[sanitizers] extracted process management functions

[aizatsky]

moved code

[aizatsky]

unittest

[aizatsky]

nits

[aizatsky]

I'm super sorry, but I have submitted this by mistake (screwed up merging branches in git).

I'll see if I can rollback this.

lib/sanitizer_common/sanitizer_common.h

 void DumpProcessMap();
 bool FileExists(const char *filename);
 const char *GetEnv(const char *name);
 bool SetEnv(const char *name, const char *value);
 const char *GetPwd();
 char *FindPathToBinary(const char *name);
 bool IsPathSeparator(const char c);
 bool IsAbsolutePath(const char *path);
+// Starts a subprocess and returs its pid.
+// If *_fd parameters are >=0 their corresponding input/output
+// streams would be redirect to the file. The files would always be closed
+// in parent process even in case of an error.
+int StartSubprocess(const char *program, char *const argv[],
+                    fd_t std_in_fd = kInvalidFd, fd_t std_out_fd = kInvalidFd,
+                    fd_t std_err_fd = kInvalidFd);
+// Checks if specified process is still running
+bool IsProcessRunning(int pid);
 
 u32 GetUid();
 void ReExec();
 char **GetArgv();
 void PrintCmdline();
 bool StackSizeIsUnlimited();
 void SetStackSizeLimitInBytes(uptr limit);
 bool AddressSpaceIsUnlimited();
struct SignalContext {
   static SignalContext Create(void *siginfo, void *context);
 };
 
 void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 
 void DisableReexec();
 void MaybeReexec();
 
+template <typename Fn>
+struct AutoRunner {
+  explicit AutoRunner(Fn fn) : fn_(fn) {}
+  ~AutoRunner() { fn_(); }
+  Fn fn_;
+};
+
+// A simple scope guard. Usage:
+// auto cleanup = at_scope_exit([]{ do_cleanup; });
+template <typename Fn>
+AutoRunner<Fn> at_scope_exit(Fn fn) { return AutoRunner<Fn>(fn); }
+
 }  // namespace __sanitizer
 
 inline void *operator new(__sanitizer::operator_new_size_type size,
                           __sanitizer::LowLevelAllocator &alloc) {
   return alloc.Allocate(size);
 }
 
 struct StackDepotStats {
   uptr n_uniq_ids;
   uptr allocated;
 };
 
 #endif  // SANITIZER_COMMON_H

lib/sanitizer_common/sanitizer_common.cc

while (templ && templ[0]) {
     asterisk = false;
   }
   return true;
 }
 
 static const char kPathSeparator = SANITIZER_WINDOWS ? ';' : ':';
 
 char *FindPathToBinary(const char *name) {
+  if (FileExists(name)) {
+    return internal_strdup(name);
+  }
+
   const char *path = GetEnv("PATH");
   if (!path)
     return nullptr;
   uptr name_len = internal_strlen(name);
   InternalScopedBuffer<char> buffer(kMaxPathLength);
   const char *beg = path;
   while (true) {
     const char *end = internal_strchrnul(beg, kPathSeparator);

lib/sanitizer_common/sanitizer_linux.cc

 #include <sched.h>
 #include <sys/mman.h>
 #include <sys/ptrace.h>
 #include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <ucontext.h>
 #include <unistd.h>
 
 #if SANITIZER_FREEBSD
 #include <sys/sysctl.h>
 #include <machine/atomic.h>
 extern "C" {
 // <sys/umtx.h> must be included after <errno.h> and <sys/types.h> on

 void DisableReexec() {
   // No need to re-exec on Linux.
 }
 
 void MaybeReexec() {
   // No need to re-exec on Linux.
 }
 
+int StartSubprocess(const char *program, char *const argv[], fd_t std_in_fd,
+                    fd_t std_out_fd, fd_t std_err_fd) {
+  auto file_closer = at_scope_exit([&] {
+    if (std_in_fd >= 0) {
+      internal_close(std_in_fd);
+    }
+    if (std_out_fd >= 0) {
+      internal_close(std_out_fd);
+    }
+    if (std_err_fd >= 0) {
+      internal_close(std_err_fd);
+    }
+  });
+
+  if (!FileExists(program)) {
+    Report("WARNING: Program %s not found!\n", program);
+    return -1;
+  }
+
+  int pid = internal_fork();
+
+  if (pid < 0) {
+    int rverrno;
+    if (internal_iserror(pid, &rverrno)) {
+      Report("WARNING: failed to fork (errno %d)\n", rverrno);
+    }
+    return pid;
+  }
+
+  if (pid == 0) {
+    // Child subprocess
+    if (std_in_fd >= 0) {
+      internal_close(STDIN_FILENO);
+      internal_dup2(std_in_fd, STDIN_FILENO);
+      internal_close(std_in_fd);
+    }
+    if (std_out_fd >= 0) {
+      internal_close(STDOUT_FILENO);
+      internal_dup2(std_out_fd, STDOUT_FILENO);
+      internal_close(std_out_fd);
+    }
+    if (std_err_fd >= 0) {
+      internal_close(STDERR_FILENO);
+      internal_dup2(std_err_fd, STDERR_FILENO);
+      internal_close(std_err_fd);
+    }
+
+    for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--)
+      internal_close(fd);
+
+    internal_execve(program, argv, nullptr);
+    internal__exit(1);
+  }
+
+  return pid;
+}
+
+bool IsProcessRunning(int pid) {
+  int process_status;
+  uptr waitpid_status = internal_waitpid(pid, &process_status, WNOHANG);
+  int local_errno;
+  if (internal_iserror(waitpid_status, &local_errno)) {
+    VReport(1, "Waiting on the process failed (errno %d).\n", local_errno);
+    return false;
+  }
+  return waitpid_status == 0;
+}
+
 } // namespace __sanitizer
 
