port, scp: distinguish end of directory from enumeration failure

- WS_FindNextFileA_ex() takes a lastError out-parameter and carries
  the body of WS_FindNextFileA(), which now calls it with NULL. A
  failing return reports the FindNextFileW() error, or
  ERROR_NO_UNICODE_TRANSLATION when the name would not convert.
- FindNextDirEntry() calls WS_FindNextFileA_ex() on Windows. An
  ERROR_NO_MORE_FILES result frees ctx->entry, sets it to NULL and
  returns WS_NEXT_ERROR so the caller pops the directory; every other
  error still returns WS_FATAL_ERROR.

Issue: F-13316

src/port.c

@@ -326,21 +326,35 @@ void* WS_FindFirstFileA(const char* fileName,
 }
 
 
-int WS_FindNextFileA(void* findHandle,
-        char* realFileName, size_t realFileNameSz)
+int WS_FindNextFileA_ex(void* findHandle,
+        char* realFileName, size_t realFileNameSz, unsigned long* lastError)
 {
     BOOL success;
     WIN32_FIND_DATAW findFileData;
-    errno_t error = 0;
+    unsigned long err = 0;
 
     success = FindNextFileW((HANDLE)findHandle, &findFileData);
 
     if (success) {
-        error = wcstombs_s(NULL, realFileName, realFileNameSz,
-            findFileData.cFileName, realFileNameSz);
+        if (wcstombs_s(NULL, realFileName, realFileNameSz,
+                findFileData.cFileName, realFileNameSz) != 0)
+            err = (unsigned long)ERROR_NO_UNICODE_TRANSLATION;
+    }
+    else {
+        err = (unsigned long)GetLastError();
     }
 
-    return (success != 0) && (error == 0);
+    if (lastError != NULL)
+        *lastError = err;
+
+    return (success != 0) && (err == 0);
+}
+
+
+int WS_FindNextFileA(void* findHandle,
+        char* realFileName, size_t realFileNameSz)
+{
+    return WS_FindNextFileA_ex(findHandle, realFileName, realFileNameSz, NULL);
 }
 
 

src/wolfscp.c

@@ -3021,10 +3021,20 @@ static int FindNextDirEntry(void *fs, ScpSendCtx* ctx)
     do {
         char realFileName[MAX_PATH];
         int  sz;
+        unsigned long lastError;
 
-        if (WS_FindNextFileA(ctx->currentDir->dir,
-            realFileName, sizeof(realFileName)) == 0) {
-            return WS_FATAL_ERROR;
+        if (WS_FindNextFileA_ex(ctx->currentDir->dir,
+            realFileName, sizeof(realFileName), &lastError) == 0) {
+            if (lastError != ERROR_NO_MORE_FILES) {
+                return WS_FATAL_ERROR;
+            }
+
+            /* end of directory, leave entry NULL so the caller pops it */
+            if (ctx->entry != NULL) {
+                WFREE(ctx->entry, NULL, DYNTYPE_SCPDIR);
+                ctx->entry = NULL;
+            }
+            return WS_NEXT_ERROR;
         }
 
         sz = (int)WSTRLEN(realFileName);

wolfssh/port.h

@@ -580,6 +580,10 @@ extern "C" {
                     void* heap);
             WOLFSSH_API int WS_FindNextFileA(void* findHandle,
                     char* realFileName, size_t realFileNameSz);
+            /* lastError is set on every return, 0 on success */
+            WOLFSSH_LOCAL int WS_FindNextFileA_ex(void* findHandle,
+                    char* realFileName, size_t realFileNameSz,
+                    unsigned long* lastError);
             WOLFSSH_LOCAL int WS_GetFileAttributesExA(const char* fileName,
                     void* fileInfo, void* heap);
             WOLFSSH_LOCAL int WS_RemoveDirectoryA(const char* dirName,