From f14decafae0d1771e16498e693e7bf2f7058e88e Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Thu, 1 Oct 2015 12:23:39 +0100 Subject: [PATCH] Save-and-restore errno more carefully in libstdc++ * doc/xml/manual/diagnostics.xml: Document use of errno. * doc/html/*: Regenerate. * config/locale/generic/c_locale.cc (_Save_errno): New helper. (__convert_to_v): Use _Save_errno. * include/ext/string_conversions.h (__stoa): Only restore errno when it isn't set to non-zero. From-SVN: r228328 --- libstdc++-v3/ChangeLog | 9 +++++ .../config/locale/generic/c_locale.cc | 16 +++++++-- .../doc/html/manual/concept_checking.html | 7 ++-- libstdc++-v3/doc/html/manual/diagnostics.html | 8 ++--- libstdc++-v3/doc/html/manual/index.html | 2 +- .../doc/html/manual/std_contents.html | 2 +- libstdc++-v3/doc/xml/manual/diagnostics.xml | 33 +++++++++++++++++++ libstdc++-v3/include/ext/string_conversions.h | 10 ++++-- 8 files changed, 70 insertions(+), 17 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index cc22cfa14c0..4199ede06fd 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,3 +1,12 @@ +2015-10-01 Jonathan Wakely + + * doc/xml/manual/diagnostics.xml: Document use of errno. + * doc/html/*: Regenerate. + * config/locale/generic/c_locale.cc (_Save_errno): New helper. + (__convert_to_v): Use _Save_errno. + * include/ext/string_conversions.h (__stoa): Only restore errno when + it isn't set to non-zero. + 2015-09-30 François Dumont Jonathan Wakely diff --git a/libstdc++-v3/config/locale/generic/c_locale.cc b/libstdc++-v3/config/locale/generic/c_locale.cc index 6da5f2256cf..8dfea6b0682 100644 --- a/libstdc++-v3/config/locale/generic/c_locale.cc +++ b/libstdc++-v3/config/locale/generic/c_locale.cc @@ -44,6 +44,16 @@ namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION + namespace + { + struct _Save_errno + { + _Save_errno() : _M_errno(errno) { errno = 0; } + ~_Save_errno() { if (errno == 0) errno = _M_errno; } + int _M_errno; + }; + } + template<> void __convert_to_v(const char* __s, float& __v, ios_base::iostate& __err, @@ -59,7 +69,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION bool __overflow = false; #if !__FLT_HAS_INFINITY__ - errno = 0; + const _Save_errno __save_errno; #endif #ifdef _GLIBCXX_HAVE_STRTOF @@ -123,7 +133,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION char* __sanity; #if !__DBL_HAS_INFINITY__ - errno = 0; + const _Save_errno __save_errno; #endif __v = strtod(__s, &__sanity); @@ -167,7 +177,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION setlocale(LC_ALL, "C"); #if !__LDBL_HAS_INFINITY__ - errno = 0; + const _Save_errno __save_errno; #endif #if defined(_GLIBCXX_HAVE_STRTOLD) && !defined(_GLIBCXX_HAVE_BROKEN_STRTOLD) diff --git a/libstdc++-v3/doc/html/manual/concept_checking.html b/libstdc++-v3/doc/html/manual/concept_checking.html index df7f22f7fcd..a01957d5e27 100644 --- a/libstdc++-v3/doc/html/manual/concept_checking.html +++ b/libstdc++-v3/doc/html/manual/concept_checking.html @@ -1,5 +1,5 @@ -Concept Checking
Concept Checking
Prev Chapter 5.  +Concept Checking
Concept Checking
Prev Chapter 5.  Diagnostics  Next

Concept Checking

@@ -41,10 +41,7 @@ for example template argument types may need to be complete when used in a template definition, rather than at the point of instantiation. There are no plans to address these shortcomings. -

Prev Up Next
Chapter 5.  - Diagnostics - - Home Chapter 6.  +

Prev Up Next
Use of errno by the library Home Chapter 6.  Utilities
\ No newline at end of file diff --git a/libstdc++-v3/doc/html/manual/diagnostics.html b/libstdc++-v3/doc/html/manual/diagnostics.html index 30002b7a96e..a90d5dfcc1d 100644 --- a/libstdc++-v3/doc/html/manual/diagnostics.html +++ b/libstdc++-v3/doc/html/manual/diagnostics.html @@ -1,13 +1,13 @@ -Chapter 5.  Diagnostics
Chapter 5.  +Chapter 5.  Diagnostics
Chapter 5.  Diagnostics
Prev Part II.  Standard Contents -  Next

Chapter 5.  +

 Next

Chapter 5.  Diagnostics -

Table of Contents

Exceptions
API Reference
Adding Data to exception
Concept Checking

Exceptions

API Reference

+

Table of Contents

Exceptions
API Reference
Adding Data to exception
Use of errno by the library
Concept Checking

