X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=cprogs%2Frcopy-repeatedly.c;h=86cd3170388c2d9a66d32b7925616411a8a38874;hb=e07e49f983756cbeb25ac4ac813e18defdca0de6;hp=489ab2daf5ec09e15cc2ae0e8d567fb09de6d36c;hpb=b04c264af5257661e52015a8895f81046a39e8d8;p=chiark-utils.git

diff --git a/cprogs/rcopy-repeatedly.c b/cprogs/rcopy-repeatedly.c
index 489ab2d..86cd317 100644
--- a/cprogs/rcopy-repeatedly.c
+++ b/cprogs/rcopy-repeatedly.c
@@ -1,7 +1,11 @@
+/*
+ * rcopy-repeatedly
+ */     
+  
 /*
  * protocol is:
  *   server sends banner
- *    - "chiark-realtime-replicator\n" [27 bytes]
+ *    - "#rcopy-repeatedly#\n"
  *    - length of declaration, as 4 hex digits, zero prefixed,
  *      and a space [5 bytes].  In this protocol version this
  *      will be "0002" but client _must_ parse it.
@@ -13,191 +17,613 @@
  *   client sends
  *    - 0x01   go
  * then for each update
- *   sender sends
- *    - 0x02   update using rle and 8-bit counts
- *    - zero or more repetitions of
- *        n    single byte giving length of data same as last time
- *        d    single byte giving length of data changed
- *        ...  d bytes of data
- *        where n!=0 or d!=0 (and for first update, n==0)
- *    - 0x00 0x00
- *       indicates file is complete and should be installed
- *   or server may send
+ *   sender sends one of
  *    - 0x03   destination file should be deleted
  *             but note that contents must be retained by receiver
  *             as it may be used for rle updates
+ *    - 0x04   complete new destination file follows, 64-bit length
+ *        l    8 bytes big endian length
+ *        ...  l bytes data
+ *             receiver must then reply with 0x01 GO
  */
 
-#define REPLMSG_GO   0x01
-#define REPLMSG_RLE8 0x02
-#define REPLMSG_RM   0x03
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <time.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+#include <assert.h>
+#include <math.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "myopt.h"
+
+#define REPLMSG_GO     0x01
+#define REPLMSG_RM     0x03
+#define REPLMSG_FILE64 0x04
+
+static const char banner[]= "#rcopy-repeatedly#\n";
+
+static FILE *commsi, *commso;
+
+static double max_bw_prop_mean= 0.2;
+static double max_bw_prop_burst= 0.8;
+static int txblocksz= INT_MAX, verbose=1;
+static int min_interval_usec= 100000; /* 100ms */
 
-static void vdie(int ec, const char *fmt, const char *emstr, va_list al) {
-  fputs("realtime-replicator: ",stderr);
+static int nsargs;
+static const char **sargs;
+
+static const char *rsh_program= 0;
+static const char *rcopy_repeatedly_program= "rcopy-repeatedly";
+static int server_upcopy=-1; /* -1 means not yet known; 0 means download */
+  /* `up' means towards the client,
+   * since we regard the subprocess as `down' */
+
+static double stream_allow_secsperbyte= 1/1e6; /* for initial transfer */
+
+static char mainbuf[65536]; /* must be at least 2^16 */
+
+#define NORETURN __attribute__((noreturn))
+
+static void vdie(int ec, const char *pfx, int eno,
+		 const char *fmt, va_list al) NORETURN;
+static void vdie(int ec, const char *pfx, int eno,
+		 const char *fmt, va_list al) {
+  fputs("rcopy-repeatedly: ",stderr);
+  if (server_upcopy>=0) fputs("server: ",stderr);
+  if (pfx) fprintf(stderr,"%s: ",pfx);
   vfprintf(stderr,fmt,al);
-  if (emstr) fprintf(stderr,": %s",emstr);
+  if (eno!=-1) fprintf(stderr,": %s",strerror(eno));
   fputc('\n',stderr);
   exit(ec);
 }
-static void die(int ec, const char *fmt, const char *emstr, ...) {
-  va_arg al;
+static void die(int ec, const char *pfx, int eno,
+		const char *fmt, ...) NORETURN;
+static void die(int ec, const char *pfx, int eno,
+		const char *fmt, ...) {
+  va_list al;
   va_start(al,fmt);
-  vdiee(ec,fmt,emstr,al);
+  vdie(ec,pfx,eno,fmt,al);
 }
 
