[llvm] Create a CharSetConverter class with both iconv and icu support (PR #74516)
Hubert Tong via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 29 11:42:28 PDT 2024
================
@@ -0,0 +1,284 @@
+//===-- 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.
+static 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;
+}
+
+static 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 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();
+}
+
+#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 CharSetConverterICU::convert(StringRef Source,
+ SmallVectorImpl<char> &Result,
+ bool ShouldAutoFlush) const {
+ // Setup the output. We directly write into the SmallVector.
+ size_t Capacity = Result.capacity();
+ size_t OutputLength = Capacity;
+ char *Output, *Out;
+ Result.resize_for_overwrite(Capacity);
+
+ 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 = static_cast<char *>(Result.data());
+ Out = Output;
+ 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);
+ continue;
+ } else
+ // Some other error occured.
+ return std::error_code(EILSEQ, std::generic_category());
+ }
+ break;
+ } while (true);
+
+ Result.resize(Output - Out);
+ 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 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))
----------------
hubert-reinterpretcast wrote:
> but I can reduce the initial size of the output buffer for one of the stateful encoding tests as well
It may be necessary to ensure that the encoding overhead of the output string is higher than for the input string because of the following: https://github.com/llvm/llvm-project/blob/19f64df438e816ffb565c05bae196cf76a877a17/llvm/lib/Support/CharSet.cpp#L196
https://github.com/llvm/llvm-project/pull/74516
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