
/*
 * XREnvironImpl.c
 * created, February 9, 1989 8:31:34 pm PST
 * bj, October 27, 1989 5:36:45 pm PDT
 * eduardo, November 20, 1989 11:43:03 am PST
 * Willie-Sue Orr, August 9, 1991 1:59:54 pm PDT
 */

#include <stdio.h>
#include <sys/types.h>

extern char **environ;
extern char *GC_malloc();
extern char *GC_realloc();

/* extern */ char **XR_environ;

extern char *XR_findenv(name, offset) register char *name; int *offset; {
/*
 * Returns pointer to value associated with name, if any, else NULL.
 * Sets offset to be the offset of the name/value combination in the environmental array,
 * for use by setenv(3) and unsetenv(3).
 * Explicitly removes '=' in argument name.
 * - result is pointer into string in env, treat as readonly!
 */
register int len;
register char **p, *c;
for ( c = name, len = 0; *c && *c != '='; ++c, ++len );
for ( p = XR_environ; *p; ++p )
if ( ! strncmp(*p, name, len) )
if ( *(c = *p + len) == '=' ) { *offset = p - XR_environ; return(++c); }
return(NULL);
}

extern char *XR_getenv(name) char *name; {
/*
 * Returns ptr to value associated with name, if any, else NULL
 * - result is pointer into string in env, treat as readonly!
 * - GC_malloc & copy would protect us from clients!
 */
int offset;
return(XR_findenv(name, &offset));
}

extern int XR_setenv(name, value, rewrite) register char *name, *value; int rewrite; {
/*
 * Set the value of the environmental variable "name" to be "value".
 * If rewrite is set, replace any current value.
 * - always GC_malloc new storage! - enforces readonly semantics invariant!
 * - alters XR_environ, should be monitor locked!
 * make XR_setenv static instead of extern, to catches uses - this code may not work
 * XR_setenv is used in LoaderUtilsImpl.c, so have to provide it, so make extern again
 */
static int alloced; /* if allocated space before */
register char *c;
int l_value, offset;
if (*value == '=') ++value; /* no `=' in value */
l_value = strlen(value);
if ( (c = XR_findenv(name, &offset)) )
{ /* find if already exists */
if ( ! rewrite ) return(0);
/* if ( strlen(c) >= l_value ) { - don't bother, always GC_malloc new storage!
old larger; copy over
while ( *c++ = *value++ );
return(0);
} */
}
else { /* create new slot */
register int cnt;
register char **p;
for ( p = XR_environ, cnt = 0; *p; ++p, ++cnt );
if ( alloced )
{ /* just increase size */
XR_environ = (char **)GC_realloc((char *)XR_environ,(u_int)(sizeof(char *) * (cnt + 2)));
if ( ! XR_environ ) return(-1);
}
else { /* get new space */
alloced = 1; /* copy old entries into it */
p = (char **)GC_malloc((u_int)(sizeof(char *) *(cnt + 2)));
if ( ! p ) return(-1);
bcopy(XR_environ, p, cnt * sizeof(char *));
XR_environ = p;
}
XR_environ[cnt + 1] = NULL;
offset = cnt;
}
for ( c = name; *c && *c != '='; ++c ); /* no `=' in name */
if ( ! (XR_environ[offset] = GC_malloc((u_int)((int)(c - name) + l_value + 2))) ) return(-1);/* name + `=' + value */
for ( c = XR_environ[offset]; (*c = *name++) && *c != '='; ++c );
for ( *c++ = '='; *c++ = *value++; );
return(0);
}

extern void XR_unsetenv(name) char *name; {
/*
 * Delete environmental variable "name"
 * - alters XR_environ, should be monitor locked!
 */
register char **p;
int offset;
while ( XR_findenv(name, &offset) ) /* if set multiple times */
for (p = &XR_environ[offset]; ; ++p)
if ( ! (*p = *(p + 1)) ) break;
}

extern void XR_install_XREnvironImpl() { /* PRE-start trap */
};

extern void XR_run_XREnvironImpl() { /* start trap */
/* little ditty to get it "out of the global frame" for threads*/
int ok;
XR_environ = environ;
ok = XR_setenv("XR_environ", "TRUE", 1);
}

/* eof */

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