你能帮我理解 GTest 和结构打包的情况吗？
问题似乎与结构在 GTest 的值参数化测试中用作值时如何打包有关。采用为每个值实例化结构的直接方法会导致与未初始化值相关的 valgrind 错误。
相关代码如下:
#include <gtest/gtest.h>
struct TestItem
{
const char * aString;
int anInt0;
int anInt1;
int anInt2;
};
class TestBase : public ::testing::Test, public ::testing::WithParamInterface<TestItem> {};
TEST_P(TestBase, TestAtoi)
{
TestItem item = GetParam();
std::cout << sizeof(TestItem) << std::endl;
ASSERT_FALSE(0); // actual test doesn't matter
}
INSTANTIATE_TEST_CASE_P(
TestBaseInstantiation,
TestBase,
::testing::Values(
TestItem { "0", 0, 0, 0 }
));
编译和链接后(我用 cmake 构建了 GTest):
g++ gtest_valgrind.c -o gtest_valgrind -I gtest-1.7.0/include -L gtest-1.7.0/build -lgtest -lpthread -lgtest_main -std=c++11
然后执行:
valgrind --leak-check=full --show-leak-kinds=all --track-origins=yes ./gtest_valgrind
产生以下输出:
==17290== Memcheck, a memory error detector
==17290== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==17290== Using Valgrind-3.10.0.SVN and LibVEX; rerun with -h for copyright info
==17290== Command: ./gtest_valgrind
==17290==
Running main() from gtest_main.cc
==17290== Use of uninitialised value of size 8
==17290== at 0x55B89F1: _itoa_word (_itoa.c:180)
==17290== by 0x55BC6F6: vfprintf (vfprintf.c:1660)
==17290== by 0x55E1578: vsnprintf (vsnprintf.c:119)
==17290== by 0x55C3531: snprintf (snprintf.c:33)
==17290== by 0x41F107: testing::(anonymous namespace)::PrintByteSegmentInObjectTo(unsigned char const*, unsigned long, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F1AA: testing::(anonymous namespace)::PrintBytesInObjectToImpl(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F252: testing::internal2::PrintBytesInObjectTo(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B8E: testing::internal2::TypeWithoutFormatter<TestItem, (testing::internal2::TypeKind)2>::PrintValue(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B63: std::basic_ostream<char, std::char_traits<char> >& testing::internal2::operator<< <char, std::char_traits<char>, TestItem>(std::basic_ostream<char, std::char_traits<char> >&, TestItem const&) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B3E: void testing_internal::DefaultPrintNonContainerTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B19: void testing::internal::DefaultPrintTo<TestItem>(char, testing::internal::bool_constant<false>, TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409ADB: void testing::internal::PrintTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== Uninitialised value was created by a stack allocation
==17290== at 0x404AAE: gtest_TestBaseInstantiationTestBase_EvalGenerator_() (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290==
==17290== Conditional jump or move depends on uninitialised value(s)
==17290== at 0x55B89F8: _itoa_word (_itoa.c:180)
==17290== by 0x55BC6F6: vfprintf (vfprintf.c:1660)
==17290== by 0x55E1578: vsnprintf (vsnprintf.c:119)
==17290== by 0x55C3531: snprintf (snprintf.c:33)
==17290== by 0x41F107: testing::(anonymous namespace)::PrintByteSegmentInObjectTo(unsigned char const*, unsigned long, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F1AA: testing::(anonymous namespace)::PrintBytesInObjectToImpl(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F252: testing::internal2::PrintBytesInObjectTo(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B8E: testing::internal2::TypeWithoutFormatter<TestItem, (testing::internal2::TypeKind)2>::PrintValue(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B63: std::basic_ostream<char, std::char_traits<char> >& testing::internal2::operator<< <char, std::char_traits<char>, TestItem>(std::basic_ostream<char, std::char_traits<char> >&, TestItem const&) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B3E: void testing_internal::DefaultPrintNonContainerTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B19: void testing::internal::DefaultPrintTo<TestItem>(char, testing::internal::bool_constant<false>, TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409ADB: void testing::internal::PrintTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== Uninitialised value was created by a stack allocation
==17290== at 0x404AAE: gtest_TestBaseInstantiationTestBase_EvalGenerator_() (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290==
==17290== Conditional jump or move depends on uninitialised value(s)
==17290== at 0x55BC742: vfprintf (vfprintf.c:1660)
==17290== by 0x55E1578: vsnprintf (vsnprintf.c:119)
==17290== by 0x55C3531: snprintf (snprintf.c:33)
