StringPrinter.cpp
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//===-- StringPrinter.cpp -------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "lldb/DataFormatters/StringPrinter.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Target/Language.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/Target.h"
#include "lldb/Utility/Status.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/ConvertUTF.h"
#include <ctype.h>
#include <locale>
#include <memory>
using namespace lldb;
using namespace lldb_private;
using namespace lldb_private::formatters;
using GetPrintableElementType = StringPrinter::GetPrintableElementType;
using StringElementType = StringPrinter::StringElementType;
/// DecodedCharBuffer stores the decoded contents of a single character. It
/// avoids managing memory on the heap by copying decoded bytes into an in-line
/// buffer.
class DecodedCharBuffer {
public:
DecodedCharBuffer(std::nullptr_t) {}
DecodedCharBuffer(const uint8_t *bytes, size_t size) : m_size(size) {
if (size > MaxLength)
llvm_unreachable("unsupported length");
memcpy(m_data, bytes, size);
}
DecodedCharBuffer(const char *bytes, size_t size)
: DecodedCharBuffer(reinterpret_cast<const uint8_t *>(bytes), size) {}
const uint8_t *GetBytes() const { return m_data; }
size_t GetSize() const { return m_size; }
private:
static constexpr unsigned MaxLength = 16;
size_t m_size = 0;
uint8_t m_data[MaxLength] = {0};
};
using EscapingHelper =
std::function<DecodedCharBuffer(uint8_t *, uint8_t *, uint8_t *&)>;
// we define this for all values of type but only implement it for those we
// care about that's good because we get linker errors for any unsupported type
template <StringElementType type>
static DecodedCharBuffer
GetPrintableImpl(uint8_t *buffer, uint8_t *buffer_end, uint8_t *&next,
StringPrinter::EscapeStyle escape_style);
// Mimic isprint() for Unicode codepoints.
static bool isprint32(char32_t codepoint) {
if (codepoint <= 0x1F || codepoint == 0x7F) // C0
{
return false;
}
if (codepoint >= 0x80 && codepoint <= 0x9F) // C1
{
return false;
}
if (codepoint == 0x2028 || codepoint == 0x2029) // line/paragraph separators
{
return false;
}
if (codepoint == 0x200E || codepoint == 0x200F ||
(codepoint >= 0x202A &&
codepoint <= 0x202E)) // bidirectional text control
{
return false;
}
if (codepoint >= 0xFFF9 &&
codepoint <= 0xFFFF) // interlinears and generally specials
{
return false;
}
return true;
}
DecodedCharBuffer attemptASCIIEscape(llvm::UTF32 c,
StringPrinter::EscapeStyle escape_style) {
const bool is_swift_escape_style =
escape_style == StringPrinter::EscapeStyle::Swift;
switch (c) {
case 0:
return {"\\0", 2};
case '\a':
return {"\\a", 2};
case '\b':
if (is_swift_escape_style)
return nullptr;
return {"\\b", 2};
case '\f':
if (is_swift_escape_style)
return nullptr;
return {"\\f", 2};
case '\n':
return {"\\n", 2};
case '\r':
return {"\\r", 2};
case '\t':
return {"\\t", 2};
case '\v':
if (is_swift_escape_style)
return nullptr;
return {"\\v", 2};
case '\"':
return {"\\\"", 2};
case '\'':
if (is_swift_escape_style)
return {"\\'", 2};
return nullptr;
case '\\':
return {"\\\\", 2};
}
return nullptr;
}
template <>
DecodedCharBuffer GetPrintableImpl<StringElementType::ASCII>(
uint8_t *buffer, uint8_t *buffer_end, uint8_t *&next,
StringPrinter::EscapeStyle escape_style) {
// The ASCII helper always advances 1 byte at a time.
next = buffer + 1;
DecodedCharBuffer retval = attemptASCIIEscape(*buffer, escape_style);
if (retval.GetSize())
return retval;
// Use llvm's locale-independent isPrint(char), instead of the libc
// implementation which may give different results on different platforms.
if (llvm::isPrint(*buffer))
return {buffer, 1};
unsigned escaped_len;
constexpr unsigned max_buffer_size = 7;
uint8_t data[max_buffer_size];
switch (escape_style) {
case StringPrinter::EscapeStyle::CXX:
// Prints 4 characters, then a \0 terminator.
