[sanitizers] extracted process management functions

Differential Revision: http://reviews.llvm.org/D16546

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@258849 91177308-0d34-0410-b5e6-96231b3b80d8

8 files changed, 148 insertions, 30 deletions

diff --git a/lib/sanitizer_common/sanitizer_common.cc b/lib/sanitizer_common/sanitizer_common.cc
index 3f2a6f4b2..ce91dc460 100644
--- a/lib/sanitizer_common/sanitizer_common.cc
+++ b/lib/sanitizer_common/sanitizer_common.cc
@@ -423,6 +423,10 @@ bool TemplateMatch(const char *templ, const char *str) {
 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;
diff --git a/lib/sanitizer_common/sanitizer_common.h b/lib/sanitizer_common/sanitizer_common.h
index 97f5cada7..c41dc9f09 100644
--- a/lib/sanitizer_common/sanitizer_common.h
+++ b/lib/sanitizer_common/sanitizer_common.h
@@ -279,6 +279,17 @@ 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 not kInvalidFd their corresponding input/output
+// streams will be redirect to the file. The files will always be closed
+// in parent process even in case of an error.
+// The child process will close all fds after STDERR_FILENO
+// before passing control to a program.
+pid_t StartSubprocess(const char *filename, const char *const argv[],
+                      fd_t stdin_fd = kInvalidFd, fd_t stdout_fd = kInvalidFd,
+                      fd_t stderr_fd = kInvalidFd);
+// Checks if specified process is still running
+bool IsProcessRunning(pid_t pid);
 
 u32 GetUid();
 void ReExec();
@@ -748,6 +759,23 @@ void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp);
 void DisableReexec();
 void MaybeReexec();
 
+template <typename Fn>
+class RunOnDestruction {
+ public:
+  explicit RunOnDestruction(Fn fn) : fn_(fn) {}
+  ~RunOnDestruction() { fn_(); }
+
+ private:
+  Fn fn_;
+};
+
+// A simple scope guard. Usage:
+// auto cleanup = at_scope_exit([]{ do_cleanup; });
+template <typename Fn>
+RunOnDestruction<Fn> at_scope_exit(Fn fn) {
+  return RunOnDestruction<Fn>(fn);
+}
+
 }  // namespace __sanitizer
 
 inline void *operator new(__sanitizer::operator_new_size_type size,
diff --git a/lib/sanitizer_common/sanitizer_internal_defs.h b/lib/sanitizer_common/sanitizer_internal_defs.h
index c78069b52..94808148f 100644
--- a/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -89,6 +89,7 @@ typedef unsigned error_t;
 typedef int fd_t;
 typedef int error_t;
 #endif
+typedef int pid_t;
 
 // WARNING: OFF_T may be different from OS type off_t, depending on the value of
 // _FILE_OFFSET_BITS. This definition of OFF_T matches the ABI of system calls
diff --git a/lib/sanitizer_common/sanitizer_posix.h b/lib/sanitizer_common/sanitizer_posix.h
index 3247b6944..ccd39166b 100644
--- a/lib/sanitizer_common/sanitizer_posix.h
+++ b/lib/sanitizer_common/sanitizer_posix.h
@@ -81,6 +81,8 @@ int my_pthread_attr_getstack(void *attr, void **addr, uptr *size);
 int internal_sigaction(int signum, const void *act, void *oldact);
 void internal_sigfillset(__sanitizer_sigset_t *set);
 
+uptr internal_execve(const char *filename, char *const argv[],
+                     char *const envp[]);
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_POSIX_H
diff --git a/lib/sanitizer_common/sanitizer_posix_libcdep.cc b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
index c158eedae..91330b555 100644
--- a/lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -34,6 +34,7 @@
 #include <sys/stat.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 #if SANITIZER_FREEBSD
@@ -320,6 +321,68 @@ void AdjustStackSize(void *attr_) {
 }
 #endif // !SANITIZER_GO
 