==17290== by 0x41F107: testing::(anonymous namespace)::PrintByteSegmentInObjectTo(unsigned char const*, unsigned long, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F1AA: testing::(anonymous namespace)::PrintBytesInObjectToImpl(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F252: testing::internal2::PrintBytesInObjectTo(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B8E: testing::internal2::TypeWithoutFormatter<TestItem, (testing::internal2::TypeKind)2>::PrintValue(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B63: std::basic_ostream<char, std::char_traits<char> >& testing::internal2::operator<< <char, std::char_traits<char>, TestItem>(std::basic_ostream<char, std::char_traits<char> >&, TestItem const&) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B3E: void testing_internal::DefaultPrintNonContainerTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B19: void testing::internal::DefaultPrintTo<TestItem>(char, testing::internal::bool_constant<false>, TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409ADB: void testing::internal::PrintTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409AA6: testing::internal::UniversalPrinter<TestItem>::Print(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== Uninitialised value was created by a stack allocation
==17290== at 0x404AAE: gtest_TestBaseInstantiationTestBase_EvalGenerator_() (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290==
==17290== Conditional jump or move depends on uninitialised value(s)
==17290== at 0x55B9659: vfprintf (vfprintf.c:1660)
==17290== by 0x55E1578: vsnprintf (vsnprintf.c:119)
==17290== by 0x55C3531: snprintf (snprintf.c:33)
==17290== by 0x41F107: testing::(anonymous namespace)::PrintByteSegmentInObjectTo(unsigned char const*, unsigned long, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F1AA: testing::(anonymous namespace)::PrintBytesInObjectToImpl(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F252: testing::internal2::PrintBytesInObjectTo(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B8E: testing::internal2::TypeWithoutFormatter<TestItem, (testing::internal2::TypeKind)2>::PrintValue(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B63: std::basic_ostream<char, std::char_traits<char> >& testing::internal2::operator<< <char, std::char_traits<char>, TestItem>(std::basic_ostream<char, std::char_traits<char> >&, TestItem const&) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B3E: void testing_internal::DefaultPrintNonContainerTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B19: void testing::internal::DefaultPrintTo<TestItem>(char, testing::internal::bool_constant<false>, TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409ADB: void testing::internal::PrintTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409AA6: testing::internal::UniversalPrinter<TestItem>::Print(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== Uninitialised value was created by a stack allocation
==17290== at 0x404AAE: gtest_TestBaseInstantiationTestBase_EvalGenerator_() (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290==
==17290== Conditional jump or move depends on uninitialised value(s)
==17290== at 0x55B96DC: vfprintf (vfprintf.c:1660)
==17290== by 0x55E1578: vsnprintf (vsnprintf.c:119)
==17290== by 0x55C3531: snprintf (snprintf.c:33)
==17290== by 0x41F107: testing::(anonymous namespace)::PrintByteSegmentInObjectTo(unsigned char const*, unsigned long, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F1AA: testing::(anonymous namespace)::PrintBytesInObjectToImpl(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x41F252: testing::internal2::PrintBytesInObjectTo(unsigned char const*, unsigned long, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B8E: testing::internal2::TypeWithoutFormatter<TestItem, (testing::internal2::TypeKind)2>::PrintValue(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B63: std::basic_ostream<char, std::char_traits<char> >& testing::internal2::operator<< <char, std::char_traits<char>, TestItem>(std::basic_ostream<char, std::char_traits<char> >&, TestItem const&) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B3E: void testing_internal::DefaultPrintNonContainerTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409B19: void testing::internal::DefaultPrintTo<TestItem>(char, testing::internal::bool_constant<false>, TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409ADB: void testing::internal::PrintTo<TestItem>(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== by 0x409AA6: testing::internal::UniversalPrinter<TestItem>::Print(TestItem const&, std::ostream*) (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290== Uninitialised value was created by a stack allocation
==17290== at 0x404AAE: gtest_TestBaseInstantiationTestBase_EvalGenerator_() (in /home/davida/git/gitlab/fcdm/lwm2m.git/gtest_valgrind)
==17290==
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from TestBaseInstantiation/TestBase
[ RUN ] TestBaseInstantiation/TestBase.TestAtoi/0
24
[ OK ] TestBaseInstantiation/TestBase.TestAtoi/0 (76 ms)
[----------] 1 test from TestBaseInstantiation/TestBase (126 ms total)
[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (246 ms total)
[ PASSED ] 1 test.
