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Fix: Handle large reverse-search limits without integer overflow #347

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Merged
ashvardanian merged 1 commit into from
Oct 18, 2026
Merged

Fix: Handle large reverse-search limits without integer overflow #347

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5 changes: 3 additions & 2 deletions include/stringzilla/stringzilla.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2656,7 +2656,8 @@ class basic_string_slice {
* @return For an @b empty `other`, `min(until, size())`.
*/
size_type rfind(string_view other, size_type until) const noexcept(false) {
return until + other.size() < length_ ? substr(0, until + other.size()).rfind(other) : rfind(other);
return other.size() < length_ && until < length_ - other.size() ? substr(0, until + other.size()).rfind(other)
: rfind(other);
}

/**
Expand Down Expand Up @@ -2775,7 +2776,7 @@ class basic_string_slice {
* @param until The offset of the last character to be considered.
*/
size_type find_last_of(byteset set, size_type until) const noexcept {
auto len = sz_min_of_two(until + 1, length_);
auto len = until < length_ ? until + 1 : length_;
auto ptr = sz_rfind_byteset(start_, len, &set.raw());
return ptr ? ptr - start_ : npos;
}
Expand Down
9 changes: 0 additions & 9 deletions test/find.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -161,15 +161,6 @@ static void check_find_unit_( //
void test_find_unit() {
std::printf(" - testing search & comparison known-answer vectors...\n");

// Default views use a null pointer, which must not turn an empty match into npos.
for (sz::string_view empty : {sz::string_view(), sz::string_view("")}) {
verify(empty.find("") == 0);
verify(empty.rfind("") == 0);
verify(empty.rfind("", sz::string_view::npos) == 0);
verify(empty.contains(""));
verify(empty.find("a") == sz::string_view::npos);
}

char const *hello = "hello world";
sz_size_t const hello_length = (sz_size_t)std::strlen(hello); // 11 bytes

Expand Down
5 changes: 5 additions & 0 deletions test/string.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -835,6 +835,8 @@ void test_stl_reads_unit() {
verify(str("hello").rfind('l', 1) == str::npos);

// Substring search in normal and reverse directions.
verify(str().find("") == 0);
verify(str().rfind("") == 0);
verify(str("hello").find("ell") == 1);
verify(str("hello").find("ell", 1) == 1);
verify(str("hello").find("ell", 2) == str::npos);
Expand Down Expand Up @@ -938,6 +940,9 @@ void test_stl_reads_unit() {
}

// Boundary conditions.
auto const max_pos = std::numeric_limits<std::size_t>::max();
verify(str("hello").rfind("ell", max_pos) == 1);
verify(str("hello").find_last_of("le", max_pos) == 3);
verify(str("hello").find_first_of("ox", 4) == 4);
verify(str("hello").find_first_of("ox", 5) == str::npos);
verify(str("hello").find_last_of("ox", 4) == 4);
Expand Down
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