move rwbuffer to new cprogs directory

[chiark-utils.git] / cprogs / rwbuffer.c

diff --git a/cprogs/rwbuffer.c b/cprogs/rwbuffer.c
new file mode 100644 (file)
index 0000000..d91a96e
--- /dev/null
+++ b/cprogs/rwbuffer.c
@@ -0,0 +1,128 @@
+/*
+ * 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 <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <assert.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/mman.h>
+
+#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;
+size_t buffersize;
+fd_set readfds;
+fd_set writefds;
+
+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);
+}
+
+static 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 startup(const char *const *argv) {
+  const char *arg;
+  char *ep;
+  unsigned long opt_buffersize=RWBUFFER_SIZE_MB_DEF;
+  int opt_mlock=0;
+  
+  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;
+  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); }
+  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(2,&readfds,&writefds,0,0);
+    if (r != -1) return;
+    if (errno != EINTR) {
+      perror("select"); exit(4);
+    }
+  }
+}