Bazel client: depend less on <unistd.h>

We moved most of the functionality (e.g. _exit,
SetupStreams) into blaze_util_<platform> or
changed to alternative functions (fwrite + stderr
instead of write + STDERR_HANDLE).

This change brings us closer to compiling blaze.cc
with MSVC. We still have to move signal handlers
out of blaze.cc as well as code dealing with the
server PID.

See #2107

--
MOS_MIGRATED_REVID=140123945

src/main/cpp/blaze.cc

@@ -1098,7 +1098,7 @@ static void handler(int signum) {
         if (globals->server_pid != -1) {
           KillServerProcess(globals->server_pid);
         }
-        _exit(1);
+        blaze::ExitImmediately(1);
       }
       sigprintf("\n%s caught interrupt signal; shutting down.\n\n",
                 globals->options->product_name.c_str());
@@ -1321,19 +1321,6 @@ static void CheckEnvironment() {
   blaze::SetEnv("LC_CTYPE", "en_US.ISO-8859-1");
 }
 
-static void SetupStreams() {
-  // Line-buffer stderr, since we always flush at the end of a server
-  // message.  This saves lots of single-char calls to write(2).
-  // This doesn't work if any writes to stderr have already occurred!
-  setlinebuf(stderr);
-
-  // Ensure we have three open fds.  Otherwise we can end up with
-  // bizarre things like stdout going to the lock file, etc.
-  if (fcntl(STDIN_FILENO, F_GETFL) == -1) open("/dev/null", O_RDONLY);
-  if (fcntl(STDOUT_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
-  if (fcntl(STDERR_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
-}
-
 static void CheckBinaryPath(const string& argv0) {
   if (argv0[0] == '/') {
     globals->binary_path = argv0;
@@ -1360,7 +1347,7 @@ int Main(int argc, const char *argv[], OptionProcessor *option_processor,
   // Logging must be set first to assure no log statements are missed.
   blaze_util::SetLogHandler(std::move(log_handler));
   globals = new GlobalVariables(option_processor);
-  SetupStreams();
+  blaze::SetupStdStreams();
 
   // Must be done before command line parsing.
   ComputeWorkspace();
@@ -1640,18 +1627,19 @@ unsigned int GrpcBlazeServer::Communicate() {
     }
 
     bool pipe_broken_now = false;
-    if (response.standard_output().size() > 0) {
-      int result = write(STDOUT_FILENO, response.standard_output().c_str(),
-                         response.standard_output().size());
-      if (result < 0 && errno == EPIPE) {
+
+    if (!response.standard_output().empty()) {
+      size_t size = response.standard_output().size();
+      size_t r = fwrite(response.standard_output().c_str(), 1, size, stdout);
+      if (r < size && errno == EPIPE) {
         pipe_broken_now = true;
       }
     }
 
-    if (response.standard_error().size() > 0) {
-      int result = write(STDERR_FILENO, response.standard_error().c_str(),
-                         response.standard_error().size());
-      if (result < 0 && errno == EPIPE) {
+    if (!response.standard_error().empty()) {
+      size_t size = response.standard_error().size();
+      size_t r = fwrite(response.standard_error().c_str(), 1, size, stderr);
+      if (r < size && errno == EPIPE) {
         pipe_broken_now = true;
       }
     }

src/main/cpp/blaze_util.h

@@ -118,7 +118,7 @@ bool CheckJavaVersionIsAtLeast(const std::string &jvm_version,
 // Returns true iff arg is a valid command line argument for bazel.
 bool IsArg(const std::string& arg);
 
-// Converts a project identifier to string.
+// Returns the string representation of `value`.
 // Workaround for mingw where std::to_string is not implemented.
 // See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52015.
 template <typename T>

src/main/cpp/blaze_util_platform.h

@@ -19,6 +19,8 @@
 
 #include <string>
 
+#include "src/main/cpp/util/port.h"
+
 namespace blaze {
 
 std::string GetProcessIdAsString();
@@ -159,6 +161,13 @@ void SetEnv(const std::string& name, const std::string& value);
 
 void UnsetEnv(const std::string& name);
 
