/*
 *  setpath	- Set the PATH environment variable for the GEM desktop.
 *		  by Dale Schumacher  <dal@syntel.uucp>
 */

#include <stdio.h>
#include <basepage.h>

extern	char	*_envp;

#define	TOS_STYLE	1	/* add TOS-style variables */

static char *findenv(var)
	register char *var;
/*
 *	INTERNAL FUNCTION.  This functions attempts to locate <var> in
 *	the environment.  If <var> is not found, NULL is returned.  If
 *	the environment is NULL, NULL is returned.  If <var> is found,
 *	a pointer to the beginning of <var> in the environment is returned.
 *	BOTH MS-DOS AND TOS ENVIRONMENT FORMATS ARE ACCOMODATED.
 */
	{
	register char *p;
	register int len;

	if((p = _envp) == NULL)
		return(NULL);
	len = strlen(var);
	while(*p)
		{
		if((p[len] == '=') && !strncmp(p, var, len))
			return(p);
		while(*p++)		/* move to next arg */
			;
		}
	return(NULL);
	}

char *getenv(var)
	register char *var;
/*
 *	Search for <var> in the environment.  If <var> is found, a pointer
 *	to it's value is returned.  NULL is returned if <var> is not found.
 *	WARNING:  The returned pointer points into the environment and
 *	must not be modified!
 */
	{
	register char *p, *q;
	register int len;

	len = strlen(var);
	if(p = findenv(var))
		{
		p += (len + 1);
		if(*p == '\0')		/* TOS env format or empty value */
			{
			q = p+1;
			if(*q == '\0')		/* empty value + end of env */
				return(p);
			while(*q && (*q != '='))
				++q;
			if(*q)			/* empty value */
				return(p);
			else			/* TOS env format */
				return(p+1);
			}
		}
	return(p);
	}

int putenv(entry)
	char *entry;
/*
 *	Add <entry> to the environment.  <entry> can be any of the following
 *	forms:
 *		<VARIABLE>
 *		<VARIABLE>=
 *		<VARIABLE>=<value>
 *	The first form removes <VARIABLE> from the environment.  getenv()
 *	will return NULL if looking for this variable.  The second form adds
 *	<VARIABLE> to the environment, with a null value.  getenv() will
 *	return a pointer to a '\0' character if looking for this variable.
 *	Many environment handlers don't support such "tag variables", so
 *	their use is not recommended.  The final form is the most common,
 *	and safest to use.  <VARIABLE> is installed (or replaced) with the
 *	value <value>.  It should be noted that this function itself is not
 *	supported in many systems and should be used will care to prevent
 *	overflowing the space allocated for the environment.
 */
	{
	register char *p, *q, *t, c;
	register int len;

	for(t=entry; (c = *t) && (c != '='); ++t)
		;
	*t = '\0';
	if(p = getenv(entry))		/* remove old var */
		{
		q = p;
		while(*q++)			/* find end of old val */
			;
		p -= (len = strlen(entry));
		while(strncmp(--p, entry, len))	/* find start of old var */
			;
		while(*q)			/* copy environment tail */
			while(*p++ = *q++)
				;
		*p++ = '\0';			/* tie off environment */
		*p = 0xFF;
		}
	if(c == '=')					/* install new var */
		{
		p = _envp;
		while(*p)			/* find end of env */
			while(*p++)
				;
#if MWC_STYLE
		*t = c;
		q = entry;
		while(*p++ = *q++)		/* copy new entry */
			;
#endif
#if TOS_STYLE
		q = entry;
		while(*p++ = *q++)		/* copy new var */
			;
		*--p = '=';
		*++p = '\0';
		while(*p++ = *q++)		/* copy new value */
			;
		*t = c;
#endif
		*p++ = '\0';			/* tie off environment */
		*p = 0xFF;
		}
	return(TRUE);
	}

main(argc, argv)
	int argc;
	char *argv[];
/*
 *	Assume that this program is being called from the desktop.
 *	To change the PATH for the desktop, you modify the environment
 *	of the parent process (the desktop).
 */
	{
	char path[256];
	register BASEPAGE *bp;

	if(argc != 2)
		{
		fprintf(stderr, "usage: SETPATH <command search path>\n");
		getch();
		exit(EXIT_FAILURE);
		}
	sprintf(path, "PATH=%s", argv[1]);
	bp = _base->p_parent;			/* locate parent's basepage */
	_envp = bp->p_env;			/* get environment pointer */
	putenv(path);
	}