Index: sdk/lib/crt/misc/getargs.c
===================================================================
--- sdk/lib/crt/misc/getargs.c	(revision 72199)
+++ sdk/lib/crt/misc/getargs.c	(working copy)
@@ -181,16 +181,19 @@
  */
 void __getmainargs(int* argc, char*** argv, char*** env, int expand_wildcards, int* new_mode)
 {
-   int i, afterlastspace, ignorespace, doexpand;
+   int i, doexpand, slashesAdded, escapedQuote, inQuotes, bufferIndex;
    size_t len;
    char* aNewCmdln;
+   char* buffer;
 
    /* missing threading init */
 
    i = 0;
-   afterlastspace = 0;
-   ignorespace = 0;
    doexpand = expand_wildcards;
+   escapedQuote = FALSE;
+   slashesAdded = 0;
+   inQuotes = 0;
+   bufferIndex = 0;
 
    if (__argv && _environ)
    {
@@ -203,51 +206,87 @@
    __argc = 0;
 
    len = strlen(_acmdln);
+   buffer = malloc(sizeof(char) * len);
 
-   /* Allocate a temporary buffer to be used instead of the original _acmdln parameter. */
-   aNewCmdln = strndup(_acmdln, len);
-
-   while (aNewCmdln[i])
+   // Reference: https://msdn.microsoft.com/en-us/library/a1y7w461(v=vs.71).aspx
+   while (TRUE)
    {
-      if (aNewCmdln[i] == '"')
-      {
-         if(ignorespace)
-         {
-            ignorespace = 0;
-         }
-         else
-         {
-            ignorespace = 1;
-            doexpand = 0;
-         }
-         memmove(aNewCmdln + i, aNewCmdln + i + 1, len - i);
-         len--;
-         continue;
-      }
+       // Arguments are delimited by white space, which is either a space or a tab.
+       if (i >= len || (_acmdln[i] == ' ' || _acmdln[i] == '\t') && !inQuotes)
+       {
+           aexpand(strndup(buffer, bufferIndex), doexpand);
+           // Copy the last element from buffer and quit the loop
+           if (i >= len)
+           {
+               break;
+           }
 
-      if (aNewCmdln[i] == ' ' && !ignorespace)
-      {
-         aexpand(strndup(aNewCmdln + afterlastspace, i - afterlastspace), doexpand);
-         i++;
-         while (aNewCmdln[i] == ' ')
-            i++;
-         afterlastspace=i;
-         doexpand = expand_wildcards;
-      }
-      else
-      {
-         i++;
-      }
-   }
+           while (_acmdln[i] == ' ' || _acmdln[i] == '\t')
+               ++i;
+           bufferIndex = 0;
+           slashesAdded = 0;
+           escapedQuote = FALSE;
+           continue;
+       }
 
-   if (aNewCmdln[afterlastspace] != 0)
-   {
-      aexpand(strndup(aNewCmdln + afterlastspace, i - afterlastspace), doexpand);
+       if (_acmdln[i] == '\\')
+       {
+            buffer[bufferIndex++] = _acmdln[i];
+            ++slashesAdded;
+            ++i;
+            escapedQuote = FALSE;
+            continue;
+       }
+
+       if (_acmdln[i] == '\"')
+       {
+           if (slashesAdded > 0)
+           {
+               if (slashesAdded % 2 == 0)
+               {
+                   // If an even number of backslashes is followed by a double quotation mark, then one backslash (\)
+                   // is placed in the argv array for every pair of backslashes (\\), and the double quotation mark (")
+                   // is interpreted as a string delimiter.
+                   bufferIndex -= slashesAdded / 2;
+               }
+               else
+               {
+                   // If an odd number of backslashes is followed by a double quotation mark, then one backslash (\)
+                   // is placed in the argv array for every pair of backslashes (\\) and the double quotation mark is
+                   // interpreted as an escape sequence by the remaining backslash, causing a literal double quotation mark (")
+                   // to be placed in argv.
+                   bufferIndex -= slashesAdded / 2 + 1;
+                   buffer[bufferIndex++] = '\"';
+                   slashesAdded = 0;
+                   escapedQuote = TRUE;
+                   ++i;
+                   continue;
+               }
+               slashesAdded = 0;
+           }
+           else if (!inQuotes && i > 0 && _acmdln[i - 1] == '\"' && !escapedQuote)
+           {
+               buffer[bufferIndex++] = '\"';
+               ++i;
+               escapedQuote = TRUE;
+               continue;
+           }
+           slashesAdded = 0;
+           escapedQuote = FALSE;
+           inQuotes = !inQuotes;
+           doexpand = inQuotes ? FALSE : expand_wildcards;
+           ++i;
+           continue;
+       }
+
+       buffer[bufferIndex++] = _acmdln[i];
+       slashesAdded = 0;
+       escapedQuote = FALSE;
+       ++i;
    }
 
