Allow mg to log its internal status to a file. At the moment it only

logs line information like front and back pointers in the linked list,
how many characters are used and where the cursor is placed in the
file.

With this diff logging is not switched on by default and has to
compiled into mg.  -DMGLOG has to be added to the Makefile:

CFLAGS+=-Wall -DREGEX -DMGLOG

And the comment character removed from:

#SRCS+=  log.c

ok bcallah@

5 files changed, 165 insertions, 3 deletions

diff --git a/usr.bin/mg/Makefile b/usr.bin/mg/Makefile
index 94ce340c452..daa9eae0498 100644
--- a/usr.bin/mg/Makefile
+++ b/usr.bin/mg/Makefile
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.33 2016/09/16 17:17:40 tedu Exp $
+# $OpenBSD: Makefile,v 1.34 2019/06/10 06:52:44 lum Exp $
 
 PROG=	mg
 
@@ -9,6 +9,7 @@ DPADD+=	${LIBCURSES} ${LIBUTIL}
 #
 #	REGEX		-- create regular expression functions.
 #	STARTUPFILE	-- look for and handle initialization file.
+#	MGLOG		-- debug mg internals to a log file.
 #
 CFLAGS+=-Wall -DREGEX
 
@@ -23,6 +24,11 @@ SRCS=	autoexec.c basic.c bell.c buffer.c cinfo.c dir.c display.c \
 #
 SRCS+=	cmode.c cscope.c dired.c grep.c tags.c
 
+#
+# -DMGLOG source file.
+#
+#SRCS+=	log.c
+
 afterinstall:
 	${INSTALL} -d -o root -g wheel ${DESTDIR}${DOCDIR}/mg
 	${INSTALL} ${INSTALL_COPY} -o ${DOCOWN} -g ${DOCGRP} -m ${DOCMODE} \
diff --git a/usr.bin/mg/kbd.c b/usr.bin/mg/kbd.c
index 1d7a1a2a39c..0e733e15712 100644
--- a/usr.bin/mg/kbd.c
+++ b/usr.bin/mg/kbd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kbd.c,v 1.30 2015/09/26 21:51:58 jasper Exp $	*/
+/*	$OpenBSD: kbd.c,v 1.31 2019/06/10 06:52:44 lum Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -15,6 +15,10 @@
 #include "key.h"
 #include "macro.h"
 
+#ifdef  MGLOG
+#include "log.h"
+#endif
+
 #define METABIT 0x80
 
 #define PROMPTL 80
@@ -152,6 +156,11 @@ doin(void)
 	    getkey(TRUE)), &curmap)) == NULL)
 		/* nothing */;
 
+#ifdef  MGLOG
+	if (!mglog(funct))
+		ewprintf("Problem with logging");
+#endif
+
 	if (macrodef && macrocount < MAXMACRO)
 		macro[macrocount++].m_funct = funct;
 
