Remove possiblity of underflows from loop variables

src/workerd/api/encoding.c++

@@ -265,7 +265,7 @@ Encoding getEncodingForLabel(kj::StringPtr label) {
             c == 0x0d /* cr  */ ||
             c == 0x20 /* sp  */;
     };
-    auto start = 0;
+    size_t start = 0;
     auto end = label.size();
     while (start < end && isAsciiWhitespace(label[start])) { start++; }
     while (end > start && isAsciiWhitespace(label[end - 1])) { end--; }

src/workerd/api/form-data.c++

@@ -421,6 +421,12 @@ void FormData::forEach(
   auto localParams = KJ_ASSERT_NONNULL(JSG_THIS.tryGetHandle(isolate));
 
   auto context = isolate->GetCurrentContext();  // Needed later for Call().
+
+  // On each iteration of the for loop, a JavaScript callback is invokved. If a new
+  // item is appended to the URLSearchParams within that function, the loop must pick
+  // it up. Using the classic for (;;) syntax here allows for that. However, this does
+  // mean that it's possible for a user to trigger an infinite loop here if new items
+  // are added to the search params unconditionally on each iteration.
   for (int i = 0; i < this->data.size(); i++) {
     auto& [key, value] = this->data[i];
     static constexpr auto ARG_COUNT = 3;

src/workerd/api/node/buffer-string-search.h

@@ -169,10 +169,10 @@ class StringSearch : private StringSearchBase {
   static inline int CharOccurrence(int* bad_char_occurrence,
                                    Char char_code) {
     if (sizeof(Char) == 1) {
-      return bad_char_occurrence[static_cast<int>(char_code)];
+      return bad_char_occurrence[static_cast<uint>(char_code)];
     }
     // Both pattern and subject are UC16. Reduce character to equivalence class.
-    int equiv_class = char_code % kUC16AlphabetSize;
+    uint equiv_class = char_code % kUC16AlphabetSize;
     return bad_char_occurrence[equiv_class];
   }
 
@@ -532,7 +532,7 @@ void StringSearch<Char>::PopulateBoyerMooreHorspoolTable() {
   }
   for (size_t i = start; i < pattern_length - 1; i++) {
     Char c = pattern_[i];
-    int bucket = (sizeof(Char) == 1) ? c : c % AlphabetSize();
+    uint bucket = (sizeof(Char) == 1) ? c : c % AlphabetSize();
     bad_char_occurrence[bucket] = i;
   }
 }

src/workerd/api/node/buffer.c++

@@ -140,7 +140,7 @@ kj::Array<byte> decodeHexTruncated(kj::ArrayPtr<kj::byte> text, bool strict = fa
   }
   kj::Vector vec = kj::Vector<kj::byte>(text.size() / 2);
 
-  for (auto i = 0; i < text.size(); i += 2) {
+  for (size_t i = 0; i < text.size(); i += 2) {
     byte b = 0;
     KJ_IF_MAYBE(d1, tryFromHexDigit(text[i])) {
       b = *d1 << 4;

src/workerd/api/sockets.c++

@@ -22,7 +22,7 @@ bool isValidHost(kj::StringPtr host) {
     return false;
   }
 
-  for (int i = 0; i < host.size(); i++) {
+  for (auto i : kj::indices(host)) {
     switch (host[i]) {
       case '-':
       case '.':

src/workerd/api/url-standard.c++

@@ -366,7 +366,7 @@ void percentEncodeCodepoint(
       return;
     }
     auto len = codepointToUtf8(buf, codepoint);
-    for (auto n = 0; n < len; n++) {
+    for (size_t n = 0; n < len; n++) {
       builder.add('%');
       hexEncode(builder, buf[n]);
     }
@@ -401,7 +401,7 @@ jsg::UsvString percentDecode(jsg::UsvStringPtr input) {
   const auto appendAsUtf8 = [&result](auto codepoint) {
     kj::byte buf[4];
     auto len = codepointToUtf8(buf, codepoint);
-    for (auto n = 0; n < len; n++) {
+    for (size_t n = 0; n < len; n++) {
       result.add(buf[n]);
     }
   };
@@ -2052,7 +2052,7 @@ void URLSearchParams::forEach(
   // it up. Using the classic for (;;) syntax here allows for that. However, this does
   // mean that it's possible for a user to trigger an infinite loop here if new items
   // are added to the search params unconditionally on each iteration.
-  for (int i = 0; i < list.size(); i++) {
+  for (size_t i = 0; i < list.size(); i++) {
     auto& entry = list[i];
     v8::Local<v8::Value> args[3] = {
       jsg::v8Str(isolate, entry.value),

src/workerd/api/url.c++

@@ -596,8 +596,13 @@ void URLSearchParams::forEach(
   // from JavaScript, which means a Headers JS wrapper object must already exist.
   auto localParams = KJ_ASSERT_NONNULL(JSG_THIS.tryGetHandle(isolate));
 
