Vladimir Panteleev : kernelbase: Fix GetEnvironmentVariableW return for empty variables.

[Alexandre Julliard]

Module: wine
Branch: stable
Commit: 094ad5199ace418822a38e412d01ef6421a19f45
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=094ad5199ace418822a38e412...

Author: Vladimir Panteleev <git(a)vladimir.panteleev.md>
Date:   Thu May 14 23:12:26 2020 +0200

kernelbase: Fix GetEnvironmentVariableW return for empty variables.

Do the same thing as Vista and up.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=48471
Signed-off-by: Vladimir Panteleev <git(a)vladimir.panteleev.md>
Signed-off-by: Gijs Vermeulen <gijsvrm(a)gmail.com>
Signed-off-by: Alexandre Julliard <julliard(a)winehq.org>
(cherry picked from commit c4ef987429cef13bec1b7762bd70d99fee10670c)
Signed-off-by: Michael Stefaniuc <mstefani(a)winehq.org>

---

 dlls/kernel32/tests/environ.c | 20 ++++++++++++++++++++
 dlls/kernelbase/process.c     |  3 ++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/dlls/kernel32/tests/environ.c b/dlls/kernel32/tests/environ.c
index ff822d0349..3144b8e04e 100644
--- a/dlls/kernel32/tests/environ.c
+++ b/dlls/kernel32/tests/environ.c
@@ -166,6 +166,16 @@ static void test_GetSetEnvironmentVariableA(void)
        "%s should be set to \"\" (NT) or removed (Win9x) but ret_size=%d GetLastError=%d and buf=%s\n",
        name, ret_size, GetLastError(), buf);
 
+    SetLastError(0xdeadbeef);
+    ret_size = GetEnvironmentVariableA(name, NULL, 0);
+    ok(ret_size == 1 ||
+       broken(ret_size == 0), /* XP */
+       "should return 1 for empty string but ret_size=%d GetLastError=%d\n",
+       ret_size, GetLastError());
+    ok(GetLastError() == 0xdeadbeef ||
+       broken(GetLastError() == ERROR_MORE_DATA), /* XP */
+       "should not fail with zero size but GetLastError=%d\n", GetLastError());
+
     /* Test the limits */
     SetLastError(0xdeadbeef);
     ret_size = GetEnvironmentVariableA(NULL, NULL, 0);
@@ -275,6 +285,16 @@ static void test_GetSetEnvironmentVariableW(void)
        ret_size, GetLastError());
     ok(lstrcmpW(buf, empty_strW) == 0, "should copy an empty string\n");
 
+    SetLastError(0xdeadbeef);
+    ret_size = GetEnvironmentVariableW(name, NULL, 0);
+    ok(ret_size == 1 ||
+       broken(ret_size == 0), /* XP */
+       "should return 1 for empty string but ret_size=%d GetLastError=%d\n",
+       ret_size, GetLastError());
+    ok(GetLastError() == 0xdeadbeef ||
+       broken(GetLastError() == ERROR_MORE_DATA), /* XP */
+       "should not fail with zero size but GetLastError=%d\n", GetLastError());
+
     /* Test the limits */
     SetLastError(0xdeadbeef);
     ret_size = GetEnvironmentVariableW(NULL, NULL, 0);
diff --git a/dlls/kernelbase/process.c b/dlls/kernelbase/process.c
index ec8b6eabab..3cd2934c20 100644
--- a/dlls/kernelbase/process.c
+++ b/dlls/kernelbase/process.c
@@ -1284,7 +1284,8 @@ DWORD WINAPI DECLSPEC_HOTPATCH GetEnvironmentVariableW( LPCWSTR name, LPWSTR val
     len = us_value.Length / sizeof(WCHAR);
     if (status == STATUS_BUFFER_TOO_SMALL) return len + 1;
     if (!set_ntstatus( status )) return 0;
-    if (size) val[len] = 0;
+    if (!size) return len + 1;
+    val[len] = 0;
     return len;
 }