nettest.c

   1 #include <stdio.h>
   2 #include <unistd.h>
   3 #include <errno.h>
   4 #include <string.h>
   5 #include <sys/types.h>
   6 #include <sys/stat.h>
   7 #include <stdlib.h>
   8
   9 static int am_sender;
  10
  11 #define rprintf fprintf
  12 #define FERROR stderr
  13 #define exit_cleanup(x) exit(1)
  14 #define do_fork fork
  15 #define STDIN_FILENO 0
  16 #define STDOUT_FILENO 1
  17
  18 #define TOTAL_SIZE (10*1024*1024)
  19
  20 static int write_loop(int fd, char *buf, int size)
  21 {
  22         int total=0;
  23
  24         while (size) {
  25                 int n = write(fd, buf, size);
  26                 if (n <= 0) break;
  27                 size -= n;
  28                 buf += n;
  29                 total += n;
  30         }
  31         return total;
  32 }
  33
  34 int piped_child(char *command,int *f_in,int *f_out)
  35 {
  36   int pid;
  37   int to_child_pipe[2];
  38   int from_child_pipe[2];
  39
  40   if (pipe(to_child_pipe) < 0 ||
  41       pipe(from_child_pipe) < 0) {
  42     rprintf(FERROR,"pipe: %s\n",strerror(errno));
  43     exit_cleanup(RERR_IPC);
  44   }
  45
  46
  47   pid = do_fork();
  48   if (pid < 0) {
  49     rprintf(FERROR,"fork: %s\n",strerror(errno));
  50     exit_cleanup(RERR_IPC);
  51   }
  52
  53   if (pid == 0)
  54     {
  55       if (dup2(to_child_pipe[0], STDIN_FILENO) < 0 ||
  56           close(to_child_pipe[1]) < 0 ||
  57           close(from_child_pipe[0]) < 0 ||
  58           dup2(from_child_pipe[1], STDOUT_FILENO) < 0) {
  59         rprintf(FERROR,"Failed to dup/close : %s\n",strerror(errno));
  60         exit_cleanup(RERR_IPC);
  61       }
  62       if (to_child_pipe[0] != STDIN_FILENO) close(to_child_pipe[0]);
  63       if (from_child_pipe[1] != STDOUT_FILENO) close(from_child_pipe[1]);
  64       system(command);
  65       exit_cleanup(RERR_IPC);
  66     }
  67
  68   if (close(from_child_pipe[1]) < 0 ||
  69       close(to_child_pipe[0]) < 0) {
  70     rprintf(FERROR,"Failed to close : %s\n",strerror(errno));
  71     exit_cleanup(RERR_IPC);
  72   }
  73
  74   *f_in = from_child_pipe[0];
  75   *f_out = to_child_pipe[1];
  76
  77   return pid;
  78 }
  79
  80 static void sender(int fin, int fout)
  81 {
  82         int n;
  83         char buf[1024];
  84         int total = 0;
  85
  86         while (total < TOTAL_SIZE) {
  87                 n = read(fin, buf, sizeof(buf));
  88                 if (n <= 0) {
  89                         fprintf(stderr,"write error in sender at %d\n", total);
  90                         break;
  91                 }
  92                 write_loop(fout, buf, n);
  93                 total += n;
  94                 fprintf(stderr, "-");
  95         }
  96         fprintf(stderr, "sender done\n");
  97 }
  98
  99 static void generator(int fd)
 100 {
 101         int n;
 102         char buf[1024];
 103         int total=0;
 104
 105         while (total < TOTAL_SIZE) {
 106                 n = 1 + random() % (sizeof(buf)-1);
 107                 n = write_loop(fd, buf, n);
 108                 if (n <= 0) {
 109                         fprintf(stderr,"write error in generator at %d\n", total);
 110                         break;
 111                 }
 112                 total += n;
 113                 fprintf(stderr, "*");
 114         }
 115         fprintf(stderr, "generator done\n");
 116 }
 117
 118 static void receiver(int fd)
 119 {
 120         ssize_t n;
 121         ssize_t total=0;
 122         char buf[1024];
 123
 124         while (total < TOTAL_SIZE) {
 125                 n = read(fd, buf, sizeof(buf));
 126                 if (n <= 0) {
 127                         fprintf(stderr,"read error in receiver\n");
 128                         break;
 129                 }
 130                 total += n;
 131                 fprintf(stderr, "+");
 132         }
 133         fprintf(stderr, "receiver done\n");
 134 }
 135
 136 int main(int argc, char *argv[])
 137 {
 138         int c, f_in, f_out;
 139
 140         while ((c = getopt(argc, argv, "s")) != -1) {
 141                 switch (c){
 142                 case 's':
 143                         am_sender = 1;
 144                         break;
 145                 }
 146         }
 147
 148         if (am_sender) {
 149                 sender(0, 1);
 150         } else {
 151                 char *command = argv[1];
 152                 printf("running %s\n", command);
 153                 piped_child(command, &f_in, &f_out);
 154                 if (fork()) {
 155                         generator(f_out);
 156                 } else {
 157                         receiver(f_in);
 158                 }
 159         }
 160
 161         return 0;
 162 }