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* path.cc: Extend two comments. Mention the name RtlpCurDirRef 

for reference.
This commit is contained in:
Corinna Vinschen 2011-10-18 08:47:08 +00:00
parent ce68abe0b4
commit 53609fd238
2 changed files with 20 additions and 5 deletions
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5
winsup/cygwin/ChangeLog
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@ -1,3 +1,8 @@
2011-10-18 Corinna Vinschen <corinna@vinschen.de>
* path.cc: Extend two comments. Mention the name RtlpCurDirRef
for reference.
2011-10-17 Christopher Faylor <me.cygwin2011@cgf.cx> 2011-10-17 Christopher Faylor <me.cygwin2011@cgf.cx>
* dcrt0.cc (dll_crt0_1): Copy argv before passing to main(). * dcrt0.cc (dll_crt0_1): Copy argv before passing to main().

20
winsup/cygwin/path.cc
View File

@ -3626,8 +3626,9 @@ public:
fcwd_access_t::fcwd_version_t fcwd_access_t::fast_cwd_version fcwd_access_t::fcwd_version_t fcwd_access_t::fast_cwd_version
__attribute__((section (".cygwin_dll_common"), shared)) __attribute__((section (".cygwin_dll_common"), shared))
= fcwd_access_t::FCWD_W7; = fcwd_access_t::FCWD_W7;
/* fast_cwd_ptr is a pointer to the global pointer in ntdll.dll pointing /* fast_cwd_ptr is a pointer to the global RtlpCurDirRef pointer in
to the FAST_CWD structure which constitutes the CWD. ntdll.dll pointing to the FAST_CWD structure which constitutes the CWD.
Unfortunately RtlpCurDirRef is not exported from ntdll.dll.
We put the pointer into the common shared DLL segment. This allows to We put the pointer into the common shared DLL segment. This allows to
restrict the call to find_fast_cwd_pointer() to once per Cygwin session restrict the call to find_fast_cwd_pointer() to once per Cygwin session
per user session. This works, because ASLR randomizes the load address per user session. This works, because ASLR randomizes the load address
@ -3718,9 +3719,18 @@ find_fast_cwd ()
} }
else else
{ {
/* If we couldn't fetch fast_cwd_ptr, or if fast_cwd_ptr is NULL(*) we /* If we couldn't fetch fast_cwd_ptr, or if fast_cwd_ptr is NULL(*)
have to figure out the version from the Buffer pointer in the we have to figure out the version from the Buffer pointer in the
ProcessParameters. */ ProcessParameters.
(*) This is very unlikely to happen when starting the first
Cygwin process, since it only happens when starting the
process in a directory which can't be used as CWD by Win32, or
if the directory doesn't exist. But *if* it happens, we have
no valid FAST_CWD structure, even though upp_cwd_str.Buffer is
not NULL in that case. So we let the OS create a valid
FAST_CWD structure temporarily to have something to work with.
We know the pipe FS works. */
PEB &peb = *NtCurrentTeb ()->Peb; PEB &peb = *NtCurrentTeb ()->Peb;
if (f_cwd_ptr /* so *f_cwd_ptr == NULL */ if (f_cwd_ptr /* so *f_cwd_ptr == NULL */