-static void diem(void) { die(16,"malloc failed",strerror(errno)); }
+static void diem(void) NORETURN;
+static void diem(void) { die(16,0,errno,"malloc failed"); }
+static void *xmalloc(size_t sz) {
+  assert(sz);
+  void *p= malloc(sz);
+  if (!p) diem();
+  return p;
+}
+static void *xrealloc(void *p, size_t sz) {
+  assert(sz);
+  p= realloc(p,sz);
+  if (!p) diem();
+  return p;
+}
 
+static void diee(const char *fmt, ...) NORETURN;
 static void diee(const char *fmt, ...) {
-  const char *em= strerror(errno);
-  va_arg al;
+  va_list al;
   va_start(al,fmt);
-  diee(8,fmt,em,al);
+  vdie(12,0,errno,fmt,al);
 }
+static void die_protocol(const char *fmt, ...) NORETURN;
 static void die_protocol(const char *fmt, ...) {
-  va_arg al;
+  va_list al;
   va_start(al,fmt);
-  diee(12,fmt,0,al);
+  vdie(10,"protocol error",-1,fmt,al);
+}
 
-static void die_badrecv(FILE *f, const char *what) {
-  if (ferror(f)) diee("transmission failed while receiving %s", what);
-  if (feof(f)) die_protocol("receiver got unexpected EOF in %s", what);
+static void die_badrecv(const char *what) NORETURN;
+static void die_badrecv(const char *what) {
+  if (ferror(commsi)) diee("communication failed while receiving %s", what);
+  if (feof(commsi)) die_protocol("receiver got unexpected EOF in %s", what);
   abort();
 }
+static void die_badsend(void) NORETURN;
+static void die_badsend(void) {
+  diee("transmission failed");
+}
+
+static void send_flush(void) {
+  if (ferror(commso) || fflush(commso))
+    die_badsend();
+}
+static void sendbyte(int c) {
+  if (putc(c,commso)==EOF)
+    die_badsend();
+}
+
+static void mpipe(int p[2]) { if (pipe(p)) diee("could not create pipe"); }
+static void mdup2(int fd, int fd2) {
+  if (dup2(fd,fd2)!=fd2) diee("could not dup2(%d,%d)",fd,fd2);
+}
+
+typedef void copyfile_die_fn(FILE *f, const char *xi);
+
+struct timespec ts_sendstart;
 
-static void receiver_write(const unsigned char *buf, int n,
-			   FILE *newfile, const char *tmpfilename) {
-  int r;
+static void mgettime(struct timespec *ts) {
+  int r= clock_gettime(CLOCK_MONOTONIC, ts);
+  if (r) diee("clock_gettime failed");
+}
+
+static void bandlimit_sendstart(void) {
+  mgettime(&ts_sendstart);
+}
+
+static double mgettime_elapsed(struct timespec ts_base,
+			       struct timespec *ts_ret) {
+  mgettime(ts_ret);
+  return (ts_ret->tv_sec - ts_base.tv_sec) +
+         (ts_ret->tv_nsec - ts_base.tv_nsec)*1e-9;
+}
 
