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fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);
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/* Invalid argument failures */
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fail += check_execveat_fail(fd, "", 0, ENOENT);
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fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);
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/* Symlink to executable file: */
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/* dfd + path */
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fail += check_execveat(dot_dfd, "execveat.symlink", 0);
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fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);
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/* absolute path */
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fail += check_execveat(AT_FDCWD, fullname_symlink, 0);
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/* fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */
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fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);
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fail += check_execveat(fd_symlink, "",
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AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
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/* Symlink fails when AT_SYMLINK_NOFOLLOW set: */
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/* dfd + path */
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fail += check_execveat_fail(dot_dfd, "execveat.symlink",
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AT_SYMLINK_NOFOLLOW, ELOOP);
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fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",
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AT_SYMLINK_NOFOLLOW, ELOOP);
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/* absolute path */
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fail += check_execveat_fail(AT_FDCWD, fullname_symlink,
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AT_SYMLINK_NOFOLLOW, ELOOP);
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/* Shell script wrapping executable file: */
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/* dfd + path */
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fail += check_execveat(subdir_dfd, "../script", 0);
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fail += check_execveat(dot_dfd, "script", 0);
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fail += check_execveat(dot_dfd_path, "script", 0);
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/* absolute path */
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fail += check_execveat(AT_FDCWD, fullname_script, 0);
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/* fd + no path */
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fail += check_execveat(fd_script, "", AT_EMPTY_PATH);
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fail += check_execveat(fd_script, "",
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AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
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/* O_CLOEXEC fd fails for a script (as script file inaccessible) */
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fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,
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ENOENT);
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fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);
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/* Mess with script file that's already open: */
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/* fd + no path to a file that's been renamed */
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rename("script.ephemeral", "script.moved");
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fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
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/* fd + no path to a file that's been deleted */
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unlink("script.moved"); /* remove the file while fd open */
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fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
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/* Rename a subdirectory in the path: */
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rename("subdir.ephemeral", "subdir.moved");
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fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
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fail += check_execveat(subdir_dfd_ephemeral, "script", 0);
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/* Remove the subdir and its contents */
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unlink("subdir.moved/script");
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unlink("subdir.moved");
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/* Shell loads via deleted subdir OK because name starts with .. */
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fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
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fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);
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/* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */
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fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);
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/* Invalid path => ENOENT */
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fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);
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fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);
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fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);
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/* Attempt to execute directory => EACCES */
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fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);
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/* Attempt to execute non-executable => EACCES */
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fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);
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fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);
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fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,
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EACCES);
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/* Attempt to execute nonsense FD => EBADF */
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fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);
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fail += check_execveat_fail(99, "execveat", 0, EBADF);
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/* Attempt to execute relative to non-directory => ENOTDIR */
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fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);
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fail += check_execveat_pathmax(dot_dfd, "execveat", 0);
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fail += check_execveat_pathmax(dot_dfd, "script", 1);
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return fail;
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}
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static void prerequisites(void)
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{
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int fd;
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const char *script = "#!/bin/sh\nexit $*\n";
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/* Create ephemeral copies of files */
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exe_cp("execveat", "execveat.ephemeral");
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exe_cp("execveat", "execveat.path.ephemeral");
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exe_cp("script", "script.ephemeral");
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mkdir("subdir.ephemeral", 0755);
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fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);
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write(fd, script, strlen(script));
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close(fd);
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}
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int main(int argc, char **argv)
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{
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int ii;
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int rc;
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const char *verbose = getenv("VERBOSE");
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if (argc >= 2) {
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/* If we are invoked with an argument, don't run tests. */
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const char *in_test = getenv("IN_TEST");
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if (verbose) {
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printf(" invoked with:");
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for (ii = 0; ii < argc; ii++)
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printf(" [%d]='%s'", ii, argv[ii]);
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printf("\n");
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}
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/* Check expected environment transferred. */
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if (!in_test || strcmp(in_test, "yes") != 0) {
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printf("[FAIL] (no IN_TEST=yes in env)\n");
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return 1;
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}
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/* Use the final argument as an exit code. */
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rc = atoi(argv[argc - 1]);
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fflush(stdout);
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} else {
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prerequisites();
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if (verbose)
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envp[1] = "VERBOSE=1";
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rc = run_tests();
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if (rc > 0)
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printf("%d tests failed\n", rc);
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}
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return rc;
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}
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