==17290==
==17290== HEAP SUMMARY:
==17290== in use at exit: 0 bytes in 0 blocks
==17290== total heap usage: 239 allocs, 239 frees, 46,622 bytes allocated
==17290==
==17290== All heap blocks were freed -- no leaks are possible
==17290==
==17290== For counts of detected and suppressed errors, rerun with: -v
==17290== ERROR SUMMARY: 20 errors from 5 contexts (suppressed: 0 from 0)
这是很多输出，但基本上我认为这表明由于 TestItem { "0", 0, 0, 0 } 中的行而实例化的结构存在一些异常 INSTANTIATE_TEST_CASE_P。
另请注意，TestItem 的大小输出为 24。在 64 位系统上，我不太确定如何协调这一点。 char * 为 8 个字节，int 成员为 4 * 3 = 12 个字节。如果它们与 8 字节边界对齐，则大小应为 24 + 4 = 28 字节(如果包括打包，则为 32)。如果它们对齐到 4 字节边界，那么这应该是 20。这里有一些关于结构打包的东西我不明白。
可以通过不同方式打包结构来消除 valgrind 警告。例如，所有这三个修改都会导致干净的 valgrind 运行:
使用#pragma pack:
#pragma pack(1)
struct TestItem
{
const char * aString;
int anInt0;
int anInt1;
int anInt2;
};
输出 20。
使用 GNU g++ 打包属性:
struct TestItem
{
const char * aString;
int anInt0;
int anInt1;
int anInt2;
} __attribute__((packed));
也输出 20。
最后，向结构中添加一个虚拟值:
struct TestItem
{
const char * aString;
int anInt0;
int anInt1;
int anInt2;
int anInt3; // add an extra member
};
输出 24。
我有相当多的项目代码使用这种精确技术进行值参数化测试，在所有情况下，如果未使用其中一种回避策略，valgrind 都会报错。
我想知道我为这个测试创建值的方法是否存在根本性错误，或者这是 gtest 在实例化测试用例时所做的事情的结果？或者，这不太可能是 gtest 错误？
最佳答案
sizeof 的输出对于 TestItem结构是编译器的结果structure alignment and trailing padding .
来自上面的链接:
[...] It is the first address following the structure data that has the same alignment as the structure.
The general rule of trailing structure padding is this: the compiler will behave as though the structure has trailing padding out to its stride address. This rule controls what sizeof() will return.
Consider this example on a 64-bit x86 or ARM machine:
struct foo3 { char *p; /* 8 bytes */ char c; /* 1 byte */ }; struct foo3 singleton; struct foo3 quad[4];You might think that
sizeof(struct foo3)should be 9, but it’s actually 16. The stride address is that of (&p)[2]. Thus, in the quad array, each member has 7 bytes of trailing padding, because the first member of each following struct wants to be self-aligned on an 8-byte boundary. The memory layout is as though the structure had been declared like this:struct foo3 { char *p; /* 8 bytes */ char c; /* 1 byte */ char pad[7]; };
这就解释了为什么 sizeof(TestItem) 是 24因为尾部填充会将结构对齐到 sizeof (const char*) 的倍数, 即 8.
这个尾部填充字节是未初始化的，这就是 valgrind 报告的内容。 Gtest 正在运行一些代码以打印 TestItem 的实际值测试失败时的参数。如果您通过了测试并且 valgrind 没有显示错误，则可以确认这一点。
当您强制编译器使用特定对齐方式或向结构添加新成员以使结构不需要任何尾随填充时，valgrind 不会在 TestItem 中找到任何未初始化的字节。实例。
Gtest 通常调用operator<<打印值时返回打印对象中的原始字节数组(如果不可用)。这可能就是访问未初始化尾随填充字节的原因。因此，您也可以通过定义 operator<< 来消除 valgrind 错误。对于 TestItem .