-  r= fwrite(dbuf,1,n,newfile);
-  if (r != n) diee("failed to write temporary receiving file `%s'",
-		   tmpfilename);
+static void flushstderr(void) {
+  if (ferror(stderr) || fflush(stderr))
+    diee("could not write progress to stderr");
+}
+
+static void verbosespinprintf(const char *fmt, ...) {
+  static const char spinnerchars[]= "/-\\";
+  static int spinnerchar;
+
+  if (!verbose)
+    return;
+
+  va_list al;
+  va_start(al,fmt);
+  fprintf(stderr,"      %c ",spinnerchars[spinnerchar]);
+  spinnerchar++; spinnerchar %= sizeof(spinnerchars)-1;
+  vfprintf(stderr,fmt,al);
+  putc('\r',stderr);
+  flushstderr();
+}
+
+static void bandlimit_sendend(uint64_t bytes, int *interval_usec_update) {
+  struct timespec ts_buf;
+  double elapsed= mgettime_elapsed(ts_sendstart, &ts_buf);
+  double secsperbyte_observed= elapsed / bytes;
+
+  stream_allow_secsperbyte=
+    secsperbyte_observed * max_bw_prop_mean / max_bw_prop_burst;
+
+  double min_update= elapsed / max_bw_prop_mean;
+  if (min_update > 1e3) min_update= 1e3;
+  int min_update_usec= min_update * 1e6;
+
+  if (*interval_usec_update > min_update_usec)
+    *interval_usec_update= min_update_usec;
+
+  verbosespinprintf("%12lluby %10.3fs %13.2fkby/s",
+		    (unsigned long long)bytes, elapsed,
+		    1e-3/secsperbyte_observed);
 }
  
-static void receiver(const char *filename, FILE *comms) {
-  FILE *lastfile=0, *newfile;
+static void copyfile(FILE *sf, copyfile_die_fn *sdie, const char *sxi,
+		     FILE *df, copyfile_die_fn *ddie, const char *dxi,
+		     uint64_t lstart, int amsender) {
+  struct timespec ts_last;
+  int now, r;
+  uint64_t l=lstart, done=0;
+
+  ts_last= ts_sendstart;
+
+  while (l>0) {
+    now= l < sizeof(mainbuf) ? l : sizeof(mainbuf);
+    if (now > txblocksz) now= txblocksz;
+
+    if (verbose) {
+      fprintf(stderr," %3d%% \r",
+	      (int)(done*100.0/lstart));
+      flushstderr();
+    }
+
+    if (amsender) {
+      double elapsed_want= now * stream_allow_secsperbyte;
+      double elapsed= mgettime_elapsed(ts_last, &ts_last);
+      double needwait= elapsed_want - elapsed;
+      if (needwait > 1) needwait= 1;
+      if (needwait > 0) usleep(ceil(needwait * 1e6));
+    }
+
+    r= fread(mainbuf,1,now,sf);  if (r!=now) sdie(sf,sxi);
+    r= fwrite(mainbuf,1,now,df);  if (r!=now) ddie(df,dxi);
+    l -= now;
+    done += now;
+  }
+}
+
+static void copydie_inputfile(FILE *f, const char *filename) {
+  diee("read failed on source file `%s'", filename);
+}
+static void copydie_tmpwrite(FILE *f, const char *tmpfilename) {
+  diee("write failed to temporary receiving file `%s'", tmpfilename);
+}
+static void copydie_commsi(FILE *f, const char *what) {
+  die_badrecv(what);
+}
+static void copydie_commso(FILE *f, const char *what) {
+  die_badsend();
+}
+  
+static void receiver(const char *filename) {
+  FILE *newfile;
   char *tmpfilename;
+  int r, c;
 
-  if (asprintf(&tmpfilename, ".realtime-replicator.#%s#")==-1) diem();
+  char *lastslash= strrchr(filename,'/');
+  if (!lastslash)
+    r= asprintf(&tmpfilename, ".rcopy-repeatedly.#%s#", filename);
+  else
+    r= asprintf(&tmpfilename, "%.*s/.rcopy-repeatedly.#%s#",
+		(int)(lastslash-filename), filename, lastslash+1);
+  if (r==-1) diem();
   
   r= unlink(tmpfilename);
   if (r && errno!=ENOENT)
     diee("could not remove temporary receiving file `%s'", tmpfilename);
   
   for (;;) {
-    c= fgetc(comms);  if (c==EOF) break;
+    send_flush();
+    c= fgetc(commsi);
+
     switch (c) {
 
