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 27  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 28  
 29  // core_handler.cc: A tool to handle coredumps on Linux
 30  
 31  #ifdef HAVE_CONFIG_H
 32  #include <config.h>  // Must come first
 33  #endif
 34  
 35  #include <pwd.h>
 36  #include <stdio.h>
 37  #include <stdlib.h>
 38  #include <sys/mman.h>
 39  #include <sys/types.h>
 40  #include <syslog.h>
 41  #include <unistd.h>
 42  #include <sstream>
 43  
 44  #include "client/linux/minidump_writer/linux_core_dumper.h"
 45  #include "client/linux/minidump_writer/minidump_writer.h"
 46  #include "common/path_helper.h"
 47  #include "common/scoped_ptr.h"
 48  
 49  namespace {
 50  
 51  using google_breakpad::AppMemoryList;
 52  using google_breakpad::LinuxCoreDumper;
 53  using google_breakpad::MappingList;
 54  using google_breakpad::scoped_array;
 55  
 56  // Size of the core dump to read in order to access all the threads
 57  // descriptions.
 58  //
 59  // The first section is the note0 section which contains the thread states. On
 60  // x86-64 a typical thread description take about 1432B. Reading 1 MB allows
 61  // several hundreds of threads.
 62  const int core_read_size = 1024 * 1024;
 63  
 64  void ShowUsage(const char* argv0) {
 65    fprintf(stderr, "Usage: %s <process id> <minidump file>\n\n",
 66            google_breakpad::BaseName(argv0).c_str());
 67    fprintf(stderr,
 68            "A tool which serves as a core dump handler and produces "
 69            "minidump files.\n");
 70    fprintf(stderr, "Please refer to the online documentation:\n");
 71    fprintf(stderr,
 72            "https://chromium.googlesource.com/breakpad/breakpad/+/HEAD"
 73            "/docs/linux_core_handler.md\n");
 74  }
 75  
 76  bool WriteMinidumpFromCore(const char* filename,
 77                             const char* core_path,
 78                             const char* procfs_override) {
 79    MappingList mappings;
 80    AppMemoryList memory_list;
 81    LinuxCoreDumper dumper(0, core_path, procfs_override);
 82    return google_breakpad::WriteMinidump(filename, mappings, memory_list,
 83                                          &dumper);
 84  }
 85  
 86  bool HandleCrash(pid_t pid, const char* procfs_dir, const char* md_filename) {
 87    int r = 0;
 88    scoped_array<char> buf(new char[core_read_size]);
 89    while (r != core_read_size) {
 90      int ret = read(STDIN_FILENO, &buf[r], core_read_size - r);
 91      if (ret == 0) {
 92        break;
 93      } else if (ret == -1) {
 94        return false;
 95      }
 96      r += ret;
 97    }
 98  
 99    int fd = memfd_create("core_file", MFD_CLOEXEC);
100    if (fd == -1) {
101      return false;
102    }
103  
104    int w = write(fd, &buf[0], r);
105    if (w != r) {
106      close(fd);
107      return false;
108    }
109  
110    std::stringstream core_file_ss;
111    core_file_ss << "/proc/self/fd/" << fd;
112    std::string core_file(core_file_ss.str());
113  
114    if (!WriteMinidumpFromCore(md_filename, core_file.c_str(), procfs_dir)) {
115      close(fd);
116      return false;
117    }
118    close(fd);
119  
120    return true;
121  }
122  
123  }  // namespace
124  
125  int main(int argc, char* argv[]) {
126    int ret = EXIT_FAILURE;
127  
128    if (argc != 3) {
129      ShowUsage(argv[0]);
130      return ret;
131    }
132  
133    const char* pid_str = argv[1];
134    const char* md_filename = argv[2];
135    pid_t pid = atoi(pid_str);
136  
137    std::stringstream proc_dir_ss;
138    proc_dir_ss << "/proc/" << pid_str;
139    std::string proc_dir(proc_dir_ss.str());
140  
141    openlog("core_handler", 0, 0);
142    if (HandleCrash(pid, proc_dir.c_str(), md_filename)) {
143      syslog(LOG_NOTICE, "Minidump generated at %s\n", md_filename);
144      ret = EXIT_SUCCESS;
145    } else {
146      syslog(LOG_ERR, "Cannot generate minidump %s\n", md_filename);
147    }
148    closelog();
149  
150    return ret;
151  }