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Define compiler string formatting utilities
- TR::[v]printfLen(): return the length of the formatted string without writing the string into any buffer - TR::[v]snprintfTrunc(): format into a fixed-size buffer, possibly truncating - TR::[v]snprintfNoTrunc(): format into a fixed-size buffer with an assertion that the result is not truncated - TR::StringBuf: a reusable growable Region-allocated buffer into which formatted text can be appended using [v]appendf() These obviate the MSVC conditional snprintf #define at use sites, and they deal with the portability concerns of that #define correctly and in a centralized place. Additionally, StringBuf makes it simple to allocate enough memory to do formatting without truncation.
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| Original file line number | Diff line number | Diff line change |
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| /******************************************************************************* | ||
| * Copyright (c) 2021, 2021 IBM Corp. and others | ||
| * | ||
| * This program and the accompanying materials are made available under | ||
| * the terms of the Eclipse Public License 2.0 which accompanies this | ||
| * distribution and is available at http://eclipse.org/legal/epl-2.0 | ||
| * or the Apache License, Version 2.0 which accompanies this distribution | ||
| * and is available at https://www.apache.org/licenses/LICENSE-2.0. | ||
| * | ||
| * This Source Code may also be made available under the following Secondary | ||
| * Licenses when the conditions for such availability set forth in the | ||
| * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License, | ||
| * version 2 with the GNU Classpath Exception [1] and GNU General Public | ||
| * License, version 2 with the OpenJDK Assembly Exception [2]. | ||
| * | ||
| * [1] https://www.gnu.org/software/classpath/license.html | ||
| * [2] http://openjdk.java.net/legal/assembly-exception.html | ||
| * | ||
| * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception | ||
| *******************************************************************************/ | ||
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| #include "infra/String.hpp" | ||
| #include "infra/Assert.hpp" | ||
| #include "env/FrontEnd.hpp" // defines va_copy for old MSVC and z/OS | ||
| #include <limits.h> | ||
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| #if defined (_MSC_VER) && (_MSC_VER < 1900) | ||
| #define stdlib_vsnprintf _vsnprintf | ||
| #else | ||
| #define stdlib_vsnprintf vsnprintf | ||
| #endif | ||
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| namespace TR { | ||
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| // Returns the length of the formatted string without writing it to memory. | ||
| int vprintfLen(const char *fmt, va_list args) | ||
| { | ||
| // This works with both standard vsnprintf() and _vsnprintf(). | ||
| return stdlib_vsnprintf(NULL, 0, fmt, args); | ||
| } | ||
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| // Returns the length of the formatted string without writing it to memory. | ||
| int printfLen(const char *fmt, ...) | ||
| { | ||
| va_list args; | ||
| va_start(args, fmt); | ||
| int len = TR::vprintfLen(fmt, args); | ||
| va_end(args); | ||
| return len; | ||
| } | ||
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| // Returns true if the formatted string was truncated. The length of the | ||
| // formatted string (excluding the NUL terminator) is stored into len. That | ||
| // length is (size - 1) if the output was truncated, because when using | ||
| // _vsnprintf() the would-be length is unknown. | ||
| bool vsnprintfTrunc(char *buf, size_t size, int *len, const char *fmt, va_list args) | ||
| { | ||
| // This assertion guarantees that (size - 1) will not overflow in the | ||
| // truncation case below, and that there is actually a location in which to | ||
| // store the terminating NUL. The only reason to pass size=0 would be to | ||
| // compute the formatted length, which should be done using | ||
| // TR::[v]printfLen() instead. | ||
| TR_ASSERT_FATAL(size > 0, "vsnprintfTrunc: no buffer space provided"); | ||
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| // This assertion guarantees that it's safe to truncate (size - 1) to int in | ||
| // the string truncation case below. | ||
| TR_ASSERT_FATAL(size - 1 <= (size_t)INT_MAX, "vsnprintfTrunc: buffer too large"); | ||
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| int n = stdlib_vsnprintf(buf, size, fmt, args); | ||
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| // The formatted length does not include the NUL, so if (n >= size), the | ||
| // result has been truncated. If we are using _vsnprintf(), it's possible to | ||
| // get (n == size), which indicates that the entire formatted string has | ||
| // been stored *without* a trailing NUL, but not (n > size). In the case | ||
| // where standard vsnprintf() produces (n > size), _vsnprintf() returns a | ||
