[newlib-cygwin] Cygwin: realpath: fix cygwin installation dir being access via junction
Corinna Vinschen
corinna@sourceware.org
Fri Feb 19 18:21:33 GMT 2021
https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=6d898f43fc87a7bf3ab100d75538e381bd86f657
commit 6d898f43fc87a7bf3ab100d75538e381bd86f657
Author: Corinna Vinschen <corinna@vinschen.de>
Date: Fri Feb 19 18:15:58 2021 +0100
Cygwin: realpath: fix cygwin installation dir being access via junction
Consider this case:
- Cygwin installed in C:\cygwin64
- mklink /j D:\cygwin64 C:\cygwin64
- create testcase calling
realpath("/", result);
printf ("%s\n", result);
- start cmd
>C:\cygwin64\bin\bash -lc <path-to-testcase>
/
>D\cygwin64\bin\bash -lc <path-to-testcase>
/cygdrive/c/cygwin64
This scenario circumventing the mount point handling which is automated
in terms of /, depending on the path returned from GetModuleFileNameW
for the Cygwin DLL. When calling D:\cygwin64\bin\bash the dir returned
from GetModuleFileNameW is D:\cygwin64\bin, thus root is D:\cygwin64.
However, junctions are treated as symlinks in Cygwin which explains why
the path gets converted to a cygdrive path.
Fix this by calling GetFinalPathNameByHandleW on the result from
GetModuleFileNameW to get the correct root path, even if accessed via
a junction point.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>
Diff:
---
winsup/cygwin/cygheap.cc | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/winsup/cygwin/cygheap.cc b/winsup/cygwin/cygheap.cc
index 3a32c352d..01b49468e 100644
--- a/winsup/cygwin/cygheap.cc
+++ b/winsup/cygwin/cygheap.cc
@@ -144,6 +144,19 @@ init_cygheap::init_installation_root ()
api_fatal ("Can't initialize Cygwin installation root dir.\n"
"GetModuleFileNameW(%p, %p, %u), %E",
cygwin_hmodule, installation_root_buf, PATH_MAX);
+
+ /* We don't care if fetching the final pathname fails, it's non-fatal and
+ the path returned by GetModuleFileNameW is still valid. */
+ HANDLE h;
+ h = CreateFileW (installation_root_buf, GENERIC_READ, FILE_SHARE_VALID_FLAGS,
+ &sec_none, OPEN_EXISTING, 0, 0);
+ if (h != INVALID_HANDLE_VALUE)
+ {
+ GetFinalPathNameByHandleW (h, installation_root_buf, PATH_MAX,
+ FILE_NAME_NORMALIZED);
+ CloseHandle (h);
+ }
+
PWCHAR p = installation_root_buf;
if (wcsncasecmp (p, L"\\\\", 2)) /* Normal drive letter path */
{
More information about the Cygwin-cvs
mailing list