+  // On each iteration of the for loop, a JavaScript callback is invokved. If a new
+  // item is appended to the this->url->query within that function, the loop must pick
+  // it up. Using the classic for (;;) syntax here allows for that. However, this does
+  // mean that it's possible for a user to trigger an infinite loop here if new items
+  // are added to the search params unconditionally on each iteration.
   auto context = isolate->GetCurrentContext();  // Needed later for Call().
-  for (int i = 0; i < this->url->query.size(); i++) {
+  for (size_t i = 0; i < this->url->query.size(); i++) {
     auto& [key, value] = this->url->query[i];
     static constexpr auto ARG_COUNT = 3;
     v8::Local<v8::Value> args[ARG_COUNT] = {

src/workerd/api/urlpattern.c++

@@ -1153,7 +1153,12 @@ jsg::UsvString generatePatternString(kj::ArrayPtr<Part> partList, const CompileO
     return false;
   };
 
-  for (auto n = 0; n < partList.size(); n++) {
+  // On each iteration of the for loop, a JavaScript callback is invokved. If a new
+  // item is appended to the partList within that function, the loop must pick
+  // it up. Using the classic for (;;) syntax here allows for that. However, this does
+  // mean that it's possible for a user to trigger an infinite loop here if new items
+  // are added to the search params unconditionally on each iteration.
+  for (size_t n = 0; n < partList.size(); n++) {
     auto& part = partList[n];
     Part* previousPart = nullptr;
     Part* nextPart = nullptr;
@@ -1481,7 +1486,7 @@ URLPattern::URLPatternInit parseConstructorString(
     }
   };
 
-  const auto getSafeToken = [&tokenList](auto index) -> Token& {
+  const auto getSafeToken = [&tokenList](size_t index) -> Token& {
     if (index < tokenList.size()) {
       return tokenList[index];
     }

src/workerd/api/util.c++

@@ -91,7 +91,7 @@ kj::Maybe<kj::ArrayPtr<const char>> readContentTypeParameter(kj::StringPtr conte
 
         if (leftover[valueStart] == '"') {
           // parameter value surrounded by quotes
-          auto pos = 0;
+          size_t pos = 0;
           auto valueStr = leftover.slice(valueStart + 1);
 
           while(pos < valueStr.size()) {

src/workerd/io/worker.c++

@@ -771,7 +771,7 @@ static void stopProfiling(v8::CpuProfiler& profiler,v8::Isolate* isolate,
   profile.setEndTime(cpuProfile->GetEndTime());
 
   auto nodes = profile.initNodes(allNodes.size());
-  for (int i=0; i < allNodes.size(); i++) {
+  for (auto i : kj::indices(allNodes)) {
     auto nodeBuilder = nodes[i];
     nodeBuilder.setId(allNodes[i]->GetNodeId());
 
@@ -798,7 +798,7 @@ static void stopProfiling(v8::CpuProfiler& profiler,v8::Isolate* isolate,
     allNodes[i]->GetLineTicks(lineBuffer, hitLineCount);
 
     auto positionTicks = nodeBuilder.initPositionTicks(hitLineCount);
-    for (int j=0; j < hitLineCount; j++) {
+    for (uint j=0; j < hitLineCount; j++) {
       auto positionTick = positionTicks[j];
       positionTick.setLine(lineBuffer[j].line);
       positionTick.setTicks(lineBuffer[j].hit_count);

src/workerd/jsg/rtti.h

@@ -536,7 +536,7 @@ struct MembersBuilder {
   Structure::Builder structure;
   capnp::List<Member>::Builder members;
   Builder<Configuration>& rtti;
-  int index = 0;
+  uint index = 0;
 
   MembersBuilder(Structure::Builder structure,
                  capnp::List<Member>::Builder members,

src/workerd/jsg/ser.c++

@@ -85,7 +85,7 @@ void Deserializer::init(
     deser.SetWireFormatVersion(*version);
   }
   KJ_IF_MAYBE(arrayBuffers, transferedArrayBuffers) {
-    for (auto n = 0; n < arrayBuffers->size(); n++) {
+    for (auto n : kj::indices(*arrayBuffers)) {
       deser.TransferArrayBuffer(n,
           v8::ArrayBuffer::New(isolate, kj::mv((*arrayBuffers)[n])));
     }