| // negative value instead. So a negative result also indicates truncation. | ||
| bool truncated = n < 0 || n >= size; | ||
| if (truncated) | ||
| { | ||
| buf[size - 1] = '\0'; // Ensure NUL-termination in the _vsnprintf() case. | ||
| *len = (int)(size - 1); | ||
| } | ||
| else | ||
| { | ||
| *len = n; | ||
| } | ||
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| return truncated; | ||
| } | ||
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| // See vsnprintfTrunc() above. | ||
| bool snprintfTrunc(char *buf, size_t size, int *len, const char *fmt, ...) | ||
| { | ||
| va_list args; | ||
| va_start(args, fmt); | ||
| bool truncated = TR::vsnprintfTrunc(buf, size, len, fmt, args); | ||
| va_end(args); | ||
| return truncated; | ||
| } | ||
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| // Variant of vsnprintfTrunc() without the len pointer, for cases where the | ||
| // caller is uninterested in the length. | ||
| bool vsnprintfTrunc(char *buf, size_t size, const char *fmt, va_list args) | ||
| { | ||
| int dummy; | ||
| return vsnprintfTrunc(buf, size, &dummy, fmt, args); | ||
| } | ||
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| // Variant of snprintfTrunc() without the len pointer, for cases where the | ||
| // caller is uninterested in the length. | ||
| bool snprintfTrunc(char *buf, size_t size, const char *fmt, ...) | ||
| { | ||
| va_list args; | ||
| va_start(args, fmt); | ||
| bool truncated = TR::vsnprintfTrunc(buf, size, fmt, args); | ||
| va_end(args); | ||
| return truncated; | ||
| } | ||
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| // Asserts that the formatted string was not truncated and returns its length | ||
| // (excluding the NUL terminator). | ||
| int vsnprintfNoTrunc(char *buf, size_t size, const char *fmt, va_list args) | ||
| { | ||
| int len; | ||
| bool truncated = TR::vsnprintfTrunc(buf, size, &len, fmt, args); | ||
| TR_ASSERT_FATAL(!truncated, "vsnprintfNoTrunc: truncation occurred"); | ||
| return len; | ||
| } | ||
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| // Asserts that the formatted string was not truncated and returns its length | ||
| // (excluding the NUL terminator). | ||
| int snprintfNoTrunc(char *buf, size_t size, const char *fmt, ...) | ||
| { | ||
| va_list args; | ||
| va_start(args, fmt); | ||
| int len = TR::vsnprintfNoTrunc(buf, size, fmt, args); | ||
| va_end(args); | ||
| return len; | ||
| } | ||
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| void TR::StringBuf::vappendf(const char *fmt, va_list args) | ||
| { | ||
| va_list argsCopy; | ||
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| va_copy(argsCopy, args); | ||
| int appendLen = TR::vprintfLen(fmt, argsCopy); | ||
| va_copy_end(argsCopy); | ||
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| TR_ASSERT_FATAL(appendLen >= 0, "error in format string"); | ||
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| size_t newLen = _len + appendLen; | ||
| ensureCapacity(newLen); | ||
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| TR_ASSERT_FATAL(appendLen + 1 <= _cap - _len, "insufficient buffer capacity"); | ||
| int realAppendLen = stdlib_vsnprintf(&_text[_len], appendLen + 1, fmt, args); | ||
| TR_ASSERT_FATAL(realAppendLen == appendLen, "incorrect predicted snprintf length"); | ||
| TR_ASSERT_FATAL(_text[newLen] == '\0', "missing NUL terminator"); | ||
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| _len = newLen; | ||
| } | ||
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| void TR::StringBuf::appendf(const char *fmt, ...) | ||
| { | ||
| va_list args; | ||
| va_start(args, fmt); | ||
| vappendf(fmt, args); | ||
| va_end(args); | ||
| } | ||
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| void TR::StringBuf::ensureCapacity(size_t newLen) | ||
| { | ||
| // Note that the capacity must always be strictly greater than the length so | ||
| // that there is room for the NUL terminator. | ||
| if (newLen < _cap) | ||
| return; // nothing to do | ||
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| size_t newCap = newLen + 1; // + 1 for NUL terminator | ||
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| // Grow the buffer geometrically each time it is reallocated to ensure that | ||
| // appends are amortized O(1) per character | ||
| if (newCap < 2 * _cap) | ||
| newCap = 2 * _cap; | ||
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| char *newText = (char*)_region.allocate(newCap); | ||
| memcpy(newText, _text, _len + 1); // + 1 for NUL terminator | ||
| _text = newText; | ||
| _cap = newCap; | ||
| } | ||
|
|
||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,114 @@ | ||
| /******************************************************************************* | ||
| * Copyright (c) 2021, 2021 IBM Corp. and others | ||
| * | ||
| * This program and the accompanying materials are made available under | ||
| * the terms of the Eclipse Public License 2.0 which accompanies this | ||
| * distribution and is available at http://eclipse.org/legal/epl-2.0 | ||
