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      1 // Copyright (c) 2009, Google Inc.
      2 // All rights reserved.
      3 //
      4 // Redistribution and use in source and binary forms, with or without
      5 // modification, are permitted provided that the following conditions are
      6 // met:
      7 //
      8 //     * Redistributions of source code must retain the above copyright
      9 // notice, this list of conditions and the following disclaimer.
     10 //     * Redistributions in binary form must reproduce the above
     11 // copyright notice, this list of conditions and the following disclaimer
     12 // in the documentation and/or other materials provided with the
     13 // distribution.
     14 //     * Neither the name of Google Inc. nor the names of its
     15 // contributors may be used to endorse or promote products derived from
     16 // this software without specific prior written permission.
     17 //
     18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29 
     30 #ifndef CLIENT_LINUX_MINIDUMP_WRITER_DIRECTORY_READER_H_
     31 #define CLIENT_LINUX_MINIDUMP_WRITER_DIRECTORY_READER_H_
     32 
     33 #include <stdint.h>
     34 #include <unistd.h>
     35 #include <limits.h>
     36 #include <assert.h>
     37 #include <errno.h>
     38 #include <string.h>
     39 
     40 #include "common/linux/linux_libc_support.h"
     41 #include "third_party/lss/linux_syscall_support.h"
     42 
     43 namespace google_breakpad {
     44 
     45 // A class for enumerating a directory without using diropen/readdir or other
     46 // functions which may allocate memory.
     47 class DirectoryReader {
     48  public:
     49   DirectoryReader(int fd)
     50       : fd_(fd),
     51         buf_used_(0) {
     52   }
     53 
     54   // Return the next entry from the directory
     55   //   name: (output) the NUL terminated entry name
     56   //
     57   // Returns true iff successful (false on EOF).
     58   //
     59   // After calling this, one must call |PopEntry| otherwise you'll get the same
     60   // entry over and over.
     61   bool GetNextEntry(const char** name) {
     62     struct kernel_dirent* const dent =
     63       reinterpret_cast<kernel_dirent*>(buf_);
     64 
     65     if (buf_used_ == 0) {
     66       // need to read more entries.
     67       const int n = sys_getdents(fd_, dent, sizeof(buf_));
     68       if (n < 0) {
     69         return false;
     70       } else if (n == 0) {
     71         hit_eof_ = true;
     72       } else {
     73         buf_used_ += n;
     74       }
     75     }
     76 
     77     if (buf_used_ == 0 && hit_eof_)
     78       return false;
     79 
     80     assert(buf_used_ > 0);
     81 
     82     *name = dent->d_name;
     83     return true;
     84   }
     85 
     86   void PopEntry() {
     87     if (!buf_used_)
     88       return;
     89 
     90     const struct kernel_dirent* const dent =
     91       reinterpret_cast<kernel_dirent*>(buf_);
     92 
     93     buf_used_ -= dent->d_reclen;
     94     my_memmove(buf_, buf_ + dent->d_reclen, buf_used_);
     95   }
     96 
     97  private:
     98   const int fd_;
     99   bool hit_eof_;
    100   unsigned buf_used_;
    101   uint8_t buf_[sizeof(struct kernel_dirent) + NAME_MAX + 1];
    102 };
    103 
    104 }  // namespace google_breakpad
    105 
    106 #endif  // CLIENT_LINUX_MINIDUMP_WRITER_DIRECTORY_READER_H_
    107