diff --git a/usr.bin/mg/log.c b/usr.bin/mg/log.c
new file mode 100644
index 00000000000..4a3fcc4fd76
--- /dev/null
+++ b/usr.bin/mg/log.c
@@ -0,0 +1,127 @@
+/*	$OpenBSD: log.c,v 1.1 2019/06/10 06:52:44 lum Exp $	*/
+
+/* 
+ * This file is in the public domain.
+ *
+ * Author: Mark Lumsden <mark@showcomplex.com>
+ *
+ */
+
+/*
+ * Record a history of an mg session for temporal debugging.
+ * Sometimes pressing a key will set the scene for a bug only visible 
+ * dozens of keystrokes later. gdb has its limitations in this scenario.
+ */
+
+#include <sys/queue.h>
+#include <sys/stat.h>
+#include <ctype.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "def.h"
+#include "log.h"
+#include "funmap.h"
+
+char	 	 mglogpath[20];
+
+int
+mglog(PF funct)
+{
+	struct line     *lp;
+	struct stat      sb;
+	char		*curline;
+	FILE            *fd;
+	int		 i;
+
+	i = 0;
+
+	if(stat(mglogpath, &sb))
+		return (FALSE);
+
+	fd = fopen(mglogpath, "a");
+	if (fprintf(fd, "%s\n", function_name(funct)) == -1) {
+		fclose(fd);
+		return (FALSE);
+	}
+	lp = bfirstlp(curbp);
+
+	for(;;) {
+		i++;
+		curline = " ";
+		if (i == curwp->w_dotline)
+			curline = ">";
+		if (fprintf(fd, "%s%p b^%p f.%p %d %d\t|%s\n", curline,
+		    lp, lp->l_bp, lp->l_fp,
+		    lp->l_size, lp->l_used, lp->l_text) == -1) {
+			fclose(fd);
+			return (FALSE);
+		}
+		lp = lforw(lp);
+		if (lp == curbp->b_headp) {
+			if (fprintf(fd, " %p b^%p f.%p [bhead]\n(EOB)\n",
+			    lp, lp->l_bp, lp->l_fp) == -1) {
+				fclose(fd);
+        	                return (FALSE);
+			}
+			if (fprintf(fd, "lines:raw%d buf%d wdot%d\n\n",
+			    i, curbp->b_lines, curwp->w_dotline)) {
+				fclose(fd);
+        	                return (FALSE);
+			}
+			break;
+		}
+	}
+	fclose(fd);
+
+	return (TRUE);
+}
+
+
+/*
+ * Make sure logging to log file can happen.
+ */
+int
+mgloginit(void)
+{
+	struct stat	 sb;
+	mode_t           dir_mode, f_mode, oumask;
+	char		*mglogdir, *mglogfile;
+	int     	 fd;
+
+	mglogdir = "./log/";
+	mglogfile = "mg.log";
+
+	oumask = umask(0);
+	f_mode = 0777& ~oumask;
+	dir_mode = f_mode | S_IWUSR | S_IXUSR;
+
+	if(stat(mglogdir, &sb)) {
+		if (mkdir(mglogdir, dir_mode) != 0)
+			return (FALSE);
+		if (chmod(mglogdir, f_mode) < 0)
+			return (FALSE);
+	}
+	if (strlcpy(mglogpath, mglogdir, sizeof(mglogpath)) >
+	    sizeof(mglogpath))
+		return (FALSE);
+	if (strlcat(mglogpath, mglogfile, sizeof(mglogpath)) >
+	    sizeof(mglogpath))
+		return (FALSE);
+
+	if(stat(mglogpath, &sb))
+		fd = open(mglogpath, O_RDWR | O_CREAT | O_TRUNC, 0644);
+	else
+		fd = open(mglogpath, O_RDWR | O_TRUNC, 0644);
+
+	if (fd == -1)
+		return (FALSE);
+
+	close(fd);	
+
+	return (TRUE);
+}
diff --git a/usr.bin/mg/log.h b/usr.bin/mg/log.h
new file mode 100644
index 00000000000..814b19b5531
--- /dev/null
+++ b/usr.bin/mg/log.h
@@ -0,0 +1,11 @@
+/*      $OpenBSD: log.h,v 1.1 2019/06/10 06:52:44 lum Exp $   */
+
+/* This file is in the public domain. */
+
+/*
+ * Specifically for mg logging functionality.
+ *
+ */
+
+int			 mglog(PF);
+int			 mgloginit(void);
diff --git a/usr.bin/mg/main.c b/usr.bin/mg/main.c
index b4cf96d426b..cbf5da60bb5 100644
--- a/usr.bin/mg/main.c
+++ b/usr.bin/mg/main.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: main.c,v 1.85 2018/12/13 14:59:16 lum Exp $	*/
+/*	$OpenBSD: main.c,v 1.86 2019/06/10 06:52:44 lum Exp $	*/
 
 /* This file is in the public domain. */
 
@@ -21,6 +21,10 @@
 #include "funmap.h"
 #include "macro.h"
 
+#ifdef  MGLOG
+#include "log.h"
+#endif
+
 int		 thisflag;			/* flags, this command	*/
 int		 lastflag;			/* flags, last command	*/
 int		 curgoal;			/* goal column		*/
@@ -87,6 +91,11 @@ main(int argc, char **argv)
 	maps_init();		/* Keymaps and modes.		*/
 	funmap_init();		/* Functions.			*/
 
+#ifdef  MGLOG
+	if (!mgloginit())
+		errx(1, "Unable to create logging environment.");
+#endif
+
 	/*
 	 * This is where we initialize standalone extensions that should
 	 * be loaded dynamically sometime in the future.