new restartable integer parsing framework.

this fixes a number of bugs in integer parsing due to lazy haphazard
wrapping, as well as some misinterpretations of the standard. the new
parser is able to work character-at-a-time or on whole strings, making
it easy to support the wide functions without unbounded space for
conversion. it will also be possible to update scanf to use the new
parser.

2 files changed, 116 insertions, 0 deletions

diff --git a/src/internal/intparse.c b/src/internal/intparse.c
new file mode 100644
index 00000000..21b07b74
--- /dev/null
+++ b/src/internal/intparse.c
@@ -0,0 +1,105 @@
+#include <stdint.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <errno.h>
+#include "intparse.h"
+
+/* Lookup table for digit values. -1==255>=36 -> invalid */
+static const unsigned char digits[] = {
+-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,
+};
+
+#define SLIM (UINT_MAX/36-1)
+#define LLIM (UINTMAX_MAX/36-1)
+
+int __intparse(struct intparse *v, const void *buf, size_t n)
+{
+	const unsigned char *s = buf;
+	int d, b = v->base;
+
+	v->cnt += n;
+	for (; n; n--, s++) switch (v->state) {
+	case 0:
+		v->state++;
+		if (*s=='+' || *s=='-') {
+			v->neg = *s=='-';
+			continue;
+		}
+	case 1:
+		v->state++;
+		if (*s=='0' && (!b || b==16)) continue;
+		if (!b) v->base = b = 10;
+		v->state++;
+		goto firstdigit;
+	case 2:
+		v->state++;
+		if ((!b || b==16) && (*s|32) == 'x') {
+			v->base = b = 16;
+			continue;
+		}
+		if (!b) v->base = b = 8;
+		goto seconddigit;
+	case 3:
+	firstdigit:
+		if (digits[*s] >= b) {
+			v->err = EINVAL;
+			return 0;
+		}
+	seconddigit:
+		v->state++;
+	case 4:
+		if (b==10) {
+			for (; n && *s-'0'<10U && v->small<=SLIM; n--, s++)
+				v->small = v->small * 10 + (*s-'0');
+		} else if ((b&-b) == b) {
+			int bs = "\0\1\2\4\7\3\6\5"[(0x17*b)>>5&7];
+			for (; n && (d=digits[*s])<b && v->small<=SLIM; n--, s++)
+				v->small = (v->small<<bs) + d;
+		} else {
+			for (; n && (d=digits[*s])<b && v->small<=SLIM; n--, s++)
+				v->small = v->small * b + d;
+		}
+		if (!n) return 1;
+		v->state++;
+		v->val = v->small;
+	case 5:
+		for (; n && (d=digits[*s])<b && v->val<=LLIM; n--, s++)
+			v->val = v->val * b + d;
+		if (!n) return 1;
+		if (d >= b) goto finished;
+		if (v->val < (UINTMAX_MAX-d)/b)
+			v->val = v->val * b + d;
+		else
+			v->err = ERANGE;
+		v->state++;
+		n--; s++;
+	case 6:
+		if (n && digits[*s]<b) {
+			v->err = ERANGE;
+			v->val = UINTMAX_MAX;
+
+			n--; s++;
+		}
+		for (; n && digits[*s]<b; n--, s++);
+		if (!n) return 1;
+	}
+	return 1;
+finished:
+	v->cnt -= n;
+	return 0;
+}
diff --git a/src/internal/intparse.h b/src/internal/intparse.h
new file mode 100644
index 00000000..78e800d1
--- /dev/null
+++ b/src/internal/intparse.h
@@ -0,0 +1,11 @@
+#include <stdint.h>
+#include <stddef.h>
+
+struct intparse {
+	uintmax_t val;
+	unsigned small;
+	size_t cnt;
+	char neg, base, state, err;
+};
+
+int __intparse(struct intparse *, const void *, size_t);