escaped_len = sprintf((char *)data, "\\x%02x", *buffer);
break;
case StringPrinter::EscapeStyle::Swift:
// Prints up to 6 characters, then a \0 terminator.
escaped_len = sprintf((char *)data, "\\u{%x}", *buffer);
break;
}
lldbassert(escaped_len > 0 && "unknown string escape style");
return {data, escaped_len};
}
template <>
DecodedCharBuffer GetPrintableImpl<StringElementType::UTF8>(
uint8_t *buffer, uint8_t *buffer_end, uint8_t *&next,
StringPrinter::EscapeStyle escape_style) {
// If the utf8 encoded length is invalid (i.e., not in the closed interval
// [1;4]), or if there aren't enough bytes to print, or if the subsequence
// isn't valid utf8, fall back to printing an ASCII-escaped subsequence.
if (!llvm::isLegalUTF8Sequence(buffer, buffer_end))
return GetPrintableImpl<StringElementType::ASCII>(buffer, buffer_end, next,
escape_style);
// Convert the valid utf8 sequence to a utf32 codepoint. This cannot fail.
llvm::UTF32 codepoint = 0;
const llvm::UTF8 *buffer_for_conversion = buffer;
llvm::ConversionResult result = llvm::convertUTF8Sequence(
&buffer_for_conversion, buffer_end, &codepoint, llvm::strictConversion);
assert(result == llvm::conversionOK &&
"Failed to convert legal utf8 sequence");
(void)result;
// The UTF8 helper always advances by the utf8 encoded length.
const unsigned utf8_encoded_len = buffer_for_conversion - buffer;
next = buffer + utf8_encoded_len;
DecodedCharBuffer retval = attemptASCIIEscape(codepoint, escape_style);
if (retval.GetSize())
return retval;
if (isprint32(codepoint))
return {buffer, utf8_encoded_len};
unsigned escaped_len;
constexpr unsigned max_buffer_size = 13;
uint8_t data[max_buffer_size];
switch (escape_style) {
case StringPrinter::EscapeStyle::CXX:
// Prints 10 characters, then a \0 terminator.
escaped_len = sprintf((char *)data, "\\U%08x", codepoint);
break;
case StringPrinter::EscapeStyle::Swift:
// Prints up to 12 characters, then a \0 terminator.
escaped_len = sprintf((char *)data, "\\u{%x}", codepoint);
break;
}
lldbassert(escaped_len > 0 && "unknown string escape style");
return {data, escaped_len};
}
// Given a sequence of bytes, this function returns: a sequence of bytes to
// actually print out + a length the following unscanned position of the buffer
// is in next
static DecodedCharBuffer GetPrintable(StringElementType type, uint8_t *buffer,
uint8_t *buffer_end, uint8_t *&next,
StringPrinter::EscapeStyle escape_style) {
if (!buffer || buffer >= buffer_end)
return {nullptr};
switch (type) {
case StringElementType::ASCII:
return GetPrintableImpl<StringElementType::ASCII>(buffer, buffer_end, next,
escape_style);
case StringElementType::UTF8:
return GetPrintableImpl<StringElementType::UTF8>(buffer, buffer_end, next,
escape_style);
default:
return {nullptr};
}
}
static EscapingHelper
GetDefaultEscapingHelper(GetPrintableElementType elem_type,
StringPrinter::EscapeStyle escape_style) {
switch (elem_type) {
case GetPrintableElementType::UTF8:
case GetPrintableElementType::ASCII:
return [escape_style, elem_type](uint8_t *buffer, uint8_t *buffer_end,
uint8_t *&next) -> DecodedCharBuffer {
return GetPrintable(elem_type == GetPrintableElementType::UTF8
? StringElementType::UTF8
: StringElementType::ASCII,
buffer, buffer_end, next, escape_style);
};
}
llvm_unreachable("bad element type");
}
/// Read a string encoded in accordance with \tparam SourceDataType from a
/// host-side LLDB buffer, then pretty-print it to a stream using \p style.