-    case REPLMSG_RLE8:
-      newfile= fopen(tmpfilename, "w");
+    case EOF:
+      if (ferror(commsi)) die_badrecv("transfer message code");
+      assert(feof(commsi));
+      return;
+
+    case REPLMSG_RM:
+      r= unlink(filename);
+      if (r && errno!=ENOENT)
+	diee("source file removed but could not remove destination file `%s'",
+	     filename);
+      break;
+      
+    case REPLMSG_FILE64:
+      newfile= fopen(tmpfilename, "wb");
       if (!newfile) diee("could not create temporary receiving file `%s'",
 			 tmpfilename);
-      for (;;) {
-	unsigned char lu[2], dbuf[255];
-	r= fread(lu,1,2,comms);  if (r!=2) die_badrecv(comms,"RLE8 elem hdr");
-	if (!lu[0] && !lu[1]) break;
-	if (lu[0]) {
-	  if (!lastfile) die_protocol("first RLE8 requests some previous");
-	  r= fread(dbuf,1,lu[0],lastfile);
-	  if (r!=lu[0]) {
-	    if (ferror(lastfile)) diee("could not read current (old) file"
-				       " `%s'", filename);
-	    assert(feof(lastfile));
-	    die_protocol("RLE8 requests more previous than is available");
-	  }
-	  receiver_write(dbuf,lu[0],newfile,tmpfilename);
-	}
-	if (lu[1]) {
-	  r= fread(dbuf,1,lu[1],comms);
-	  if (r!=lu[1]) die_badrecv(comms,"RLE8 literal data");
-	  receiver_write(dbuf,lu[1],newfile,tmpfilename);
-	}
-      }
-      if (fflush(newfile)) diee("could not flush temporary receiving file"
-				" `%s'", tmpfilename);
+      uint8_t lbuf[8];
+      r= fread(lbuf,1,8,commsi);  if (r!=8) die_badrecv("FILE64 l");
+
+      uint64_t l=
+	(lbuf[0] << 28 << 28) |
+	(lbuf[1] << 24 << 24) |
+	(lbuf[2] << 16 << 24) |
+	(lbuf[3] <<  8 << 24) |
+	(lbuf[4]       << 24) |
+	(lbuf[5]       << 16) |
+	(lbuf[6]       <<  8) |
+	(lbuf[7]            ) ;
+
+      copyfile(commsi, copydie_commsi,"FILE64 file data",
+	       newfile, copydie_tmpwrite,tmpfilename,
+	       l, 0);
+
+      if (fclose(newfile)) diee("could not flush and close temporary"
+				" receiving file `%s'", tmpfilename);
       if (rename(tmpfilename, filename))
 	diee("could not install new version of destination file `%s'",
 	     filename);
-      if (fclose(lastfile)) diee("failed to close old (now unlinked) file");
-      lastfile= newfile;
-      r= fseek(lastfile,0,SEEK_SET);
-      if (r) diee("failed to seek installed destination file `%s'", filename);
-      continue;
 
-    case REPLMSG_RM:
-      r= unlink(filename);
-      if (r && errno!=ENOENT)
-	diee("could not remove destination file `%s' (as instructed"
-	     " by sender)", filename);
-      continue;
+      sendbyte(REPLMSG_GO);
+      break;
 
     default:
       die_protocol("unknown transfer message code 0x%02x",c);
+
     }
   }
-  if (feof(comms)) return 0;
-  die_badrecv(comms,"transfer message code");
 }
 
- static void sender(const char *filename, FILE *comms,
-		    unsigned long interval_usec) {
-  struct stat stab, laststab;
-  memset(&stab,0,sizeof(stab));
-  FILE *lastfile, *newfile;
-  int told_removed= 0;
+static void sender(const char *filename) {
+  FILE *f, *fold;
+  int interval_usec, r, c;
+  struct stat stabtest, stab;
+  enum { told_nothing, told_file, told_remove } told;
 
