[PATCH v3] kernel32: make GetEnvironmentStringsW returns a copy of the environment

[Jon Doron]

There are certain applications which try to traverse the environement
being returned, but this is problematic since they cannot acquire the
PEB Lock (i.e cl.exe on Visual Studio 14.15) .

To resolve the issue provide a copy of the current environment same as
in GetEnvironmentStringsA .

Signed-off-by: Jon Doron <arilou(a)gmail.com>
---
 dlls/kernel32/environ.c       | 27 +++++++++++++++++++++++++--
 dlls/kernel32/tests/environ.c | 15 +++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/dlls/kernel32/environ.c b/dlls/kernel32/environ.c
index 99bf706e95..5a5f50340e 100644
--- a/dlls/kernel32/environ.c
+++ b/dlls/kernel32/environ.c
@@ -139,7 +139,30 @@ LPSTR WINAPI GetEnvironmentStringsA(void)
  */
 LPWSTR WINAPI GetEnvironmentStringsW(void)
 {
-    return NtCurrentTeb()->Peb->ProcessParameters->Environment;
+    LPWSTR ret, ptrW;
+    unsigned len;
+
+    RtlAcquirePebLock();
+
+    ptrW = NtCurrentTeb()->Peb->ProcessParameters->Environment;
+    if (!ptrW || !*ptrW)
+    {
+        RtlReleasePebLock();
+        return HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(WCHAR) * 2);
+    }
+
+    while (*ptrW)
+        ptrW += strlenW(ptrW) + 1;
+
+    len = (ULONG_PTR)ptrW - (ULONG_PTR)NtCurrentTeb()->Peb->ProcessParameters->Environment;
+    ret = HeapAlloc(GetProcessHeap(), 0, len + sizeof(WCHAR));
+    if (ret) {
+        memcpy(ret, NtCurrentTeb()->Peb->ProcessParameters->Environment, len);
+        ret[len / 2] = 0;
+    }
+
+    RtlReleasePebLock();
+    return ret;
 }
 
 
@@ -157,7 +180,7 @@ BOOL WINAPI FreeEnvironmentStringsA( LPSTR ptr )
  */
 BOOL WINAPI FreeEnvironmentStringsW( LPWSTR ptr )
 {
-    return TRUE;
+    return HeapFree( GetProcessHeap(), 0, ptr );
 }
 
 
diff --git a/dlls/kernel32/tests/environ.c b/dlls/kernel32/tests/environ.c
index f8452be2ee..4249ea7ebe 100644
--- a/dlls/kernel32/tests/environ.c
+++ b/dlls/kernel32/tests/environ.c
@@ -554,6 +554,20 @@ static void test_GetComputerNameExW(void)
     HeapFree(GetProcessHeap(), 0, nameW);
 }
 
+static void test_GetEnvironmentStringsW(void)
+{
+    PWCHAR env1;
+    PWCHAR env2;
+
+    env1 = GetEnvironmentStringsW();
+    env2 = GetEnvironmentStringsW();
+    ok(env1 != env2 ||
+       broken(env1 == env2), /* NT <= 5.1 */
+       "should return different copies\n");
+    FreeEnvironmentStringsW(env1);
+    FreeEnvironmentStringsW(env2);
+}
+
 START_TEST(environ)
 {
     init_functionpointers();
@@ -565,4 +579,5 @@ START_TEST(environ)
     test_GetComputerName();
     test_GetComputerNameExA();
     test_GetComputerNameExW();
+    test_GetEnvironmentStringsW();
 }
-- 
2.19.2