+// Terminate the process immediately.
+// This is a wrapper around POSIX's _exit(2).
+ATTRIBUTE_NORETURN void ExitImmediately(int exit_code);
+
+// Ensure we have open file descriptors for stdin/stdout/stderr.
+void SetupStdStreams();
+
 }  // namespace blaze
 
 #endif  // BAZEL_SRC_MAIN_CPP_BLAZE_UTIL_PLATFORM_H_

src/main/cpp/blaze_util_posix.cc

@@ -16,6 +16,7 @@
 #include <fcntl.h>
 #include <limits.h>  // PATH_MAX
 #include <signal.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -375,4 +376,25 @@ void UnsetEnv(const string& name) {
   unsetenv(name.c_str());
 }
 
+ATTRIBUTE_NORETURN void ExitImmediately(int exit_code) {
+  _exit(exit_code);
+}
+
+void SetupStdStreams() {
+  // Set non-buffered output mode for stderr/stdout. The server already
+  // line-buffers messages where it makes sense, so there's no need to do set
+  // line-buffering here. On the other hand the server sometimes sends binary
+  // output (when for example a query returns results as proto), in which case
+  // we must not perform line buffering on the client side. So turn off
+  // buffering here completely.
+  setvbuf(stdout, NULL, _IONBF, 0);
+  setvbuf(stderr, NULL, _IONBF, 0);
+
+  // Ensure we have three open fds.  Otherwise we can end up with
+  // bizarre things like stdout going to the lock file, etc.
+  if (fcntl(STDIN_FILENO, F_GETFL) == -1) open("/dev/null", O_RDONLY);
+  if (fcntl(STDOUT_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
+  if (fcntl(STDERR_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
+}
+
 }   // namespace blaze.

src/main/cpp/blaze_util_windows.cc

@@ -1070,6 +1070,37 @@ void UnsetEnv(const string& name) {
 #endif  // COMPILER_MSVC
 }
 
+ATTRIBUTE_NORETURN void ExitImmediately(int exit_code) {
+#ifdef COMPILER_MSVC
+  // TODO(bazel-team): implement this.
+  pdie(255, "blaze::ExitImmediately is not implemented on Windows");
+#else  // not COMPILER_MSVC
+  _exit(exit_code);
+#endif  // COMPILER_MSVC
+}
+
+void SetupStdStreams() {
+#ifdef COMPILER_MSVC
+  // TODO(bazel-team): implement this.
+  pdie(255, "blaze::SetupStdStreams is not implemented on Windows");
+#else  // not COMPILER_MSVC
+  // Set non-buffered output mode for stderr/stdout. The server already
+  // line-buffers messages where it makes sense, so there's no need to do set
+  // line-buffering here. On the other hand the server sometimes sends binary
+  // output (when for example a query returns results as proto), in which case
+  // we must not perform line buffering on the client side. So turn off
+  // buffering here completely.
+  setvbuf(stdout, NULL, _IONBF, 0);
+  setvbuf(stderr, NULL, _IONBF, 0);
+
+  // Ensure we have three open fds.  Otherwise we can end up with
+  // bizarre things like stdout going to the lock file, etc.
+  if (fcntl(STDIN_FILENO, F_GETFL) == -1) open("/dev/null", O_RDONLY);
+  if (fcntl(STDOUT_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
+  if (fcntl(STDERR_FILENO, F_GETFL) == -1) open("/dev/null", O_WRONLY);
+#endif  // COMPILER_MSVC
+}
+
 LARGE_INTEGER WindowsClock::GetFrequency() {
   LARGE_INTEGER result;
   if (!QueryPerformanceFrequency(&result)) {

src/main/cpp/workspace_layout.h

@@ -69,7 +69,7 @@ class WorkspaceLayout {
   static bool WorkspaceRelativizeRcFilePath(const std::string& workspace,
                                             std::string* path_fragment);
 
-  static constexpr char WorkspacePrefix[] = "%workspace%/";
+  static constexpr const char WorkspacePrefix[] = "%workspace%/";
   static const int WorkspacePrefixLength = sizeof WorkspacePrefix - 1;
 };