265 lines
6.9 KiB
C
265 lines
6.9 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <limits.h>
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#include <poll.h>
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#include <stdio.h>
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#include <time.h>
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#include <unistd.h>
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#include "io-util.h"
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#include "string-util.h"
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#include "time-util.h"
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int flush_fd(int fd) {
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struct pollfd pollfd = {
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.fd = fd,
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.events = POLLIN,
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};
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int count = 0;
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/* Read from the specified file descriptor, until POLLIN is not set anymore, throwing away everything
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* read. Note that some file descriptors (notable IP sockets) will trigger POLLIN even when no data can be read
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* (due to IP packet checksum mismatches), hence this function is only safe to be non-blocking if the fd used
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* was set to non-blocking too. */
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for (;;) {
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char buf[LINE_MAX];
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ssize_t l;
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int r;
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r = poll(&pollfd, 1, 0);
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if (r < 0) {
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if (errno == EINTR)
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continue;
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return -errno;
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} else if (r == 0)
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return count;
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l = read(fd, buf, sizeof(buf));
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if (l < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN)
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return count;
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return -errno;
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} else if (l == 0)
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return count;
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count += (int) l;
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}
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}
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ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
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uint8_t *p = buf;
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ssize_t n = 0;
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assert(fd >= 0);
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assert(buf);
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/* If called with nbytes == 0, let's call read() at least
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* once, to validate the operation */
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if (nbytes > (size_t) SSIZE_MAX)
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return -EINVAL;
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do {
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ssize_t k;
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k = read(fd, p, nbytes);
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if (k < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN && do_poll) {
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/* We knowingly ignore any return value here,
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* and expect that any error/EOF is reported
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* via read() */
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(void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
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continue;
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}
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return n > 0 ? n : -errno;
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}
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if (k == 0)
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return n;
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assert((size_t) k <= nbytes);
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p += k;
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nbytes -= k;
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n += k;
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} while (nbytes > 0);
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return n;
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}
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int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) {
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ssize_t n;
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n = loop_read(fd, buf, nbytes, do_poll);
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if (n < 0)
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return (int) n;
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if ((size_t) n != nbytes)
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return -EIO;
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return 0;
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}
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int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
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const uint8_t *p = buf;
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assert(fd >= 0);
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assert(buf);
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if (_unlikely_(nbytes > (size_t) SSIZE_MAX))
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return -EINVAL;
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do {
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ssize_t k;
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k = write(fd, p, nbytes);
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if (k < 0) {
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if (errno == EINTR)
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continue;
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if (errno == EAGAIN && do_poll) {
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/* We knowingly ignore any return value here,
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* and expect that any error/EOF is reported
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* via write() */
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(void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
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continue;
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}
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return -errno;
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}
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if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */
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return -EIO;
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assert((size_t) k <= nbytes);
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p += k;
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nbytes -= k;
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} while (nbytes > 0);
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return 0;
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}
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int pipe_eof(int fd) {
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struct pollfd pollfd = {
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.fd = fd,
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.events = POLLIN|POLLHUP,
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};
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int r;
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r = poll(&pollfd, 1, 0);
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if (r < 0)
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return -errno;
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if (r == 0)
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return 0;
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return pollfd.revents & POLLHUP;
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}
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int fd_wait_for_event(int fd, int event, usec_t t) {
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struct pollfd pollfd = {
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.fd = fd,
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.events = event,
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};
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struct timespec ts;
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int r;
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r = ppoll(&pollfd, 1, t == USEC_INFINITY ? NULL : timespec_store(&ts, t), NULL);
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if (r < 0)
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return -errno;
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if (r == 0)
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return 0;
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return pollfd.revents;
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}
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static size_t nul_length(const uint8_t *p, size_t sz) {
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size_t n = 0;
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while (sz > 0) {
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if (*p != 0)
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break;
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n++;
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p++;
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sz--;
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}
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return n;
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}
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ssize_t sparse_write(int fd, const void *p, size_t sz, size_t run_length) {
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const uint8_t *q, *w, *e;
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ssize_t l;
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q = w = p;
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e = q + sz;
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while (q < e) {
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size_t n;
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n = nul_length(q, e - q);
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/* If there are more than the specified run length of
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* NUL bytes, or if this is the beginning or the end
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* of the buffer, then seek instead of write */
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if ((n > run_length) ||
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(n > 0 && q == p) ||
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(n > 0 && q + n >= e)) {
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if (q > w) {
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l = write(fd, w, q - w);
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if (l < 0)
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return -errno;
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if (l != q -w)
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return -EIO;
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}
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if (lseek(fd, n, SEEK_CUR) == (off_t) -1)
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return -errno;
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q += n;
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w = q;
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} else if (n > 0)
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q += n;
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else
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q++;
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}
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if (q > w) {
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l = write(fd, w, q - w);
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if (l < 0)
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return -errno;
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if (l != q - w)
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return -EIO;
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}
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return q - (const uint8_t*) p;
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}
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char* set_iovec_string_field(struct iovec *iovec, size_t *n_iovec, const char *field, const char *value) {
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char *x;
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x = strappend(field, value);
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if (x)
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iovec[(*n_iovec)++] = IOVEC_MAKE_STRING(x);
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return x;
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}
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