Re: bin/59587: ftp client ascii transfers with progress report fail

["Luke Mewburn via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR bin/59587; it has been noted by GNATS.

From: Luke Mewburn <luke%mewburn.net@localhost>
To: Taylor R Campbell <riastradh%netbsd.org@localhost>
Cc: Luke Mewburn <lukem%netbsd.org@localhost>, source-changes-d%netbsd.org@localhost,
	gnats-bugs%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost,
	Johnny Billquist <bqt%softjar.se@localhost>
Subject: Re: bin/59587: ftp client ascii transfers with progress report fail
Date: Thu, 15 Jan 2026 16:34:48 +1100

 On 26-01-15 04:19, Taylor R Campbell wrote:
   | > From: Taylor R Campbell <riastradh%NetBSD.org@localhost>
   | > 
   | > > Module Name:    src
   | > > Committed By:   lukem
   | > > Date:           Sat Dec  6 06:20:23 UTC 2025
   | > > 
   | > > Modified Files:
   | > >         src/usr.bin/ftp: extern.h ftp.c util.c version.h
   | > > 
   | > > Log Message:
   | > > ftp: fix ascii transfers with progress bar
   | > > 
   | > > Handle stdio interruption by signals and improve error handling
   | > > in getc() and putc() on the control and data channels.
   | > > Provide ftp_getc() and ftp_putc() wrappers that:
   | > > - Retry the operation on EINTR or EAGAIN instead of failing.
   | 
   | Alternatively: Why not use SA_RESTART, so you don't have to track down
   | all the I/O logic that might be interrupted by a signal and arrange to
   | run it in a loop?
 
 Even on NetBSD, the previous use of restartable signals (SA_RESTART)
 caused issues with the implementation of -q QUITTIME.
 That's why I changed ftp 20210106 to always use interruptable
 signals for PR 55857 - as confirmed by the submitter.
 
 
   | There's nothing here that behaves differently if it received a signal,
   | like printing a progress bar if the I/O was interrupted by a signal --
   | that's already done in the signal handler itself, isn't it?
   | 
   | (Except you should probably use snprintf_ss, not snprintf, in
   | progressbar.c, if you want to print the progress bar in the signal
   | handler itself: snprintf is technically not async-signal-safe.  In
   | practice on NetBSD, though, I think it matters only for the
   | floating-point formatters, which may use malloc in gdtoa; the rest of
   | it like %d and %s is probably safe.)