/*
 * 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 */