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/*
* rwbuffer.c
* common definitions for readbuffer/writebuffer
*
* readbuffer and writebuffer are:
* Copyright (C) 1997-1998,2000-2001 Ian Jackson <ian@chiark.greenend.org.uk>
*
* readbuffer is part of chiark backup, a system for backing up GNU/Linux and
* other UN*X-compatible machines, as used on chiark.greenend.org.uk.
* chiark backup is:
* Copyright (C) 1997-1998,2000-2001 Ian Jackson <ian@chiark.greenend.org.uk>
* Copyright (C) 1999 Peter Maydell <pmaydell@chiark.greenend.org.uk>
*
* This is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2,
* or (at your option) any later version.
*
* This is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this file; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/
#include "rwbuffer.h"
#ifndef RWBUFFER_SIZE_MB_DEF
#define RWBUFFER_SIZE_MB_DEF 16
#endif
#ifndef RWBUFFER_SIZE_MB_MAX
#define RWBUFFER_SIZE_MB_MAX 512
#endif
unsigned char *buf, *wp, *rp;
int used, seeneof, maxselfd;
size_t buffersize;
fd_set readfds;
fd_set writefds;
static int opt_mlock=0;
int min(int a, int b) { return a<=b ? a : b; }
static void usage(FILE *f) {
if (fprintf(f,"usage: %s [--mlock] [<megabytes>]\n",progname) < 0)
{ perror("print usage"); exit(16); }
}
static void usageerr(const char *what) {
fprintf(stderr,"%s: bad usage: %s\n",progname,what);
usage(stderr);
exit(12);
}
void nonblock(int fd, int yesno) {
int r;
r= fcntl(fd,F_GETFL,0); if (r == -1) { perror("fcntl getfl"); exit(8); }
if (yesno) r |= O_NDELAY;
else r &= ~O_NDELAY;
if (fcntl(fd,F_SETFL,r) == -1) { perror("fcntl setfl"); exit(8); }
}
static void unnonblock(void) {
nonblock(0,0); nonblock(1,0);
}
void startupcore(void) {
buf= xmalloc(buffersize);
if (opt_mlock) {
if (mlock(buf,buffersize)) { perror("mlock"); exit(2); }
}
used=0; wp=rp=buf; seeneof=0;
if (atexit(unnonblock)) { perror("atexit"); exit(16); }
}
void startup(const char *const *argv) {
const char *arg;
char *ep;
unsigned long opt_buffersize=RWBUFFER_SIZE_MB_DEF;
assert(argv[0]);
while ((arg= *++argv)) {
if (!strcmp(arg,"--mlock")) {
opt_mlock= 1;
} else if (isdigit((unsigned char)arg[0])) {
opt_buffersize= strtoul(arg,&ep,0);
if (opt_buffersize > RWBUFFER_SIZE_MB_MAX)
usageerr("buffer size too big");
} else {
usageerr("invalid option");
}
}
buffersize= opt_buffersize*1024*1024;
startupcore();
nonblock(0,1); nonblock(1,1);
}
void *xmalloc(size_t sz) {
void *r= malloc(sz); if (!r) { perror("malloc"); exit(6); }; return r;
}
void callselect(void) {
int r;
for (;;) {
r= select(maxselfd,&readfds,&writefds,0,0);
if (r != -1) return;
if (errno != EINTR) {
perror("select"); exit(4);
}
}
}
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