1 files changed, 138 insertions, 0 deletions
diff --git a/libadhocutil/processPipes.cpp b/libadhocutil/processPipes.cpp
new file mode 100644
index 0000000..55050ae
--- /dev/null
+++ b/libadhocutil/processPipes.cpp
@@ -0,0 +1,138 @@
+#include "processPipes.h"
+#include <unistd.h>
+#include <poll.h>
+#include <string.h>
+#include <sys/resource.h>
+#include <stdexcept>
+
+ProcessPipes::ProcessPipes(const std::vector<std::string> & args, bool i, bool o, bool e) :
+	in(-1),
+	out(-1),
+	error(-1)
+{
+	int ipipes[2], opipes[2], epipes[2];
+	if (i) {
+		if (pipe(ipipes)) {
+			throw std::runtime_error("Failed to create stdin pipe");
+		}
+	}
+	if (o) {
+		if (pipe(opipes)) {
+			if (i) {
+				close(ipipes[0]);
+				close(ipipes[1]);
+			}
+			throw std::runtime_error("Failed to create stdout pipe");
+		}
+	}
+	if (e) {
+		if (pipe(epipes)) {
+			if (i) {
+				close(ipipes[0]);
+				close(ipipes[1]);
+			}
+			if (o) {
+				close(opipes[0]);
+				close(opipes[1]);
+			}
+			throw std::runtime_error("Failed to create stderr pipe");
+		}
+	}
+	switch (child = fork()) {
+		case -1: // fail
+			if (i) {
+				close(ipipes[0]);
+				close(ipipes[1]);
+			}
+			if (o) {
+				close(opipes[0]);
+				close(opipes[1]);
+			}
+			if (e) {
+				close(epipes[0]);
+				close(epipes[1]);
+			}
+			throw std::runtime_error("Failed to fork");
+		default: // parent
+			if (i) {
+				close(ipipes[0]);
+				in = ipipes[1];
+			}
+			if (o) {
+				close(opipes[1]);
+				out = opipes[0];
+			}
+			if (e) {
+				close(epipes[1]);
+				error = epipes[0];
+			}
+			break;
+		case 0: // in child
+			rlimit lim;
+			getrlimit(RLIMIT_NOFILE, &lim);
+			if (i) {
+				close(ipipes[1]);
+				dup2(ipipes[0], 0);
+			}
+			if (o) {
+				close(opipes[0]);
+				dup2(opipes[1], 1);
+			}
+			if (e) {
+				close(epipes[0]);
+				dup2(epipes[1], 2);
+			}
+			std::vector<struct pollfd> fds;
+			fds.reserve(lim.rlim_max);
+			for (int n = 3; n < (int)lim.rlim_max; n += 1) {
+				fds.push_back({n, 0, 0});
+			}
+			poll(&fds.front(), fds.size(), 0);
+			for(const auto & pfd : fds) {
+				if (!(pfd.revents & POLLNVAL)) {
+					close(pfd.fd);
+				}
+			}
+			char * buf[100];
+			char ** w = &buf[0];
+			for (const auto & p : args) {
+				*w++ = strdup(p.c_str());
+			}
+			*w = NULL;
+			execv(buf[0], buf);
+			abort();
+			break;
+	}
+}
+
+ProcessPipes::~ProcessPipes()
+{
+	if (in) close(in);
+	if (out) close(out);
+	if (error) close(error);
+}
+
+int
+ProcessPipes::fdIn() const
+{
+	return in;
+}
+
+int
+ProcessPipes::fdOut() const
+{
+	return out;
+}
+
+int
+ProcessPipes::fdError() const
+{
+	return error;
+}
+
+pid_t
+ProcessPipes::pid() const
+{
+	return child;
+}
+