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
43namespace google_breakpad {
44
45// A class for enumerating a directory without using diropen/readdir or other
46// functions which may allocate memory.
47class 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