LU-14034 hsm: add PID file handling to lhsmtool_posix

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

diff --git a/lustre/utils/pid_file.c b/lustre/utils/pid_file.c
new file mode 100644 (file)
index 0000000..2d19c70
--- /dev/null
+++ b/lustre/utils/pid_file.c
@@ -0,0 +1,78 @@
+/*
+ * 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 2020, DataDirect Networks Storage.
+ */
+#include <stddef.h>
+#include <stdio.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <unistd.h>
+#include "pid_file.h"
+
+int create_pid_file(const char *path)
+{
+       char buf[3 * sizeof(long long) + 2];
+       size_t buf_len;
+       int fd = -1;
+       int rc2;
+
+       fd = open(path, O_RDWR|O_CREAT|O_CLOEXEC, 0600);
+       if (fd < 0) {
+               fprintf(stderr, "%s: cannot open '%s': %s\n",
+                       program_invocation_short_name, path, strerror(errno));
+               return -1;
+       }
+
+       struct flock fl = {
+               .l_type = F_WRLCK,
+               .l_whence = SEEK_SET,
+       };
+
+       rc2 = fcntl(fd, F_SETLK, &fl);
+       if (rc2 < 0) {
+               fprintf(stderr, "%s: cannot lock '%s': %s\n",
+                       program_invocation_short_name, path, strerror(errno));
+               goto out;
+       }
+
+       rc2 = ftruncate(fd, 0);
+       if (rc2 < 0) {
+               fprintf(stderr, "%s: cannot truncate '%s': %s\n",
+                       program_invocation_short_name, path, strerror(errno));
+               goto out;
+       }
+
+       buf_len = snprintf(buf, sizeof(buf), "%lld\n", (long long)getpid());
+       rc2 = write(fd, buf, buf_len);
+       if (rc2 < 0) {
+               fprintf(stderr, "%s: cannot write '%s': %s\n",
+                       program_invocation_short_name, path, strerror(errno));
+               goto out;
+       }
+out:
+       if (rc2 < 0 && !(fd < 0)) {
+               close(fd);
+               fd = -1;
+       }
+
+       return fd;
+}