+pid_t StartSubprocess(const char *program, const char *const argv[],
+                      fd_t stdin_fd, fd_t stdout_fd, fd_t stderr_fd) {
+  auto file_closer = at_scope_exit([&] {
+    if (stdin_fd != kInvalidFd) {
+      internal_close(stdin_fd);
+    }
+    if (stdout_fd != kInvalidFd) {
+      internal_close(stdout_fd);
+    }
+    if (stderr_fd != kInvalidFd) {
+      internal_close(stderr_fd);
+    }
+  });
+
+  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 (stdin_fd != kInvalidFd) {
+      internal_close(STDIN_FILENO);
+      internal_dup2(stdin_fd, STDIN_FILENO);
+      internal_close(stdin_fd);
+    }
+    if (stdout_fd != kInvalidFd) {
+      internal_close(STDOUT_FILENO);
+      internal_dup2(stdout_fd, STDOUT_FILENO);
+      internal_close(stdout_fd);
+    }
+    if (stderr_fd != kInvalidFd) {
+      internal_close(STDERR_FILENO);
+      internal_dup2(stderr_fd, STDERR_FILENO);
+      internal_close(stderr_fd);
+    }
+
+    for (int fd = sysconf(_SC_OPEN_MAX); fd > 2; fd--) internal_close(fd);
+
+    internal_execve(program, const_cast<char **>(&argv[0]), nullptr);
+    internal__exit(1);
+  }
+
+  return pid;
+}
+
+bool IsProcessRunning(pid_t 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_POSIX
diff --git a/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc b/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
index fc8a7d91a..e84fef09f 100644
--- a/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
+++ b/lib/sanitizer_common/sanitizer_symbolizer_posix_libcdep.cc
@@ -137,47 +137,23 @@ bool SymbolizerProcess::StartSymbolizerSubprocess() {
     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_, argv, /* stdin */ outfd[0],
+                          /* stdout */ infd[1]);
+    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;
diff --git a/lib/sanitizer_common/sanitizer_win.cc b/lib/sanitizer_common/sanitizer_win.cc
index 0c1ee81ac..46bdca6e4 100644
--- a/lib/sanitizer_common/sanitizer_win.cc
+++ b/lib/sanitizer_common/sanitizer_win.cc
@@ -775,6 +775,20 @@ char **GetArgv() {
   return 0;
 }
 
+pid_t StartSubprocess(const char *program, const char *const argv[],
+                      fd_t stdin_fd, fd_t stdout_fd, fd_t stderr_fd) {
+  // FIXME: implement on this platform
+  // Should be implemented based on
+  // SymbolizerProcess::StarAtSymbolizerSubprocess
+  // from lib/sanitizer_common/sanitizer_symbolizer_win.cc.
+  return -1;
+}
+
+bool IsProcessRunning(pid_t pid) {
+  // FIXME: implement on this platform.
+  return false;
+}
+
 }  // namespace __sanitizer
 
 #endif  // _WIN32
diff --git a/lib/sanitizer_common/tests/sanitizer_linux_test.cc b/lib/sanitizer_common/tests/sanitizer_linux_test.cc
index eef71010a..92d495e10 100644
--- a/lib/sanitizer_common/tests/sanitizer_linux_test.cc
+++ b/lib/sanitizer_common/tests/sanitizer_linux_test.cc
@@ -263,6 +263,36 @@ TEST(SanitizerLinux, ThreadSelfTest) {
 }
 #endif
 
+TEST(SanitizerCommon, StartSubprocessTest) {
+  int pipe_fds[2];
+  ASSERT_EQ(0, pipe(pipe_fds));
+  const char *argv[] = {"/bin/sh", "-c", "echo -n 'hello'"};
+  int pid = StartSubprocess("/bin/sh", const_cast<char **>(&argv[0]),
+                            kInvalidFd /* stdin */, pipe_fds[1] /* stdout */);
+  ASSERT_GT(pid, 0);
+
+  // wait for process to finish.
+  while (IsProcessRunning(pid)) {
+  }
+  ASSERT_FALSE(IsProcessRunning(pid));
+
+  char buffer[256];
+  {
+    char *ptr = buffer;
+    uptr bytes_read;
+    while (ReadFromFile(pipe_fds[0], ptr, 256, &bytes_read)) {
+      if (!bytes_read) {
+        break;
+      }
+      ptr += bytes_read;
+    }
+    ASSERT_EQ(5, ptr - buffer);
+    *ptr = 0;
+  }
+  ASSERT_EQ(0, strcmp(buffer, "hello")) << "Buffer: " << buffer;
+  internal_close(pipe_fds[0]);
+}
+
 }  // namespace __sanitizer
 
 #endif  // SANITIZER_LINUX