pathaccess.c   [plain text]

#pragma prototyped
/*
 * Glenn Fowler
 * AT&T Bell Laboratories
 *
 * return path to file a/b with access mode using : separated dirs
 * both a and b may be 0
 * if (mode&PATH_REGULAR) then path must not be a directory
 * if (mode&PATH_ABSOLUTE) then path must be rooted
 * path returned in path buffer
 */

#include <ast.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

/* #include <ls.h> */

char* pathcanon(char* path, int flags);

char*
pathaccess(register char* path, register const char* dirs, const char* a, const char* b, register int mode)
{
	register int	m = 0;
	int		sep = ':';
	char		cwd[PATH_MAX];
	struct stat	st;

#ifdef EFF_ONLY_OK
	m |= EFF_ONLY_OK;
#endif
#ifdef EX_OK
	if (mode == (PATH_EXECUTE|PATH_REGULAR))
	{
		mode &= ~PATH_REGULAR;
		m |= EX_OK;
	}
	else
#endif
	{
		if (mode & PATH_READ) m |= R_OK;
		if (mode & PATH_WRITE) m |= W_OK;
		if (mode & PATH_EXECUTE) m |= X_OK;
	}
	do
	{
		dirs = pathcat(path, dirs, sep, a, b);
		pathcanon(path, 0);
		if (!access(path, m))
		{
			if ((mode & PATH_REGULAR) && (stat(path, &st) || S_ISDIR(st.st_mode))) continue;
			if (*path == '/' || !(mode & PATH_ABSOLUTE)) return(path);
			dirs = getcwd(cwd, sizeof(cwd));
			sep = 0;
		}
	} while (dirs);
	return(0);
}