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.
32 #ifndef RWBUFFER_SIZE_MB_DEF
33 #define RWBUFFER_SIZE_MB_DEF 16
36 #ifndef RWBUFFER_SIZE_MB_MAX
37 #define RWBUFFER_SIZE_MB_MAX 512
40 unsigned char *buf, *wp, *rp;
41 int used, seeneof, maxselfd;
46 static int opt_mlock=0;
48 int min(int a, int b) { return a<=b ? a : b; }
50 static void usage(FILE *f) {
51 if (fprintf(f,"usage: %s [--mlock] [<megabytes>]\n",progname) < 0)
52 { perror("print usage"); exit(16); }
55 static void usageerr(const char *what) {
56 fprintf(stderr,"%s: bad usage: %s\n",progname,what);
61 void nonblock(int fd, int yesno) {
63 r= fcntl(fd,F_GETFL,0); if (r == -1) { perror("fcntl getfl"); exit(8); }
64 if (yesno) r |= O_NDELAY;
66 if (fcntl(fd,F_SETFL,r) == -1) { perror("fcntl setfl"); exit(8); }
69 static void unnonblock(void) {
70 nonblock(0,0); nonblock(1,0);
73 void startupcore(void) {
74 buf= xmalloc(buffersize);
77 if (mlock(buf,buffersize)) { perror("mlock"); exit(2); }
80 used=0; wp=rp=buf; seeneof=0;
81 if (atexit(unnonblock)) { perror("atexit"); exit(16); }
84 void startup(const char *const *argv) {
87 unsigned long opt_buffersize=RWBUFFER_SIZE_MB_DEF;
91 while ((arg= *++argv)) {
92 if (!strcmp(arg,"--mlock")) {
94 } else if (isdigit((unsigned char)arg[0])) {
95 opt_buffersize= strtoul(arg,&ep,0);
96 if (opt_buffersize > RWBUFFER_SIZE_MB_MAX)
97 usageerr("buffer size too big");
99 usageerr("invalid option");
103 buffersize= opt_buffersize*1024*1024;
105 nonblock(0,1); nonblock(1,1);
108 void *xmalloc(size_t sz) {
109 void *r= malloc(sz); if (!r) { perror("malloc"); exit(6); }; return r;
112 void callselect(void) {
116 r= select(maxselfd,&readfds,&writefds,0,0);
118 if (errno != EINTR) {
119 perror("select"); exit(4);