3 * common definitions for readbuffer/writebuffer
5 * readbuffer and writebuffer are:
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 2,
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, write to the Free Software
26 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
31 #include <sys/types.h>
43 #ifndef RWBUFFER_SIZE_MB_DEF
44 #define RWBUFFER_SIZE_MB_DEF 16
47 #ifndef RWBUFFER_SIZE_MB_MAX
48 #define RWBUFFER_SIZE_MB_MAX 512
51 unsigned char *buf, *wp, *rp;
57 int min(int a, int b) { return a<=b ? a : b; }
59 static void usage(FILE *f) {
60 if (fprintf(f,"usage: %s [--mlock] [<megabytes>]\n",progname) < 0)
61 { perror("print usage"); exit(16); }
64 static void usageerr(const char *what) {
65 fprintf(stderr,"%s: bad usage: %s\n",progname,what);
70 static void nonblock(int fd, int yesno) {
72 r= fcntl(fd,F_GETFL,0); if (r == -1) { perror("fcntl getfl"); exit(8); }
73 if (yesno) r |= O_NDELAY;
75 if (fcntl(fd,F_SETFL,r) == -1) { perror("fcntl setfl"); exit(8); }
78 static void unnonblock(void) {
79 nonblock(0,0); nonblock(1,0);
82 void startup(const char *const *argv) {
85 unsigned long opt_buffersize=RWBUFFER_SIZE_MB_DEF;
90 while ((arg= *++argv)) {
91 if (!strcmp(arg,"--mlock")) {
93 } else if (isdigit((unsigned char)arg[0])) {
94 opt_buffersize= strtoul(arg,&ep,0);
95 if (opt_buffersize > RWBUFFER_SIZE_MB_MAX)
96 usageerr("buffer size too big");
98 usageerr("invalid option");
102 buffersize= opt_buffersize*1024*1024;
103 buf= malloc(buffersize);
104 if (!buf) { perror("malloc buffer"); exit(6); }
107 if (mlock(buf,buffersize)) { perror("mlock"); exit(2); }
110 used=0; wp=rp=buf; seeneof=0;
111 if (atexit(unnonblock)) { perror("atexit"); exit(16); }
112 nonblock(0,1); nonblock(1,1);
115 void callselect(void) {
119 r= select(2,&readfds,&writefds,0,0);
121 if (errno != EINTR) {
122 perror("select"); exit(4);