Fix remaining MinGW build errors in the regress/unit test build

apps/wolfssh/common.c declared a CONSOLE_SCREEN_BUFFER_INFO local in
ClientSetEcho that nothing ever read; the Windows echo toggling never
grew the code that would have used it. Drop the unused declaration.

wolfssh/port.h defined WSTRSEP as strsep(), a BSD extension MSVCRT
and MinGW do not provide. Add a portable wstrsep() in src/port.c,
matching the wstrnstr/wstrncat/wstrdup pattern already used for other
missing string functions, and route WSTRSEP through it under
USE_WINDOWS_API.

tests/regress.c called the two argument POSIX mkdir(path, mode) and
setenv()/unsetenv() directly in TestKnownHostsLastEntry. Use the
existing WMKDIR macro for the directory creation, and add small
TEST_SETENV/TEST_UNSETENV macros backed by _putenv_s() on Windows so
the HOME juggling this test does still works there.

src/wolfsftp.c had three separate issues in code paths that had never
been compiled before this job existed. wolfSSH_SFTP_RecvOpen declared
a flagsAndAttrs DWORD that nothing read, since WS_CreateFileA is
called with a hardcoded FILE_ATTRIBUTE_NORMAL instead.
wolfSSH_SFTP_RecvOpenDir compared a signed loop counter against a
sizeof expression while building ssh->driveList, so make the counter
word32. wolfSSH_SFTP_Put passed &state->rSz, an int, to ReadFile()'s
DWORD* output parameter; read into a local DWORD and copy it into
state->rSz afterward, since that field is also assigned from
WFREAD() on non-Windows builds.

src/wolfterm.c's wolfSSH_DoOSC never used its handle parameter. Mark
it with WOLFSSH_UNUSED rather than removing it, since the parameter
matches the signature its two call sites already pass and future OSC
handling such as window titles is a natural use for it.

Verified against a real x86_64-w64-mingw32 cross compiler with a
config.h edited to match the sizes and header availability the
actual Windows CI run reported (SIZEOF_LONG 4, HAVE_SYS_IOCTL_H
undefined, and so on): every file this job compiles builds cleanly
under the same -Werror flag set. Also reconfirmed a clean, unmodified
Linux build still passes both tests/regress.test and tests/unit.test.

apps/wolfssh/common.c

@@ -721,7 +721,6 @@ int ClientSetEcho(int type)
 #else
     static int echoInit = 0;
     static DWORD originalTerm;
-    static CONSOLE_SCREEN_BUFFER_INFO screenOrig;
     HANDLE stdinHandle = GetStdHandle(STD_INPUT_HANDLE);
     if (!echoInit) {
         if (GetConsoleMode(stdinHandle, &originalTerm) == 0) {

src/port.c

@@ -939,4 +939,32 @@ char* wstrncat(char* s1, const char* s2, size_t n)
     return NULL;
 }
 
+
+#ifdef USE_WINDOWS_API
+/* strsep() equivalent for platforms whose C library does not provide the
+ * BSD extension (MSVCRT/MinGW). Splits *s1 on the first character found
+ * in delim, NUL-terminates the token in place, and advances *s1 past it
+ * (NULL when no delimiter remains). Returns the start of the token, or
+ * NULL if *s1 was already NULL. */
+char* wstrsep(char** s1, const char* delim)
+{
+    char* start = *s1;
+    char* p;
+
+    if (start == NULL)
+        return NULL;
+
+    for (p = start; *p != '\0'; p++) {
+        if (WSTRCHR(delim, *p) != NULL) {
+            *p = '\0';
+            *s1 = p + 1;
+            return start;
+        }
+    }
+
+    *s1 = NULL;
+    return start;
+}
+#endif /* USE_WINDOWS_API */
+
 #endif /* WSTRING_USER */

src/wolfsftp.c

@@ -2622,7 +2622,6 @@ cleanup:
     word32 idx = 0;
     DWORD desiredAccess = 0;
     DWORD creationDisp = 0;
-    DWORD flagsAndAttrs = 0;
     int ret = WS_SUCCESS;
     int rc;
     int fileHandleOpened = 0;
@@ -3037,7 +3036,7 @@ int wolfSSH_SFTP_RecvOpenDir(WOLFSSH* ssh, int reqId, byte* data, word32 maxSz)
         DWORD drives, mask;
         UINT driveType;
         char driveName[] = " :\\";
-        int i;
+        word32 i;
 
