1 files changed, 77 insertions, 0 deletions
diff --git a/process.cpp b/process.cpp
index 41325c3..061737e 100644
--- a/process.cpp
+++ b/process.cpp
@@ -3,6 +3,8 @@
 #include <fcntl.h>
 #include <signal.h>
 #include <sys/wait.h>
+#include <sys/select.h>
+#include <sys/time.h>
 #include "process.h"
 #include "error.h"
 
@@ -189,6 +191,81 @@ optional<string> Process::readLine() {
 	}
 }
 
+optional<string> Process::readLineTimeout(size_t millis) {
+	if (pid == -1) {
+		cout << "-- readLineTimeout on pid==-1 --" << endl;
+		return nullopt;
+	}
+
+	size_t idx = readBuf.find('\n');
+	if (idx != string::npos) {
+		string res = readBuf.substr(0, idx);
+		readBuf = readBuf.substr(idx + 1);
+		return res;
+	}
+
+	struct timeval start;
+	gettimeofday(&start, nullptr);
+
+	struct timeval totaltime;
+	totaltime.tv_sec = millis / 1000;
+	totaltime.tv_usec = millis % 1000 * 1000;
+
+	struct timeval left = totaltime;
+
+	while (true) {
+		string s(1024, '\0');
+
+		ssize_t nr;
+
+		fd_set inset;
+		FD_ZERO(&inset);
+		FD_SET(outfd, &inset);
+		int ret = select(outfd + 1, &inset, nullptr, nullptr, &left);
+		if (ret < 0) {
+			if (errno == EINTR) goto continue_adjust_time_left;
+			perror("select");
+			return nullopt;
+		}
+
+		if (!FD_ISSET(outfd, &inset)) goto continue_adjust_time_left;
+
+		nr = read(outfd, &s[0], s.size());
+		if (nr < 0) {
+			if (errno == EINTR) goto continue_adjust_time_left;
+			perror("read");
+			return nullopt;
+		}
+		if (nr == 0) {  // EOF
+			cout << "-- eof in readLine --" << endl;
+			return nullopt;
+		}
+		s.resize(nr);
+
+		idx = s.find('\n');
+		if (idx != string::npos) {
+			string res = readBuf + s.substr(0, idx);
+			readBuf = s.substr(idx + 1);
+			return res;
+		}
+
+		readBuf += s;
+
+	continue_adjust_time_left:
+		struct timeval now, delta;
+		gettimeofday(&now, nullptr);
+		timersub(&now, &start, &delta);
+		timersub(&totaltime, &delta, &left);
+
+		struct timeval zero;
+		timerclear(&zero);
+		// Not greater, so less-equal; c.f. manpage
+		if (!timercmp(&left, &zero, >)) {
+			return nullopt;  // Exceeded timeout
+		}
+	}
+}
+
 int Process::terminate() {
 	// TODO: send only SIGTERM, then wait a little while, then send
 	// SIGKILL if necessary