+  interval_usec= 0;
+  fold= 0;
+  told= told_nothing;
+  
   for (;;) {
-    r= stat(filename, &stab);
+    if (interval_usec) {
+      send_flush();
+      usleep(interval_usec);
+    }
+    interval_usec= min_interval_usec;
+
+    r= stat(filename, &stabtest);
     if (r) {
-      newfile= 0;
+      f= 0;
     } else {
-      if (stab.st_dev == laststab.st_dev &&
-	  stab.st_ino == laststab.st_ino) {
-	usleep(interval_usec);
+      if (told == told_file &&
+	  stabtest.st_mode  == stab.st_mode  &&
+	  stabtest.st_dev   == stab.st_dev   &&
+	  stabtest.st_ino   == stab.st_ino   &&
+	  stabtest.st_mtime == stab.st_mtime &&
+	  stabtest.st_size  == stab.st_size)
 	continue;
-      }
-      newfile= fopen(filename, "r");
+      f= fopen(filename, "rb");
     }
-    if (!newfile) {
+    
+    if (!f) {
       if (errno!=ENOENT) diee("could not access source file `%s'",filename);
-      if (told_removed) {
-	usleep(interval_usec);
-	continue;
+      if (told != told_remove) {
+	verbosespinprintf(" ENOENT                                       ");
+	sendbyte(REPLMSG_RM);
+	told= told_remove;
       }
-      sender_sendbyte(REPLMSG_RM);
       continue;
     }
 
