[llvm] Create a CharSetConverter class with both iconv and icu support (PR #74516)
Hubert Tong via llvm-commits
llvm-commits at lists.llvm.org
Thu Apr 18 14:19:33 PDT 2024
================
@@ -0,0 +1,318 @@
+//===-- CharSet.cpp - Characters sets conversion class ------------*- C++ -*-=//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file provides utility classes to convert between different character
+/// set encoding.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/CharSet.h"
+#include "llvm/ADT/SmallString.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/Support/ConvertEBCDIC.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <limits>
+#include <system_error>
+
+#ifdef HAVE_ICU
+#include <unicode/ucnv.h>
+#elif defined(HAVE_ICONV)
+#include <iconv.h>
+#endif
+
+using namespace llvm;
+
+// Normalize the charset name with the charset alias matching algorithm proposed
+// in https://www.unicode.org/reports/tr22/tr22-8.html#Charset_Alias_Matching.
+static void normalizeCharSetName(StringRef CSName,
+ SmallVectorImpl<char> &Normalized) {
+ bool PrevDigit = false;
+ for (auto Ch : CSName) {
+ if (isAlnum(Ch)) {
+ Ch = toLower(Ch);
+ if (Ch != '0' || PrevDigit) {
+ PrevDigit = isDigit(Ch);
+ Normalized.push_back(Ch);
+ }
+ }
+ }
+}
+
+// Maps the charset name to enum constant if possible.
+std::optional<text_encoding::id> getKnownCharSet(StringRef CSName) {
+ SmallString<16> Normalized;
+ normalizeCharSetName(CSName, Normalized);
+ if (Normalized.equals("utf8"))
+ return text_encoding::id::UTF8;
+ if (Normalized.equals("ibm1047"))
+ return text_encoding::id::IBM1047;
+ return std::nullopt;
+}
+
+void HandleOverflow(size_t &Capacity, char *&Output, size_t &OutputLength,
+ SmallVectorImpl<char> &Result) {
+ // No space left in output buffer. Double the size of the underlying
+ // memory in the SmallVectorImpl, adjust pointer and length and continue
+ // the conversion.
+ Capacity = (Capacity < std::numeric_limits<size_t>::max() / 2)
+ ? 2 * Capacity
+ : std::numeric_limits<size_t>::max();
+ Result.resize_for_overwrite(Capacity);
+ Output = static_cast<char *>(Result.data());
+ OutputLength = Capacity;
+}
+
+namespace {
+enum ConversionType {
+ UTFToIBM1047,
+ IBM1047ToUTF,
+};
+
+// Support conversion between EBCDIC 1047 and UTF8. This class uses
+// built-in translation tables that allow for translation between the
+// aforementioned character sets. The use of tables for conversion is only
+// possible because EBCDIC 1047 is a single-byte, stateless encoding; other
+// character sets are not supported.
+class CharSetConverterTable : public details::CharSetConverterImplBase {
+ ConversionType ConvType;
+
+public:
+ CharSetConverterTable(ConversionType ConvType) : ConvType(ConvType) {}
+
+ std::error_code convert(StringRef Source, SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const override;
+ std::error_code flush() const override;
+ std::error_code flush(SmallVectorImpl<char> &Result) const override;
+};
+
+std::error_code CharSetConverterTable::convert(StringRef Source,
+ SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const {
+ if (ConvType == IBM1047ToUTF) {
+ ConverterEBCDIC::convertToUTF8(Source, Result);
+ return std::error_code();
+ } else if (ConvType == UTFToIBM1047) {
+ return ConverterEBCDIC::convertToEBCDIC(Source, Result);
+ }
+ llvm_unreachable("Invalid ConvType!");
+ return std::error_code();
+}
+
+std::error_code CharSetConverterTable::flush() const {
+ return std::error_code();
+}
+
+std::error_code
+CharSetConverterTable::flush(SmallVectorImpl<char> &Result) const {
+ return std::error_code();
+}
+
+#ifdef HAVE_ICU
+class CharSetConverterICU : public details::CharSetConverterImplBase {
+ UConverter *FromConvDesc;
+ UConverter *ToConvDesc;
+
+public:
+ CharSetConverterICU(UConverter *Converter) {
+ UErrorCode EC = U_ZERO_ERROR;
+ FromConvDesc = nullptr;
+ ToConvDesc = ucnv_safeClone(Converter, nullptr, nullptr, &EC);
+ if (U_FAILURE(EC)) {
+ ToConvDesc = nullptr;
+ }
+ };
+
+ CharSetConverterICU(UConverter *FromConverter, UConverter *ToConverter) {
+ UErrorCode EC = U_ZERO_ERROR;
+ FromConvDesc = ucnv_safeClone(FromConverter, nullptr, nullptr, &EC);
+ if (U_FAILURE(EC))
+ FromConvDesc = nullptr;
+ ToConvDesc = ucnv_safeClone(ToConverter, nullptr, nullptr, &EC);
+ if (U_FAILURE(EC))
+ ToConvDesc = nullptr;
+ }
+
+ std::error_code convert(StringRef Source, SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const override;
+ std::error_code flush() const override;
+ std::error_code flush(SmallVectorImpl<char> &Result) const override;
+};
+
+std::error_code CharSetConverterICU::convert(StringRef Source,
+ SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const {
+ // Setup the output. We directly write into the SmallVector.