关于C++ - 对结构使用 GTest 值参数化测试会导致 valgrind 错误，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33747056/
我正在学习如何使用Nokogiri，根据这段代码我遇到了一些问题:require'rubygems'require'mechanize'post_agent=WWW::Mechanize.newpost_page=post_agent.get('http://www.vbulletin.org/forum/showthread.php?t=230708')puts"\nabsolutepathwithtbodygivesnil"putspost_page.parser.xpath('/html/body/div/div/div/div/div/table/tbody/tr/td/div
我有一个Ruby程序，它使用rubyzip压缩XML文件的目录树。gem。我的问题是文件开始变得很重，我想提高压缩级别，因为压缩时间不是问题。我在rubyzipdocumentation中找不到一种为创建的ZIP文件指定压缩级别的方法。有人知道如何更改此设置吗？是否有另一个允许指定压缩级别的Ruby库？ 最佳答案 这是我通过查看rubyzip内部创建的代码。level=Zlib::BEST_COMPRESSIONZip::ZipOutputStream.open(zip_file)do|zip|Dir.glob("**/*")d
类classAprivatedeffooputs:fooendpublicdefbarputs:barendprivatedefzimputs:zimendprotecteddefdibputs:dibendendA的实例a=A.new测试a.foorescueputs:faila.barrescueputs:faila.zimrescueputs:faila.dibrescueputs:faila.gazrescueputs:fail测试输出failbarfailfailfail.发送测试[:foo,:bar,:zim,:dib,:gaz].each{|m|a.send(m)resc
很好奇，就使用rubyonrails自动化单元测试而言，你们正在做什么？您是否创建了一个脚本来在cron中运行rake作业并将结果邮寄给您？git中的预提交Hook？只是手动调用？我完全理解测试，但想知道在错误发生之前捕获错误的最佳实践是什么。让我们理所当然地认为测试本身是完美无缺的，并且可以正常工作。下一步是什么以确保他们在正确的时间将可能有害的结果传达给您？ 最佳答案 不确定您到底想听什么，但是有几个级别的自动代码库控制:在处理某项功能时，您可以使用类似autotest的内容获得关于哪些有效，哪些无效的即时反馈。要确保您的提
假设我做了一个模块如下:m=Module.newdoclassCendend三个问题:除了对m的引用之外，还有什么方法可以访问C和m中的其他内容？我可以在创建匿名模块后为其命名吗(就像我输入“module...”一样)？如何在使用完匿名模块后将其删除，使其定义的常量不再存在？ 最佳答案 三个答案:是的，使用ObjectSpace.此代码使c引用你的类(class)C不引用m:c=nilObjectSpace.each_object{|obj|c=objif(Class===objandobj.name=~/::C$/)}当然这取决于
我正在尝试使用ruby和Savon来使用网络服务。测试服务为http://www.webservicex.net/WS/WSDetails.aspx?WSID=9&CATID=2require'rubygems'require'savon'client=Savon::Client.new"http://www.webservicex.net/stockquote.asmx?WSDL"client.get_quotedo|soap|soap.body={:symbol=>"AAPL"}end返回SOAP异常。检查soap信封，在我看来soap请求没有正确的命名空间。任何人都可以建议我
关闭。这个问题是opinion-based.它目前不接受答案。想要改进这个问题？更新问题，以便editingthispost可以用事实和引用来回答它.关闭4年前。Improvethisquestion我想在固定时间创建一系列低音和高音调的哔哔声。例如:在150毫秒时发出高音调的蜂鸣声在151毫秒时发出低音调的蜂鸣声200毫秒时发出低音调的蜂鸣声250毫秒的高音调蜂鸣声有没有办法在Ruby或Python中做到这一点？我真的不在乎输出编码是什么(.wav、.mp3、.ogg等等)，但我确实想创建一个输出文件。
我在我的项目目录中完成了compasscreate.和compassinitrails。几个问题:我已将我的.sass文件放在public/stylesheets中。这是放置它们的正确位置吗？当我运行compasswatch时，它不会自动编译这些.sass文件。我必须手动指定文件:compasswatchpublic/stylesheets/myfile.sass等。如何让它自动运行？文件ie.css、print.css和screen.css已放在stylesheets/compiled。如何在编译后不让它们重新出现的情况下删除它们？我自己编译的.sass文件编译成compiled/t
我想将html转换为纯文本。不过，我不想只删除标签，我想智能地保留尽可能多的格式。为插入换行符标签，检测段落并格式化它们等。输入非常简单，通常是格式良好的html(不是整个文档，只是一堆内容，通常没有anchor或图像)。我可以将几个正则表达式放在一起，让我达到80%，但我认为可能有一些现有的解决方案更智能。 最佳答案 首先，不要尝试为此使用正则表达式。很有可能你会想出一个脆弱/脆弱的解决方案，它会随着HTML的变化而崩溃，或者很难管理和维护。您可以使用Nokogiri快速解析HTML并提取文本:require'nokogiri'h
我想为Heroku构建一个Rails3应用程序。他们使用Postgres作为他们的数据库，所以我通过MacPorts安装了postgres9.0。现在我需要一个postgresgem并且共识是出于性能原因你想要pggem。但是我对我得到的错误感到非常困惑当我尝试在rvm下通过geminstall安装pg时。我已经非常明确地指定了所有postgres目录的位置可以找到但仍然无法完成安装:$envARCHFLAGS='-archx86_64'geminstallpg--\--with-pg-config=/opt/local/var/db/postgresql90/defaultdb/po