    /* Free the temporary buffer. */
-   free(aNewCmdln);
-
+   free(buffer);
    HeapValidate(GetProcessHeap(), 0, NULL);
 
    *argc = __argc;
@@ -269,16 +308,18 @@
 void __wgetmainargs(int* argc, wchar_t*** wargv, wchar_t*** wenv,
                     int expand_wildcards, int* new_mode)
 {
-   int i, afterlastspace, ignorespace, doexpand;
+   int i, doexpand, slashesAdded, escapedQuote, inQuotes, bufferIndex;
    size_t len;
-   wchar_t* wNewCmdln;
+   wchar_t* buffer;
 
    /* missing threading init */
 
    i = 0;
-   afterlastspace = 0;
-   ignorespace = 0;
    doexpand = expand_wildcards;
+   escapedQuote = FALSE;
+   slashesAdded = 0;
+   inQuotes = 0;
+   bufferIndex = 0;
 
    if (__wargv && __winitenv)
    {
@@ -289,52 +330,88 @@
    }
 
    __argc = 0;
-
    len = wcslen(_wcmdln);
+   buffer = malloc(sizeof(wchar_t) * len);
 
-   /* Allocate a temporary buffer to be used instead of the original _wcmdln parameter. */
-   wNewCmdln = wcsndup(_wcmdln, len);
-
-   while (wNewCmdln[i])
+   // Reference: https://msdn.microsoft.com/en-us/library/a1y7w461(v=vs.71).aspx
+   while (TRUE)
    {
-      if (wNewCmdln[i] == L'"')
-      {
-         if(ignorespace)
-         {
-            ignorespace = 0;
-         }
-         else
-         {
-            ignorespace = 1;
-            doexpand = 0;
-         }
-         memmove(wNewCmdln + i, wNewCmdln + i + 1, (len - i) * sizeof(wchar_t));
-         len--;
-         continue;
-      }
+       // Arguments are delimited by white space, which is either a space or a tab.
+       if (i >= len || (_wcmdln[i] == ' ' || _wcmdln[i] == '\t') && !inQuotes)
+       {
+           wexpand(wcsndup(buffer, bufferIndex), doexpand);
+           // Copy the last element from buffer and quit the loop
+           if (i >= len)
+           {
+               break;
+           }
 
-      if (wNewCmdln[i] == L' ' && !ignorespace)
-      {
-         wexpand(wcsndup(wNewCmdln + afterlastspace, i - afterlastspace), doexpand);
-         i++;
-         while (wNewCmdln[i] == L' ')
-            i++;
-         afterlastspace=i;
-         doexpand = expand_wildcards;
-      }
-      else
-      {
-         i++;
-      }
-   }
+           while (_wcmdln[i] == ' ' || _wcmdln[i] == '\t')
+               ++i;
+           bufferIndex = 0;
+           slashesAdded = 0;
+           escapedQuote = FALSE;
+           continue;
+       }
 
-   if (wNewCmdln[afterlastspace] != 0)
-   {
-      wexpand(wcsndup(wNewCmdln + afterlastspace, i - afterlastspace), doexpand);
+       if (_wcmdln[i] == '\\')
+       {
+            buffer[bufferIndex++] = _wcmdln[i];
+            ++slashesAdded;
+            ++i;
+            escapedQuote = FALSE;
+            continue;
+       }
+
+       if (_wcmdln[i] == '\"')
+       {
+           if (slashesAdded > 0)
+           {
+               if (slashesAdded % 2 == 0)
+               {
+                   // If an even number of backslashes is followed by a double quotation mark, then one backslash (\)
+                   // is placed in the argv array for every pair of backslashes (\\), and the double quotation mark (")
+                   // is interpreted as a string delimiter.
+                   bufferIndex -= slashesAdded / 2;
+               }
+               else
+               {
+                   // If an odd number of backslashes is followed by a double quotation mark, then one backslash (\)
+                   // is placed in the argv array for every pair of backslashes (\\) and the double quotation mark is
+                   // interpreted as an escape sequence by the remaining backslash, causing a literal double quotation mark (")
+                   // to be placed in argv.
+                   bufferIndex -= slashesAdded / 2 + 1;
+                   buffer[bufferIndex++] = '\"';
+                   slashesAdded = 0;
+                   escapedQuote = TRUE;
+                   ++i;
+                   continue;
+               }
+               slashesAdded = 0;
+           }
+           else if (!inQuotes && i > 0 && _wcmdln[i - 1] == '\"' && !escapedQuote)
+           {
+               buffer[bufferIndex++] = '\"';
+               ++i;
+               escapedQuote = TRUE;
+               continue;
+           }
+           slashesAdded = 0;
+           escapedQuote = FALSE;
+           inQuotes = !inQuotes;
+           doexpand = inQuotes ? FALSE : expand_wildcards;
+           ++i;
+           continue;
+       }
+
+       buffer[bufferIndex++] = _wcmdln[i];
+       slashesAdded = 0;
+       escapedQuote = FALSE;
+       ++i;
    }
 