 #endif // SANITIZER_FREEBSD || SANITIZER_LINUX

lib/sanitizer_common/sanitizer_mac.cc

void MaybeReexec() {
   if (new_env_pos == new_env + env_name_len + 1) new_env = NULL;
   LeakyResetEnv(kDyldInsertLibraries, new_env);
 }
 
 char **GetArgv() {
   return *_NSGetArgv();
 }
 
+int StartSubprocess(const char *program, char *const argv[],
+                    fd_t std_in_fd = kInvalidFd, fd_t std_out_fd = kInvalidFd,
+                    fd_t std_err_fd = kInvalidFd) {
+  // FIXME: implement on this platform.
+  return -1;
+}
+
+bool IsProcessRunning(int pid) {
+  // FIXME: implement on this platform.
+  return false;
+}
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_MAC

lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc

for (int i = 0; i < 5; i++) {
           }
           break;
         }
       }
     }
     CHECK(infd);
     CHECK(outfd);
 
-    // Real fork() may call user callbacks registered with pthread_atfork().
-    pid = internal_fork();
-    if (pid == -1) {
-      // Fork() failed.
+    const char *argv[kArgVMax];
+    GetArgV(path_, argv);
+    pid = StartSubprocess(path_, const_cast<char **>(&argv[0]),
+                          outfd[0] /* stdin */, infd[1] /* stdout */);
+    if (pid < 0) {
       internal_close(infd[0]);
-      internal_close(infd[1]);
       internal_close(outfd[0]);
-      internal_close(outfd[1]);
-      Report("WARNING: failed to fork external symbolizer "
-             " (errno: %d)\n", errno);
       return false;
-    } else if (pid == 0) {
-      // Child subprocess.
-      internal_close(STDOUT_FILENO);
-      internal_close(STDIN_FILENO);
-      internal_dup2(outfd[0], STDIN_FILENO);
-      internal_dup2(infd[1], STDOUT_FILENO);
-      internal_close(outfd[0]);
-      internal_close(outfd[1]);
-      internal_close(infd[0]);
-      internal_close(infd[1]);
-      for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--)
-        internal_close(fd);
-      const char *argv[kArgVMax];
-      GetArgV(path_, argv);
-      execv(path_, const_cast<char **>(&argv[0]));
-      internal__exit(1);
     }
 
-    // Continue execution in parent process.
-    internal_close(outfd[0]);
-    internal_close(infd[1]);
     input_fd_ = infd[0];
     output_fd_ = outfd[1];
   }
 
   // Check that symbolizer subprocess started successfully.
-  int pid_status;
   SleepForMillis(kSymbolizerStartupTimeMillis);
-  int exited_pid = waitpid(pid, &pid_status, WNOHANG);
-  if (exited_pid != 0) {
+  if (!IsProcessRunning(pid)) {
     // Either waitpid failed, or child has already exited.
     Report("WARNING: external symbolizer didn't start up correctly!\n");
     return false;
   }
 
   return true;
 }
 

lib/sanitizer_common/sanitizer_win.cc

void MaybeReexec() {
   // No need to re-exec on Windows.
 }
 
 char **GetArgv() {
   // FIXME: Actually implement this function.
   return 0;
 }
 
+int StartSubprocess(const char *program, char *const argv[],
+                    fd_t std_in_fd = kInvalidFd, fd_t std_out_fd = kInvalidFd,
+                    fd_t std_err_fd = kInvalidFd) {
+  // FIXME: implement on this platform.
+  return -1;
+}
+
+bool IsProcessRunning(int pid) {
+  // FIXME: implement on this platform.
+  return false;
+}
+
 }  // namespace __sanitizer
 
 #endif  // _WIN32