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Fix undefined behavior in StringView trimming and validate positive number parsing #471

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Fix undefined behavior in StringView trimming and validate positive number parsing #471

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11 changes: 8 additions & 3 deletions src/string_view.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@

#include <assert.h>
#include <ctype.h>
#include <limits.h>

#include "copy.inl"
#include "equals.inl"
Expand Down Expand Up @@ -101,9 +102,11 @@ char CpuFeatures_StringView_Back(const StringView view) {
}

StringView CpuFeatures_StringView_TrimWhitespace(StringView view) {
while (view.size && isspace(CpuFeatures_StringView_Front(view)))
while (view.size &&
isspace((unsigned char)CpuFeatures_StringView_Front(view)))
view = CpuFeatures_StringView_PopFront(view, 1);
while (view.size && isspace(CpuFeatures_StringView_Back(view)))
while (view.size &&
isspace((unsigned char)CpuFeatures_StringView_Back(view)))
view = CpuFeatures_StringView_PopBack(view, 1);
return view;
}
Expand All @@ -115,14 +118,16 @@ static int HexValue(const char c) {
return -1;
}

// Returns -1 if view contains non digits.
// Returns -1 if view contains non digits, is empty, or overflows.
static int ParsePositiveNumberWithBase(const StringView view, int base) {
if (view.size == 0) return -1;
int result = 0;
StringView remainder = view;
for (; remainder.size;
remainder = CpuFeatures_StringView_PopFront(remainder, 1)) {
const int value = HexValue(CpuFeatures_StringView_Front(remainder));
if (value < 0 || value >= base) return -1;
if (result > (INT_MAX - value) / base) return -1;
result = (result * base) + value;
}
return result;
Expand Down
18 changes: 18 additions & 0 deletions test/string_view_test.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -124,19 +124,37 @@ TEST(StringViewTest, CpuFeatures_StringView_TrimWhitespace) {
str("first middle last"));
EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("first middle last")),
str("first middle last"));
EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str("")), str(""));
EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str(" ")), str(""));
// Ensure non-ASCII characters (with high bit set) do not cause undefined behavior in isspace().
EXPECT_EQ(CpuFeatures_StringView_TrimWhitespace(str(" \xff abc \x80 ")),
str("\xff abc \x80"));
}

TEST(StringViewTest, CpuFeatures_StringView_ParsePositiveNumber) {
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("42")), 42);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0")), 0);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x0")), 0);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2a")), 42);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2A")), 42);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2A2a")), 10794);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x2a2A")), 10794);

EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0x ")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("0xG")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("-10")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("-0x2A")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("abc")), -1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(str("")), -1);

// Overflow handling
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(
str("999999999999999999999999999999")),
-1);
EXPECT_EQ(CpuFeatures_StringView_ParsePositiveNumber(
str("0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF")),
-1);
}

TEST(StringViewTest, CpuFeatures_StringView_CopyString) {
Expand Down