2 % (c) The GRASP/AQUA Project, Glasgow University, 1995
4 \subsection[env.lc]{Environment Handling for LibPosix}
6 Many useful environment functions are not necessarily provided by libc.
7 To get around this problem, we introduce our own. The first time that
8 you modify your environment, we copy the environment wholesale into
9 malloc'ed locations, so that subsequent modifications can do proper
10 memory management. The $environ$ variable is updated with a pointer
11 to the current environment so that the normal $getenv$ and $exec*$ functions
12 should continue to work properly.
20 /* Switch this on once we've moved the environment to the malloc arena */
24 * For some reason, OSF turns off the prototype for this if we're
25 * _POSIX_SOURCE. Seems to me that this ought to be an ANSI-ism
26 * rather than a POSIX-ism, but no matter. (JSM(?))
30 strDup(const char *src)
32 int len = strlen(src) + 1;
35 if ((dst = malloc(len)) != NULL)
36 memcpy(dst, src, len);
40 /* Replace the entire environment */
46 int dirtyOld = dirtyEnv;
49 /* A quick hack to move the strings out of the heap */
55 /* Release the old space if we allocated it ourselves earlier */
57 for (i = 0; old[i] != NULL; i++)
64 /* Copy initial environment into malloc arena */
71 for (i = 0; environ[i] != NULL; i++);
73 if ((new = (char **) malloc((i + 1) * sizeof(char *))) == NULL)
79 if ((new[i] = strDup(environ[i])) == NULL) {
80 while (new[++i] != NULL)
91 /* Set or replace an environment variable */
100 /* We must have a non-empty key and an '=' */
101 if (mapping[0] == '=' || (p = strchr(mapping, '=')) == NULL) {
105 /* Include through the '=' for matching */
106 keylen = p - mapping + 1;
108 if (!dirtyEnv && copyenv() != 0)
111 if ((p = strDup(mapping)) == NULL)
114 /* Look for an existing key that matches */
115 for (i = 0; environ[i] != NULL && strncmp(environ[i], p, keylen) != 0; i++);
117 if (environ[i] != NULL) {
121 if ((new = (char **) realloc(environ, (i + 1) * sizeof(char *))) == NULL) {
132 /* Delete a variable from the environment */
139 if (strchr(name, '=') != NULL) {
143 keylen = strlen(name);
145 if (!dirtyEnv && copyenv() != 0)
148 /* Look for a matching key */
149 for (i = 0; environ[i] != NULL &&
150 (strncmp(environ[i], name, keylen) != 0 || environ[i][keylen] != '='); i++);
152 /* Don't complain if it wasn't there to begin with */
153 if (environ[i] == NULL) {
159 environ[i] = environ[i + 1];
161 } while (environ[i] != NULL);