lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc

   1 //===-- sanitizer_symbolizer_posix_libcdep.cc -----------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file is shared between AddressSanitizer and ThreadSanitizer
  11 // run-time libraries.
  12 // POSIX-specific implementation of symbolizer parts.
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "sanitizer_platform.h"
  16 #if SANITIZER_POSIX
  17 #include "sanitizer_common.h"
  18 #include "sanitizer_internal_defs.h"
  19 #include "sanitizer_symbolizer.h"
  20
  21 #include <errno.h>
  22 #include <sys/wait.h>
  23 #include <unistd.h>
  24
  25 namespace __sanitizer {
  26
  27 bool StartSymbolizerSubprocess(const char *path_to_symbolizer,
  28                                int *input_fd, int *output_fd) {
  29   if (!FileExists(path_to_symbolizer)) {
  30     Report("WARNING: invalid path to external symbolizer!\n");
  31     return false;
  32   }
  33
  34   int *infd = NULL;
  35   int *outfd = NULL;
  36   // The client program may close its stdin and/or stdout and/or stderr
  37   // thus allowing socketpair to reuse file descriptors 0, 1 or 2.
  38   // In this case the communication between the forked processes may be
  39   // broken if either the parent or the child tries to close or duplicate
  40   // these descriptors. The loop below produces two pairs of file
  41   // descriptors, each greater than 2 (stderr).
  42   int sock_pair[5][2];
  43   for (int i = 0; i < 5; i++) {
  44     if (pipe(sock_pair[i]) == -1) {
  45       for (int j = 0; j < i; j++) {
  46         internal_close(sock_pair[j][0]);
  47         internal_close(sock_pair[j][1]);
  48       }
  49       Report("WARNING: Can't create a socket pair to start "
  50              "external symbolizer (errno: %d)\n", errno);
  51       return false;
  52     } else if (sock_pair[i][0] > 2 && sock_pair[i][1] > 2) {
  53       if (infd == NULL) {
  54         infd = sock_pair[i];
  55       } else {
  56         outfd = sock_pair[i];
  57         for (int j = 0; j < i; j++) {
  58           if (sock_pair[j] == infd) continue;
  59           internal_close(sock_pair[j][0]);
  60           internal_close(sock_pair[j][1]);
  61         }
  62         break;
  63       }
  64     }
  65   }
  66   CHECK(infd);
  67   CHECK(outfd);
  68
  69   int pid = fork();
  70   if (pid == -1) {
  71     // Fork() failed.
  72     internal_close(infd[0]);
  73     internal_close(infd[1]);
  74     internal_close(outfd[0]);
  75     internal_close(outfd[1]);
  76     Report("WARNING: failed to fork external symbolizer "
  77            " (errno: %d)\n", errno);
  78     return false;
  79   } else if (pid == 0) {
  80     // Child subprocess.
  81     internal_close(STDOUT_FILENO);
  82     internal_close(STDIN_FILENO);
  83     internal_dup2(outfd[0], STDIN_FILENO);
  84     internal_dup2(infd[1], STDOUT_FILENO);
  85     internal_close(outfd[0]);
  86     internal_close(outfd[1]);
  87     internal_close(infd[0]);
  88     internal_close(infd[1]);
  89     for (int fd = getdtablesize(); fd > 2; fd--)
  90       internal_close(fd);
  91     execl(path_to_symbolizer, path_to_symbolizer, (char*)0);
  92     internal__exit(1);
  93   }
  94
  95   // Continue execution in parent process.
  96   internal_close(outfd[0]);
  97   internal_close(infd[1]);
  98   *input_fd = infd[0];
  99   *output_fd = outfd[1];
 100
 101   // Check that symbolizer subprocess started successfully.
 102   int pid_status;
 103   SleepForMillis(kSymbolizerStartupTimeMillis);
 104   int exited_pid = waitpid(pid, &pid_status, WNOHANG);
 105   if (exited_pid != 0) {
 106     // Either waitpid failed, or child has already exited.
 107     Report("WARNING: external symbolizer didn't start up correctly!\n");
 108     return false;
 109   }
 110
 111   return true;
 112 }
 113
 114
 115 }  // namespace __sanitizer
 116
 117 #endif  // SANITIZER_POSIX