sys/src/cmd/con/xmr.c

   1 #include <u.h>
   2 #include <libc.h>
   3
   4 enum {
   5         Soh=    0x1,
   6         Eot=    0x4,
   7         Ack=    0x6,
   8         Nak=    0x15,
   9         Cancel= 0x18,
  10 };
  11
  12 int notifyf(void*, char*);
  13 int readupto(uchar*, int);
  14 int receive(int, uchar);
  15 void send(int);
  16
  17 int debug, dfd;
  18
  19 void
  20 main(int argc, char **argv)
  21 {
  22         int fd;
  23         uchar seqno;
  24         ulong bytes;
  25
  26         ARGBEGIN {
  27         case 'd':
  28                 dfd = 2;
  29                 debug = 1;
  30                 break;
  31         } ARGEND
  32
  33         if(argc != 1){
  34                 fprint(2, "usage: xmr filename\n");
  35                 exits("usage");
  36         }
  37         fd = open("/dev/consctl", OWRITE);
  38         if(fd >= 0)
  39                 write(fd, "rawon", 5);
  40         fd = create(argv[0], ORDWR, 0666);
  41         if(fd < 0){
  42                 perror("xmr: create");
  43                 exits("create");
  44         }
  45
  46         atnotify(notifyf, 1);
  47         send(Nak);
  48
  49         /*
  50          *  keep receiving till the other side gives up
  51          */
  52         bytes = 0;
  53         for(seqno = 1; ; seqno++){
  54                 if(receive(fd, seqno) == -1)
  55                         break;
  56                 bytes += 128;
  57         }
  58         fprint(2, "xmr: received %ld bytes\n", bytes);
  59         exits(0);
  60 }
  61
  62 void
  63 send(int byte)
  64 {
  65         uchar c;
  66
  67         c = byte;
  68         if(write(1, &c, 1) != 1){
  69                 fprint(2, "xmr: hungup\n");
  70                 exits("hangup");
  71         }
  72 }
  73
  74 int
  75 readupto(uchar *a, int len)
  76 {
  77         int n;
  78         int sofar;
  79
  80         for(sofar = 0; sofar < len; sofar += n){
  81                 n = read(0, a, len-sofar);
  82                 if(n <= 0){
  83                         send(Nak);
  84                         return sofar;
  85                 }
  86                 if(*a == Eot || *a == Cancel)
  87                         return sofar + n;
  88                 a += n;
  89         }
  90         return sofar;
  91
  92 }
  93
  94 int
  95 receive(int fd, uchar seqno)
  96 {
  97         uchar buf[128+4];
  98         uchar sum;
  99         uchar *p;
 100         int n;
 101         int tries;
 102         int have;
 103
 104         for(have = 0, tries = 0;; tries++){
 105                 if(debug)
 106                         fprint(dfd, "have == %d\n", have);
 107                 if(tries > 10){
 108                         fprint(2, "xmr: timed out\n");
 109                         if(debug)
 110                                 close(dfd);
 111                         exits("timeout");
 112                 }
 113
 114                 /* try to gather up a block */
 115                 alarm(15*1000);
 116                 n = readupto(&buf[have], 132-have);
 117                 alarm(0);
 118                 have += n;
 119                 if(have){
 120                         switch(buf[0]){
 121                         case Eot:
 122                                 send(Ack);
 123                                 return -1;
 124                         case Cancel:
 125                                 fprint(2, "xmr: transfer aborted by sender\n");
 126                                 exits("cancel");
 127                         }
 128                 }
 129                 if(have != 132)
 130                         continue;
 131
 132                 /* checksum */
 133                 for(p = buf, sum = 0; p < &buf[128+3]; p++)
 134                         sum += *p;
 135
 136                 /* If invalid block, resynchronize */
 137                 if(buf[0] != Soh || buf[2] != (255-buf[1]) || sum != buf[131]){
 138                         if(debug){
 139                                 fprint(dfd, "resync %2.2ux %d %d %ux %ux\n", buf[0],
 140                                         buf[1], buf[2], sum, buf[131]);
 141                                 write(dfd, (char*)buf+3, 128);
 142                                 fprint(dfd, "\n");
 143                         }
 144                         p = memchr(buf+1, Soh, 131);
 145                         if(p){
 146                                 have = 132-(p-buf);
 147                                 memmove(buf, p, have);
 148                         } else
 149                                 have = 0;
 150                         continue;
 151                 }
 152
 153                 /* it's probably a real block, so dump it if there's an error */
 154                 have = 0;
 155
 156                 /* if this is the last block, ack */
 157                 if(buf[1] == seqno-1){
 158                         tries = 0;
 159                         send(Ack);
 160                 }else if(buf[1] == seqno){
 161                         if(debug)
 162                                 fprint(dfd, "Ack\n");
 163                         send(Ack);
 164                         if(write(fd, buf+3, 128) != 128){
 165                                 fprint(2, "xmr: abort, error writing file\n");
 166                                 exits("write");
 167                         }
 168                         return 0;
 169                 } else {
 170                         send(Nak);
 171                 }
 172         }
 173 }
 174
 175 int
 176 notifyf(void *a, char *msg)
 177 {
 178         USED(a);
 179         if(strcmp(msg, "alarm") == 0)
 180                 return 1;
 181         return 0;
 182 }