| * or the Apache License, Version 2.0 which accompanies this distribution | ||
| * and is available at https://www.apache.org/licenses/LICENSE-2.0. | ||
| * | ||
| * This Source Code may also be made available under the following Secondary | ||
| * Licenses when the conditions for such availability set forth in the | ||
| * Eclipse Public License, v. 2.0 are satisfied: GNU General Public License, | ||
| * version 2 with the GNU Classpath Exception [1] and GNU General Public | ||
| * License, version 2 with the OpenJDK Assembly Exception [2]. | ||
| * | ||
| * [1] https://www.gnu.org/software/classpath/license.html | ||
| * [2] http://openjdk.java.net/legal/assembly-exception.html | ||
| * | ||
| * SPDX-License-Identifier: EPL-2.0 OR Apache-2.0 OR GPL-2.0 WITH Classpath-exception-2.0 OR LicenseRef-GPL-2.0 WITH Assembly-exception | ||
| *******************************************************************************/ | ||
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| #ifndef TR_STRING_INCL | ||
| #define TR_STRING_INCL | ||
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| #include <stdarg.h> | ||
| #include <stddef.h> | ||
| #include "env/defines.h" | ||
| #include "env/TRMemory.hpp" | ||
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| #if HOST_COMPILER == COMPILER_GCC || HOST_COMPILER == COMPILER_CLANG | ||
| #define TR_PRINTF_FORMAT_ATTR(fmtIndex, argsIndex) \ | ||
| __attribute__((format(printf, (fmtIndex), (argsIndex)))) | ||
| #else | ||
| #define TR_PRINTF_FORMAT_ATTR(fmtIndex, argsIndex) | ||
| #endif | ||
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| namespace TR { | ||
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| int vprintfLen(const char *fmt, va_list args); | ||
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| int printfLen(const char *fmt, ...) TR_PRINTF_FORMAT_ATTR(1, 2); | ||
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| bool vsnprintfTrunc(char *buf, size_t size, int *len, const char *fmt, va_list args); | ||
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| bool snprintfTrunc(char *buf, size_t size, int *len, const char *fmt, ...) | ||
| TR_PRINTF_FORMAT_ATTR(4, 5); | ||
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| bool vsnprintfTrunc(char *buf, size_t size, const char *fmt, va_list args); | ||
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| bool snprintfTrunc(char *buf, size_t size, const char *fmt, ...) | ||
| TR_PRINTF_FORMAT_ATTR(3, 4); | ||
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| int vsnprintfNoTrunc(char *buf, size_t size, const char *fmt, va_list args); | ||
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| int snprintfNoTrunc(char *buf, size_t size, const char *fmt, ...) | ||
| TR_PRINTF_FORMAT_ATTR(3, 4); | ||
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| class StringBuf | ||
| { | ||
| TR::Region &_region; | ||
| size_t _cap; | ||
| size_t _len; | ||
| char *_text; | ||
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| // can't use a delegating constructor | ||
| void initEmptyBuffer() | ||
| { | ||
| TR_ASSERT_FATAL(_cap > 0, "StringBuf: no buffer space"); | ||
| TR_ASSERT_FATAL(_text != NULL, "StringBuf: buffer is null"); | ||
| _text[0] = '\0'; | ||
| } | ||
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| public: | ||
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| // region, initialBuffer must both outlive this StringBuffer | ||
| StringBuf(TR::Region ®ion, char *initialBuffer, size_t capacity) | ||
| : _region(region), _cap(capacity), _len(0), _text(initialBuffer) | ||
| { | ||
| initEmptyBuffer(); | ||
| } | ||
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| // region must outlive this StringBuffer | ||
| StringBuf(TR::Region ®ion, size_t capacity = 32) | ||
| : _region(region), _cap(capacity), _len(0), _text((char*)region.allocate(capacity)) | ||
| { | ||
| initEmptyBuffer(); | ||
| } | ||
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| size_t len() const { return _len; } | ||
| const char *text() const { return _text; } | ||
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| void clear() | ||
| { | ||
| _len = 0; | ||
| _text[0] = '\0'; | ||
| } | ||
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| void vappendf(const char *fmt, va_list args); | ||
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| void appendf(const char *fmt, ...) TR_PRINTF_FORMAT_ATTR(2, 3); | ||
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| private: | ||
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| // Non-copyable. These are undefined and will cause a link error if anything | ||
| // attempts to use them accidentally. | ||
| StringBuf(const StringBuf &); | ||
| StringBuf &operator=(const StringBuf &); | ||
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| void ensureCapacity(size_t newLen); | ||
| }; | ||
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| } | ||
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| #endif |
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