examples

commit 539e3e7517fc4138a64aeaa3caf90cc8818cd677
parent 96e8d55747cc8e0e1b0082464be2ca874567976b
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Wed, 17 Aug 2022 23:48:19 +0100

hush: Add pipelining

Diffstat:
M
src/hush.cpp
 | 
102
++++++++++++++++++++++++++++++++++++++++++++++++++++++++-----------------------

1 file changed, 72 insertions(+), 30 deletions(-)
diff --git a/src/hush.cpp b/src/hush.cpp
@@ -10,6 +10,16 @@
 
 using namespace std;
 
+struct fifo
+{
+	int read, write;
+
+	operator int*()
+	{
+		return &read;
+	}
+};
+
 void show_clear_warn(char const* msg)
 {
 	if (errno)
@@ -56,42 +66,74 @@ int main(int, char**)
 		if (!getline(cin, buf))
 			break;
 
-		istringstream is(buf);
-		vector<string> args;
-		while (getline(is, buf, ' '))
-			args.push_back(buf);
+		istringstream ip(buf);
+		vector<string> pipelines;
 
-		if (args.empty())
-		{
-			cout << '\n';
-			continue;
-		}
-		string arg0 = args.front();
-		std::vector<char*> argp;
-		for (auto& a : args)
-		{
-			a.push_back('\0');
-			argp.push_back(a.data());
-		}
+		while (getline(ip, buf, '|'))
+			pipelines.push_back(buf);
 
-		if (intrinsics.contains(arg0))
-		{
-			intrinsics[arg0](argp);
-			continue;
-		}
-		argp.push_back(nullptr);
+		fifo f;
 
-		if (fork())
-		{
-			int status;
-			wait(&status);
-			if (WEXITSTATUS(status))
-				std::cout << "\nResult: " << WEXITSTATUS(status) << '\n';
-		} else
+		for (unsigned i = 0; i < pipelines.size(); ++i)
 		{
+			int in;
+			bool make_pipe = i+1 < pipelines.size();
+			if (i)
+				in = f.read;
+
+			if (make_pipe)
+				pipe(f);
+
+			if (fork())
+			{
+				if (make_pipe)
+					close(f.write);
+				if (i)
+					close(in);
+
+				continue;
+			}
+
+			if (make_pipe)
+			{
+				dup2(f.write, STDOUT_FILENO);
+				close(f.write);
+			}
+
+			if (i)
+			{
+				dup2(in, STDIN_FILENO);
+				close(in);
+			}
+
+			istringstream is(pipelines[i]);
+			vector<string> args;
+			while (is.peek() == ' ')
+				is.get();
+			while (getline(is, buf, ' '))
+				args.push_back(buf);
+
+			if (args.empty())
+				err(1, "empty command?");
+
+
+			string arg0 = args.front();
+			std::vector<char*> argp;
+			for (auto& a : args)
+			{
+				a.push_back('\0');
+				argp.push_back(a.data());
+			}
+
+			if (intrinsics.contains(arg0))
+				exit(intrinsics[arg0](argp));
+
+			argp.push_back(nullptr);
 			execvp(argp[0], argp.data());
-			err(66, "execv");
+			err(66, argp[0]);
 		}
+		for (unsigned i = 0; i < pipelines.size(); ++i)
+			wait(NULL);
 	}
 
 	cout << "Done!\n";