+#endif
+
+static const char **prepare_shell_cmd(const char **argv)
+{
+ int argc, nargc = 0;
+ const char **nargv;
+
+ for (argc = 0; argv[argc]; argc++)
+ ; /* just counting */
+ /* +1 for NULL, +3 for "sh -c" plus extra $0 */
+ nargv = xmalloc(sizeof(*nargv) * (argc + 1 + 3));
+
+ if (argc < 1)
+ die("BUG: shell command is empty");
+
+ if (strcspn(argv[0], "|&;<>()$`\\\"' \t\n*?[#~=%") != strlen(argv[0])) {
+ nargv[nargc++] = "sh";
+ nargv[nargc++] = "-c";
+
+ if (argc < 2)
+ nargv[nargc++] = argv[0];
+ else {
+ struct strbuf arg0 = STRBUF_INIT;
+ strbuf_addf(&arg0, "%s \"$@\"", argv[0]);
+ nargv[nargc++] = strbuf_detach(&arg0, NULL);
+ }
+ }
+
+ for (argc = 0; argv[argc]; argc++)
+ nargv[nargc++] = argv[argc];
+ nargv[nargc] = NULL;
+
+ return nargv;
+}
+
+#ifndef WIN32
+static int execv_shell_cmd(const char **argv)
+{
+ const char **nargv = prepare_shell_cmd(argv);
+ trace_argv_printf(nargv, "trace: exec:");
+ execvp(nargv[0], (char **)nargv);
+ free(nargv);
+ return -1;
+}
+#endif
+
+#ifndef WIN32
+static int child_err = 2;
+static int child_notifier = -1;
+
+static void notify_parent(void)
+{
+ write(child_notifier, "", 1);
+}
+
+static NORETURN void die_child(const char *err, va_list params)
+{
+ char msg[4096];
+ int len = vsnprintf(msg, sizeof(msg), err, params);
+ if (len > sizeof(msg))
+ len = sizeof(msg);
+
+ write(child_err, "fatal: ", 7);
+ write(child_err, msg, len);
+ write(child_err, "\n", 1);
+ exit(128);
+}
+
+static inline void set_cloexec(int fd)
+{
+ int flags = fcntl(fd, F_GETFD);
+ if (flags >= 0)
+ fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+}
+#endif
+
+static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
+{
+ int status, code = -1;
+ pid_t waiting;
+ int failed_errno = 0;
+
+ while ((waiting = waitpid(pid, &status, 0)) < 0 && errno == EINTR)
+ ; /* nothing */
+
+ if (waiting < 0) {
+ failed_errno = errno;
+ error("waitpid for %s failed: %s", argv0, strerror(errno));
+ } else if (waiting != pid) {
+ error("waitpid is confused (%s)", argv0);
+ } else if (WIFSIGNALED(status)) {
+ code = WTERMSIG(status);
+ error("%s died of signal %d", argv0, code);
+ /*
+ * This return value is chosen so that code & 0xff
+ * mimics the exit code that a POSIX shell would report for
+ * a program that died from this signal.
+ */
+ code -= 128;
+ } else if (WIFEXITED(status)) {
+ code = WEXITSTATUS(status);
+ /*
+ * Convert special exit code when execvp failed.
+ */
+ if (code == 127) {
+ code = -1;
+ failed_errno = ENOENT;
+ if (!silent_exec_failure)
+ error("cannot run %s: %s", argv0,
+ strerror(ENOENT));
+ }
+ } else {
+ error("waitpid is confused (%s)", argv0);
+ }
+ errno = failed_errno;
+ return code;
+}