add posix %z flag.  (also add zero left padding)

Reference: /n/atom/patch/applied/zfmt
Date: Wed Sep  9 07:24:40 CES 2015
Signed-off-by: quanstro@quanstro.net

--- /sys/src/libc/fmt/dofmt.c	Wed Sep  9 07:23:59 2015
+++ /sys/src/libc/fmt/dofmt.c	Wed Sep  9 07:24:00 2015
@@ -87,13 +87,14 @@
 int
 _fmtpad(Fmt *f, int n)
 {
-	char *t, *s;
+	char *t, *s, c;
 	int i;
 
 	t = f->to;
 	s = f->stop;
+	c = f->flags&FmtZero? '0': ' ';
 	for(i = 0; i < n; i++)
-		FMTCHAR(f, t, s, ' ');
+		FMTCHAR(f, t, s, c);
 	f->nfmt += t - (char *)f->to;
 	f->to = t;
 	return 0;
@@ -102,13 +103,14 @@
 int
 _rfmtpad(Fmt *f, int n)
 {
-	Rune *t, *s;
+	Rune *t, *s, r;
 	int i;
 
 	t = f->to;
 	s = f->stop;
+	r = f->flags&FmtZero? '0': ' ';
 	for(i = 0; i < n; i++)
-		FMTRCHAR(f, t, s, ' ');
+		FMTRCHAR(f, t, s, r);
 	f->nfmt += t - (Rune *)f->to;
 	f->to = t;
 	return 0;
@@ -314,10 +316,11 @@
 int
 _ifmt(Fmt *f)
 {
-	char buf[Maxintwidth + 1], *p, *conv;
+	char buf[Maxintwidth], *p, *conv;
 	uvlong vu;
 	ulong u;
 	uintptr pu;
+	usize uu;
 	int neg, base, i, n, fl, w, isv;
 
 	neg = 0;
@@ -340,6 +343,14 @@
 			vu = va_arg(f->args, uvlong);
 		else
 			vu = va_arg(f->args, vlong);
+	}else if(fl & FmtUsize){
+		uu = va_arg(f->args, usize);
+		if(sizeof(usize) == sizeof(uvlong)){
+			vu = uu;
+			isv = 1;
+		}else
+			u = uu;
+		fl |= FmtUnsigned;
 	}else if(fl & FmtLong){
 		if(fl & FmtUnsigned)
 			u = va_arg(f->args, ulong);
@@ -518,6 +529,9 @@
 		if(f->flags & FmtLong)
 			f->flags |= FmtVLong;
 		f->flags |= FmtLong;
+		break;
+	case 'z':
+		f->flags |= FmtUsize;
 		break;
 	}
 	return 1;
--- /sys/include/libc.h	Wed Sep  9 07:24:03 2015
+++ /sys/include/libc.h	Wed Sep  9 07:24:04 2015
@@ -145,8 +145,10 @@
 	FmtVLong	= FmtLong << 1,
 	FmtComma	= FmtVLong << 1,
 	FmtByte		= FmtComma << 1,
+	FmtUsize	= FmtByte << 1,
+	FmtPtrdiff	= FmtUsize << 1,
 
-	FmtFlag		= FmtByte << 1
+	FmtFlag		= FmtPtrdiff << 1
 };
 
 extern	int	print(char*, ...);
@@ -195,6 +197,10 @@
 #pragma	varargck	type	"llo"	uvlong
 #pragma	varargck	type	"llx"	uvlong
 #pragma	varargck	type	"llb"	uvlong
+#pragma	varargck	type	"zd"	usize
+#pragma	varargck	type	"zo"	usize
+#pragma	varargck	type	"zx"	usize
+#pragma	varargck	type	"zb"	usize
 #pragma	varargck	type	"ld"	long
 #pragma	varargck	type	"lo"	long
 #pragma	varargck	type	"lx"	long
--- /sys/src/9/port/lib.h	Wed Sep  9 07:24:06 2015
+++ /sys/src/9/port/lib.h	Wed Sep  9 07:24:07 2015
@@ -88,8 +88,10 @@
 	FmtVLong	= FmtLong<<1,
 	FmtComma	= FmtVLong<<1,
 	FmtByte		= FmtComma<<1,
+	FmtUsize	= FmtByte << 1,
+	FmtPtrdiff	= FmtUsize << 1,
 
