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[glibc.git] / posix / execlp.c
blob6cad6402ec655d531c8a3b9aa947b3cf341f7cfb
1 /* Copyright (C) 1991, 1993, 1996, 1997, 1998 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 The GNU C Library 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 GNU
12 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 Boston, MA 02111-1307, USA. */
19 #include <alloca.h>
20 #include <unistd.h>
21 #include <stdarg.h>
22 #include <stddef.h>
23 #include <string.h>
25 /* Execute FILE, searching in the `PATH' environment variable if
26 it contains no slashes, with all arguments after FILE until a
27 NULL pointer and environment from `environ'. */
28 int
29 execlp (const char *file, const char *arg, ...)
31 size_t argv_max = 1024;
32 const char **argv = alloca (argv_max * sizeof (const char *));
33 unsigned int i;
34 va_list args;
36 argv[0] = arg;
38 va_start (args, arg);
39 i = 0;
40 while (argv[i++] != NULL)
42 if (i == argv_max)
44 const char **nptr = alloca ((argv_max *= 2) * sizeof (const char *));
46 if ((char *) nptr + argv_max == (char *) argv)
48 /* Stack grows down. */
49 argv = (const char **) memcpy (nptr, argv, i);
50 argv_max += i;
52 else if ((char *) argv + i == (char *) nptr)
53 /* Stack grows up. */
54 argv_max += i;
55 else
56 /* We have a hole in the stack. */
57 argv = (const char **) memcpy (nptr, argv, i);
60 argv[i] = va_arg (args, const char *);
62 va_end (args);
64 return execvp (file, (char *const *) argv);