template <typename SourceDataType>
static bool DumpEncodedBufferToStream(
GetPrintableElementType style,
llvm::ConversionResult (*ConvertFunction)(const SourceDataType **,
const SourceDataType *,
llvm::UTF8 **, llvm::UTF8 *,
llvm::ConversionFlags),
const StringPrinter::ReadBufferAndDumpToStreamOptions &dump_options) {
assert(dump_options.GetStream() && "need a Stream to print the string to");
Stream &stream(*dump_options.GetStream());
if (dump_options.GetPrefixToken() != nullptr)
stream.Printf("%s", dump_options.GetPrefixToken());
if (dump_options.GetQuote() != 0)
stream.Printf("%c", dump_options.GetQuote());
auto data(dump_options.GetData());
auto source_size(dump_options.GetSourceSize());
if (data.GetByteSize() && data.GetDataStart() && data.GetDataEnd()) {
const int bufferSPSize = data.GetByteSize();
if (dump_options.GetSourceSize() == 0) {
const int origin_encoding = 8 * sizeof(SourceDataType);
source_size = bufferSPSize / (origin_encoding / 4);
}
const SourceDataType *data_ptr =
(const SourceDataType *)data.GetDataStart();
const SourceDataType *data_end_ptr = data_ptr + source_size;
const bool zero_is_terminator = dump_options.GetBinaryZeroIsTerminator();
if (zero_is_terminator) {
while (data_ptr < data_end_ptr) {
if (!*data_ptr) {
data_end_ptr = data_ptr;
break;
}
data_ptr++;
}
data_ptr = (const SourceDataType *)data.GetDataStart();
}
lldb::DataBufferSP utf8_data_buffer_sp;
llvm::UTF8 *utf8_data_ptr = nullptr;
llvm::UTF8 *utf8_data_end_ptr = nullptr;
if (ConvertFunction) {
utf8_data_buffer_sp =
std::make_shared<DataBufferHeap>(4 * bufferSPSize, 0);
utf8_data_ptr = (llvm::UTF8 *)utf8_data_buffer_sp->GetBytes();
utf8_data_end_ptr = utf8_data_ptr + utf8_data_buffer_sp->GetByteSize();
ConvertFunction(&data_ptr, data_end_ptr, &utf8_data_ptr,
utf8_data_end_ptr, llvm::lenientConversion);
if (!zero_is_terminator)
utf8_data_end_ptr = utf8_data_ptr;
// needed because the ConvertFunction will change the value of the
// data_ptr.
utf8_data_ptr =
(llvm::UTF8 *)utf8_data_buffer_sp->GetBytes();
} else {
// just copy the pointers - the cast is necessary to make the compiler
// happy but this should only happen if we are reading UTF8 data
utf8_data_ptr = const_cast<llvm::UTF8 *>(
reinterpret_cast<const llvm::UTF8 *>(data_ptr));
utf8_data_end_ptr = const_cast<llvm::UTF8 *>(
reinterpret_cast<const llvm::UTF8 *>(data_end_ptr));
}
const bool escape_non_printables = dump_options.GetEscapeNonPrintables();
EscapingHelper escaping_callback;
if (escape_non_printables)
escaping_callback =
GetDefaultEscapingHelper(style, dump_options.GetEscapeStyle());
// since we tend to accept partial data (and even partially malformed data)
// we might end up with no NULL terminator before the end_ptr hence we need
// to take a slower route and ensure we stay within boundaries
for (; utf8_data_ptr < utf8_data_end_ptr;) {
if (zero_is_terminator && !*utf8_data_ptr)
break;
if (escape_non_printables) {
uint8_t *next_data = nullptr;
auto printable =
escaping_callback(utf8_data_ptr, utf8_data_end_ptr, next_data);
auto printable_bytes = printable.GetBytes();
auto printable_size = printable.GetSize();
// We failed to figure out how to print this string.
