From f6f5f31067cdee2d7003d8209361ac9e5b6975c5 Mon Sep 17 00:00:00 2001
From: Bent Bisballe Nyeng <deva@aasimon.org>
Date: Sun, 13 Jun 2021 12:42:52 +0200
Subject: Use vfork/exec instead of system for compiler invocation.

---
 cppbuild.cc    | 21 +++++++++++++--
 libcppbuild.cc |  6 ++---
 libcppbuild.h  |  4 +--
 task.cc        | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
 4 files changed, 98 insertions(+), 17 deletions(-)

diff --git a/cppbuild.cc b/cppbuild.cc
index 77ed1f3..ae6fd8d 100644
--- a/cppbuild.cc
+++ b/cppbuild.cc
@@ -138,10 +138,27 @@ BuildConfiguration configs()
 		},
 
 		// cxx flags
-		"-DUI_X11 -g -Wall -Werror -std=c++11 -Idrumgizmo/getoptpp -Idrumgizmo/ -Idrumgizmo/hugin -Idrumgizmo/plugingui/ -Idrumgizmo/src/ -Idrumgizmo/zita-resampler/libs -Idrumgizmo/pugixml/src",
+		{
+			"-DUI_X11",
+			"-g",
+			"-Wall",
+			"-Werror",
+			"-std=c++11",
+			"-Idrumgizmo/getoptpp",
+			"-Idrumgizmo/",
+			"-Idrumgizmo/hugin",
+			"-Idrumgizmo/plugingui/",
+			"-Idrumgizmo/src/",
+			"-Idrumgizmo/zita-resampler/libs",
+			"-Idrumgizmo/pugixml/src",
+		},
 
 		// c flags
-		"-g -Wall -Werror",
+		{
+			"-g",
+			"-Wall",
+			"-Werror",
+		},
 
 		// linker flags
 		"-lm -lX11 -lXext -pthread -lsndfile",
diff --git a/libcppbuild.cc b/libcppbuild.cc
index 82a70d1..2167173 100644
--- a/libcppbuild.cc
+++ b/libcppbuild.cc
@@ -23,7 +23,7 @@ int main(int argc, const char* argv[])
 	settings.builddir = "build/foo";
 
 	settings.parallel_processes =
-		std::max(1u, std::thread::hardware_concurrency() * 3);
+		std::max(1u, std::thread::hardware_concurrency() * 2 - 1);
 
 	std::filesystem::path builddir(settings.builddir);
 	std::filesystem::create_directories(builddir);
@@ -82,7 +82,7 @@ int main(int argc, const char* argv[])
 					           return task->run();
 				           }));
 			++task;
-			std::this_thread::sleep_for(10ms);
+			std::this_thread::sleep_for(2ms);
 		}
 
 		for(auto process = processes.begin();
@@ -100,7 +100,7 @@ int main(int argc, const char* argv[])
 			}
 		}
 
-		std::this_thread::sleep_for(10ms);
+		std::this_thread::sleep_for(2ms);
 	}
 
 	for(auto process = processes.begin();
diff --git a/libcppbuild.h b/libcppbuild.h
index e9599fc..e4a7801 100644
--- a/libcppbuild.h
+++ b/libcppbuild.h
@@ -7,8 +7,8 @@ struct BuildConfiguration
 {
 	std::string target;
 	std::vector<std::string> sources;
-	std::string cxxflags;
-	std::string cflags;
+	std::vector<std::string> cxxflags;
+	std::vector<std::string> cflags;
 	std::string ldflags;
 };
 
diff --git a/task.cc b/task.cc
index 29e18cb..030932e 100644
--- a/task.cc
+++ b/task.cc
@@ -2,6 +2,11 @@
 
 #include <iostream>
 #include <fstream>
+#include <unistd.h>
+#include <cstring>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <spawn.h>
 
 #include "libcppbuild.h"
 #include "settings.h"
@@ -143,6 +148,17 @@ bool Task::dirty()
 	return false;
 }
 
+int parent_waitpid(pid_t pid)
+{
+	int status;
+
+	if(waitpid(pid, &status, 0) != pid)
+	{
+		return 1;
+	}
+
+	return status;
+}
 int Task::run()
 {
 	if(!std::filesystem::exists(sourceFile))
@@ -151,24 +167,72 @@ int Task::run()
 		return 1;
 	}
 
-	std::string comp = "g++";
-	std::string flags = config.cxxflags;
+	std::string comp = "/usr/bin/g++";
+	auto flags = config.cxxflags;
 	if(std::string(sourceFile.extension()) == ".c")
 	{
-		comp = "gcc";
+		comp = "/usr/bin/gcc";
 		flags = config.cflags;
 	}
-	std::string cmd = comp +
-		" -MMD -c " + std::string(sourceFile) + " " +
-		flags + " " +
-		"-o " + std::string(targetFile);
+
+	char source[256];
+	strcpy(source, std::string(sourceFile).data());
+	char target[256];
+	strcpy(target, std::string(targetFile).data());
+	char pwd[256];
+	strcpy(pwd, std::string(std::filesystem::current_path()).data());
+	std::vector<const char*> argv;
+	//args.push_back("/bin/echo");
+	if(comp == "/usr/bin/gcc")
+	{
+		argv.push_back("/usr/bin/gcc");
+	}
+	else
+	{
+		argv.push_back("/usr/bin/g++");
+	}
+
+	argv.push_back("-MMD");
+	argv.push_back("-c");
+	argv.push_back(source);
+	argv.push_back("-o");
+	argv.push_back(target);
+
+	for(const auto& flag : flags)
+	{
+		argv.push_back(flag.data());
+	}
+
+	std::string cmd;
+	for(const auto& arg : argv)
+	{
+		if(arg == nullptr)
+		{
+			break;
+		}
+		if(!cmd.empty())
+		{
+			cmd += " ";
+		}
+		cmd += arg;
+	}
 	std::cout << cmd << "\n";
 
-	if(system(cmd.data()))
+#if 0
+	auto pid = vfork();
+	if(pid == 0)
 	{
-		return 1;
+		execv(comp.data(), (char**)argv.data());
 	}
-	return 0;
+#else
+	pid_t pid;
+	if(posix_spawn(&pid, comp.data(), nullptr, nullptr, (char**)argv.data(), nullptr))
+	{
+		return 1;//exit(1);
+	}
+#endif
+
+	return parent_waitpid(pid);
 }
 
 int Task::clean()
-- 
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