-    for (;;) {
-      n= 0;
-      while (n<255) {
-	cl= nextchar(lastfile);
-	cn= nextchar(newfile);
-	if (cl!=cn) { 
+    if (fold) fclose(fold);
+    fold= 0;
+
+    r= fstat(fileno(f),&stab);
+    if (r) diee("could not fstat source file `%s'",filename);
+
+    if (!S_ISREG(stab.st_mode))
+      die(8,0,-1,"source file `%s' is not a plain file",filename);
+
+    uint8_t hbuf[9]= {
+      REPLMSG_FILE64,
+      stab.st_size >> 28 >> 28,
+      stab.st_size >> 24 >> 24,
+      stab.st_size >> 16 >> 24,
+      stab.st_size >>  8 >> 24,
+      stab.st_size       >> 24,
+      stab.st_size       >> 16,
+      stab.st_size       >>  8,
+      stab.st_size
+    };
+
+    bandlimit_sendstart();
+    
+    r= fwrite(hbuf,1,9,commso);  if (r!=9) die_badsend();
+
+    copyfile(f, copydie_inputfile,filename,
+	     commso, copydie_commso,0,
+	     stab.st_size, 1);
+
+    send_flush();
+
+    c= fgetc(commsi);  if (c==EOF) die_badrecv("ack");
+    if (c!=REPLMSG_GO) die_protocol("got %#02x instead of GO",c);
+
+    bandlimit_sendend(stab.st_size, &interval_usec);
+
+    fold= f;
+    told= told_file;
+  }
+}
+
+void usagemessage(void) {
+  puts("usage: rcopy-repeatedly [<options>] <file> <file>\n"
+       " <file> may be <local-file> or [<user>@]<host>:<file>\n"
+       " exactly one of each of the two forms must be provided\n"
+       " a file is taken as remote if it has a : before the first /\n"
+       "options\n"
+       " --help\n");
+}
+
+typedef struct {
+  const char *userhost, *path;
+} FileSpecification;
+
+static FileSpecification srcspec, dstspec;
+
+static void of__server(const struct cmdinfo *ci, const char *val) {
+  int ncount= nsargs + 1 + !!val;
+  sargs= xrealloc(sargs, sizeof(*sargs) * ncount);
+  sargs[nsargs++]= ci->olong;
+  if (val)
+    sargs[nsargs++]= val;
+}
+
+static int of__server_int(const struct cmdinfo *ci, const char *val) {
+  of__server(ci,val);
+  long v;
+  char *ep;
+  errno= 0; v= strtol(val,&ep,10);
+  if (!*val || *ep || errno || v<INT_MIN || v>INT_MAX)
+    badusage("bad integer argument `%s' for --%s",val,ci->olong);
+  return v;
+}
+
+static void of_help(const struct cmdinfo *ci, const char *val) {
+  usagemessage();
+  if (ferror(stdout)) diee("could not write usage message to stdout");
+  exit(0);
+}
+
+static void of_bw(const struct cmdinfo *ci, const char *val) {
+  int pct= of__server_int(ci,val);
+  if (pct<1 || pct>100)
+    badusage("bandwidth percentage must be between 1 and 100 inclusive");
+  *(double*)ci->parg= pct * 0.01;
+}
+
+static void of_server_int(const struct cmdinfo *ci, const char *val) {
+  *(int*)ci->parg= of__server_int(ci,val);
+}
+
+static const struct cmdinfo cmdinfos[]= {
+  { "help",     .call= of_help },
+  { "max-bandwidth-percent-mean", 0,1,.call=of_bw,.parg=&max_bw_prop_mean  },
+  { "max-bandwidth-percent-burst",0,1,.call=of_bw,.parg=&max_bw_prop_burst },
+  { "tx-block-size",     0,1,.call=of_server_int, .parg=&txblocksz         },
+  { "min-interval-usec", 0,1,.call=of_server_int, .parg=&min_interval_usec },
+  { "rcopy-repeatedly",  0,1, .sassignto=&rcopy_repeatedly_program         },
+  { "ssh-program",       0,1, .sassignto=&rsh_program                      },
+  { "receiver", .iassignto=&server_upcopy, .arg=0                          },
+  { "sender",   .iassignto=&server_upcopy, .arg=1                          },
+  { 0 }
+};
+
+static void server(const char *filename) {
+  int c;
+  commsi= stdin;
+  commso= stdout;
+  fprintf(commso, "%s0002 %c\n", banner, server_upcopy?'u':'d');
+  send_flush();
+  c= fgetc(commsi);  if (c==EOF) die_badrecv("initial go");
+  if (c!=REPLMSG_GO) die_protocol("initial go message was %#02x instead",c);
+
+  if (server_upcopy)
+    sender(filename);
+  else
+    receiver(filename);
+}
+
+static void client(void) {
+  int uppipe[2], downpipe[2], r;
+  pid_t child;
+
+  mpipe(uppipe);
+  mpipe(downpipe);
+
+  FileSpecification *remotespec= srcspec.userhost ? &srcspec : &dstspec;
+  const char *remotemode= srcspec.userhost ? "--sender" : "--receiver";
+
+  sargs= xrealloc(sargs, sizeof(*sargs) * (7 + nsargs));
+  memmove(sargs+5, sargs, sizeof(*sargs) * nsargs);
+  sargs[0]= rsh_program;
+  sargs[1]= remotespec->userhost;
+  sargs[2]= rcopy_repeatedly_program;
+  sargs[3]= remotemode;
+  sargs[4]= "--";
+  sargs[5+nsargs]= remotespec->path;
+  sargs[6+nsargs]= 0;
+    
+  child= fork();
+  if (child==-1) diee("fork failed");
+  if (!child) {
+    mdup2(downpipe[0],0);
+    mdup2(uppipe[1],1);
+    close(uppipe[0]); close(downpipe[0]);
+    close(uppipe[1]); close(downpipe[1]);
+
+    execvp(rsh_program, (char**)sargs);
+    diee("failed to execute rsh program `%s'",rsh_program);
+  }
+
+  commso= fdopen(downpipe[1],"wb");
+  commsi= fdopen(uppipe[0],"rb");
+  if (!commso || !commsi) diee("fdopen failed");
+  close(downpipe[0]);
+  close(uppipe[1]);
+  
+  char banbuf[sizeof(banner)-1 + 5 + 1];
+  r= fread(banbuf,1,sizeof(banbuf)-1,commsi);
+  if (ferror(commsi)) die_badrecv("read banner");
+
+  if (r!=sizeof(banbuf)-1 ||
+      memcmp(banbuf,banner,sizeof(banner)-1) ||
+      banbuf[sizeof(banner)-1 + 4] != ' ') {
+    const char **sap;
+    int count=0;
+    for (count=0, sap=sargs; *sap; sap++) count+= strlen(*sap)+1;
+    char *cmdline= xmalloc(count+1);
+    cmdline[0]=' ';
+    for (sap=sargs; *sap; sap++) {
+      strcat(cmdline," ");
+      strcat(cmdline,*sap);
+    }
+    
+    die(8,0,-1,"did not receive banner as expected -"
+	" shell dirty? ssh broken?\n"
+	" try running\n"
+	"  %s\n"
+	" and expect the first line to be\n"
+	"  %s",
+	cmdline, banner);
+  }
+  
+  banbuf[sizeof(banbuf)-1]= 0;
+  char *ep;
+  long decllen= strtoul(banbuf + sizeof(banner)-1, &ep, 16);
+  if (ep!=banbuf + sizeof(banner)-1 + 4 || *ep!=' ')
+    die_protocol("declaration length syntax error (`%s')",ep);
+  assert(decllen <= sizeof(mainbuf));
+  if (decllen<2) die_protocol("declaration too short");
+
+  r= fread(mainbuf,1,decllen,commsi);
+  if (r!=decllen) die_badrecv("declaration");
+  if (mainbuf[decllen-1] != '\n')
+    die_protocol("declaration missing final newline");
+  if (mainbuf[0] != (remotespec==&srcspec ? 'u' : 'd'))
+    die_protocol("declaration incorrect direction indicator");
+
+  sendbyte(REPLMSG_GO);
 
