Hello, All!


I want to redirect both stdin and stdout when spawning another program. I
have some examples using the OS/2 API calls, but I want to avoid that if it
is possible and only use the C library to stay portable. The program should
also compile on AIX and IRIX (at least I hope so).

This is just a small test program; the "production" thing will
have to redirect sockets.

I can write to the pipe that is connected to stdin of the child process,
but I don't get anything back from stdout.

Where is my error?


=== Cut ===
#define INCL_DOSPROCESS
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define STDIN  0
#define STDOUT 1

int savein,saveout,rc,status,arg;
int inpipe[2],outpipe[2];

static void redir_init(void) {
  int rc;

  savein=dup(STDIN);   close(STDIN);
  saveout=dup(STDOUT); close(STDOUT);

  rc=pipe(inpipe); /* 0=r 1=w */
  rc=pipe(outpipe);

  rc=dup2(inpipe[0], STDIN);  close(inpipe[0]);
  rc=dup2(outpipe[1],STDOUT); close(outpipe[1]);
}

static void redir_restore(void) {
  int rc;

  close(STDIN);  rc=dup2(savein, STDIN);  close(savein);
  close(STDOUT); rc=dup2(saveout,STDOUT); close(saveout);
}

static void redir_end(void) {
  close(inpipe[1]);
  close(outpipe[0]);
}

#ifdef TEST
int main(int argc, char **argv) {
  char buf[1024];

  if (argc<3)
    return 1;
  puts(argv[1]);
  puts(argv[2]);
  remove(argv[2]);
  redir_init();
 
rc=spawnlp(P_NOWAIT,"upper.exe","upper.exe","hallo",(char
*)NULL);
  redir_restore();
  printf("pid=%d\n",rc);

/* write  to inpipe[0]  */
/* read from outpipe[1] */
  arg=open(argv[1],O_RDONLY);
  do {
    rc=read(arg,buf,sizeof(buf));
    if (rc>0)
      write(inpipe[1],buf,rc);
  } while (rc>0);
  close(arg);

  DosSleep(1000);

  arg=open(argv[2],O_WRONLY|O_CREAT,S_IREAD|S_IWRITE);
  do {
    rc=read(outpipe[0],buf,sizeof(buf));
    if (rc>0)
      write(arg,buf,rc);
  } while (rc>0);
  close(arg);

  redir_end();
  rc=wait(&status);
  printf("pid=%d, rc %d (%0x)\n",rc,status,status);
  return 0;
}
#endif
=== Cut ===

"upper.exe" just outputs all its input in upper case and counts chars.

=== Cut ===
#include 
#include 
#include 

int main(int argc, char **argv) {
  char t[1024],*u=NULL;
  int  c=0;

  if (argc>1)
    puts(argv[1]);

  do {
    if (!(feof(stdin) || ferror(stdin)))
      u=fgets(t,sizeof(t),stdin);
    if (u) {
      for ( ; *u; ++u) {
        if (islower(*u))
          putchar(toupper(*u));
        else
          putchar(*u);
        ++c;
      }
    }
  } while (u);
  return 0;
}
=== Cut ===


Tschau...Thomas

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