more robust implementation

1 files changed, 82 insertions, 6 deletions

diff --git a/src/stdlib/_strtoi.h b/src/stdlib/_strtoi.h
index 7a2d5cdf..a46d6c0c 100644
--- a/src/stdlib/_strtoi.h
+++ b/src/stdlib/_strtoi.h
@@ -1,12 +1,56 @@
 	/* int iswide = (sizeof(*nptr) == sizeof(wchar_t)); */
-	(void)max;
+	void *start = (void*)nptr;
+	int sign = 0;
+	int overflow = 0;
+
+	/* skip leading whitespace */
+	while (isspace(*nptr)) {
+		nptr++;
+	}
+
+	/* get sign, if any */
+	if (*nptr == '+') {
+		sign = 1;
+		nptr++;
+	} else if (*nptr == '-') {
+		sign = -1;
+		nptr++;
+	}
+
+	/* fail if sign is negative but we are doing unsigned conversion */
+	if (min == 0 && sign == -1) {
+		if (endptr) {
+			*endptr = start;
+		}
+		return 0;
+	} else if (sign == 0) {
+		sign = 1;
+	}
 	
+	/* determine base */
 	if (base == 0) {
-		/* determine base from prefix */
+		if (nptr[0] == '0') {
+			if (nptr[1] == 'x' || nptr[1] == 'X') {
+				base = 16;
+			} else {
+				base = 8;
+			}
+		} else {
+			base = 10;
+		}
+	}
+
+	/* verify valid base */
+	if (base < 2 || base > 36) {
+		if (endptr) {
+			*endptr = start;
+		}
+		return 0;
 	}
 
-	if (min == 0) {
-		/* unsigned */
+	/* skip leading 0x if appropriate */
+	if (base == 16 && nptr[0] == '0' && (nptr[1] == 'x' || nptr[1] == 'X')) {
+		nptr += 2;
 	}
 
 	while (*nptr) {
@@ -30,14 +74,46 @@
 		case 'd': case 'D': n = 0xd; break;
 		case 'e': case 'E': n = 0xe; break;
 		case 'f': case 'F': n = 0xf; break;
+		case 'g': case 'G': n = 0x10; break;
+		case 'h': case 'H': n = 0x11; break;
+		case 'i': case 'I': n = 0x12; break;
+		case 'j': case 'J': n = 0x13; break;
+		case 'k': case 'K': n = 0x14; break;
+		case 'l': case 'L': n = 0x15; break;
+		case 'm': case 'M': n = 0x16; break;
+		case 'n': case 'N': n = 0x17; break;
+		case 'o': case 'O': n = 0x18; break;
+		case 'p': case 'P': n = 0x19; break;
+		case 'q': case 'Q': n = 0x1a; break;
+		case 'r': case 'R': n = 0x1b; break;
+		case 's': case 'S': n = 0x1c; break;
+		case 't': case 'T': n = 0x1d; break;
+		case 'u': case 'U': n = 0x1e; break;
+		case 'v': case 'V': n = 0x1f; break;
+		case 'w': case 'W': n = 0x20; break;
+		case 'x': case 'X': n = 0x21; break;
+		case 'y': case 'Y': n = 0x22; break;
+		case 'z': case 'Z': n = 0x23; break;
 		default: n = -1; break;
 		}
 
 		if (n >= base || n < 0) {
-			*endptr = (void*)nptr;
+			if (endptr) {
+				*endptr = (void*)nptr;
+			}
 			break;
 		}
 
-		ret = (ret * base) + n;
+		if (ret > max / base) {
+			overflow = 1;
+		} else {
+			ret = (ret * base) + n;
+		}
 		nptr++;
 	}
+
+	if (overflow) {
+		ret = (sign == 1) ? max : min;
+	} else {
+		ret *= sign;
+	}