Add Google-style StringPrintf. (6b3be290) · Commits · e / os / android_system_core

include/utils/stringprintf.h

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		/*
		* Copyright (C) 2011 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#ifndef UTILS_STRINGPRINTF_H_
		#define UTILS_STRINGPRINTF_H_

		#include <stdarg.h>
		#include <string>

		namespace android {

		// Returns a string corresponding to printf-like formatting of the arguments.
		std::string StringPrintf(const char* fmt, ...)
		__attribute__((__format__(__printf__, 1, 2)));

		// Appends a printf-like formatting of the arguments to 'dst'.
		void StringAppendF(std::string* dst, const char* fmt, ...)
		__attribute__((__format__(__printf__, 2, 3)));

		// Appends a printf-like formatting of the arguments to 'dst'.
		void StringAppendV(std::string* dst, const char* format, va_list ap);

		} // namespace android

		#endif

libutils/Android.mk

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		@@ -41,6 +41,7 @@ commonSources:= \
		VectorImpl.cpp \
		file.cpp \
		misc.cpp \
		stringprintf.cpp \

		host_commonCflags := -DLIBUTILS_NATIVE=1 $(TOOL_CFLAGS) -Werror

libutils/stringprintf.cpp

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		/*
		* Copyright (C) 2011 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <utils/stringprintf.h>

		#include <stdio.h>

		void android::StringAppendV(std::string* dst, const char* format, va_list ap) {
		// First try with a small fixed size buffer
		char space[1024];

		// It's possible for methods that use a va_list to invalidate
		// the data in it upon use. The fix is to make a copy
		// of the structure before using it and use that copy instead.
		va_list backup_ap;
		va_copy(backup_ap, ap);
		int result = vsnprintf(space, sizeof(space), format, backup_ap);
		va_end(backup_ap);

		if (result < static_cast<int>(sizeof(space))) {
		if (result >= 0) {
		// Normal case -- everything fit.
		dst->append(space, result);
		return;
		}

		if (result < 0) {
		// Just an error.
		return;
		}
		}

		// Increase the buffer size to the size requested by vsnprintf,
		// plus one for the closing \0.
		int length = result+1;
		char* buf = new char[length];

		// Restore the va_list before we use it again
		va_copy(backup_ap, ap);
		result = vsnprintf(buf, length, format, backup_ap);
		va_end(backup_ap);

		if (result >= 0 && result < length) {
		// It fit
		dst->append(buf, result);
		}
		delete[] buf;
		}

		std::string android::StringPrintf(const char* fmt, ...) {
		va_list ap;
		va_start(ap, fmt);
		std::string result;
		StringAppendV(&result, fmt, ap);
		va_end(ap);
		return result;
		}

		void android::StringAppendF(std::string* dst, const char* format, ...) {
		va_list ap;
		va_start(ap, format);
		StringAppendV(dst, format, ap);
		va_end(ap);
		}

libutils/tests/Android.mk

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		@@ -30,6 +30,7 @@ LOCAL_SRC_FILES := \
		Looper_test.cpp \
		LruCache_test.cpp \
		String8_test.cpp \
		stringprintf_test.cpp \
		Unicode_test.cpp \
		Vector_test.cpp \

libutils/tests/stringprintf_test.cpp

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		/*
		* Copyright (C) 2011 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		#include <utils/stringprintf.h>

		#include <gtest/gtest.h>

		TEST(StringPrintfTest, HexSizeT) {
		size_t size = 0x00107e59;
		EXPECT_EQ("00107e59", android::StringPrintf("%08zx", size));
		EXPECT_EQ("0x00107e59", android::StringPrintf("0x%08zx", size));
		}

		TEST(StringPrintfTest, StringAppendF) {
		std::string s("a");
		android::StringAppendF(&s, "b");
		EXPECT_EQ("ab", s);
		}

		TEST(StringPrintfTest, Errno) {
		errno = 123;
		android::StringPrintf("hello %s", "world");
		EXPECT_EQ(123, errno);
		}

		void TestN(size_t n) {
		char* buf = new char[n + 1];
		memset(buf, 'x', n);
		buf[n] = '\0';
		std::string s(android::StringPrintf("%s", buf));
		EXPECT_EQ(buf, s);
		delete[] buf;
		}

		TEST(StringPrintfTest, At1023) {
		TestN(1023);
		}

		TEST(StringPrintfTest, At1024) {
		TestN(1024);
		}

		TEST(StringPrintfTest, At1025) {
		TestN(1025);
		}