lib/libc/posix/_execl.c

   1 /*-
   2  * Copyright (c) 1991, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #define execl _execl
  31 #define execve _execve
  32 #include <unistd.h>
  33 #include <minix/compiler.h>
  34 #include <errno.h>
  35 #include <stdarg.h>
  36 #include <sys/types.h>
  37 #include <stdlib.h>
  38 #include <alloca.h>
  39 #include <lib.h>
  40
  41 #ifndef __UNCONST
  42 #define __UNCONST(x) ((void *) (x))
  43 #endif
  44
  45 extern char * const **_penviron;        /* The default environment. */
  46
  47 int
  48 execl(const char *path, const char *arg, ...)
  49 /* execl("/bin/sh", "sh", "-c", "example", (char *) 0); */
  50 {
  51 #if FUNC_ARGS_ARRAY
  52         /*
  53     * Assumption:  The C-implementation for this machine pushes
  54          * function arguments downwards on the stack making a perfect
  55          * argument array.  Luckily this is almost always so.
  56          *
  57          * execl() - execute     Author: Kees J. Bot, 21 Jan 1994
  58          */
  59         return execve(path, (char * const *) &arg, *_penviron);
  60 #else
  61    /*
  62     * Indeed, GCC (4.4.1) behaves similarly to ACK. Nonetheless, let's
  63     * stay the safe side. LLVM (llvm-gcc) doesn't make the aforementioned
  64          * assumption.
  65          */
  66         va_list ap;
  67         char **argv;
  68         int i;
  69
  70         va_start(ap, arg);
  71         for (i = 2; va_arg(ap, char *) != NULL; i++)
  72           continue;
  73         va_end(ap);
  74
  75         if ((argv = alloca(i * sizeof (char *))) == NULL) {
  76                 errno = ENOMEM;
  77                 return -1;
  78         }
  79
  80         va_start(ap, arg);
  81         argv[0] = __UNCONST(arg);
  82         for (i = 1; (argv[i] = va_arg(ap, char *)) != NULL; i++)
  83                 continue;
  84         va_end(ap);
  85
  86         return execve(path, (char * const *) argv, *_penviron);
  87 #endif
  88 }
  89