tidy-up: comments, messages, formatting

- 'null-terminate', sync casing.
- add an `#endif` comment.
- avoid a few instances of 'will'.
- configure: 'aws' -> 'aws-sigv4', where missing.
- unfold/fold lines.
- update memzero/strzero comments.
- uppercase 'CRLF'.

Closes #22443

tests/ftpserver.pl

@@ -2574,8 +2574,8 @@ sub PASV_ftp {
         sendcontrol sprintf("229 Entering Passive Mode (|||%d|)\r\n", $pasvport);
     }
 
-    logmsg "Client has been notified that DATA conn ".
-           "will be accepted on port $pasvport\n";
+    logmsg "Client has been notified that upcoming DATA connection ".
+           "is awaited on port $pasvport\n";
 
     if($nodataconn) {
         my $str = nodataconn_str();
@@ -2765,7 +2765,7 @@ sub datasockf_state {
     }
     elsif($state eq 'PASSIVE_NODATACONN') {
         # Data sockfilter bound port without listening,
-        # client will not be able to establish data connection.
+        # client is unable to establish data connection.
         $datasockf_state = $state;
         $datasockf_mode = 'passive';
         $datasockf_runs = 'yes';

tests/negtelnetserver.py

@@ -126,7 +126,7 @@ class Negotiator:
         """
         buffer = bytearray()
 
-        # If we keep receiving negotiation sequences, we will not fill the buffer.
+        # If we keep receiving negotiation sequences, we do not fill the buffer.
         # Keep looping while we can, and until we have something to give back
         # to the caller.
         while len(buffer) == 0:

tests/server/tftpd.c

@@ -186,7 +186,7 @@ static struct bf bfs[2];
 static int nextone;     /* index of next buffer to use */
 static int current;     /* index of buffer in use */
 
-                           /* control flags for crlf conversions */
+                           /* control flags for CRLF conversions */
 static int newline = 0;    /* fillbuf: in middle of newline expansion */
 static int prevchar = -1;  /* putbuf: previous char (cr check) */
 
@@ -296,7 +296,7 @@ static void nak(int error)
  */
 static struct tftphdr *rw_init(int x)
 {
-  newline = 0;                    /* init crlf flag */
+  newline = 0;                    /* init CRLF flag */
   prevchar = -1;
   bfs[0].counter = BF_ALLOC;      /* pass out the first buffer */
   current = 0;