diff options
Diffstat (limited to 'src')
-rw-r--r-- | src/util/atomic_io.c | 60 | ||||
-rw-r--r-- | src/util/atomic_io.h | 40 | ||||
-rw-r--r-- | src/util/util.h | 1 |
3 files changed, 101 insertions, 0 deletions
diff --git a/src/util/atomic_io.c b/src/util/atomic_io.c new file mode 100644 index 000000000..1543af9a0 --- /dev/null +++ b/src/util/atomic_io.c @@ -0,0 +1,60 @@ +/* + Authors: + Jan Cholasta <jcholast@redhat.com> + + Copyright (C) 2012 Red Hat + + 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 <http://www.gnu.org/licenses/>. +*/ + +#include "util/atomic_io.h" + +/* based on code from libssh <http://www.libssh.org> */ +ssize_t sss_atomic_io_s(int fd, void *buf, size_t n, bool do_read) +{ + char *b = buf; + size_t pos = 0; + ssize_t res; + struct pollfd pfd; + + pfd.fd = fd; + pfd.events = do_read ? POLLIN : POLLOUT; + + while (n > pos) { + if (do_read) { + res = read(fd, b + pos, n - pos); + } else { + res = write(fd, b + pos, n - pos); + } + switch (res) { + case -1: + if (errno == EINTR) { + continue; + } + if (errno == EAGAIN || errno == EWOULDBLOCK) { + (void) poll(&pfd, 1, -1); + continue; + } + return -1; + case 0: + /* read returns 0 on end-of-file */ + errno = do_read ? 0 : EPIPE; + return pos; + default: + pos += (size_t) res; + } + } + + return pos; +} diff --git a/src/util/atomic_io.h b/src/util/atomic_io.h new file mode 100644 index 000000000..ffae31d6c --- /dev/null +++ b/src/util/atomic_io.h @@ -0,0 +1,40 @@ +/* + Authors: + Jan Cholasta <jcholast@redhat.com> + + Copyright (C) 2012 Red Hat + + 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 <http://www.gnu.org/licenses/>. +*/ + +#ifndef __SSSD_ATOMIC_IO_H__ +#define __SSSD_ATOMIC_IO_H__ + +#include <unistd.h> +#include <stdbool.h> +#include <poll.h> +#include <errno.h> + +/* Performs a read or write operation in an manner that is seemingly atomic + * to the caller. + * + * Please note that the function does not perform any asynchronous operation + * so the operation might potentially block + */ +ssize_t sss_atomic_io_s(int fd, void *buf, size_t n, bool do_read); + +#define sss_atomic_read_s(fd, buf, n) sss_atomic_io_s(fd, buf, n, true) +#define sss_atomic_write_s(fd, buf, n) sss_atomic_io_s(fd, buf, n, false) + +#endif /* __SSSD_ATOMIC_IO_H__ */ diff --git a/src/util/util.h b/src/util/util.h index 43fb007cb..43017aa0d 100644 --- a/src/util/util.h +++ b/src/util/util.h @@ -42,6 +42,7 @@ #include <tevent.h> #include <ldb.h> #include <dhash.h> +#include "util/atomic_io.h" #ifndef HAVE_ERRNO_T #define HAVE_ERRNO_T |