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posix-fs.cpp

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * $URL: https://scummvm.svn.sourceforge.net/svnroot/scummvm/scummvm/tags/release-0-11-1/backends/fs/posix/posix-fs.cpp $
 * $Id: posix-fs.cpp 30944 2008-02-23 22:50:18Z sev $
 */

#if defined(UNIX)

#include "backends/fs/abstract-fs.h"

#ifdef MACOSX
#include <sys/types.h>
#endif
#include <sys/param.h>
#include <sys/stat.h>
#include <dirent.h>
#include <stdio.h>
#include <unistd.h>

/**
 * Implementation of the ScummVM file system API based on POSIX.
 * 
 * Parts of this class are documented in the base interface class, AbstractFilesystemNode.
 */
class POSIXFilesystemNode : public AbstractFilesystemNode {
protected:
      String _displayName;
      String _path;
      bool _isDirectory;
      bool _isValid;

public:
      /**
       * Creates a POSIXFilesystemNode with the root node as path.
       */
      POSIXFilesystemNode();
      
      /**
       * Creates a POSIXFilesystemNode for a given path.
       * 
       * @param path String with the path the new node should point to.
       * @param verify true if the isValid and isDirectory flags should be verified during the construction.
       */
      POSIXFilesystemNode(const String &path, bool verify);
      
      virtual bool exists() const { return access(_path.c_str(), F_OK) == 0; }
      virtual String getDisplayName() const { return _displayName; }
      virtual String getName() const { return _displayName; }
      virtual String getPath() const { return _path; }
      virtual bool isDirectory() const { return _isDirectory; }
      virtual bool isReadable() const { return access(_path.c_str(), R_OK) == 0; }
      virtual bool isWritable() const { return access(_path.c_str(), W_OK) == 0; }
      
      virtual AbstractFilesystemNode *getChild(const String &n) const;
      virtual bool getChildren(AbstractFSList &list, ListMode mode, bool hidden) const;
      virtual AbstractFilesystemNode *getParent() const;
      
private:
      /**
       * Tests and sets the _isValid and _isDirectory flags, using the stat() function.
       */
      virtual void setFlags();
};

/**
 * Returns the last component of a given path.
 * 
 * Examples:
 *                /foo/bar.txt would return /bar.txt
 *                /foo/bar/    would return /bar/
 *  
 * @param str String containing the path.
 * @return Pointer to the first char of the last component inside str.
 */
const char *lastPathComponent(const Common::String &str) {
      if(str.empty())
            return "";
      
      const char *start = str.c_str();
      const char *cur = start + str.size() - 2;

      while (cur >= start && *cur != '/') {
            --cur;
      }

      return cur + 1;
}

void POSIXFilesystemNode::setFlags() {
      struct stat st;
      
      _isValid = (0 == stat(_path.c_str(), &st));
      _isDirectory = _isValid ? S_ISDIR(st.st_mode) : false;
}

POSIXFilesystemNode::POSIXFilesystemNode() {
      // The root dir.
      _path = "/";
      _displayName = _path;
      _isValid = true;
      _isDirectory = true;
}

POSIXFilesystemNode::POSIXFilesystemNode(const String &p, bool verify) {
      assert(p.size() > 0);

      // Expand "~/" to the value of the HOME env variable
      if (p.hasPrefix("~/")) {
            const char *home = getenv("HOME");
            if (home != NULL && strlen(home) < MAXPATHLEN) {
                  _path = home;
                  // Skip over the tilda.  We know that p contains at least
                  // two chars, so this is safe:
                  _path += p.c_str() + 1;
            }
      } else {
            _path = p;
      }

      _displayName = lastPathComponent(_path);

      if (verify) {
            setFlags();
      }
}

AbstractFilesystemNode *POSIXFilesystemNode::getChild(const String &n) const {
      // FIXME: Pretty lame implementation! We do no error checking to speak
      // of, do not check if this is a special node, etc.
      assert(_isDirectory);
      
      String newPath(_path);
      if (_path.lastChar() != '/')
            newPath += '/';
      newPath += n;
      
      return new POSIXFilesystemNode(newPath, true);
}

bool POSIXFilesystemNode::getChildren(AbstractFSList &myList, ListMode mode, bool hidden) const {
      assert(_isDirectory);
      
      DIR *dirp = opendir(_path.c_str());
      struct dirent *dp;

      if (dirp == NULL)
            return false;

      // loop over dir entries using readdir
      while ((dp = readdir(dirp)) != NULL) {
            // Skip 'invisible' files if necessary
            if (dp->d_name[0] == '.' && !hidden) {
                  continue;
            }
            // Skip '.' and '..' to avoid cycles
            if ((dp->d_name[0] == '.' && dp->d_name[1] == 0) || (dp->d_name[0] == '.' && dp->d_name[1] == '.')) {
                  continue;
            }

            String newPath(_path);
            if (newPath.lastChar() != '/')
                  newPath += '/';
            newPath += dp->d_name;

            POSIXFilesystemNode entry(newPath, false);

#if defined(SYSTEM_NOT_SUPPORTING_D_TYPE)
            /* TODO: d_type is not part of POSIX, so it might not be supported
             * on some of our targets. For those systems where it isn't supported,
             * add this #elif case, which tries to use stat() instead.
             * 
             * The d_type method is used to avoid costly recurrent stat() calls in big
             * directories.
             */
            entry.setFlags();
#else
            if (dp->d_type == DT_UNKNOWN) {
                  // Fall back to stat()
                  entry.setFlags();
            } else {
                  entry._isValid = (dp->d_type == DT_DIR) || (dp->d_type == DT_REG) || (dp->d_type == DT_LNK);
                  if (dp->d_type == DT_LNK) {
                        struct stat st;
                        if (stat(entry._path.c_str(), &st) == 0)
                              entry._isDirectory = S_ISDIR(st.st_mode);
                        else
                              entry._isDirectory = false;
                  } else {
                        entry._isDirectory = (dp->d_type == DT_DIR);
                  }
            }
#endif

            // Skip files that are invalid for some reason (e.g. because we couldn't
            // properly stat them).
            if (!entry._isValid)
                  continue;

            // Honor the chosen mode
            if ((mode == FilesystemNode::kListFilesOnly && entry._isDirectory) ||
                  (mode == FilesystemNode::kListDirectoriesOnly && !entry._isDirectory))
                  continue;

            if (entry._isDirectory)
                  entry._path += "/";
                  
            myList.push_back(new POSIXFilesystemNode(entry));
      }
      closedir(dirp);
      
      return true;
}

AbstractFilesystemNode *POSIXFilesystemNode::getParent() const {
      if (_path == "/")
            return 0;

      const char *start = _path.c_str();
      const char *end = lastPathComponent(_path);

      return new POSIXFilesystemNode(String(start, end - start), true);
}

#endif //#if defined(UNIX)

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