lib/execl.c

   1 /* execl() function: Execute a program, replacing the current process.
   2    Copyright (C) 2020-2024 Free Software Foundation, Inc.
   3
   4    This file is free software: you can redistribute it and/or modify
   5    it under the terms of the GNU Lesser General Public License as
   6    published by the Free Software Foundation; either version 2.1 of the
   7    License, or (at your option) any later version.
   8
   9    This file is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public License
  15    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  16
  17 /* Written by Bruno Haible <bruno@clisp.org>, 2020.  */
  18
  19 /* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
  20    may optimize away the arg0 == NULL test below.  */
  21 #define _GL_ARG_NONNULL(params)
  22
  23 #include <config.h>
  24
  25 /* Specification.  */
  26 #include <unistd.h>
  27
  28 #include <errno.h>
  29 #include <stdarg.h>
  30
  31 #include "malloca.h"
  32
  33 int
  34 execl (const char *program, const char *arg0, ...)
  35 {
  36   va_list args;
  37
  38   /* The callee is not expecting a NULL argv[0].  */
  39   if (arg0 == NULL)
  40     {
  41       errno = EINVAL;
  42       return -1;
  43     }
  44
  45   /* Count the number of arguments (including arg0 and the trailing NULL).  */
  46   size_t count = 1;
  47   va_start (args, arg0);
  48   for (;;)
  49     {
  50       count++;
  51       if (va_arg (args, const char *) == NULL)
  52         break;
  53     }
  54   va_end (args);
  55
  56   /* Allocate the argument vector.  */
  57   const char **argv = (const char **) malloca (count * sizeof (const char *));
  58   if (argv == NULL)
  59     {
  60       errno = ENOMEM;
  61       return -1;
  62     }
  63
  64   /* Copy the arguments into the argument vector.  */
  65   {
  66     size_t i = 0;
  67     argv[i++] = arg0;
  68     va_start (args, arg0);
  69     for (; i < count;)
  70       argv[i++] = va_arg (args, const char *);
  71     va_end (args);
  72   }
  73
  74   /* Invoke execv.  */
  75   execv (program, argv);
  76
  77   /* If execv returned, it must have failed.  */
  78   int saved_errno = errno;
  79   freea (argv);
  80   errno = saved_errno;
  81   return -1;
  82 }