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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:
DirectoryReader(int fd)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.
GetNextEntry(const char ** name)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 
PopEntry()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