util.cc

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/*
 * Copyright 2006-2009 Savarese Software Research Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.savarese.com/software/ApacheLicense-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>

#include <ssrc/wispers/renderer/util.h>

#include <boost/filesystem/convenience.hpp>

__BEGIN_NS_SSRC_WSPR_RENDERER

void cache_to_file(const char* buf, const unsigned int content_length,
                   const path & cached_path)
{
  const path dir = cached_path.parent_path();

  if(!boost::filesystem::exists(dir)) {
    boost::filesystem::create_directories(dir);
  }

  // TODO: how about O_NONBLOCK and handling I/O in event loop?
  // Probably not doable.
  int fd(::open(cached_path.string().c_str(),
                O_CREAT | O_WRONLY | O_EXCL, S_IRUSR | S_IRGRP));
  
  if(fd != -1) {
    struct ::flock lock;

    lock.l_type = F_WRLCK;
    lock.l_whence = SEEK_SET;
    lock.l_start = lock.l_len = 0;

    // If we can't get the lock, assume other process is rendering the file.
    if(::fcntl(fd, F_SETLK, &lock) == 0) {
      ::ssize_t written(0);
      // TODO: handle error where written == -1.
      // encapsulate this in a utility function or other.  See LAF.
      for(unsigned int length = content_length; length > 0 && written > -1;
          length-=written, buf+=written)
        written = ::write(fd, buf, length);
    }
    ::close(fd);
  }
}

void init_path_pattern(boost::regex & path_pattern,
                       const std::vector<string> & directories,
                       const string & leaf_pattern)
{
  unsigned int i = directories.size();
  string pattern;

  if(i > 0) {
    pattern.append("\\A(?:");
    while(i-- > 1)
      pattern.append("\\Q").append(directories[i])
        .append("\\E|");
    pattern.append("\\Q").append(directories[0]).append("\\E)/")
      .append(leaf_pattern).append("\\Z");

    path_pattern = pattern;
  }
}

__END_NS_SSRC_WSPR_RENDERER