ack/mach/minixST/libsys/exec.c

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1988-04-19 09:34:37 +00:00
#include "lib.h"
char *nullptr[1]; /* the EXEC calls need a zero pointer */
#define PTRSIZE sizeof(char *)
PUBLIC int execl(name, arg0)
char *name;
char *arg0;
{
return execve(name, &arg0, nullptr);
}
PUBLIC int execle(name, argv)
char *name, *argv;
{
char **p;
p = (char **) &argv;
while (*p++) /* null statement */ ;
return execve(name, &argv, *p);
}
PUBLIC int execv(name, argv)
char *name, *argv[];
{
return execve(name, argv, nullptr);
}
PUBLIC int execve(name, argv, envp)
char *name; /* pointer to name of file to be executed */
char *argv[]; /* pointer to argument array */
char *envp[]; /* pointer to environment */
{
char stack[MAX_ISTACK_BYTES];
char **argorg, **envorg, *hp, **ap, *p;
int i, nargs, nenvps, stackbytes, offset;
extern errno;
/* Count the argument pointers and environment pointers. */
nargs = 0;
nenvps = 0;
argorg = argv;
envorg = envp;
while (*argorg++ != NIL_PTR) nargs++;
while (*envorg++ != NIL_PTR) nenvps++;
/* Prepare to set up the initial stack. */
hp = &stack[(nargs + nenvps + 3) * PTRSIZE];
if (hp + nargs + nenvps >= &stack[MAX_ISTACK_BYTES]) {
errno = E2BIG;
return(-1);
}
ap = (char **) stack;
*ap++ = (char *) nargs;
/* Prepare the argument pointers and strings. */
for (i = 0; i < nargs; i++) {
offset = hp - stack;
*ap++ = (char *) offset;
p = *argv++;
while (*p) {
*hp++ = *p++;
if (hp >= &stack[MAX_ISTACK_BYTES]) {
errno = E2BIG;
return(-1);
}
}
*hp++ = (char) 0;
}
*ap++ = NIL_PTR;
/* Prepare the environment pointers and strings. */
for (i = 0; i < nenvps; i++) {
offset = hp - stack;
*ap++ = (char *) offset;
p = *envp++;
while (*p) {
*hp++ = *p++;
if (hp >= &stack[MAX_ISTACK_BYTES]) {
errno = E2BIG;
return(-1);
}
}
*hp++ = (char) 0;
}
*ap++ = NIL_PTR;
stackbytes = ( ( (int)(hp - stack) + PTRSIZE - 1)/PTRSIZE) * PTRSIZE;
return callm1(MM_PROC_NR, EXEC, len(name), stackbytes, 0,name, stack,NIL_PTR);
}
PUBLIC execn(name)
char *name; /* pointer to file to be exec'd */
{
/* Special version used when there are no args and no environment. This call
* is principally used by INIT, to avoid having to allocate MAX_ISTACK_BYTES.
*/
static char stack[3 * PTRSIZE];
return callm1(MM_PROC_NR, EXEC, len(name), sizeof(stack), 0, name, stack, NIL_PTR);
}