@@ -3,6 +3,7 @@

[chiark-utils.git] / backup / readbuffer.c

diff --git a/backup/readbuffer.c b/backup/readbuffer.c
index 4cd31afb864ce6c966062038c9a5ad5631d5b57b..e48e78c6ff9fd2819e4747ddd6565ec9c269e9b8 100644 (file)
--- a/backup/readbuffer.c
+++ b/backup/readbuffer.c
@@ -1,4 +1,31 @@
-/**/
+/*
+ * readbuffer.c
+ *
+ * A program for reading input from devices which don't like constant
+ * stopping and starting, such as tape drives.  readbuffer is:
+ *  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>
@@ -7,85 +34,58 @@
 #include <stdio.h>
 #include <errno.h>
 #include <unistd.h>
-#include <sys/mman.h>
 
-#define BUFFER 16*1024*1024
-#define WAITEMPTY ((BUFFER*1)/4)
+#include "rwbuffer.h"
 
-static inline int min(int a, int b) { return a<=b ? a : b; }
+const char *progname= "readbuffer";
 
-static void nonblock(int fd) {
-  int r;
-  r= fcntl(fd,F_GETFL,0); if (r == -1) { perror("fcntl getfl"); exit(1); }
-  r |= O_NDELAY;
-  if (fcntl(fd,F_SETFL,r) == -1) { perror("fcntl setfl"); exit(1); }
-}
+static size_t waitempty;
 
 int main(int argc, const char *const *argv) {
-  static unsigned char buf[BUFFER];
-  
-  unsigned char *wp, *rp;
-  int used,r,reading,seeneof;
-  fd_set readfds;
-  fd_set writefds;
+  int r,reading;
 
-  used=0; wp=rp=buf; reading=1; seeneof=0;
-  nonblock(0); nonblock(1);
-  if (argv[1] && !strcmp(argv[1],"--mlock")) {
-    if (mlock(buf,sizeof(buf))) { perror("mlock"); exit(1); }
-    argv++; argc--;
-  }
-  if (argv[1]) { fputs("usage: readbuffer [--mlock]\n",stderr); exit(1); }
+  startup(argv);
+  waitempty= (buffersize*1)/4;
+  reading=1;
+  
   while (!seeneof || used) {
+    
     FD_ZERO(&readfds);
     if (reading) {
-      if (used<BUFFER-1) {
+      if (used<buffersize-1) {
        FD_SET(0,&readfds);
       } else {
-/*fprintf(stderr,"\t buffers full - stopping\n");*/
        reading=0;
       }
     }
     FD_ZERO(&writefds); if (used) FD_SET(1,&writefds);
-/*fprintf(stderr,"used %6d reading %d seeneof %d wp %8lx rp %8lx read %d write %d\n",
-        used,reading,seeneof,(unsigned long)(wp-buf),(unsigned long)(rp-buf),
-        FD_ISSET(0,&readfds),FD_ISSET(1,&writefds));*/
-    r= select(2,&readfds,&writefds,0,0);
-/*fprintf(stderr,"\t readable %d writeable %d\n",
-        FD_ISSET(0,&readfds),FD_ISSET(1,&writefds));*/
-    if (r == -1) {
-      if (errno == EINTR) continue;
-      perror("select"); exit(1);
-    }
+
+    callselect();
+
     if (FD_ISSET(0,&readfds)) {
-      r= read(0,rp,min(BUFFER-1-used,buf+BUFFER-rp));
+      r= read(0,rp,min(buffersize-1-used,buf+buffersize-rp));
       if (!r) {
-/*fprintf(stderr,"\t eof detected\n");*/
         seeneof=1; reading=0;
       } else if (r<0) {
         if (!(errno == EAGAIN || errno == EINTR)) { perror("read"); exit(1); }
-/*fprintf(stderr,"\t read transient error\n");*/
       } else {
-/*fprintf(stderr,"\t read %d\n",r);*/
         used+= r;
         rp+= r;
-        if (rp == buf+BUFFER) rp=buf;
+        if (rp == buf+buffersize) rp=buf;
       }
     }
+
     if (FD_ISSET(1,&writefds)) {
       assert(used);
-      r= write(1,wp,min(used,buf+BUFFER-wp));
+      r= write(1,wp,min(used,buf+buffersize-wp));
       if (r<=0) {
         if (!(errno == EAGAIN || errno == EINTR)) { perror("write"); exit(1); }
-/*fprintf(stderr,"\t write transient error\n");*/
       } else {
-/*fprintf(stderr,"\t wrote %d\n",r);*/
         used-= r;
         wp+= r;
-        if (wp == buf+BUFFER) wp=buf;
+        if (wp == buf+buffersize) wp=buf;
       }
-      if (used < WAITEMPTY && !seeneof) {
-/*fprintf(stderr,"\t starting writes\n");*/
+      if (used < waitempty && !seeneof) {
        reading=1;
       }
     }