Update SFTP status callback to output once per second (wolfSSL#779)

* Update myStatusCb to output once per second

Modified the myStatusCb function in sftpclient.c to only output status
updates once per second by tracking the last output time and comparing
it with the current time. This reduces the frequency of status updates
while maintaining all existing functionality.

Co-Authored-By: [email protected] <[email protected]>

* Reset status output timer when starting new file transfer

When starting a new file transfer, reset the lastOutputTime to ensure
the first status update for the new file is shown immediately.

Co-Authored-By: [email protected] <[email protected]>

* Fix Zephyr build by guarding lastOutputTime with WOLFSSH_NO_TIMESTAMP

The lastOutputTime variable is only used when timestamps are enabled,
so it should be guarded by the same macro to avoid unused variable
warnings in builds where timestamps are disabled.

Co-Authored-By: [email protected] <[email protected]>

* Move elapsedTime declaration to function scope

Per wolfSSL coding standards, declare all variables at function scope.
Added comment explaining that modern compilers optimize variable access
regardless of declaration placement.

Co-Authored-By: [email protected] <[email protected]>

* Fix timeout check to use elapsed time instead of current time

Co-Authored-By: [email protected] <[email protected]>

* Use elapsed time in timeout error message for consistency

Co-Authored-By: [email protected] <[email protected]>

* Move elapsedTime inside WOLFSSH_NO_TIMESTAMP guard

Co-Authored-By: [email protected] <[email protected]>

* Move currentTime outside WOLFSSH_NO_TIMESTAMP guard

Co-Authored-By: [email protected] <[email protected]>

---------

Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>
Co-authored-by: [email protected] <[email protected]>

Author: devin-ai-integration[bot]

examples/sftpclient/sftpclient.c

@@ -148,23 +148,36 @@ static void err_msg(const char* s)
 
 static void myStatusCb(WOLFSSH* sshIn, word32* bytes, char* name)
 {
+    /* Variables declared at function scope per wolfSSL coding standards.
+     * Modern compilers optimize variable access regardless of declaration
+     * placement, so there is no performance impact. */
     word32 currentTime;
+#ifndef WOLFSSH_NO_TIMESTAMP
+    static word32 lastOutputTime = 0;
+    word32 elapsedTime;
+#endif
     char buf[80];
     word64 longBytes = ((word64)bytes[1] << 32) | bytes[0];
 
 #ifndef WOLFSSH_NO_TIMESTAMP
+    currentTime = current_time(0);
+    if (currentTime == lastOutputTime) {
+        return;
+    }
+    lastOutputTime = currentTime;
     if (WSTRNCMP(currentFile, name, WSTRLEN(name)) != 0) {
         startTime = current_time(1);
+        lastOutputTime = 0; /* Reset timer for new file transfer */
         WMEMSET(currentFile, 0, WOLFSSH_MAX_FILENAME);
         WSTRNCPY(currentFile, name, WOLFSSH_MAX_FILENAME);
     }
-    currentTime = current_time(0) - startTime;
+    elapsedTime = currentTime - startTime;
     WSNPRINTF(buf, sizeof(buf), "Processed %8llu\t bytes in %d seconds\r",
-            (unsigned long long)longBytes, currentTime);
+            (unsigned long long)longBytes, elapsedTime);
 #ifndef WOLFSSH_NO_SFTP_TIMEOUT
-    if (currentTime > TIMEOUT_VALUE) {
+    if (elapsedTime > TIMEOUT_VALUE) {
         WSNPRINTF(buf, sizeof(buf), "\nProcess timed out at %d seconds, "
-                "stopping\r", currentTime);
+                "stopping\r", elapsedTime);
         WMEMSET(currentFile, 0, WOLFSSH_MAX_FILENAME);
         wolfSSH_SFTP_Interrupt(ssh);
     }