BSD 4_1_snap release

[unix-history] / usr / src / libc / gen / execvp.c

/* @(#)execvp.c 4.1 (Berkeley) 12/21/80 */
/*
*      execlp(name, arg,...,0) (like execl, but does path search)
*      execvp(name, argv)      (like execv, but does path search)
*/
#include <errno.h>
#define NULL    0

static  char shell[] =  "/bin/sh";
char    *execat(), *getenv();
extern  errno;

execlp(name, argv)
char *name, *argv;
{
       return(execvp(name, &argv));
}

execvp(name, argv)
char *name, **argv;
{
       char *pathstr;
       register char *cp;
       char fname[128];
       char *newargs[256];
       int i;
       register unsigned etxtbsy = 1;
       register eacces = 0;

       if ((pathstr = getenv("PATH")) == NULL)
               pathstr = ":/bin:/usr/bin";
       cp = index(name, '/')? "": pathstr;

       do {
               cp = execat(cp, name, fname);
       retry:
               execv(fname, argv);
               switch(errno) {
               case ENOEXEC:
                       newargs[0] = "sh";
                       newargs[1] = fname;
                       for (i=1; newargs[i+1]=argv[i]; i++) {
                               if (i>=254) {
                                       errno = E2BIG;
                                       return(-1);
                               }
                       }
                       execv(shell, newargs);
                       return(-1);
               case ETXTBSY:
                       if (++etxtbsy > 5)
                               return(-1);
                       sleep(etxtbsy);
                       goto retry;
               case EACCES:
                       eacces++;
                       break;
               case ENOMEM:
               case E2BIG:
                       return(-1);
               }
       } while (cp);
       if (eacces)
               errno = EACCES;
       return(-1);
}

static char *
execat(s1, s2, si)
register char *s1, *s2;
char *si;
{
       register char *s;

       s = si;
       while (*s1 && *s1 != ':' && *s1 != '-')
               *s++ = *s1++;
       if (si != s)
               *s++ = '/';
       while (*s2)
               *s++ = *s2++;
       *s = '\0';
       return(*s1? ++s1: 0);
}