/* Create and remove pidfile Copyright (C) Amitay Isaacs 2016 This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. This program 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 General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, see . */ #include "replace.h" #include "system/filesys.h" #include #include "common/pidfile.h" struct pidfile_context { const char *pidfile; int fd; pid_t pid; }; static int pidfile_context_destructor(struct pidfile_context *pid_ctx); int pidfile_create(TALLOC_CTX *mem_ctx, const char *pidfile, struct pidfile_context **result) { struct pidfile_context *pid_ctx; struct flock lck; char tmp[64]; int fd, ret = 0; int len; ssize_t nwritten; pid_ctx = talloc_zero(mem_ctx, struct pidfile_context); if (pid_ctx == NULL) { return ENOMEM; } pid_ctx->pidfile = talloc_strdup(pid_ctx, pidfile); if (pid_ctx->pidfile == NULL) { ret = ENOMEM; goto fail; } pid_ctx->pid = getpid(); fd = open(pidfile, O_CREAT|O_WRONLY|O_NONBLOCK, 0644); if (fd == -1) { ret = errno; goto fail; } pid_ctx->fd = fd; lck = (struct flock) { .l_type = F_WRLCK, .l_whence = SEEK_SET, }; do { ret = fcntl(fd, F_SETLK, &lck); } while ((ret == -1) && (errno == EINTR)); if (ret != 0) { ret = errno; goto fail; } do { ret = ftruncate(fd, 0); } while ((ret == -1) && (errno == EINTR)); if (ret == -1) { ret = EIO; goto fail_unlink; } len = snprintf(tmp, sizeof(tmp), "%u\n", pid_ctx->pid); if (len < 0) { ret = EIO; goto fail_unlink; } do { nwritten = write(fd, tmp, len); } while ((nwritten == -1) && (errno == EINTR)); if ((nwritten == -1) || (nwritten != len)) { ret = EIO; goto fail_unlink; } talloc_set_destructor(pid_ctx, pidfile_context_destructor); *result = pid_ctx; return 0; fail_unlink: unlink(pidfile); close(fd); fail: talloc_free(pid_ctx); return ret; } static int pidfile_context_destructor(struct pidfile_context *pid_ctx) { struct flock lck; int ret; if (getpid() != pid_ctx->pid) { return 0; } lck = (struct flock) { .l_type = F_UNLCK, .l_whence = SEEK_SET, }; (void) unlink(pid_ctx->pidfile); do { ret = fcntl(pid_ctx->fd, F_SETLK, &lck); } while ((ret == -1) && (errno == EINTR)); do { ret = close(pid_ctx->fd); } while ((ret == -1) && (errno == EINTR)); return 0; }