-	if (!feof(lastfile)) {
-	  cl= fgetc(lastfile);
-	  if (ferror(lastfile))
-	    diee("could not read old source file `%s'",filename);
-	  assert(cl != EOF || feof(lastfile));
-	}
-	
-      if (errno!=ENOENT) diee("could not open source file `%s'",filename);
-      sender_send
+  if (remotespec==&srcspec)
+    receiver(dstspec.path);
+  else
+    sender(srcspec.path);
+}
+
+static void parse_file_specification(FileSpecification *fs, const char *arg,
+				     const char *what) {
+  const char *colon;
+  
+  if (!arg) badusage("too few arguments - missing %s\n",what);
 
-    if (r) 
+  for (colon=arg; ; colon++) {
+    if (!*colon || *colon=='/') {
+      fs->userhost=0;
+      fs->path= arg;
+      return;
+    }
+    if (*colon==':') {
+      char *uh= xmalloc(colon-arg + 1);
+      memcpy(uh,arg, colon-arg);  uh[colon-arg]= 0;
+      fs->userhost= uh;
+      fs->path= colon+1;
+      return;
+    }
+  }
 }
 
-static void sender( 
+int main(int argc, const char *const *argv) {
+  setvbuf(stderr,0,_IOLBF,BUFSIZ);
 
-	    assert(ferror(newfile));
-	    
+  myopt(&argv, cmdinfos);
 
-	  r= fread(dbuf,1,lu[0],comms);
-	  if (r!=lu[0]) die_badrecv(comms,
-	    
+  if (!rsh_program) rsh_program= getenv("RCOPY_REPEATEDLY_RSH");
+  if (!rsh_program) rsh_program= getenv("RSYNC_RSH");
+  if (!rsh_program) rsh_program= "ssh";
 
-	c= fgetc(comms);
+  if (max_bw_prop_burst / max_bw_prop_mean < 1.1)
+    badusage("max bandwidth prop burst must be at least 1.1x"
+             " max bandwidth prop mean");
 
+  if (txblocksz<1) badusage("transmit block size must be at least 1");
+  if (min_interval_usec<0) badusage("minimum update interval may not be -ve");
 
-int main(int argc, const char **argv) {
-  for (
+  if (server_upcopy>=0) {
+    if (!argv[0] || argv[1])
+      badusage("server mode must have just the filename as non-option arg");
+    server(argv[0]);
+  } else {
+    parse_file_specification(&srcspec, argv[0], "source");
+    parse_file_specification(&dstspec, argv[1], "destination");
+    if (argv[2]) badusage("too many non-option arguments");
+    if (!!srcspec.userhost == !!dstspec.userhost)
+      badusage("need exactly one remote file argument");
+    client();
+  }
+  return 0;
+}