[newlib-cygwin] Cygwin: passwd/group: store account name case correct

[newlib-cygwin] Cygwin: passwd/group: store account name case correct

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=9a3cc77b2afc52a2faa5e4daeb59dfd4506c0693

commit 9a3cc77b2afc52a2faa5e4daeb59dfd4506c0693
Author: Corinna Vinschen <corinna@vinschen.de>
Date:   Wed Feb 13 11:10:55 2019 +0100

    Cygwin: passwd/group: store account name case correct
    
    When looking up valid accounts by name, LookupAccountName returns
    a SID and a case-correct domain name.  However, the name was input
    and LookupAccountName is case-insensitive, so the name is not
    necessarily written the same way as in SAM or AD.
    
    Fix that by doing a reverse lookup on the just fetched SID.  This
    fetches the account name in the correct case.  Override the
    incoming name with the case correct name from LookupAccountSid.
    
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/release/3.0 |  4 ++++
 winsup/cygwin/uinfo.cc    | 10 ++++++++++
 2 files changed, 14 insertions(+)

diff --git a/winsup/cygwin/release/3.0 b/winsup/cygwin/release/3.0
index da35755..444e71a 100644
--- a/winsup/cygwin/release/3.0
+++ b/winsup/cygwin/release/3.0
@@ -109,3 +109,7 @@ Bug Fixes
 
 - Fix O_APPEND handling on files when calling non-Cygwin applications
   Addresses: https://cygwin.com/ml/cygwin/2019-02/msg00081.html
+
+- Fix case correctness of passwd/group entries fetched via getpwnam
+  or getgrnam.
+  Addresses: https://cygwin.com/ml/cygwin/2019-02/msg00109.html
diff --git a/winsup/cygwin/uinfo.cc b/winsup/cygwin/uinfo.cc
index 22cae5e..4a5fa34 100644
--- a/winsup/cygwin/uinfo.cc
+++ b/winsup/cygwin/uinfo.cc
@@ -2046,6 +2046,16 @@ pwdgrp::fetch_account_from_windows (fetch_user_arg_t &arg, cyg_ldap *pldap)
       /* We can skip the backslash in the rest of this function. */
       if (p)
 	name = p + 1;
+      /* Reverse lookup name from sid to make sure the username in
+	 our passwd/group data is written exactly as in the user DB. */
+      nlen = UNLEN + 1;
+      dlen = DNLEN + 1;
+      ret = LookupAccountSidW (NULL, sid, name, &nlen, dom, &dlen, &acc_type);
+      if (!ret)
+	{
+	  system_printf ("LookupAccountNameW (%W), %E", name);
+	  return NULL;
+	}
       /* Last but not least, some validity checks on the name style. */
       if (!fq_name)
 	{