Re: [boost] [filesystem] temp_directory_path() behavior on Windows

Subject: Re: [boost] [filesystem] temp_directory_path() behavior on Windows
From: Peter Dimov (lists_at_[hidden])
Date: 2015-01-31 11:29:38

Beman Dawes wrote:
> temp_directory_path() on Windows is currently implemented by calling the 
> Windows API GetTempPath() function.
>
> Ticket https://svn.boost.org/trac/boost/ticket/5300 points out that 
> GetTempPath() does not work as expected for environmental variables longer 
> than roughly 130 characters. I've added a test to Boost.Filesystem that 
> verifies that boost::filesystem::temp_directory() is affected.
>
> The suggested fix is to use GetEnvironmentVariable to in effect implement 
> GetTempPath() the way we would like it to work.

Not that the documented behavior of GetTempPath makes any sense to me - the 
default temp directory is at %LOCALAPPDATA%\Temp since Win95 or so - but the 
suggested fix is actually:

"A workaround is to first try to use GetEnvironmentVariable on "TMP" and 
"TEMP", then fall back on GetTempPath."

So, if implemented, it makes

> OTOH, excluding the Windows directory is a breaking change for anyone 
> currently depending on that behavior, so I thought it best to ask for 
> comments before charging ahead.

a non-issue, unless you want to avoid calling GetTempPath entirely, in which 
case I would return %LOCALAPPDATA%\Temp at step 3, obtained via 
SHGetFolderPath.