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author | Ondrej Kos <okos@redhat.com> | 2013-02-07 12:11:43 +0100 |
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committer | Jakub Hrozek <jhrozek@redhat.com> | 2013-02-11 15:45:10 +0100 |
commit | 075df914c0355e1dcafad1a128877be11241725c (patch) | |
tree | c8709f4da7e8c48c22958ecf9f58ac27347076a8 | |
parent | 9ec97a7502739c4966b5f3eb9d6b6ed282cf954b (diff) | |
download | sssd2-075df914c0355e1dcafad1a128877be11241725c.tar.gz sssd2-075df914c0355e1dcafad1a128877be11241725c.tar.xz sssd2-075df914c0355e1dcafad1a128877be11241725c.zip |
UTIL: Add function for atomic I/O
-rw-r--r-- | Makefile.am | 2 | ||||
-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 |
4 files changed, 103 insertions, 0 deletions
diff --git a/Makefile.am b/Makefile.am index e00b7ca5..d668acc2 100644 --- a/Makefile.am +++ b/Makefile.am @@ -237,6 +237,7 @@ SSSD_UTIL_OBJ = \ src/util/backup_file.c \ src/util/strtonum.c \ src/util/check_and_open.c \ + src/util/atomic_io.c \ src/util/refcount.c \ $(SSSD_DEBUG_OBJ) @@ -321,6 +322,7 @@ endif dist_noinst_HEADERS = \ src/monitor/monitor.h \ + src/util/atomic_io.h \ src/util/crypto/sss_crypto.h \ src/util/dlinklist.h \ src/util/util.h \ diff --git a/src/util/atomic_io.c b/src/util/atomic_io.c new file mode 100644 index 00000000..1543af9a --- /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 00000000..ffae31d6 --- /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 43fb007c..43017aa0 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 |