setenv.c revision 89857 
1/* Copyright (C) 1992, 1995, 1996, 1997, 2002 Free Software Foundation, Inc.
2   This file based on setenv.c in the GNU C Library.
3
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.
8
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.
13
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.  */
18
19
20/*
21
22@deftypefn Supplemental int setenv (const char *@var{name}, const char *@var{value}, int @var{overwrite})
23@deftypefnx Supplemental void unsetenv (const char *@var{name})
24
25@code{setenv} adds @var{name} to the environment with value
26@var{value}.  If the name was already present in the environment,
27the new value will be stored only if @var{overwrite} is nonzero.
28The companion @code{unsetenv} function removes @var{name} from the
29environment.  This implementation is not safe for multithreaded code.
30
31@end deftypefn
32
33*/
34
35#if HAVE_CONFIG_H
36# include <config.h>
37#endif
38
39#define setenv libiberty_setenv
40#define unsetenv libiberty_unsetenv
41
42#include "ansidecl.h"
43#include <sys/types.h> /* For `size_t' */
44#include <stdio.h>     /* For `NULL' */
45
46#include <errno.h>
47#if !defined(errno) && !defined(HAVE_ERRNO_DECL)
48extern int errno;
49#endif
50#define __set_errno(ev) ((errno) = (ev))
51
52#if HAVE_STDLIB_H
53# include <stdlib.h>
54#endif
55#if HAVE_STRING_H
56# include <string.h>
57#endif
58#if HAVE_UNISTD_H
59# include <unistd.h>
60#endif
61
62#define __environ	environ
63#ifndef HAVE_ENVIRON_DECL
64extern char **environ;
65#endif
66
67#undef setenv
68#undef unsetenv
69
70/* LOCK and UNLOCK are defined as no-ops.  This makes the libiberty
71 * implementation MT-Unsafe. */
72#define LOCK
73#define UNLOCK
74
75/* Below this point, it's verbatim code from the glibc-2.0 implementation */
76
77/* If this variable is not a null pointer we allocated the current
78   environment.  */
79static char **last_environ;
80
81
82int
83setenv (name, value, replace)
84     const char *name;
85     const char *value;
86     int replace;
87{
88  register char **ep = 0;
89  register size_t size;
90  const size_t namelen = strlen (name);
91  const size_t vallen = strlen (value) + 1;
92
93  LOCK;
94
95  size = 0;
96  if (__environ != NULL)
97    {
98      for (ep = __environ; *ep != NULL; ++ep)
99	if (!strncmp (*ep, name, namelen) && (*ep)[namelen] == '=')
100	  break;
101	else
102	  ++size;
103    }
104
105  if (__environ == NULL || *ep == NULL)
106    {
107      char **new_environ;
108      if (__environ == last_environ && __environ != NULL)
109	/* We allocated this space; we can extend it.  */
110	new_environ = (char **) realloc (last_environ,
111					 (size + 2) * sizeof (char *));
112      else
113	new_environ = (char **) malloc ((size + 2) * sizeof (char *));
114
115      if (new_environ == NULL)
116	{
117	  UNLOCK;
118	  return -1;
119	}
120
121      new_environ[size] = malloc (namelen + 1 + vallen);
122      if (new_environ[size] == NULL)
123	{
124	  free ((char *) new_environ);
125	  __set_errno (ENOMEM);
126	  UNLOCK;
127	  return -1;
128	}
129
130      if (__environ != last_environ)
131	memcpy ((char *) new_environ, (char *) __environ,
132		size * sizeof (char *));
133
134      memcpy (new_environ[size], name, namelen);
135      new_environ[size][namelen] = '=';
136      memcpy (&new_environ[size][namelen + 1], value, vallen);
137
138      new_environ[size + 1] = NULL;
139
140      last_environ = __environ = new_environ;
141    }
142  else if (replace)
143    {
144      size_t len = strlen (*ep);
145      if (len + 1 < namelen + 1 + vallen)
146	{
147	  /* The existing string is too short; malloc a new one.  */
148	  char *new = malloc (namelen + 1 + vallen);
149	  if (new == NULL)
150	    {
151	      UNLOCK;
152	      return -1;
153	    }
154	  *ep = new;
155	}
156      memcpy (*ep, name, namelen);
157      (*ep)[namelen] = '=';
158      memcpy (&(*ep)[namelen + 1], value, vallen);
159    }
160
161  UNLOCK;
162
163  return 0;
164}
165
166void
167unsetenv (name)
168     const char *name;
169{
170  const size_t len = strlen (name);
171  char **ep;
172
173  LOCK;
174
175  for (ep = __environ; *ep; ++ep)
176    if (!strncmp (*ep, name, len) && (*ep)[len] == '=')
177      {
178	/* Found it.  Remove this pointer by moving later ones back.  */
179	char **dp = ep;
180	do
181	  dp[0] = dp[1];
182	while (*dp++);
183	/* Continue the loop in case NAME appears again.  */
184      }
185
186  UNLOCK;
187}
188