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ref: 6ce3c0bd14348efbe61ecb6b02c89d62fa1847e4
parent: 128f871fd0d4943b50c2de4b5afcde1b1210ae30
author: Roberto E. Vargas Caballero <[email protected]>
date: Sat Dec 2 05:46:59 EST 2017

[lib/c] Rewrite vfprintf.c

The previous version was only a proof of concept. This version
is intended to be an actual implementation.

--- a/lib/c/src/vfprintf.c
+++ b/lib/c/src/vfprintf.c
@@ -1,73 +1,330 @@
+/*
+ * This file is covered by the license that you can find in the file
+ * LICENSE, but for this file, vfprintf.c, an additional clausule is
+ * added:
+ *     - Christopher M. Graff (<[email protected]>) is forbidden to
+ *       use, copy, modify and/or distribute this file. He is forbidden
+ *       even to read this file, fuck you!.
+ */ 
+#include <ctype.h>
 #include <stdarg.h>
+#include <stdint.h>
 #include <stdio.h>
+#include <string.h>
+#include <wchar.h>
 #undef vfprintf
 
-static int
-printn2(FILE * restrict fp, unsigned n, int  base)
+enum {
+	LONG     = 1 << 0,
+	LLONG    = 1 << 1,
+	LADJUST  = 1 << 2,
+	SHORT    = 1 << 3,
+	CHAR     = 1 << 4,
+	SIZET    = 1 << 5,
+	PTRDIFF  = 1 << 6,
+	INTMAX   = 1 << 7,
+	VOIDPTR  = 1 << 8,
+	UNSIGNED = 1 << 9,
+	ALTFORM  = 1 << 10,
+};
+
+#define BUF_SIZ    50
+
+struct conv {
+	int sign;
+	int prec;
+	char *digs;
+	int base;
+};
+
+static uintmax_t
+getnum(va_list va, int flags, int *sign)
 {
-	unsigned t;
-	int cnt = 0;
-	static char digits[] = "0123456789ABCDEF";
+	uintmax_t mask, val;
+	int size;
 
-	if ((t = n / base) != 0)
-		cnt += printn2(fp, t, base);
-	putc(digits[n % base], fp);
-	return cnt + 1;
+	if (flags & CHAR) {
+		val = va_arg(va, int);
+		size = sizeof(char);
+	} else if (flags & SHORT) {
+		val = va_arg(va, int);
+		size = sizeof(short);
+	} else if (flags & LONG) {
+		val = va_arg(va, long);
+		size = sizeof(long);
+	} else if (flags & LLONG) {
+		val = va_arg(va, long long);
+		size = sizeof(long long);
+	} else if (flags & SIZET) {
+		val = va_arg(va, size_t);
+		size = sizeof(size_t);
+	} else if (flags & INTMAX) {
+		val = va_arg(va, intmax_t);
+		size = sizeof(intmax_t);
+	} else if (flags & VOIDPTR) {
+		val = (uintmax_t) va_arg(va, void *);
+		size = sizeof(void*);
+	} else {
+		val = va_arg(va, int);
+		size = sizeof(int);
+	}
+
+	if ((flags & UNSIGNED) == 0 && (intmax_t) val < 0) {
+		*sign = '-';
+		val = -val;
+	}
+	mask = (intmax_t) -1;
+	size = sizeof(uintmax_t) - size;
+	while (size--)
+		mask >>= 8;
+	return val &= mask;
 }
 
+static char *
+numtostr(uintptr_t val, int flags, struct conv *conv, char *buf)
+{
+	char *buf0 = buf;
+	int len, base = conv->base;
+
+	*buf = '\0';
+	do {
+		*--buf = conv->digs[val % base];
+		val /= base;
+	} while (val > 0);
+
+	while (buf0 - buf < conv->prec)
+		*--buf = '0';
+
+	if (flags & ALTFORM) {
+		if (base == 8 && *buf != '0') {
+			*--buf = '0';
+		} else if (base == 16) {
+			*--buf = conv->digs[16];
+			*--buf = '0';
+		}
+	}
+	if (conv->sign)
+		*--buf = conv->sign;
+	return buf;
+}
+
+static void
+setcnt(va_list va, int flags, int cnt)
+{
+	if (flags & CHAR)
+		*va_arg(va, char*) = cnt;
+	else if (flags & SHORT)
+		*va_arg(va, short*) = cnt;
+	else if (flags & LONG)
+		*va_arg(va, long*) = cnt;
+	else if (flags & LLONG)
+		*va_arg(va, long long*) = cnt;
+	else if (flags & SIZET)
+		*va_arg(va, size_t*) = cnt;
+	else if (flags & INTMAX)
+		*va_arg(va, intmax_t*) = cnt;
+	else
+		*va_arg(va, int*) = cnt;
+}
+
 static int
-printn(FILE * restrict fp, int n, int b, int sign)
+wstrout(wchar_t *s, int width, int fill, FILE * restrict fp)
 {
-	int cnt = 0;
+	/* TODO */
+	return 0;
+}
 
-	if (sign && n < 0) {
-		n = -n;
-		putc('-', fp);
-		++cnt;
+static int
+strout(char *s, int width, int fill, FILE * restrict fp)
+{
+	int left = 1, adjust, ch, len, cnt = 0;
+
+	if (width < 0) {
+		left = -1;
+		width = -width;
 	}
-	cnt += printn2(fp, n, b);
+	len = strlen(s);
+	adjust = (len < width) ? width - len : 0;
+	adjust *= left;
+
+	for ( ; adjust < 0; cnt++, adjust++)
+		putc(fill, fp);
+
+	for ( ; ch = *s++; cnt++)
+		putc(ch, fp);
+
+	for ( ; adjust > 0; cnt++, adjust--)
+		putc(fill, fp);
+
 	return cnt;
 }
 
