From a8a699133e14507e360d93603f685878a9cec1fd Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Sat, 9 Nov 2019 06:28:55 +0100
Subject: [PATCH] Fix child-process communication (video monitor in particular)

103ef2ba08e5 introduced an API to write raw data (const void*)
to a child process, along with the previous API to
write (std::string const&)

VideoMonitor uses write_to_stdin("fixed text"), and g++
interprets this to use the (const void*) API instead
of the std::string, which breaks communication.
---
 libs/pbd/pbd/system_exec.h | 8 ++++++++
 libs/pbd/system_exec.cc    | 9 +++++++++
 2 files changed, 17 insertions(+)

diff --git a/libs/pbd/pbd/system_exec.h b/libs/pbd/pbd/system_exec.h
index 9247323786..1d7e631f54 100644
--- a/libs/pbd/pbd/system_exec.h
+++ b/libs/pbd/pbd/system_exec.h
@@ -180,6 +180,14 @@ class LIBPBD_API SystemExec
 		 */
 		size_t write_to_stdin (std::string const& d, size_t len=0);
 
+		/** write into child-program's STDIN
+		 * @param d text to write
+		 * @param len length of data to write, if it is 0 (zero), d.length() is
+		 * used to determine the number of bytes to transmit.
+		 * @return number of bytes written.
+		 */
+		size_t write_to_stdin (const char* d, size_t len=0);
+
 		/** write into child-program's STDIN
 		 * @param data data to write
 		 * @param bytes length of data to write
diff --git a/libs/pbd/system_exec.cc b/libs/pbd/system_exec.cc
index 7e24e8d1b3..56eba6959e 100644
--- a/libs/pbd/system_exec.cc
+++ b/libs/pbd/system_exec.cc
@@ -401,6 +401,15 @@ SystemExec::write_to_stdin (std::string const& d, size_t len)
 	return write_to_stdin ((const void*)data, len);
 }
 
+size_t
+SystemExec::write_to_stdin (const char* data, size_t len)
+{
+	if (len == 0) {
+		len = strlen (data);
+	}
+	return write_to_stdin ((const void*)data, len);
+}
+
 #ifdef PLATFORM_WINDOWS /* Windows Process */
 
 /* HELPER FUNCTIONS */