environ.c revision 1.2 
1/* environ.c -- library for manipulating environments for GNU.
2   Copyright (C) 1986, 1989 Free Software Foundation, Inc.
3
4This program is free software; you can redistribute it and/or modify
5it under the terms of the GNU General Public License as published by
6the Free Software Foundation; either version 2 of the License, or
7(at your option) any later version.
8
9This program is distributed in the hope that it will be useful,
10but WITHOUT ANY WARRANTY; without even the implied warranty of
11MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12GNU General Public License for more details.
13
14You should have received a copy of the GNU General Public License
15along with this program; if not, write to the Free Software
16Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
17
18#define min(a, b) ((a) < (b) ? (a) : (b))
19#define max(a, b) ((a) > (b) ? (a) : (b))
20
21#include "defs.h"
22#include "environ.h"
23#include "gdb_string.h"
24#include "gdbcore.h"
25
26
27/* Return a new environment object.  */
28
29struct environ *
30make_environ ()
31{
32  register struct environ *e;
33
34  e = (struct environ *) xmalloc (sizeof (struct environ));
35
36  e->allocated = 10;
37  e->vector = (char **) xmalloc ((e->allocated + 1) * sizeof (char *));
38  e->vector[0] = 0;
39  return e;
40}
41
42/* Free an environment and all the strings in it.  */
43
44void
45free_environ (e)
46     register struct environ *e;
47{
48  register char **vector = e->vector;
49
50  while (*vector)
51    free (*vector++);
52
53  free (e);
54}
55
56/* Copy the environment given to this process into E.
57   Also copies all the strings in it, so we can be sure
58   that all strings in these environments are safe to free.  */
59
60void
61init_environ (e)
62     register struct environ *e;
63{
64  extern char **environ;
65  register int i;
66
67  if (environ == NULL)
68    return;
69
70  for (i = 0; environ[i]; i++) /*EMPTY*/;
71
72  if (e->allocated < i)
73    {
74      e->allocated = max (i, e->allocated + 10);
75      e->vector = (char **) xrealloc ((char *)e->vector,
76				      (e->allocated + 1) * sizeof (char *));
77    }
78
79  memcpy (e->vector, environ, (i + 1) * sizeof (char *));
80
81  while (--i >= 0)
82    {
83      register int len = strlen (e->vector[i]);
84      register char *new = (char *) xmalloc (len + 1);
85      memcpy (new, e->vector[i], len + 1);
86      e->vector[i] = new;
87    }
88}
89
90/* Return the vector of environment E.
91   This is used to get something to pass to execve.  */
92
93char **
94environ_vector (e)
95     struct environ *e;
96{
97  return e->vector;
98}
99
100/* Return the value in environment E of variable VAR.  */
101
102char *
103get_in_environ (e, var)
104     const struct environ *e;
105     const char *var;
106{
107  register int len = strlen (var);
108  register char **vector = e->vector;
109  register char *s;
110
111  for (; (s = *vector) != NULL; vector++)
112    if (STREQN (s, var, len) && s[len] == '=')
113      return &s[len + 1];
114
115  return 0;
116}
117
118/* Store the value in E of VAR as VALUE.  */
119
120void
121set_in_environ (e, var, value)
122     struct environ *e;
123     const char *var;
124     const char *value;
125{
126  register int i;
127  register int len = strlen (var);
128  register char **vector = e->vector;
129  register char *s;
130
131  for (i = 0; (s = vector[i]) != NULL; i++)
132    if (STREQN (s, var, len) && s[len] == '=')
133      break;
134
135  if (s == 0)
136    {
137      if (i == e->allocated)
138	{
139	  e->allocated += 10;
140	  vector = (char **) xrealloc ((char *)vector,
141				       (e->allocated + 1) * sizeof (char *));
142	  e->vector = vector;
143	}
144      vector[i + 1] = 0;
145    }
146  else
147    free (s);
148
149  s = (char *) xmalloc (len + strlen (value) + 2);
150  strcpy (s, var);
151  strcat (s, "=");
152  strcat (s, value);
153  vector[i] = s;
154
155  /* This used to handle setting the PATH and GNUTARGET variables
156     specially.  The latter has been replaced by "set gnutarget"
157     (which has worked since GDB 4.11).  The former affects searching
158     the PATH to find SHELL, and searching the PATH to find the
159     argument of "symbol-file" or "exec-file".  Maybe we should have
160     some kind of "set exec-path" for that.  But in any event, having
161     "set env" affect anything besides the inferior is a bad idea.
162     What if we want to change the environment we pass to the program
163     without afecting GDB's behavior?  */
164
165  return;
166}
167
168/* Remove the setting for variable VAR from environment E.  */
169
170void
171unset_in_environ (e, var)
172     struct environ *e;
173     char *var;
174{
175  register int len = strlen (var);
176  register char **vector = e->vector;
177  register char *s;
178
179  for (; (s = *vector) != NULL; vector++)
180    {
181      if (STREQN (s, var, len) && s[len] == '=')
182	{
183	  free (s);
184	  /* Walk through the vector, shuffling args down by one, including
185	     the NULL terminator.  Can't use memcpy() here since the regions
186	     overlap, and memmove() might not be available. */
187	  while ((vector[0] = vector[1]) != NULL)
188	    {
189	      vector++;
190	    }
191	  break;
192	}
193    }
194}
195