--- /dev/null
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+ This file is part of systemd.
+
+ Copyright 2010 Lennart Poettering
+
+ systemd 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.
+
+ systemd 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 systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <poll.h>
+#include <unistd.h>
+
+#include "io-util.h"
+
+int flush_fd(int fd) {
+ struct pollfd pollfd = {
+ .fd = fd,
+ .events = POLLIN,
+ };
+
+ for (;;) {
+ char buf[LINE_MAX];
+ ssize_t l;
+ int r;
+
+ r = poll(&pollfd, 1, 0);
+ if (r < 0) {
+ if (errno == EINTR)
+ continue;
+
+ return -errno;
+
+ } else if (r == 0)
+ return 0;
+
+ l = read(fd, buf, sizeof(buf));
+ if (l < 0) {
+
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN)
+ return 0;
+
+ return -errno;
+ } else if (l == 0)
+ return 0;
+ }
+}
+
+ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
+ uint8_t *p = buf;
+ ssize_t n = 0;
+
+ assert(fd >= 0);
+ assert(buf);
+
+ /* If called with nbytes == 0, let's call read() at least
+ * once, to validate the operation */
+
+ if (nbytes > (size_t) SSIZE_MAX)
+ return -EINVAL;
+
+ do {
+ ssize_t k;
+
+ k = read(fd, p, nbytes);
+ if (k < 0) {
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN && do_poll) {
+
+ /* We knowingly ignore any return value here,
+ * and expect that any error/EOF is reported
+ * via read() */
+
+ (void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
+ continue;
+ }
+
+ return n > 0 ? n : -errno;
+ }
+
+ if (k == 0)
+ return n;
+
+ assert((size_t) k <= nbytes);
+
+ p += k;
+ nbytes -= k;
+ n += k;
+ } while (nbytes > 0);
+
+ return n;
+}
+
+int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) {
+ ssize_t n;
+
+ n = loop_read(fd, buf, nbytes, do_poll);
+ if (n < 0)
+ return (int) n;
+ if ((size_t) n != nbytes)
+ return -EIO;
+
+ return 0;
+}
+
+int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
+ const uint8_t *p = buf;
+
+ assert(fd >= 0);
+ assert(buf);
+
+ if (nbytes > (size_t) SSIZE_MAX)
+ return -EINVAL;
+
+ do {
+ ssize_t k;
+
+ k = write(fd, p, nbytes);
+ if (k < 0) {
+ if (errno == EINTR)
+ continue;
+
+ if (errno == EAGAIN && do_poll) {
+ /* We knowingly ignore any return value here,
+ * and expect that any error/EOF is reported
+ * via write() */
+
+ (void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
+ continue;
+ }
+
+ return -errno;
+ }
+
+ if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */
+ return -EIO;
+
+ assert((size_t) k <= nbytes);
+
+ p += k;
+ nbytes -= k;
+ } while (nbytes > 0);
+
+ return 0;
+}
+
+int pipe_eof(int fd) {
+ struct pollfd pollfd = {
+ .fd = fd,
+ .events = POLLIN|POLLHUP,
+ };
+
+ int r;
+
+ r = poll(&pollfd, 1, 0);
+ if (r < 0)
+ return -errno;
+
+ if (r == 0)
+ return 0;
+
+ return pollfd.revents & POLLHUP;
+}
+
+int fd_wait_for_event(int fd, int event, usec_t t) {
+
+ struct pollfd pollfd = {
+ .fd = fd,
+ .events = event,
+ };
+
+ struct timespec ts;
+ int r;
+
+ r = ppoll(&pollfd, 1, t == USEC_INFINITY ? NULL : timespec_store(&ts, t), NULL);
+ if (r < 0)
+ return -errno;
+
+ if (r == 0)
+ return 0;
+
+ return pollfd.revents;
+}
+
+static size_t nul_length(const uint8_t *p, size_t sz) {
+ size_t n = 0;
+
+ while (sz > 0) {
+ if (*p != 0)
+ break;
+
+ n++;
+ p++;
+ sz--;
+ }
+
+ return n;
+}
+
+ssize_t sparse_write(int fd, const void *p, size_t sz, size_t run_length) {
+ const uint8_t *q, *w, *e;
+ ssize_t l;
+
+ q = w = p;
+ e = q + sz;
+ while (q < e) {
+ size_t n;
+
+ n = nul_length(q, e - q);
+
+ /* If there are more than the specified run length of
+ * NUL bytes, or if this is the beginning or the end
+ * of the buffer, then seek instead of write */
+ if ((n > run_length) ||
+ (n > 0 && q == p) ||
+ (n > 0 && q + n >= e)) {
+ if (q > w) {
+ l = write(fd, w, q - w);
+ if (l < 0)
+ return -errno;
+ if (l != q -w)
+ return -EIO;
+ }
+
+ if (lseek(fd, n, SEEK_CUR) == (off_t) -1)
+ return -errno;
+
+ q += n;
+ w = q;
+ } else if (n > 0)
+ q += n;
+ else
+ q ++;
+ }
+
+ if (q > w) {
+ l = write(fd, w, q - w);
+ if (l < 0)
+ return -errno;
+ if (l != q - w)
+ return -EIO;
+ }
+
+ return q - (const uint8_t*) p;
+}
~ianmdlvl / elogind.git / blobdiff