if (!printable_bytes || !next_data)
return false;
for (unsigned c = 0; c < printable_size; c++)
stream.Printf("%c", *(printable_bytes + c));
utf8_data_ptr = (uint8_t *)next_data;
} else {
stream.Printf("%c", *utf8_data_ptr);
utf8_data_ptr++;
}
}
}
if (dump_options.GetQuote() != 0)
stream.Printf("%c", dump_options.GetQuote());
if (dump_options.GetSuffixToken() != nullptr)
stream.Printf("%s", dump_options.GetSuffixToken());
if (dump_options.GetIsTruncated())
stream.Printf("...");
return true;
}
lldb_private::formatters::StringPrinter::ReadStringAndDumpToStreamOptions::
ReadStringAndDumpToStreamOptions(ValueObject &valobj)
: ReadStringAndDumpToStreamOptions() {
SetEscapeNonPrintables(
valobj.GetTargetSP()->GetDebugger().GetEscapeNonPrintables());
}
lldb_private::formatters::StringPrinter::ReadBufferAndDumpToStreamOptions::
ReadBufferAndDumpToStreamOptions(ValueObject &valobj)
: ReadBufferAndDumpToStreamOptions() {
SetEscapeNonPrintables(
valobj.GetTargetSP()->GetDebugger().GetEscapeNonPrintables());
}
lldb_private::formatters::StringPrinter::ReadBufferAndDumpToStreamOptions::
ReadBufferAndDumpToStreamOptions(
const ReadStringAndDumpToStreamOptions &options)
: ReadBufferAndDumpToStreamOptions() {
SetStream(options.GetStream());
SetPrefixToken(options.GetPrefixToken());
SetSuffixToken(options.GetSuffixToken());
SetQuote(options.GetQuote());
SetEscapeNonPrintables(options.GetEscapeNonPrintables());
SetBinaryZeroIsTerminator(options.GetBinaryZeroIsTerminator());
SetEscapeStyle(options.GetEscapeStyle());
}
namespace lldb_private {
namespace formatters {
template <typename SourceDataType>
static bool ReadEncodedBufferAndDumpToStream(
StringElementType elem_type,
const StringPrinter::ReadStringAndDumpToStreamOptions &options,
llvm::ConversionResult (*ConvertFunction)(const SourceDataType **,
const SourceDataType *,
llvm::UTF8 **, llvm::UTF8 *,
llvm::ConversionFlags)) {
assert(options.GetStream() && "need a Stream to print the string to");
if (!options.GetStream())
return false;
if (options.GetLocation() == 0 ||
options.GetLocation() == LLDB_INVALID_ADDRESS)
return false;
lldb::ProcessSP process_sp(options.GetProcessSP());
if (!process_sp)
return false;
constexpr int type_width = sizeof(SourceDataType);
constexpr int origin_encoding = 8 * type_width;
if (origin_encoding != 8 && origin_encoding != 16 && origin_encoding != 32)
return false;
// If not UTF8 or ASCII, conversion to UTF8 is necessary.
if (origin_encoding != 8 && !ConvertFunction)
return false;
bool needs_zero_terminator = options.GetNeedsZeroTermination();
bool is_truncated = false;
const auto max_size = process_sp->GetTarget().GetMaximumSizeOfStringSummary();
uint32_t sourceSize;
if (elem_type == StringElementType::ASCII && !options.GetSourceSize()) {
// FIXME: The NSString formatter sets HasSourceSize(true) when the size is
// actually unknown, as well as SetBinaryZeroIsTerminator(false). IIUC the
// C++ formatter also sets SetBinaryZeroIsTerminator(false) when it doesn't
// mean to. I don't see how this makes sense: we should fix the formatters.
//
// Until then, the behavior that's expected for ASCII strings with unknown
// lengths is to read up to the max size and then null-terminate. Do that.
sourceSize = max_size;
needs_zero_terminator = true;
} else if (options.HasSourceSize()) {
sourceSize = options.GetSourceSize();
if (!options.GetIgnoreMaxLength()) {
if (sourceSize > max_size) {
sourceSize = max_size;
is_truncated = true;
}
}
} else {
sourceSize = max_size;
needs_zero_terminator = true;
}
const int bufferSPSize = sourceSize * type_width;
lldb::DataBufferSP buffer_sp(new DataBufferHeap(bufferSPSize, 0));
// Check if we got bytes. We never get any bytes if we have an empty
// string, but we still continue so that we end up actually printing
// an empty string ("").
