[Bug 48491] New: _searchenv & co do not understand quoted directories

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=48491

Bug ID: 48491
           Summary: _searchenv & co do not understand quoted directories
           Product: Wine
           Version: 5.0-rc4
          Hardware: x86
                OS: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: msvcrt
          Assignee: [e-mail]
          Reporter: [e-mail]
      Distribution: ---

The following test program produces the expected result ("testdir\testfile") on
Windows, but fails on Wine:

#include <io.h>
#include <direct.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <stdio.h>

int main(void)
{
    char buf[64];

_mkdir("testdir");
    _close(_creat("testdir\testfile", _S_IREAD | _S_IWRITE));

_putenv("TESTVAR="testdir"");
    _searchenv("testfile", "TESTVAR", buf);
    printf("Result: %s\n", buf);
}

The cause seems to be that Wine doesn't seem to implement the quoting syntax in
the searchenv function family.

The problem was noticed when MS link.exe invocation failed on Wine but not
Windows, with identical environment / inputs. Such environment variables can
occur when building search paths for linker libraries (%LIB%), as seen here:

https://github.com/dlang/dmd/blob/81710a5e548f047588bd3ee6ffb13a8d6f1b9bff/i...