-	FmtFlag		= FmtByte<<1
+	FmtFlag		= FmtPtrdiff << 1
 };
 extern	int	print(char*, ...);
 extern	char*	seprint(char*, char*, char*, ...);
@@ -111,7 +113,10 @@
 #pragma	varargck	type	"llb"	uvlong
 #pragma	varargck	type	"lld"	uvlong
 #pragma	varargck	type	"llx"	uvlong
-#pragma	varargck	type	"lx"	void*
+#pragma	varargck	type	"zd"	usize
+#pragma	varargck	type	"zo"	usize
+#pragma	varargck	type	"zx"	usize
+#pragma	varargck	type	"zb"	usize
 #pragma	varargck	type	"lb"	long
 #pragma	varargck	type	"ld"	long
 #pragma	varargck	type	"lx"	long
--- /sys/src/nix/port/lib.h	Wed Sep  9 07:24:09 2015
+++ /sys/src/nix/port/lib.h	Wed Sep  9 07:24:11 2015
@@ -98,9 +98,11 @@
 	FmtLong		= FmtShort<<1,
 	FmtVLong	= FmtLong<<1,
 	FmtComma	= FmtVLong<<1,
-	FmtByte		= FmtComma<<1,
+	FmtByte		= FmtComma << 1,
+	FmtUsize	= FmtByte << 1,
+	FmtPtrdiff	= FmtUsize << 1,
 
-	FmtFlag		= FmtByte<<1
+	FmtFlag		= FmtPtrdiff << 1
 };
 
 extern	int	print(char*, ...);
@@ -121,6 +123,10 @@
 #pragma	varargck	type	"lld"	uvlong
 #pragma	varargck	type	"llx"	uvlong
 #pragma	varargck	type	"llb"	uvlong
+#pragma	varargck	type	"zd"	usize
+#pragma	varargck	type	"zo"	usize
+#pragma	varargck	type	"zx"	usize
+#pragma	varargck	type	"zb"	usize
 #pragma	varargck	type	"ld"	long
 #pragma	varargck	type	"lx"	long
 #pragma	varargck	type	"lb"	long
@@ -154,6 +160,7 @@
 #pragma	varargck	flag	','
 #pragma	varargck	flag	' '
 #pragma	varargck	flag	'h'
+#pragma	varargck	flag	'z'
 
 extern	int	fmtinstall(int, int (*)(Fmt*));
 extern	int	fmtprint(Fmt*, char*, ...);
--- /sys/src/fs/port/lib.h	Wed Sep  9 07:24:12 2015
+++ /sys/src/fs/port/lib.h	Wed Sep  9 07:24:13 2015
@@ -65,8 +65,10 @@
 	FmtVLong	= FmtLong << 1,
 	FmtComma	= FmtVLong << 1,
 	FmtByte		= FmtComma << 1,
+	FmtUsize	= FmtByte << 1,
+	FmtPtrdiff	= FmtUsize << 1,
 
-	FmtFlag		= FmtByte << 1
+	FmtFlag		= FmtPtrdiff << 1
 };
 
 typedef struct Fmt	Fmt;
@@ -107,6 +109,10 @@
 #pragma	varargck	type	"llx"	vlong
 #pragma	varargck	type	"lld"	uvlong
 #pragma	varargck	type	"llx"	uvlong
+#pragma	varargck	type	"zd"	usize
+#pragma	varargck	type	"zo"	usize
+#pragma	varargck	type	"zx"	usize
+#pragma	varargck	type	"zb"	usize
 #pragma	varargck	type	"ld"	long
 #pragma	varargck	type	"lx"	long
 #pragma	varargck	type	"ld"	ulong