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popen.c
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popen.c
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#include <stdio.h>
#include <string.h>
#define DEBUG
#define TYPELANG 0x11 /* type 1 program - language 1 machine code */
#define DEFDATSIZ 0 /* Default data size */
#define IN 0
#define OUT 1
#define ERR 2
FILE *popen(cmd, type)
char *cmd; char *type;
{
int in, out, paramsiz = 0, pid;
char *modname, *params = NULL, *spaceptr;
FILE *fpipe;
int pn, fd;
/* determine stdin or stdout */
switch (toupper(*type))
{
case 'W': /* fork a process and connect pipe to the cmd's stdin */
pn = IN;
break;
case 'R': /* fork a process and connect pipe to the cmd's stdout */
pn = OUT;
break;
default:
return NULL;
}
#ifdef DEBUG
fprintf(stderr, "Path number %d\n", pn);
#endif
/* open a pipe and dup it into stdin or stdout */
fpipe = fopen("/pipe", type); /* use fopen instead of open because popen returns a FILE* */
#ifdef DEBUG
fprintf(stderr, "Pipe Path number %d\n", fpipe->_fd);
#endif
fd = dup(pn);
/* make the pipe be the stdin or stdout of the child task */
close(pn);
dup(fpipe->_fd); /* get the path number from the FILE structure */
/* Split the cmd into a cmd and a seperate params suitable for os9fork */
modname = cmd;
spaceptr = index(cmd, ' ');
if (spaceptr)
{
*spaceptr = 0; /* terminate module name at space */
params = spaceptr + 1;
paramsiz = strlen(params);
}
#ifdef DEBUG
fprintf(stderr, "Forking %s with %s\n", modname, params);
#endif
pid = os9fork(modname, paramsiz, params, TYPELANG, DEFDATSIZ);
/* restore stdin or stdout */
close(pn);
dup(fd);
#ifdef DEBUG
fprintf(stderr, "Returning\n");
#endif
return fpipe;
}