    /* Free the temporary buffer. */
-   free(wNewCmdln);
+   free(buffer);
 
    HeapValidate(GetProcessHeap(), 0, NULL);
 
Index: modules/rostests/apitests/crt/__getmainargs.c
===================================================================
--- modules/rostests/apitests/crt/__getmainargs.c	(nonexistent)
+++ modules/rostests/apitests/crt/__getmainargs.c	(working copy)
@@ -0,0 +1,57 @@
+/*
+ * PROJECT:         ReactOS api tests
+ * LICENSE:         GPLv2+ - See COPYING in the top level directory
+ * PURPOSE:         Test for __getmainargs
+ * PROGRAMMER:      Yaroslav Veremenko <yaroslav@veremenko.info>
+ */
+
+#include <apitest.h>
+#include <stdio.h>
+#include <string.h>
+
+const char **__p__acmdln(void);
+void __getmainargs(int* argc, char*** argv, char*** env, int expand_wildcards, int* new_mode);
+
+#define winetest_ok_str(x, y) \
+    winetest_ok(strcmp(x, y) == 0, "Wrong string. Expected '%s', got '%s'\n", y, x)
+#define ok_args  (winetest_set_location(__FILE__, __LINE__), 0) ? (void)0 : ok_args_imp
+
+
+void
+ok_args_imp(const char* input_args, /*char** argv,*/ const char* arg1, const char* arg2, const char* arg3)
+{
+    int argc = 0, mode = 0;
+    char** argv, **env;
+
+    /* Remove cached argv, setup our input as program argument. */
+    *__p___argv() = NULL;
+    *__p__acmdln() = input_args;
+
+    /* Process the commandline stored in _acmdln */
+    __getmainargs(&argc, &argv, &env, 0, &mode);
+
+    winetest_ok(argc == 4, "Wrong value for argc, expected: 4, got: %d\n", argc);
+    if(argc != 4)
+        return;
+
+    winetest_ok_str(argv[0], "test.exe");
+    winetest_ok_str(argv[1], arg1);
+    winetest_ok_str(argv[2], arg2);
+    winetest_ok_str(argv[3], arg3);
+}
+
+START_TEST(__getmainargs)
+{
+    ok_args("test.exe \"a b c\" d e", "a b c", "d", "e");
+    ok_args("test.exe \"ab\\\"c\" \"\\\\\" d", "ab\"c", "\\", "d");
+    ok_args("test.exe a\\\\\\b d\"e f\"g h", "a\\\\\\b", "de fg", "h");
+    ok_args("test.exe a\\\\\\\"b c d", "a\\\"b", "c", "d");
+    ok_args("test.exe a\\\\\\\\\"b c\" d e", "a\\\\b c", "d", "e");
+    ok_args("test.exe a b \"\"", "a", "b", "");
+    ok_args("test.exe a \"\" b", "a", "", "b");
+    ok_args("test.exe a \"b\"\" c", "a", "b\"", "c");
+    ok_args("test.exe a \"b\\\"\" c", "a", "b\"", "c");
+    ok_args("test.exe a  \"  b\\  \"\"  c", "a", "  b\\  \"", "c");
+    ok_args("test.exe a  \"b\\  \"\"\"  c\" d", "a", "b\\  \"  c", "d");
+    ok_args("test.exe a  \"b\\  \"\"\"  \"c  \"\"\"\" d", "a", "b\\  \"  c", "\" d");
+}

Property changes on: rostests/apitests/crt/__getmainargs.c
___________________________________________________________________
Added: svn:eol-style
## -0,0 +1 ##
+native
\ No newline at end of property
Index: rostests/apitests/crt/msvcrt_crt_apitest.cmake
===================================================================
--- modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake	(revision 72199)
+++ modules/rostests/apitests/crt/msvcrt_crt_apitest.cmake	(working copy)
@@ -66,7 +66,7 @@
 #    __doserrno.c
 #    __fpecode.c
 #    __get_app_type.c
-#    __getmainargs.c
+    __getmainargs.c
 #    __initenv
 #    __iob_func.c
 #    __isascii.c
Index: modules/rostests/apitests/crt/testlist.c
===================================================================
--- modules/rostests/apitests/crt/testlist.c	(revision 72199)
+++ modules/rostests/apitests/crt/testlist.c	(working copy)
@@ -25,6 +25,7 @@
 extern void func_wcsnlen(void);
 extern void func_wcstombs(void);
 extern void func_wcstoul(void);
+extern void func___getmainargs(void);
 
 extern void func_static_construct(void);
 extern void func_static_init(void);
@@ -50,6 +51,7 @@
 #endif
 #if defined(TEST_STATIC_CRT)
 #elif defined(TEST_MSVCRT)
+    { "__getmainargs", func___getmainargs },
     { "_vscprintf", func__vscprintf },
     { "_vscwprintf", func__vscwprintf },