4 * A program for reading input from devices which don't like constant
5 * stopping and starting, such as tape drives. readbuffer is:
6 * Copyright (C) 1997-1998,2000-2001 Ian Jackson <ian@chiark.greenend.org.uk>
8 * readbuffer is part of chiark backup, a system for backing up GNU/Linux and
9 * other UN*X-compatible machines, as used on chiark.greenend.org.uk.
11 * Copyright (C) 1997-1998,2000-2001 Ian Jackson <ian@chiark.greenend.org.uk>
12 * Copyright (C) 1999 Peter Maydell <pmaydell@chiark.greenend.org.uk>
14 * This is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as
16 * published by the Free Software Foundation; either version 3,
17 * or (at your option) any later version.
19 * This is distributed in the hope that it will be useful, but
20 * WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
24 * You should have received a copy of the GNU General Public
25 * License along with this file; if not, consult the Free Software
26 * Foundation's website at www.fsf.org, or the GNU Project website at
33 const char *progname= "readbuffer";
35 static size_t waitempty;
37 int main(int argc, const char *const *argv) {
41 waitempty= (buffersize*1)/4;
45 while (!seeneof || used) {
49 if (used<buffersize-1) {
55 FD_ZERO(&writefds); if (used) FD_SET(1,&writefds);
59 if (FD_ISSET(0,&readfds)) {
60 r= read(0,rp,min(buffersize-1-used,buf+buffersize-rp));
64 if (!(errno == EAGAIN || errno == EINTR)) { perror("read"); exit(1); }
68 if (rp == buf+buffersize) rp=buf;
72 if (FD_ISSET(1,&writefds)) {
74 r= write(1,wp,min(used,buf+buffersize-wp));
76 if (!(errno == EAGAIN || errno == EINTR)) { perror("write"); exit(1); }
80 if (wp == buf+buffersize) wp=buf;
82 if (used < waitempty && !seeneof) {