LU-10508 utils: use callvpe() in lustre_rsync

[fs/lustre-release.git] / lustre / utils / callvpe.c

diff --git a/lustre/utils/callvpe.c b/lustre/utils/callvpe.c
new file mode 100644 (file)
index 0000000..5c98a05
--- /dev/null
+++ b/lustre/utils/callvpe.c
@@ -0,0 +1,116 @@
+/*
+ * LGPL HEADER START
+ *
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of the
+ * License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * LGPL HEADER END
+ *
+ * Copyright (c) 2018, Intel Corporation.
+ */
+
+#include <signal.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include "callvpe.h"
+
+/**
+ * callvpe() - execute a file with given arguments and environment.
+ * \param file[in] name or path of file to be executed.
+ * \param args[in] arguments to file.
+ * \param envp[in] execution environment.
+ * \return -1 on failure (for example if fork() failed).
+ * \return process return status on success.
+ *
+ * callvpe() is intended as a safer replacement for system(). It
+ * executes the file specified and returns after it has completed. As
+ * with system during execution of the command, SIGCHLD will be
+ * blocked, and SIGINT and SIGQUIT will be ignored. The main
+ * difference between system(cmd) and callvpe(file, args, envp) is
+ * that system() calls exec("/bin/sh" "-c" "cmd") whereas callvpe()
+ * bypasses the shell and passes the args given directly to execvpe().
+ *
+ * Rather than:
+ *
+ *      snprintf(cmd, sizeof(cmd), "rm -rf %s\n", path);
+ *      rc = system(cmd);
+ *
+ * instead use:
+ *
+ *      char *args[] = { "rm", "-rf", "--", path, NULL };
+ *      extern char **environ;
+ *      rc = callvpe("/bin/rm", args, environ);
+ *
+ * Note that since callvpe() does not use the shell, IO redirection
+ * and pipelines (cmd > /dev/null, cmd 2>&1, cmd1 | cmd2, ...) are not
+ * supported.
+ */
+int callvpe(const char *file, char *const args[], char *const envp[])
+{
+       struct sigaction sa = {
+               .sa_handler = SIG_IGN,
+       };
+       struct sigaction sa_int_saved;
+       struct sigaction sa_quit_saved;
+       sigset_t sigset_saved;
+       pid_t pid;
+       pid_t pid2;
+       int status;
+       int rc;
+
+       sigemptyset(&sa.sa_mask);
+
+       rc = sigaction(SIGINT, &sa, &sa_int_saved);
+       if (rc < 0)
+               return rc;
+
+       rc = sigaction(SIGQUIT, &sa, &sa_quit_saved);
+       if (rc < 0)
+               goto out_sa_int;
+
+       sigaddset(&sa.sa_mask, SIGCHLD);
+       rc = sigprocmask(SIG_BLOCK, &sa.sa_mask, &sigset_saved);
+       if (rc < 0)
+               goto out_sa_quit;
+
+       pid = fork();
+       if (pid < 0) {
+               rc = -1;
+               goto out_sigset;
+       }
+
+       if (pid == 0) {
+               execvpe(file, args, envp);
+               _exit(127);
+       }
+
+       pid2 = waitpid(pid, &status, 0);
+       if (pid2 < 0) {
+               rc = -1;
+               goto out_sigset;
+       }
+
+       rc = status;
+
+out_sigset:
+       sigprocmask(SIG_SETMASK, &sigset_saved, NULL);
+out_sa_quit:
+       sigaction(SIGQUIT, &sa_quit_saved, NULL);
+out_sa_int:
+       sigaction(SIGINT, &sa_int_saved, NULL);
+
+       return rc;
+}