Exceptions

API Reference

All exception objects are defined in one of the standard header files: exception, stdexcept, new, and @@ -39,4 +39,4 @@ int e; DBID id; // some user-defined type }; -

Prev Up Next
Termination Home Concept Checking
\ No newline at end of file +
Prev Up Next
Termination Home Use of errno by the library
\ No newline at end of file diff --git a/libstdc++-v3/doc/html/manual/index.html b/libstdc++-v3/doc/html/manual/index.html index d48e49b26d8..fbe657ef9dc 100644 --- a/libstdc++-v3/doc/html/manual/index.html +++ b/libstdc++-v3/doc/html/manual/index.html @@ -12,7 +12,7 @@
Types
Fundamental Types
Numeric Properties
NULL
Dynamic Memory
Termination
Termination Handlers
Verbose Terminate Handler
5. Diagnostics -
Exceptions
API Reference
Adding Data to exception
Concept Checking
6. +
Exceptions
API Reference
Adding Data to exception
Use of errno by the library
Concept Checking
6. Utilities
Functors
Pairs
Memory
Allocators
Requirements
Design Issues
Implementation
Interface Design
Selecting Default Allocation Policy
Disabling Memory Caching
Using a Specific Allocator
Custom Allocators
Extension Allocators
auto_ptr
Limitations
Use in Containers
shared_ptr
Requirements
Design Issues
Implementation
Class Hierarchy
Thread Safety
Selecting Lock Policy
Related functions and classes
Use
Examples
Unresolved Issues
Acknowledgments
Traits
7. diff --git a/libstdc++-v3/doc/html/manual/std_contents.html b/libstdc++-v3/doc/html/manual/std_contents.html index db4e46e9cb1..c7c6114aa63 100644 --- a/libstdc++-v3/doc/html/manual/std_contents.html +++ b/libstdc++-v3/doc/html/manual/std_contents.html @@ -9,7 +9,7 @@
Types
Fundamental Types
Numeric Properties
NULL
Dynamic Memory
Termination
Termination Handlers
Verbose Terminate Handler
5. Diagnostics -
Exceptions
API Reference
Adding Data to exception
Concept Checking
6. +
Exceptions
API Reference
Adding Data to exception
Use of errno by the library
Concept Checking
6. Utilities
Functors
Pairs
Memory
Allocators
Requirements
Design Issues
Implementation
Interface Design
Selecting Default Allocation Policy
Disabling Memory Caching
Using a Specific Allocator
Custom Allocators
Extension Allocators
auto_ptr
Limitations
Use in Containers
shared_ptr
Requirements
Design Issues
Implementation
Class Hierarchy
Thread Safety
Selecting Lock Policy
Related functions and classes
Use
Examples
Unresolved Issues
Acknowledgments
Traits
7. diff --git a/libstdc++-v3/doc/xml/manual/diagnostics.xml b/libstdc++-v3/doc/xml/manual/diagnostics.xml index 88ed2e28057..67620e2cb40 100644 --- a/libstdc++-v3/doc/xml/manual/diagnostics.xml +++ b/libstdc++-v3/doc/xml/manual/diagnostics.xml @@ -71,6 +71,39 @@ +
Use of errno by the library + + + + The C and POSIX standards guarantee that errno + is never set to zero by any library function. + The C++ standard has less to say about when errno + is or isn't set, but libstdc++ follows the same rule and never sets + it to zero. + + + + On the other hand, there are few guarantees about when the C++ library + sets errno on error, beyond what is specified for + functions that come from the C library. + For example, when std::stoi throws an exception of + type std::out_of_range, errno + may or may not have been set to ERANGE. + + + + Parts of the C++ library may be implemented in terms of C library + functions, which may result in errno being set + with no explicit call to a C function. For example, on a target where + operator new uses malloc + a failed memory allocation with operator new might + set errno to ENOMEM. + Which C++ library functions can set errno in this way + is unspecified because it may vary between platforms and between releases. + + +
+
Concept Checking diff --git a/libstdc++-v3/include/ext/string_conversions.h b/libstdc++-v3/include/ext/string_conversions.h index 58387a282ef..7f37e694182 100644 --- a/libstdc++-v3/include/ext/string_conversions.h +++ b/libstdc++-v3/include/ext/string_conversions.h @@ -58,8 +58,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION _Ret __ret; _CharT* __endptr; - const int __saved_errno = errno; - errno = 0; + + struct _Save_errno { + _Save_errno() : _M_errno(errno) { errno = 0; } + ~_Save_errno() { if (errno == 0) errno = _M_errno; } + int _M_errno; + } const __save_errno; + const _TRet __tmp = __convf(__str, &__endptr, __base...); if (__endptr == __str) @@ -71,7 +76,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION std::__throw_out_of_range(__name); else __ret = __tmp; - errno = __saved_errno; if (__idx) *__idx = __endptr - __str; -- 2.30.2