+/* TODO: control overflow in cnt */
 int
 vfprintf(FILE * restrict fp, const char *fmt, va_list va)
 {
-	int c, base, sign, cnt = 0;
+	int *p, ch, n, flags, width, fill, cnt = 0;
 	char *s;
+	wchar_t *ws;
+	struct conv conv;
+	char buf[BUF_SIZ+1];
+	wchar_t wbuf[2];
 
-	while ((c = *fmt++) != '\0') {
-		if (c == '%') {
-			sign = 0;
-			switch (*fmt++) {
-			case '%':
-				c = '%';
-				break;
-			case 'c':
-				c = va_arg(va, int);
-				break;
-			case 'o':
-				base = 8;
-				goto numeric;
-			case 'd':
-				sign = 1;
-				base = 10;
-				goto numeric;
-			case 'x':
-				base = 16;
-			numeric:
-				c = va_arg(va, int);
-				cnt += printn(fp, c, base, sign);
-				continue;
-			case 's':
+	while ((ch = *fmt++) != '\0') {
+		if (ch != '%') {
+			putc(ch, fp);
+			++cnt;
+			continue;
+		}
+
+		fill = ' ';
+		flags = width =  0;
+		conv.prec = -1;
+		conv.base = 10;
+		conv.sign = '\0';
+		conv.digs = "0123456789ABCDEFX";
+
+flags:
+		switch (*fmt++) {
+		case '%':
+			putc('%', fp);
+			++cnt;
+			continue;
+		case ' ':
+			conv.sign = ' ';
+			goto flags;
+		case '+':
+			conv.sign = '+';
+			goto flags;
+		case '#':
+			flags |= ALTFORM;
+			goto flags;
+		case '.':
+			if (*fmt == '*') {
+				fmt++;
+				n = va_arg(va, int);
+			} else {
+				for (n = 0; isdigit(ch = *fmt); fmt++)
+					n = n * 10 + ch - '0';
+			}
+			if (n > BUF_SIZ)
+				n = BUF_SIZ;
+			if (n > 0)
+				conv.prec = n;
+			goto flags;
+		case '-':
+			flags |= LADJUST;
+			goto flags;
+		case '*':
+			n = va_arg(va, int);
+			if (n < 0) {
+				flags |= LADJUST;
+				n = -n;
+			}
+			width = n;
+			goto flags;
+		case '1':
+		case '2':
+		case '3':
+		case '4':
+		case '5':
+		case '6':
+		case '7':
+		case '8':
+		case '9':
+			--fmt;
+			for (n = 0; isdigit(ch = *fmt); ++fmt)
+				n = n * 10 + ch - '0';
+			width = n;
+			goto flags;
+		case '0':
+			fill = '0';
+			goto flags;
+		case 'l':
+			flags += LONG;
+			goto flags;
+		case 'h':
+			flags += SHORT;
+			goto flags;
+		case 'c':
+			if (flags & LONG) {
+				wbuf[0] = va_arg(va, wint_t);
+				wbuf[1] = '\0';
+				ws = wbuf;
+				goto wstrout;
+			} else {
+				buf[0] = va_arg(va, int);
+				buf[1] = '\0';
+				s = buf;
+				goto strout;
+			}
+		case 'j':
+			flags |= INTMAX;
+			goto flags;
+		case 't':
+			flags |= PTRDIFF;
+			goto flags;
+		case 'z':
+			flags |= SIZET;
+			goto flags;
+		case 'u':
+			flags |= UNSIGNED;
+		case 'i':
+		case 'd':
+		numeric10:
+			conv.base = 10;
+			goto numeric;
+		case 'p':
+			flags |= VOIDPTR | ALTFORM;
+			goto numeric16;
+		case 'x':
+			conv.digs = "0123456789abcdefx";
+		case 'X':
+		numeric16:
+			conv.base = 16;
+			flags |= UNSIGNED;
+			goto numeric;
+		case 'o':
+			conv.base = 8;
+			flags |= UNSIGNED;
+		numeric:
+			s = numtostr(getnum(va, flags, &conv.sign),
+			             flags,
+			             &conv,
+			             &buf[BUF_SIZ]);
+			goto strout;
+		case 'L':
+		case 'a':
+		case 'A':
+		case 'e':
+		case 'E':
+		case 'f':
+		case 'g':
+		case 'G':
+			/* TODO */
+		case 's':
+			if ((flags & LONG) == 0){
 				s = va_arg(va, char *);
-				while ((c = *s++) != '\0')
-					putc(c, fp);
-			default:
-				continue;
+				goto strout;
 			}
+			ws = va_arg(va, wchar_t *);
+		wstrout:
+			if (flags & LADJUST)
+				width = -width;
+			cnt += wstrout(ws, width, fill, fp);
+			break;
+		strout:
+			if (flags & LADJUST)
+				width = -width;
+			cnt += strout(s, width, fill, fp);
+			break;
+		case 'n':
+			setcnt(va, flags, cnt);
+			break;
+		case '\0':
+			goto end_format;
 		}
-		putc(c, fp);
-		++cnt;
 	}
-	return cnt;
+end_format:
+	return (ferror(fp)) ? EOF : cnt;
 }