base/dir_reader_linux.h

   1 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef BASE_DIR_READER_LINUX_H_
   6 #define BASE_DIR_READER_LINUX_H_
   7 #pragma once
   8
   9 #include <errno.h>
  10 #include <fcntl.h>
  11 #include <stdint.h>
  12 #include <sys/syscall.h>
  13 #include <unistd.h>
  14
  15 #include "base/logging.h"
  16 #include "base/eintr_wrapper.h"
  17
  18 // See the comments in dir_reader_posix.h about this.
  19
  20 namespace base {
  21
  22 struct linux_dirent {
  23   uint64_t        d_ino;
  24   int64_t         d_off;
  25   unsigned short  d_reclen;
  26   unsigned char   d_type;
  27   char            d_name[0];
  28 };
  29
  30 class DirReaderLinux {
  31  public:
  32   explicit DirReaderLinux(const char* directory_path)
  33       : fd_(open(directory_path, O_RDONLY | O_DIRECTORY)),
  34         offset_(0),
  35         size_(0) {
  36     memset(buf_, 0, sizeof(buf_));
  37   }
  38
  39   ~DirReaderLinux() {
  40     if (fd_ >= 0) {
  41       if (HANDLE_EINTR(close(fd_)))
  42         RAW_LOG(ERROR, "Failed to close directory handle");
  43     }
  44   }
  45
  46   bool IsValid() const {
  47     return fd_ >= 0;
  48   }
  49
  50   // Move to the next entry returning false if the iteration is complete.
  51   bool Next() {
  52     if (size_) {
  53       linux_dirent* dirent = reinterpret_cast<linux_dirent*>(&buf_[offset_]);
  54       offset_ += dirent->d_reclen;
  55     }
  56
  57     if (offset_ != size_)
  58       return true;
  59
  60     const int r = syscall(__NR_getdents64, fd_, buf_, sizeof(buf_));
  61     if (r == 0)
  62       return false;
  63     if (r == -1) {
  64       DPLOG(FATAL) << "getdents64 returned an error: " << errno;
  65       return false;
  66     }
  67     size_ = r;
  68     offset_ = 0;
  69     return true;
  70   }
  71
  72   const char* name() const {
  73     if (!size_)
  74       return NULL;
  75
  76     const linux_dirent* dirent =
  77         reinterpret_cast<const linux_dirent*>(&buf_[offset_]);
  78     return dirent->d_name;
  79   }
  80
  81   int fd() const {
  82     return fd_;
  83   }
  84
  85   static bool IsFallback() {
  86     return false;
  87   }
  88
  89  private:
  90   const int fd_;
  91   unsigned char buf_[512];
  92   size_t offset_, size_;
  93
  94   DISALLOW_COPY_AND_ASSIGN(DirReaderLinux);
  95 };
  96
  97 }  // namespace base
  98
  99 #endif // BASE_DIR_READER_LINUX_H_