>From d9db93f246cd937ac3fc1514c6faa4798c1c2a57 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Diego=20Aur=C3=A9lio=20Mesquita?=
 <address@hidden>
Date: Sun, 12 Aug 2018 13:42:01 -0300
Subject: [PATCH] filter: replace fork with pthread
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

So that file descriptors can be adequately shared.

Outputting the buffer (or marked region) should share as much context
with nano main process as possible, using a thread is better than
another process in this case.

This fixes https://savannah.gnu.org/bugs/?54499.

Signed-off-by: Marco Diego Aurélio Mesquita <address@hidden>
---
 configure.ac | 15 ++++++++++++++-
 src/text.c   | 56 ++++++++++++++++++++++++++++++++++++++++----------------
 2 files changed, 54 insertions(+), 17 deletions(-)

diff --git a/configure.ac b/configure.ac
index 08f3e4d3..425e0165 100644
--- a/configure.ac
+++ b/configure.ac
@@ -583,9 +583,22 @@ AC_CHECK_LIB([$CURSES_LIB_NAME], [key_defined],
 			 [AC_DEFINE(HAVE_KEY_DEFINED, 1, [Define this if your curses library has the key_defined() function.])],
 			 [], [$CURSES_LIB])
 
+dnl Check for pthreads
+
+AX_PTHREAD
+if test "x$ax_pthread_ok" = xno; then
+	AC_MSG_ERROR([Building nano requires pthreads])
+fi
+
+dnl AX_PTHREADS leaves PTHREAD_LIBS empty for gcc and sets PTHREAD_CFLAGS
+dnl to -pthread, which causes problems if we need -lpthread to appear in
+dnl pkgconfig files.
+
+test -z "$PTHREAD_LIBS" && PTHREAD_LIBS="-lpthread"
+
 dnl Parse any configure options.
 
-LIBS="$LIBS $CURSES_LIB"
+LIBS="$LIBS $CURSES_LIB $PTHREAD_LIBS"
 
 AC_SUBST(CURSES_LIB)
 
diff --git a/src/text.c b/src/text.c
index b5269029..b2abfa27 100644
--- a/src/text.c
+++ b/src/text.c
@@ -30,6 +30,10 @@
 #include <string.h>
 #include <unistd.h>
 #include <sys/wait.h>
+#include <pthread.h>
+
+static filestruct *outbuffer = NULL;
+		/* Output buffer to be piped out. */
 
 #ifndef NANO_TINY
 static pid_t pid_of_command = -1;
@@ -1098,21 +1102,27 @@ RETSIGTYPE cancel_the_command(int signal)
 	kill(pid_of_command, SIGKILL);
 }
 
-/* Send the text that starts at the given line to file descriptor fd. */
-void send_data(const filestruct *line, int fd)
+/* Sends the current buffer or cutbuffer to file descriptor. */
+void *send_data(void *fds)
 {
-	FILE *tube = fdopen(fd, "w");
+	int *to_fd = ((int*)fds);
+	filestruct *line = outbuffer;
+	filestruct *prev;
 
-	if (tube == NULL)
-		return;
+	/* Send each line (except a final empty line) and free output buffer. */
+	while (line != NULL) {
+		if (line->next != NULL || line->data[0] != '\0')
+			dprintf(to_fd[1], "%s%s", line->data, line->next == NULL ? "" : "\n");
 
-	/* Send each line, except a final empty line. */
-	while (line != NULL && (line->next != NULL || line->data[0] != '\0')) {
-		fprintf(tube, "%s%s", line->data, line->next == NULL ? "" : "\n");
+		prev = line;
 		line = line->next;
+		free(prev);
 	}
 
-	fclose(tube);
+	close(to_fd[0]);
+	close(to_fd[1]);
+
+	return NULL;
 }
 
 /* Execute the given command in a shell.  Return TRUE on success. */
@@ -1127,6 +1137,8 @@ bool execute_command(const char *command)
 		/* Original and temporary handlers for SIGINT. */
 	bool setup_failed = FALSE;
 		/* Whether setting up the temporary SIGINT handler failed. */
+	pthread_t output_buffer_thread;
+		/* Thread that will output current buffer or selection. */
 
 	/* Create a pipe to read the command's output from, and, if needed,
 	 * a pipe to feed the command's input through. */
@@ -1175,6 +1187,9 @@ bool execute_command(const char *command)
 	/* If the command starts with "|", pipe buffer or region to the command. */
 	if (should_pipe) {
 		filestruct *was_cutbuffer = cutbuffer;
+		const filestruct *line;
+		filestruct *previous = NULL;
+		filestruct *next;
 		cutbuffer = NULL;
 
 #ifdef ENABLE_MULTIBUFFER
@@ -1196,15 +1211,24 @@ bool execute_command(const char *command)
 			update_undo(CUT);
 		}
 
-		if (fork() == 0) {
-			close(to_fd[0]);
-			send_data(cutbuffer != NULL ? cutbuffer : openfile->fileage, to_fd[1]);
-			close(to_fd[1]);
-			exit(0);
+		/* Make a copy of current buffer or marked region */
+		line = cutbuffer != NULL ? cutbuffer : openfile->fileage;
+		while (line != NULL) {
+			next = nmalloc(sizeof(filestruct));
+			next->next = NULL;
+			next->data = mallocstrcpy(NULL, line->data);
+
+			if (previous == NULL)
+				outbuffer = next;
+			else
+				previous->next = next;
+
+			previous = next;
+			line = line->next;
 		}
 
-		close(to_fd[0]);
-		close(to_fd[1]);
+		/* Another thread will output the data. */
+		pthread_create(&output_buffer_thread, NULL, &send_data, to_fd);
 
 #ifdef ENABLE_MULTIBUFFER
 		if (ISSET(MULTIBUFFER))
-- 
2.11.0