libs-base/Source/find_exec.c

/*
    find_exec.c - routine to find the executable path

    From the dld distribution -- copyrighted below.
    Modified by Adam Fedor - traverse links

    Given a filename, objc_find_executable searches the directories listed in 
    environment variable PATH for a file with that filename.
    A new copy of the complete path name of that file is returned.  This new
    string may be disposed by free() later on.
*/

/* This file is part of DLD, a dynamic link/unlink editor for C.
   
   Copyright (C) 1990 by W. Wilson Ho.

   The author can be reached electronically by how@cs.ucdavis.edu or
   through physical mail at:

   W. Wilson Ho
   Division of Computer Science
   University of California at Davis
   Davis, CA 95616
*/

/* This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 1, or (at your option) any
   later version. 
*/

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

#ifdef __WIN32__
#include <limits.h>
#define S_IFLNK 0120000
int readlink(char *path, char *buf, int bufsiz) { return (-1); }
int lstat(char *path, struct stat *buf) { return (-1); }
#define MAXPATHLEN 255
#else
#include <sys/file.h>
#include <sys/param.h>
#include <unistd.h>
#endif /* __WIN32__ */

#include <stdlib.h>
#include <string.h>

#define DEFAULT_PATH ".:~/bin::/usr/local/bin:/usr/new:/usr/ucb:/usr/bin:/bin:/usr/hosts"

/* ABSOLUTE_FILENAME_P (fname): True if fname is an absolute filename */
#ifdef atarist
#define ABSOLUTE_FILENAME_P(fname)	((fname[0] == '/') || \
	(fname[0] && (fname[1] == ':')))
#else
#define ABSOLUTE_FILENAME_P(fname)	(fname[0] == '/')
#endif /* atarist */

static char *
copy_of (s)
register char *s;
{
    register char *p = (char *) malloc (strlen(s)+1);

    if (!p) return 0;

    *p = 0;
    strcpy (p, s);
    return p;
}

static int
find_full_path(char *path) 
{
    struct stat statbuf;

    if ( stat(path, &statbuf) != 0) 
	return -1;

    if ( (lstat(path, &statbuf) == 0) 
		&& (statbuf.st_mode & S_IFLNK) == S_IFLNK) {
	char link[MAXPATHLEN+1];
	int cc;
	cc = readlink(path, link, MAXPATHLEN);
	if (cc == -1)
	    return -1;
	link[cc] = '\0';
	if (ABSOLUTE_FILENAME_P(link)) {
	    strcpy(path, link);
	} else if (strlen(path)+strlen(link) < MAXPATHLEN) {
	    char *p;
	    p = strrchr(path, '/');
	    if (p)
		*(p+1) = '\0';
	    strcat(path, link);
	} else
	    return -1;
    }

    return 0;
}

char *
objc_find_executable (const char *file)
{
    char *search;
    register char *p;
    int cwd_in_path = 0;
    
    if (ABSOLUTE_FILENAME_P(file)) {
	search = copy_of(file);
	find_full_path(search);
	return search;
/*
	return copy_of (file);
*/
    }
    
    if ((search = (char *) getenv("PATH")) == 0)
	search = DEFAULT_PATH;
	
    p = search;
    
    while (*p) {
	char  name[MAXPATHLEN];
	register char *next;

	next = name;
	
	/* copy directory name into [name] */
	while (*p && *p != ':') *next++ = *p++;
	*next = 0;
	if (*p) p++;

	if (name[0] == '.' && name[1] == 0) {
#ifndef NeXT
	    getcwd (name, MAXPATHLEN);
#else
	  /*
	    Reported by Gregor Hoffleit <flight@mathi.uni-heidelberg.DE>
	    Date: Fri, 12 Jan 96 16:00:42 +0100
	    */
	    getwd (name);
#endif
	    cwd_in_path = 1;
	}
	
	strcat (name, "/");
	strcat (name, file);
	      
/*
	if (access (name, X_OK) == 0)
*/
	if (find_full_path (name) == 0)
	    return copy_of (name);
    }

    /*
      If '.' not in PATH, check this too
    */
    if (!cwd_in_path) {
	char  name[MAXPATHLEN];

#ifndef NeXT
	getcwd (name, MAXPATHLEN);
#else
	getwd (name);
#endif
	strcat (name, "/");
	strcat (name, file);

/*
	if (access (name, X_OK) == 0)
*/
	if (find_full_path (name) == 0)
	    return copy_of (name);
    }

    return 0;
}