code: drawterm

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devcons: add #c/kmesg, redraw kmesg buffer after resize

when resizing the screen, the text contents where lost.
with the kmesg buffer, we can just re-render the text.

--- a/kern/dat.h

+++ b/kern/dat.h

@@ -350,8 +350,8 @@

 struct Proc

 {

-	uint		state;

-	uint		mach;

+	uint	state;

+	uint	mach;

 	ulong	pid;

 	ulong	parentpid;

@@ -358,7 +358,7 @@

 	Pgrp	*pgrp;		/* Process group for namespace */

 	Fgrp	*fgrp;		/* File descriptor group */

-	Rgrp *rgrp;

+	Rgrp	*rgrp;

 	Lock	rlock;		/* sync sleep/wakeup with postnote */

 	Rendez	*r;		/* rendezvous point slept on */

@@ -372,21 +372,21 @@

 	int	nerrlab;

 	Label	errlab[NERR];

-	char user[KNAMELEN];

+	char	user[KNAMELEN];

 	char	*syserrstr;	/* last error from a system call, errbuf0 or 1 */

 	char	*errstr;	/* reason we're unwinding the error stack, errbuf1 or 0 */

 	char	errbuf0[ERRMAX];

 	char	errbuf1[ERRMAX];

 	char	genbuf[128];	/* buffer used e.g. for last name element from namec */

-	char text[KNAMELEN];

+	char	text[KNAMELEN];

 	Chan	*slash;

 	Chan	*dot;

-	Proc		*qnext;

+	Proc	*qnext;

 	void	(*fn)(void*);

-	void *arg;

+	void	*arg;

 	char oproc[1024];	/* reserved for os */

@@ -469,6 +469,16 @@

 #define DEVDOTDOT -1

-extern Proc *_getproc(void);

-extern void _setproc(Proc*);

+extern Proc	*_getproc(void);

+extern void	_setproc(Proc*);

 #define	up	(_getproc())

+

+/*

+ * Log console output so it can be retrieved via /dev/kmesg.

+ * This is good for catching boot-time messages after the fact.

+ */

+struct {

+	Lock lk;

+	uint n;

+	char buf[16384];

+} kmesg;

--- a/kern/devcons.c

+++ b/kern/devcons.c

@@ -97,6 +97,35 @@

 	qnoblock(kbdq, 1);

 }

+static void

+kmesgputs(char *str, int n)

+{

+	uint nn, d;

+

+	ilock(&kmesg.lk);

+	/* take the tail of huge writes */

+	if(n > sizeof kmesg.buf){

+		d = n - sizeof kmesg.buf;

+		str += d;

+		n -= d;

+	}

+

+	/* slide the buffer down to make room */

+	nn = kmesg.n;

+	if(nn + n >= sizeof kmesg.buf){

+		d = nn + n - sizeof kmesg.buf;

+		if(d)

+			memmove(kmesg.buf, kmesg.buf+d, sizeof kmesg.buf-d);

+		nn -= d;

+	}

+

+	/* copy the data in */

+	memmove(kmesg.buf+nn, str, n);

+	nn += n;

+	kmesg.n = nn;

+	iunlock(&kmesg.lk);

+}

+

 /*

  *   Print a string on the console.  Convert \n to \r\n for serial

  *   line consoles.  Locking of the queues is left up to the screen

@@ -107,6 +136,11 @@

 putstrn0(char *str, int n, int usewrite)

 {

 	/*

+	 *  how many different output devices do we need?

+	 */

+	kmesgputs(str, n);

+

+	/*

 	 *  if someone is reading /dev/kprint,

 	 *  put the message there.

 	 *  if not and there's an attached bit mapped display,

@@ -298,6 +332,7 @@

 	Qconsctl,

 	Qcputime,

 	Qdrivers,

+	Qkmesg,

 	Qkprint,

 	Qhostdomain,

 	Qhostowner,

@@ -331,7 +366,8 @@

 	"drivers",	{Qdrivers},	0,		0444,

 	"hostdomain",	{Qhostdomain},	DOMLEN,		0664,

 	"hostowner",	{Qhostowner},	0,	0664,

-	"kprint",		{Qkprint, 0, QTEXCL},	0,	DMEXCL|0440,

+	"kmesg",	{Qkmesg},	0,		0440,

+	"kprint",	{Qkprint, 0, QTEXCL},	0,	DMEXCL|0440,

 	"null",		{Qnull},	0,		0666,

 	"osversion",	{Qosversion},	0,		0444,

 	"pgrpid",	{Qpgrpid},	NUMSIZE,	0444,

@@ -554,6 +590,22 @@

 	case Qcputime:

 		return 0;

+	case Qkmesg:

+		/*

+		 * This is unlocked to avoid tying up a process

+		 * that's writing to the buffer.  kmesg.n never 

+		 * gets smaller, so worst case the reader will

+		 * see a slurred buffer.

+		 */

+		if(off >= kmesg.n)

+			n = 0;

+		else{

+			if(off+n > kmesg.n)

+				n = kmesg.n - off;

+			memmove(buf, kmesg.buf+off, n);

+		}

+		return n;

+		

 	case Qkprint:

 		return qread(kprintoq, buf, n);

--- a/kern/term.c

+++ b/kern/term.c

@@ -8,29 +8,19 @@

 #include	<memdraw.h>

 #include	"screen.h"

-#define	MINX	8

-#define	Backgnd		0xFF	/* white */

+extern Memimage		*gscreen;

-		Memsubfont	*memdefont;

-		

-struct{

-	Point	pos;

-	int	bwid;

-}out;

+static Memsubfont	*memdefont;

+static Lock		screenlock;

+static Memimage		*conscol;

+static Memimage		*back;

+static Rectangle	flushr;

+static Rectangle	window;

+static Point		curpos;

+static int		h;

-Lock	screenlock;

+static void termscreenputs(char*, int);

-Memimage *conscol;

-Memimage *back;

-extern Memimage *gscreen;

-

-static Rectangle flushr;

-static Rectangle window;

-static Point curpos;

-static int h;

-static void	termscreenputs(char*, int);

-

-

 static void

 screenflush(void)

 {

@@ -84,6 +74,8 @@

 	window.max.y = window.min.y+((window.max.y-window.min.y)/h)*h;

 	flushmemscreen(gscreen->r);

 	qunlock(&drawlock);

+

+	termscreenputs(kmesg.buf, kmesg.n);

 }

 static struct {

@@ -137,9 +129,6 @@

 terminit(void)

 {

 	memdefont = getmemdefont();

-	out.pos.x = MINX;

-	out.pos.y = 0;

-	out.bwid = memdefont->info[' '].width;

 	screenwin();

 	screenputs = termscreenputs;

 	kproc("resize", resizeproc, nil);