/*-*- 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; }