Merge pull request #8705 from calewis/suppress_stdout

Utility to temporarily suppress stdout

Author: maliberty

src/rmp/src/annealing_strategy.cpp

@@ -33,6 +33,7 @@
 #include "sta/Search.hh"
 #include "utils.h"
 #include "utl/Logger.h"
+#include "utl/SuppressStdout.h"
 #include "utl/deleter.h"
 #include "utl/unique_name.h"
 
@@ -76,37 +77,6 @@ extern void Abc_NtkRedirectCiCo(Abc_Ntk_t* pNtk);
 namespace rmp {
 using utl::RMP;
 
-class SuppressStdout
-{
-#ifndef _WIN32
- public:
-  SuppressStdout(utl::Logger* logger)
-  {
-    // This is a hack to suppress excessive logs from ABC
-    // Redirects stdout to /dev/null, preserves original stdout
-    fflush(stdout);
-    saved_stdout_fd = dup(1);
-    const int dev_null_fd = open("/dev/null", O_WRONLY);
-    if (dev_null_fd < 0) {
-      logger->error(utl::RMP, 58, "Can't open /dev/null");
-    }
-    dup2(dev_null_fd, 1);
-    close(dev_null_fd);
-  }
-
-  ~SuppressStdout()
-  {
-    // Restore stdout
-    fflush(stdout);
-    dup2(saved_stdout_fd, 1);
-    close(saved_stdout_fd);
-  }
-
- private:
-  int saved_stdout_fd;
-#endif
-};
-
 static void replaceGia(abc::Gia_Man_t*& gia, abc::Gia_Man_t* new_gia)
 {
   if (gia == new_gia) {
@@ -224,7 +194,7 @@ void AnnealingStrategy::OptimizeDesign(sta::dbSta* sta,
            // &false
            debugPrint(
                logger, RMP, "annealing", 1, "Starting false path elimination");
-           SuppressStdout nostdout(logger);
+           utl::SuppressStdout nostdout(logger);
            replaceGia(gia, Gia_ManCheckFalse(gia, 0, 0, false, false));
          },
 
@@ -637,7 +607,7 @@ void AnnealingStrategy::RunGia(
     }
 
     {
-      SuppressStdout nostdout(logger);
+      utl::SuppressStdout nostdout(logger);
       current_network = WrapUnique(abc::Abc_NtkMap(current_network.get(),
                                                    nullptr,
                                                    /*DelayTarget=*/1.0,
@@ -661,7 +631,7 @@ void AnnealingStrategy::RunGia(
 
     if (resize_iters > 0) {
       // All the magic numbers are defaults from abc/src/base/abci/abc.c
-      SuppressStdout nostdout(logger);
+      utl::SuppressStdout nostdout(logger);
       abc::SC_SizePars pars = {};
       pars.nIters = resize_iters;
       pars.nIterNoChange = 50;

src/utl/BUILD

@@ -28,6 +28,7 @@ cc_library(
         "src/Metrics.cpp",
         "src/Progress.cpp",
         "src/ScopedTemporaryFile.cpp",
+        "src/SuppressStdout.cpp",
         "src/decode.cpp",
         "src/histogram.cpp",
         "src/mem_stats.cpp",
@@ -42,6 +43,7 @@ cc_library(
         "include/utl/Metrics.h",
         "include/utl/Progress.h",
         "include/utl/ScopedTemporaryFile.h",
+        "include/utl/SuppressStdout.h",
         "include/utl/algorithms.h",
         "include/utl/decode.h",
         "include/utl/deleter.h",

src/utl/CMakeLists.txt

@@ -41,6 +41,7 @@ add_library(utl_lib
   src/Metrics.cpp
   src/CFileUtils.cpp
   src/ScopedTemporaryFile.cpp
+  src/SuppressStdout.cpp
   src/Logger.cpp
   src/Progress.cpp
   src/CommandLineProgress.cpp

src/utl/include/utl/SuppressStdout.h

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2025, The OpenROAD Authors
+
+#pragma once
+
+#include "utl/Logger.h"
+
+namespace utl {
+
+// Redirects stdout to /dev/null while in scope
+class SuppressStdout
+{
+ public:
+  SuppressStdout(Logger* logger);
+  ~SuppressStdout();
+
+  // Don't copy or move
+  SuppressStdout(SuppressStdout const&) = delete;
+  SuppressStdout(SuppressStdout&&) = delete;
+  SuppressStdout& operator=(SuppressStdout const&) = delete;
+  SuppressStdout& operator=(SuppressStdout&&) = delete;
+
+ private:
+  int saved_fd_ = -1;
+  Logger* logger_ = nullptr;
+};
+
+}  // namespace utl