+ Result.resize_for_overwrite(Source.size());
+ size_t OutputLength, Capacity = Result.capacity();
+ char *Output, *Out;
+
+ UErrorCode EC = U_ZERO_ERROR;
+
+ do {
+ EC = U_ZERO_ERROR;
+ size_t InputLength = Source.size();
+ const char *Input =
+ InputLength ? const_cast<char *>(Source.data()) : nullptr;
+ const char *In = Input;
+ Output = InputLength ? static_cast<char *>(Result.data()) : nullptr;
+ OutputLength = Capacity;
+ Out = Output;
+ Result.resize_for_overwrite(Capacity);
+ ucnv_convertEx(ToConvDesc, FromConvDesc, &Output, Out + OutputLength,
+ &Input, In + InputLength, /*pivotStart=*/NULL,
+ /*pivotSource=*/NULL, /*pivotTarget=*/NULL,
+ /*pivotLimit=*/NULL, /*reset=*/true,
+ /*flush=*/ShouldAutoFlush, &EC);
+ if (U_FAILURE(EC)) {
+ if (EC == U_BUFFER_OVERFLOW_ERROR &&
+ Capacity < std::numeric_limits<size_t>::max())
+ HandleOverflow(Capacity, Output, OutputLength, Result);
+ else
+ // Some other error occured.
+ return std::error_code(errno, std::generic_category());
+ } else if (U_SUCCESS(EC))
+ break;
+ } while (U_FAILURE(EC));
+
+ Result.resize(Output - Out);
+ return std::error_code();
+}
+
+std::error_code CharSetConverterICU::flush() const { return std::error_code(); }
+
+std::error_code
+CharSetConverterICU::flush(SmallVectorImpl<char> &Result) const {
+ return std::error_code();
+}
+
+#elif defined(HAVE_ICONV)
+class CharSetConverterIconv : public details::CharSetConverterImplBase {
+ iconv_t ConvDesc;
+
+public:
+ CharSetConverterIconv(iconv_t ConvDesc) : ConvDesc(ConvDesc) {}
+
+ std::error_code convert(StringRef Source, SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const override;
+ std::error_code flush() const override;
+ std::error_code flush(SmallVectorImpl<char> &Result) const override;
+};
+
+std::error_code CharSetConverterIconv::convert(StringRef Source,
+ SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const {
+ // Setup the input. Use nullptr to reset iconv state if input length is zero.
+ size_t InputLength = Source.size();
+ char *Input = InputLength ? const_cast<char *>(Source.data()) : nullptr;
+ // Setup the output. We directly write into the SmallVector.
+ Result.resize_for_overwrite(Source.size());
+ size_t Capacity = Result.capacity();
+ char *Output = static_cast<char *>(Result.data());
+ size_t OutputLength = Capacity;
+
+ size_t Ret;
+
+ // Handle errors returned from iconv().
+ auto HandleError = [&Capacity, &Output, &OutputLength, &Result](size_t Ret) {
+ if (Ret == static_cast<size_t>(-1)) {
+ // An error occured. Check if we can gracefully handle it.
+ if (errno == E2BIG && Capacity < std::numeric_limits<size_t>::max()) {
+ HandleOverflow(Capacity, Output, OutputLength, Result);
+ return std::error_code();
+ } else {
+ // Some other error occured.
+ return std::error_code(errno, std::generic_category());
+ }
+ } else {
+ // A positive return value indicates that some characters were converted
+ // in a nonreversible way, that is, replaced with a SUB symbol. Returning
+ // an error in this case makes sure that both conversion routines behave
+ // in the same way.
+ return std::make_error_code(std::errc::illegal_byte_sequence);
+ }
+ };
+
+ // Convert the string.
+ while ((Ret = iconv(ConvDesc, &Input, &InputLength, &Output, &OutputLength)))
+ if (auto EC = HandleError(Ret))
+ return EC;
+ if (ShouldAutoFlush) {
+ while ((Ret = iconv(ConvDesc, nullptr, nullptr, &Output, &OutputLength)))
+ if (auto EC = HandleError(Ret))
+ return EC;
+ }
+
+ // Re-adjust size to actual size.
+ Result.resize(Capacity - OutputLength);
+ return std::error_code();
+}
+
+std::error_code CharSetConverterIconv::flush() const {
+ size_t Ret = iconv(ConvDesc, nullptr, nullptr, nullptr, nullptr);
+ if (Ret == static_cast<size_t>(-1)) {
+ return std::error_code(errno, std::generic_category());
+ }
+ return std::error_code();
+}
+
+std::error_code
+CharSetConverterIconv::flush(SmallVectorImpl<char> &Result) const {
+ return convert("", Result, /*ShouldAutoFlush=*/true);
----------------
hubert-reinterpretcast wrote:
> So a nullptr gets passed to the iconv function even if given an empty null-terminated string from the flush function. So I think we won't hit the problem you're describing
Then we have a different problem: A request for no output (substring happens to be zero-sized) would potentially generate output.
Aside: `StringRef()` generates a `StringRef` that has `data()` being `nullptr`; however, I think we need to treat it like any other "empty string".
https://github.com/llvm/llvm-project/pull/74516
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