#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Research
 *
 * return full path to p with mode access using $PATH
 * if a!=0 then it and $0 and $_ with $PWD are used for
 * related root searching
 * the related root must have a bin subdir
 * p==0 sets the cached relative dir to a
 * p==0 a=="" disables $0 $_ $PWD relative search
 * full path returned in path buffer
 * if path==0 then the space is malloc'd
 */

#include <ast.h>
#include <string.h>
#include <unistd.h>

/* #include <option.h> */
extern char**          environ;
char** opt_info_argv;

char*
pathpath(register char* path, const char* p, const char* a, int mode)
{
	register char*	s;
	char*		x;
	char		buf[PATH_MAX];

	static char*	cmd;

	if (!path)
		path = buf;
	if (!p)
	{
		if (cmd)
			free(cmd);
		cmd = a ? strdup(a) : (char*)0;
		return 0;
	}
	if (strlen(p) < PATH_MAX)
	{
		strcpy(path, p);
		if (pathexists(path, mode))
			return (path == buf) ? strdup(path) : path;
	}
	if (*p == '/')
		a = 0;
	else if ((s = (char*)a))
	{
		x = s;
		if (strchr(p, '/'))
		{
			a = p;
			p = "..";
		}
		else
			a = 0;
		if ((!cmd || *cmd) && 
             (strchr(s, '/') ||
		     (((s = cmd) || (opt_info_argv && (s = *opt_info_argv))) &&
			 strchr(s, '/') && !strchr(s, '\n') && !access(s, F_OK)) ||
		     (environ && (s = *environ) && *s++ == '_' && 
              *s++ == '=' && strchr(s, '/') && !strneq(s, "/bin/", 5) && 
              !strneq(s, "/usr/bin/", 9)) ||
		     (*x && !access(x, F_OK) && (s = getenv("PWD")) && *s == '/')
             )
           )
		{
			if (!cmd)
				cmd = strdup(s);
			if (strlen(s) < (sizeof(buf) - 6))
			{
				s = strcopy(path, s);
				for (;;)
				{
					do if (s <= path) goto normal; while (*--s == '/');
					do if (s <= path) goto normal; while (*--s != '/');
					strcpy(s + 1, "bin");
					if (pathexists(path, PATH_EXECUTE))
					{
						if ((s = pathaccess(path, path, p, a, mode)))
							return path == buf ? strdup(s) : s;
						goto normal;
					}
				}
			normal: ;
			}
		}
	}
	x = !a && strchr(p, '/') ? "" : pathbin();
	if (!(s = pathaccess(path, x, p, a, mode)) && !*x && (x = getenv("FPATH")))
		s = pathaccess(path, x, p, a, mode);
	return (s && path == buf) ? strdup(s) : s;
}
