+
+/* Like read(), but keep trying until everything has been written or we know for
+ * sure that there was an error (or end-of-file). */
+size_t
+full_read(int fd, void *buf, size_t count)
+{
+ ssize_t bytes_read;
+ size_t bytes_remaining;
+
+ for (bytes_remaining = count;
+ bytes_remaining != 0;
+ bytes_remaining -= bytes_read, buf += bytes_read)
+ {
+ bytes_read = read(fd, buf, bytes_remaining);
+ if (bytes_read <= 0) {
+ if (bytes_read == 0)
+ errno = EIO;
+ else if (errno == EINTR)
+ continue;
+ break;
+ }
+ }
+ return count - bytes_remaining;
+}
+
+/* Like write(), but keep trying until everything has been written or we know
+ * for sure that there was an error. */
+size_t
+full_write(int fd, const void *buf, size_t count)
+{
+ ssize_t bytes_written;
+ size_t bytes_remaining;
+
+ for (bytes_remaining = count;
+ bytes_remaining != 0;
+ bytes_remaining -= bytes_written, buf += bytes_written)
+ {
+ bytes_written = write(fd, buf, bytes_remaining);
+ if (bytes_written < 0) {
+ if (errno == EINTR)
+ continue;
+ break;
+ }
+ }
+ return count - bytes_remaining;
+}
+
+/* Like pread(), but keep trying until everything has been read or we know for
+ * sure that there was an error (or end-of-file) */
+size_t
+full_pread(int fd, void *buf, size_t count, off_t offset)
+{
+ ssize_t bytes_read;
+ size_t bytes_remaining;
+
+ for (bytes_remaining = count;
+ bytes_remaining != 0;
+ bytes_remaining -= bytes_read, buf += bytes_read,
+ offset += bytes_read)
+ {
+ bytes_read = pread(fd, buf, bytes_remaining, offset);
+ if (bytes_read <= 0) {
+ if (bytes_read == 0)
+ errno = EIO;
+ else if (errno == EINTR)
+ continue;
+ break;
+ }
+ }
+ return count - bytes_remaining;
+}
+
+/* Like pwrite(), but keep trying until everything has been written or we know
+ * for sure that there was an error. */
+size_t
+full_pwrite(int fd, const void *buf, size_t count, off_t offset)
+{
+ ssize_t bytes_written;
+ size_t bytes_remaining;
+
+ for (bytes_remaining = count;
+ bytes_remaining != 0;
+ bytes_remaining -= bytes_written, buf += bytes_written,
+ offset += bytes_written)
+ {
+ bytes_written = pwrite(fd, buf, bytes_remaining, offset);
+ if (bytes_written < 0) {
+ if (errno == EINTR)
+ continue;
+ break;
+ }
+ }
+ return count - bytes_remaining;
+}
+
+/* Like writev(), but keep trying until everything has been written or we know
+ * for sure that there was an error. */
+size_t
+full_writev(int fd, struct iovec *iov, int iovcnt)
+{
+ size_t total_bytes_written = 0;
+ while (iovcnt > 0) {
+ ssize_t bytes_written;
+
+ bytes_written = writev(fd, iov, iovcnt);
+ if (bytes_written < 0) {
+ if (errno == EINTR)
+ continue;
+ break;
+ }
+ total_bytes_written += bytes_written;
+ while (bytes_written) {
+ if (bytes_written >= iov[0].iov_len) {
+ bytes_written -= iov[0].iov_len;
+ iov++;
+ iovcnt--;
+ } else {
+ iov[0].iov_base += bytes_written;
+ iov[0].iov_len -= bytes_written;
+ bytes_written = 0;
+ }
+ }
+ }
+ return total_bytes_written;
+}
+
+off_t
+filedes_offset(int fd)
+{
+ return lseek(fd, 0, SEEK_CUR);
+}