src/utl/src/SuppressStdout.cpp

@@ -0,0 +1,56 @@
+#include "utl/SuppressStdout.h"
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <cstdio>
+
+#include "utl/Logger.h"
+
+namespace utl {
+
+SuppressStdout::SuppressStdout(utl::Logger* logger) : logger_(logger)
+{
+  fflush(stdout);
+
+  saved_fd_ = dup(STDOUT_FILENO);
+  if (saved_fd_ < 0) {
+    logger_->error(UTL, 73, "Failed to dup STDOUT_FILENO");
+    return;
+  }
+
+  const int dev_null_fd = open("/dev/null", O_WRONLY);
+  if (dev_null_fd < 0) {
+    close(saved_fd_);
+    saved_fd_ = -1;
+    logger_->error(UTL, 74, "Failed to open /dev/null");
+    return;
+  }
+
+  if (dup2(dev_null_fd, STDOUT_FILENO) < 0) {
+    close(saved_fd_);
+    saved_fd_ = -1;
+    logger_->error(UTL, 75, "dup2 failed to redirect STDOUT_FILENO");
+  }
+
+  close(dev_null_fd);
+}
+
+SuppressStdout::~SuppressStdout()
+{
+  fflush(stdout);
+  if (saved_fd_ == -1) {
+    return;
+  }
+
+  if (dup2(saved_fd_, STDOUT_FILENO) < 0) {
+    logger_->error(UTL,
+                   76,
+                   "dup2 failed to restore stdout, all stdout is likely broken "
+                   "from this point forward.");
+  } else {
+    close(saved_fd_);
+  }
+}
+
+}  // namespace utl

src/utl/test/BUILD

@@ -98,3 +98,13 @@ cc_test(
         "@googletest//:gtest_main",
     ],
 )
+
+cc_test(
+    name = "TestSuppressStdout",
+    srcs = ["cpp/TestSuppressStdout.cpp"],
+    deps = [
+        "//src/utl",
+        "@googletest//:gtest",
+        "@googletest//:gtest_main",
+    ],
+)

src/utl/test/cpp/CMakeLists.txt

@@ -31,3 +31,15 @@ gtest_discover_tests(TestMetrics
 add_dependencies(build_and_test
   TestMetrics
 )
+
+add_executable(TestSuppressStdout TestSuppressStdout.cpp)
+
+target_link_libraries(TestSuppressStdout ${TEST_LIBS})
+
+gtest_discover_tests(TestSuppressStdout
+  WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR}
+)
+
+add_dependencies(build_and_test
+  TestSuppressStdout
+)

src/utl/test/cpp/TestSuppressStdout.cpp

@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: BSD-3-Clause
+// Copyright (c) 2024, The OpenROAD Authors
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <cstdio>
+#include <fstream>
+#include <string>
+
+#include "gtest/gtest.h"
+#include "utl/Logger.h"
+#include "utl/SuppressStdout.h"
+
+namespace utl {
+
+TEST(Utl, SuppressStdout)
+{
+  Logger logger;
+
+  // 1. Create a temporary directory managed by GTest
+  auto temp_dir = testing::TempDir();
+  std::string file_path = temp_dir + "/my_file.txt";
+
+  // 3. Create the file and get the file descriptor (fd)
+  int fd = open(file_path.c_str(), O_WRONLY | O_CREAT, 0600);
+  ASSERT_NE(fd, -1);
+
+  int saved_stdout = dup(STDOUT_FILENO);
+  ASSERT_NE(saved_stdout, -1);
+
+  ASSERT_NE(dup2(fd, STDOUT_FILENO), -1);
+
+  fprintf(stdout, "Before suppression\n");
+  {
+    SuppressStdout so(&logger);
+    fprintf(stdout, "During suppression\n");
+  }
+
+  fprintf(stdout, "After suppression\n");
+  fflush(stdout);
+
+  close(fd);
+  dup2(saved_stdout, STDOUT_FILENO);
+  close(saved_stdout);
+
+  std::ifstream log_file(file_path);
+  std::string line;
+
+  bool before_found = false;
+  bool during_found = false;
+  bool after_found = false;
+
+  while (std::getline(log_file, line)) {
+    if (line == "Before suppression") {
+      before_found = true;
+    } else if (line == "During suppression") {
+      during_found = true;
+    } else if (line == "After suppression") {
+      after_found = true;
+    }
+  }
+
+  EXPECT_TRUE(before_found);
+  EXPECT_FALSE(during_found);
+  EXPECT_TRUE(after_found);
+}
+
+}  // namespace utl