         WMEMSET(ssh->driveList, 0, sizeof ssh->driveList);
         ssh->driveListCount = 0;
@@ -10401,11 +10400,16 @@ int wolfSSH_SFTP_Put(WOLFSSH* ssh, char* from, char* to, byte resume,
                             break; /* either at end of file or error */
                         }
                     #else /* USE_WINDOWS_API */
+                        /* ReadFile() wants a DWORD* out param; state->rSz is
+                         * an int shared with the WFREAD() branch above. */
+                        DWORD wRSz = 0;
+
                         if (ReadFile(state->fileHandle, state->r,
-                                     WOLFSSH_MAX_SFTP_RW, &state->rSz,
+                                     WOLFSSH_MAX_SFTP_RW, &wRSz,
                                      &state->offset) == 0) {
                             break; /* either at end of file or error */
                         }
+                        state->rSz = (int)wRSz;
                     #endif /* USE_WINDOWS_API */
                     }
                     sz = wolfSSH_SFTP_SendWritePacket(ssh,

src/wolfterm.c

@@ -374,6 +374,8 @@ static int wolfSSH_DoOSC(WOLFSSH* ssh, WOLFSSH_HANDLE handle, byte* buf,
      * not saved to escBuf and escState is never set to WS_ESC_OSC, so there is
      * no resume path. Returning WS_SUCCESS lets the caller advance past the
      * sequence and reset escState cleanly. */
+    WOLFSSH_UNUSED(handle);
+
     if (*idx >= bufSz) {
         /* missing the OSC command byte, drop the sequence */
         return WS_SUCCESS;

tests/regress.c

@@ -13357,6 +13357,17 @@ static int KnownHostsCheckCapture(const byte* pubKey, word32 pubKeySz,
 }
 
 
+/* setenv()/unsetenv() are POSIX and have no MSVCRT equivalent; _putenv_s()
+ * matches their (name, value) shape and success/failure return closely
+ * enough for this test's own HOME juggling. */
+#ifdef USE_WINDOWS_API
+    #define TEST_SETENV(n,v)   _putenv_s((n), (v))
+    #define TEST_UNSETENV(n)   _putenv_s((n), "")
+#else
+    #define TEST_SETENV(n,v)   setenv((n), (v), 1)
+    #define TEST_UNSETENV(n)   unsetenv((n))
+#endif
+
 /* known_hosts is a text file and POSIX lets its last line end without a
  * newline, and a file written on Windows ends its lines with CRLF. Match the
  * last entry with a trailing newline, without one, and with CRLF line
@@ -13421,9 +13432,9 @@ static void TestKnownHostsLastEntry(void)
     (void)rmdir(homeDir);
 
     /* Use a single flag to avoid duplicate errors below. */
-    ready = (mkdir(homeDir, 0700) == 0)
-            && (mkdir(sshDir, 0700) == 0)
-            && (setenv("HOME", homeDir, 1) == 0);
+    ready = (WMKDIR(NULL, homeDir, 0700) == 0)
+            && (WMKDIR(NULL, sshDir, 0700) == 0)
+            && (TEST_SETENV("HOME", homeDir) == 0);
     AssertTrue(ready);
 
     /* A regression falls through to the "add it to known hosts?" prompt, so
@@ -13486,11 +13497,11 @@ static void TestKnownHostsLastEntry(void)
     }
 
     if (savedHome != NULL) {
-        AssertIntEQ(setenv("HOME", savedHome, 1), 0);
+        AssertIntEQ(TEST_SETENV("HOME", savedHome), 0);
         WFREE(savedHome, NULL, 0);
     }
     else {
-        unsetenv("HOME");
+        TEST_UNSETENV("HOME");
     }
 
     (void)remove(hostsPath);

wolfssh/port.h

@@ -632,7 +632,6 @@ extern "C" {
     #define WSTRNCMP(s1,s2,n) strncmp((s1),(s2),(n))
     #define WSTRSPN(s1,s2)    strspn((s1),(s2))
     #define WSTRCSPN(s1,s2)   strcspn((s1),(s2))
-    #define WSTRSEP(s,d)      strsep((s),(d))
     #define WSTRCAT(s1,s2)    strcat((s1),(s2))
     #define WSTRCPY(s1,s2)    strcpy((s1),(s2))
 
@@ -645,6 +644,14 @@ extern "C" {
     #define WSTRDUP(s,h,t)    wstrdup((s),(h),(t))
     #define WSTRCHR(s,c) strchr((s),(c))
 
+    #ifndef USE_WINDOWS_API
+        #define WSTRSEP(s,d)      strsep((s),(d))
+    #else
+        /* strsep() is a BSD extension not provided by MSVCRT/MinGW */
+        WOLFSSH_API char* wstrsep(char** s1, const char* delim);
+        #define WSTRSEP(s,d)      wstrsep((s),(d))
+    #endif
+
     #ifdef USE_WINDOWS_API
         #define WSTRNCPY(s1,s2,n) strncpy_s((s1),(n),(s2),(n))
         #define WSTRNCASECMP(s1,s2,n) _strnicmp((s1),(s2),(n))