From 18efeb320b763e541a7dbf61a7da1cbe13ab2be9 Mon Sep 17 00:00:00 2001
From: Rich Felker <dalias@aerifal.cx>
Date: Mon, 16 Apr 2012 16:03:45 -0400
Subject: new scanf implementation and corresponding integer parser/converter

advantages over the old code:
- correct results for floating point (old code was bogus)
- wide/regular scanf separated so scanf does not pull in wide code
- well-defined behavior on integers that overflow dest type
- support for %[a-b] ranges with %[ (impl-defined by widely used)
- no intermediate conversion of fmt string to wide string
- cleaner, easier to share code with strto* functions
- better standards conformance for corner cases

the old code remains in the source tree, as the wide versions of the
scanf-family functions are still using it. it will be removed when no
longer needed.
---
 src/internal/intscan.c | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 src/internal/intscan.c

(limited to 'src/internal/intscan.c')

diff --git a/src/internal/intscan.c b/src/internal/intscan.c
new file mode 100644
index 00000000..a00f2ccc
--- /dev/null
+++ b/src/internal/intscan.c
@@ -0,0 +1,97 @@
+#include <limits.h>
+#include <errno.h>
+#include "shgetc.h"
+
+/* Lookup table for digit values. -1==255>=36 -> invalid */
+static const unsigned char table[] = { -1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,-1,-1,-1,-1,-1,-1,
+-1,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,
+25,26,27,28,29,30,31,32,33,34,35,-1,-1,-1,-1,-1,
+-1,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,
+25,26,27,28,29,30,31,32,33,34,35,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,
+};
+
+unsigned long long __intscan(FILE *f, unsigned base, int pok, unsigned long long lim)
+{
+	const unsigned char *val = table+1;
+	int c, neg=0;
+	unsigned x;
+	unsigned long long y;
+	if (base > 36) {
+		errno = EINVAL;
+		return 0;
+	}
+	c = shgetc(f);
+	if (c=='+' || c=='-') {
+		neg = -(c=='-');
+		c = shgetc(f);
+	}
+	if ((base == 0 || base == 16) && c=='0') {
+		c = shgetc(f);
+		if ((c|32)=='x') {
+			c = shgetc(f);
+			if (val[c]>=16) {
+				shunget(f);
+				if (pok) shunget(f);
+				else shlim(f, 0);
+				return 0;
+			}
+			base = 16;
+		} else if (base == 0) {
+			base = 8;
+		}
+	} else {
+		if (base == 0) base = 10;
+		if (val[c] >= base) {
+			shlim(f, 0);
+			errno = EINVAL;
+			return 0;
+		}
+	}
+	if (base == 10) {
+		for (x=0; c-'0'<10U && x<=UINT_MAX/10-1; c=shgetc(f))
+			x = x*10 + (c-'0');
+		for (y=x; c-'0'<10U && y<=ULLONG_MAX/10 && 10*y<=ULLONG_MAX-(c-'0'); c=shgetc(f))
+			y = y*10 + (c-'0');
+		if (c-'0'>=10U) goto done;
+	} else if (!(base & base-1)) {
+		int bs = "\0\1\2\4\7\3\6\5"[(0x17*base)>>5&7];
+		for (x=0; val[c]<base && x<=UINT_MAX/32; c=shgetc(f))
+			x = x<<bs | val[c];
+		for (y=x; val[c]<base && y<=ULLONG_MAX>>bs; c=shgetc(f))
+			y = y<<bs | val[c];
+	} else {
+		for (x=0; val[c]<base && x<=UINT_MAX/36-1; c=shgetc(f))
+			x = x*base + val[c];
+		for (y=x; val[c]<base && y<=ULLONG_MAX/base && base*y<=ULLONG_MAX-val[c]; c=shgetc(f))
+			y = y*base + val[c];
+	}
+	if (val[c]<base) {
+		for (; val[c]<base; c=shgetc(f));
+		errno = ERANGE;
+		y = lim;
+	}
+done:
+	shunget(f);
+	if (y>=lim) {
+		if (!(lim&1) && !neg) {
+			errno = ERANGE;
+			return lim-1;
+		} else if (y>lim) {
+			errno = ERANGE;
+			return lim;
+		}
+	}
+	return (y^neg)-neg;
+}
-- 
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