1 files changed, 82 insertions, 0 deletions
diff --git a/command.cpp b/command.cpp
new file mode 100644
index 0000000..7d62163
--- /dev/null
+++ b/command.cpp
@@ -0,0 +1,82 @@
+#include <stdexcept>
+#include <cstring>
+#include <errno.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sys/wait.h>
+#include "command.h"
+
+
+std::pair<int, std::string> readCommand(const std::vector<std::string> &args) {
+	int pipefd[2];
+	if (pipe(pipefd) < 0) {
+		throw std::runtime_error("readCommand: pipe: " + std::string{strerror(errno)});
+	}
+
+	pid_t pid = fork();
+	if (pid < 0) {
+		throw std::runtime_error("readCommand: fork: " + std::string{strerror(errno)});
+	}
+
+	if (pid == 0) {
+		close(STDOUT_FILENO);
+		dup2(pipefd[1], STDOUT_FILENO);
+		close(pipefd[0]);
+		close(pipefd[1]);
+
+		std::vector<char*> argv(args.size() + 1);
+		for (size_t i = 0; i < args.size(); i++) {
+			argv[i] = new char[args[i].size() + 1];
+			memcpy(argv[i], args[i].data(), args[i].size() + 1);
+		}
+		argv[args.size()] = nullptr;
+
+		execvp(argv[0], argv.data());
+		perror("execvp");
+		exit(255);
+	}
+
+	close(pipefd[1]);
+
+	std::string output;
+	while (true) {
+		size_t base = output.size();
+		output.resize(base + 4096);
+		ssize_t nr = read(pipefd[0], output.data() + base, 4096);
+		if (nr < 0) {
+			if (errno == EINTR) {
+				output.resize(base);
+				continue;
+			}
+			kill(pid, SIGTERM);
+			throw std::runtime_error("readCommand: read: " + std::string{strerror(errno)});
+		}
+		output.resize(base + nr);
+		if (nr == 0) break;
+	}
+
+	while (true) {
+		int status;
+		pid_t wpid = waitpid(pid, &status, 0);
+		if (wpid < 0) {
+			if (errno == EINTR) continue;
+			kill(pid, SIGTERM);
+			throw std::runtime_error("readCommand: wait: " + std::string{strerror(errno)});
+		}
+		if (WIFEXITED(status)) {
+			return std::make_pair(WEXITSTATUS(status), output);
+		}
+	}
+}
+
+std::string runCommand(const std::vector<std::string> &args) {
+	auto result = readCommand(args);
+	if (result.first != 0) {
+		std::string cmdline;
+		for (const std::string &a : args) cmdline += " " + a;
+		throw std::runtime_error(
+			"Command exited with exit code " + std::to_string(result.first) + ":" + cmdline
+		);
+	}
+	return result.second;
+}