if (sourceSize != 0 && !buffer_sp->GetBytes())
return false;
Status error;
char *buffer = reinterpret_cast<char *>(buffer_sp->GetBytes());
if (elem_type == StringElementType::ASCII)
process_sp->ReadCStringFromMemory(options.GetLocation(), buffer,
bufferSPSize, error);
else if (needs_zero_terminator)
process_sp->ReadStringFromMemory(options.GetLocation(), buffer,
bufferSPSize, error, type_width);
else
process_sp->ReadMemoryFromInferior(options.GetLocation(), buffer,
bufferSPSize, error);
if (error.Fail()) {
options.GetStream()->Printf("unable to read data");
return true;
}
DataExtractor data(buffer_sp, process_sp->GetByteOrder(),
process_sp->GetAddressByteSize());
StringPrinter::ReadBufferAndDumpToStreamOptions dump_options(options);
dump_options.SetData(data);
dump_options.SetSourceSize(sourceSize);
dump_options.SetIsTruncated(is_truncated);
dump_options.SetNeedsZeroTermination(needs_zero_terminator);
if (needs_zero_terminator)
dump_options.SetBinaryZeroIsTerminator(true);
GetPrintableElementType print_style = (elem_type == StringElementType::ASCII)
? GetPrintableElementType::ASCII
: GetPrintableElementType::UTF8;
return DumpEncodedBufferToStream(print_style, ConvertFunction, dump_options);
}
template <>
bool StringPrinter::ReadStringAndDumpToStream<StringElementType::UTF8>(
const ReadStringAndDumpToStreamOptions &options) {
return ReadEncodedBufferAndDumpToStream<llvm::UTF8>(StringElementType::UTF8,
options, nullptr);
}
template <>
bool StringPrinter::ReadStringAndDumpToStream<StringElementType::UTF16>(
const ReadStringAndDumpToStreamOptions &options) {
return ReadEncodedBufferAndDumpToStream<llvm::UTF16>(
StringElementType::UTF16, options, llvm::ConvertUTF16toUTF8);
}
template <>
bool StringPrinter::ReadStringAndDumpToStream<StringElementType::UTF32>(
const ReadStringAndDumpToStreamOptions &options) {
return ReadEncodedBufferAndDumpToStream<llvm::UTF32>(
StringElementType::UTF32, options, llvm::ConvertUTF32toUTF8);
}
template <>
bool StringPrinter::ReadStringAndDumpToStream<StringElementType::ASCII>(
const ReadStringAndDumpToStreamOptions &options) {
return ReadEncodedBufferAndDumpToStream<char>(StringElementType::ASCII,
options, nullptr);
}
template <>
bool StringPrinter::ReadBufferAndDumpToStream<StringElementType::UTF8>(
const ReadBufferAndDumpToStreamOptions &options) {
return DumpEncodedBufferToStream<llvm::UTF8>(GetPrintableElementType::UTF8,
nullptr, options);
}
template <>
bool StringPrinter::ReadBufferAndDumpToStream<StringElementType::UTF16>(
const ReadBufferAndDumpToStreamOptions &options) {
return DumpEncodedBufferToStream(GetPrintableElementType::UTF8,
llvm::ConvertUTF16toUTF8, options);
}
template <>
bool StringPrinter::ReadBufferAndDumpToStream<StringElementType::UTF32>(
const ReadBufferAndDumpToStreamOptions &options) {
return DumpEncodedBufferToStream(GetPrintableElementType::UTF8,
llvm::ConvertUTF32toUTF8, options);
}
template <>
bool StringPrinter::ReadBufferAndDumpToStream<StringElementType::ASCII>(
const ReadBufferAndDumpToStreamOptions &options) {
// Treat ASCII the same as UTF8.
//
// FIXME: This is probably not the right thing to do (well, it's debatable).
// If an ASCII-encoded string happens to contain a sequence of invalid bytes
// that forms a valid UTF8 character, we'll print out that character. This is
// good if you're playing fast and loose with encodings (probably good for
// std::string users), but maybe not so good if you care about your string
// formatter respecting the semantics of your selected string encoding. In
// the latter case you'd want to see the character byte sequence ('\x..'), not
// the UTF8 character itself.
return ReadBufferAndDumpToStream<StringElementType::UTF8>(options);
}
} // namespace formatters
} // namespace lldb_private