base/files/dir_reader_linux.h

   1 // Copyright (c) 2012 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_FILES_DIR_READER_LINUX_H_
   6 #define BASE_FILES_DIR_READER_LINUX_H_
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <stdint.h>
  11 #include <sys/syscall.h>
  12 #include <unistd.h>
  13
  14 #include "base/logging.h"
  15 #include "base/posix/eintr_wrapper.h"
  16
  17 // See the comments in dir_reader_posix.h about this.
  18
  19 namespace base {
  20
  21 struct linux_dirent {
  22   uint64_t        d_ino;
  23   int64_t         d_off;
  24   unsigned short  d_reclen;
  25   unsigned char   d_type;
  26   char            d_name[0];
  27 };
  28
  29 class DirReaderLinux {
  30  public:
  31   explicit DirReaderLinux(const char* directory_path)
  32       : fd_(open(directory_path, O_RDONLY | O_DIRECTORY)),
  33         offset_(0),
  34         size_(0) {
  35     memset(buf_, 0, sizeof(buf_));
  36   }
  37
  38   ~DirReaderLinux() {
  39     if (fd_ >= 0) {
  40       if (HANDLE_EINTR(close(fd_)))
  41         RAW_LOG(ERROR, "Failed to close directory handle");
  42     }
  43   }
  44
  45   bool IsValid() const {
  46     return fd_ >= 0;
  47   }
  48
  49   // Move to the next entry returning false if the iteration is complete.
  50   bool Next() {
  51     if (size_) {
  52       linux_dirent* dirent = reinterpret_cast<linux_dirent*>(&buf_[offset_]);
  53       offset_ += dirent->d_reclen;
  54     }
  55
  56     if (offset_ != size_)
  57       return true;
  58
  59     const int r = syscall(__NR_getdents64, fd_, buf_, sizeof(buf_));
  60     if (r == 0)
  61       return false;
  62     if (r == -1) {
  63       DPLOG(FATAL) << "getdents64 returned an error: " << errno;
  64       return false;
  65     }
  66     size_ = r;
  67     offset_ = 0;
  68     return true;
  69   }
  70
  71   const char* name() const {
  72     if (!size_)
  73       return NULL;
  74
  75     const linux_dirent* dirent =
  76         reinterpret_cast<const linux_dirent*>(&buf_[offset_]);
  77     return dirent->d_name;
  78   }
  79
  80   int fd() const {
  81     return fd_;
  82   }
  83
  84   static bool IsFallback() {
  85     return false;
  86   }
  87
  88  private:
  89   const int fd_;
  90   unsigned char buf_[512];
  91   size_t offset_, size_;
  92
  93   DISALLOW_COPY_AND_ASSIGN(DirReaderLinux);
  94 };
  95
  96 }  // namespace base
  97
  98 #endif // BASE_FILES_DIR_READER_LINUX_H_