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Fix issue #315: Provide platform support for strnlen

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Neil MacIntosh 2016-08-19 09:26:49 -07:00 committed by GitHub
commit 5112ba02f6
1 changed files with 29 additions and 4 deletions
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33
gsl/string_span
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@ -56,6 +56,10 @@
#endif // _MSC_VER <= 1800 #endif // _MSC_VER <= 1800
#endif // _MSC_VER #endif // _MSC_VER
#ifndef __CYGWIN__
#define GSL_PLATFORM_HAS_STRNLEN
#endif
// In order to test the library, we need it to throw exceptions that we can catch // In order to test the library, we need it to throw exceptions that we can catch
#ifdef GSL_THROW_ON_CONTRACT_VIOLATION #ifdef GSL_THROW_ON_CONTRACT_VIOLATION
@ -95,6 +99,27 @@ using zstring = basic_zstring<char, Extent>;
template <std::ptrdiff_t Extent = dynamic_extent> template <std::ptrdiff_t Extent = dynamic_extent>
using wzstring = basic_zstring<wchar_t, Extent>; using wzstring = basic_zstring<wchar_t, Extent>;
namespace details
{
inline std::size_t string_length(const char *str, std::size_t n)
{
#ifdef GSL_PLATFORM_HAS_STRNLEN
return strnlen(str, n);
#else
if (str == nullptr || n == 0)
return 0;
std::size_t len = 0;
span<const char> str_span{str, n};
while (len < n && str_span[len])
len++;
return len;
#endif
}
}
// //
// ensure_sentinel() // ensure_sentinel()
// //
@ -127,14 +152,14 @@ inline span<T, dynamic_extent> ensure_z(T* const& sz, std::ptrdiff_t max = PTRDI
// overloads to share an implementation // overloads to share an implementation
inline span<char, dynamic_extent> ensure_z(char* const& sz, std::ptrdiff_t max) inline span<char, dynamic_extent> ensure_z(char* const& sz, std::ptrdiff_t max)
{ {
auto len = strnlen(sz, narrow_cast<size_t>(max)); auto len = details::string_length(sz, narrow_cast<size_t>(max));
Ensures(sz[len] == 0); Ensures(sz[len] == 0);
return {sz, static_cast<std::ptrdiff_t>(len)}; return {sz, static_cast<std::ptrdiff_t>(len)};
} }
inline span<const char, dynamic_extent> ensure_z(const char* const& sz, std::ptrdiff_t max) inline span<const char, dynamic_extent> ensure_z(const char* const& sz, std::ptrdiff_t max)
{ {
auto len = strnlen(sz, narrow_cast<size_t>(max)); auto len = details::string_length(sz, narrow_cast<size_t>(max));
Ensures(sz[len] == 0); Ensures(sz[len] == 0);
return {sz, static_cast<std::ptrdiff_t>(len)}; return {sz, static_cast<std::ptrdiff_t>(len)};
} }
@ -196,7 +221,7 @@ namespace details
{ {
std::ptrdiff_t operator()(char* const ptr, std::ptrdiff_t length) noexcept std::ptrdiff_t operator()(char* const ptr, std::ptrdiff_t length) noexcept
{ {
return narrow_cast<std::ptrdiff_t>(strnlen(ptr, narrow_cast<size_t>(length))); return narrow_cast<std::ptrdiff_t>(details::string_length(ptr, narrow_cast<size_t>(length)));
} }
}; };
@ -214,7 +239,7 @@ namespace details
{ {
std::ptrdiff_t operator()(const char* const ptr, std::ptrdiff_t length) noexcept std::ptrdiff_t operator()(const char* const ptr, std::ptrdiff_t length) noexcept
{ {
return narrow_cast<std::ptrdiff_t>(strnlen(ptr, narrow_cast<size_t>(length))); return narrow_cast<std::ptrdiff_t>(details::string_length(ptr, narrow_cast<size_t>(length)));
} }
}; };