Package: apt-listchanges
Version: 3.24
Severity: normal
Tags: patch
Dear Maintainer,
when using the "--confirm" option, apt-listchanges writes a prompt to
stderr, flushes stderr and waits for the user to confirm before
continuing. This assumes that the frontend already informed the user
about all relevant changes.
When using the "text" frontend, those changelogs will have been written
to stdout. But unless stdout is a tty, they will have not yet been
flushed.
That means everything works fine if stdout is a tty:
$ apt-listchanges --confirm --frontend=text --latest=1
/var/cache/apt/archives/apt_1.8.2.3_amd64.deb
apt-listchanges: Reading changelogs...
apt-listchanges: News
---------------------
[...]
apt-listchanges: Changelogs
---------------------------
[...]
apt-listchanges: Do you want to continue? [Y/n]
But if stdout is something else, stdout is not flushed before waiting
for user input. The user is asked to confirm changes, they have not yet
seen:
$ apt-listchanges --confirm --frontend=text --latest=1
/var/cache/apt/archives/apt_1.8.2.3_amd64.deb | cat
apt-listchanges: Do you want to continue? [Y/n]
Only after the user gives an answer, the actual changelogs appear:
$ apt-listchanges --confirm --frontend=text --latest=1
/var/cache/apt/archives/apt_1.8.2.3_amd64.deb | cat
apt-listchanges: Do you want to continue? [Y/n] y
apt-listchanges: Reading changelogs...
apt-listchanges: News
---------------------
[...]
apt-listchanges: Changelogs
---------------------------
[...]
To be able to make an informed decision on whether to continue, the user
should be able to see the changelog before having to answer the prompt.
To facilitate this, apt-listchanges should flush stdout before propting
the user:
--- /usr/share/apt-listchanges/apt_listchanges.py.orig
+++ /usr/share/apt-listchanges/apt_listchanges.py
@@ -295,6 +295,7 @@
return enc.from_bytes(tty.readline()).rstrip()
def confirm(self):
+ sys.stdout.flush()
response = self.ttyask('apt-listchanges: ' + _('Do you want to
continue? [Y/n] '))
return response == '' or re.search(locale.nl_langinfo(locale.YESEXPR),
response)
--
-- Package-specific info:
==> /etc/apt/listchanges.conf <==
[apt]
frontend=pager
which=news
email_address=root
email_format=text
confirm=false
headers=false
reverse=false
save_seen=/var/lib/apt/listchanges.db
-- System Information:
Debian Release: 11.6
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 4.19.0 (SMP w/4 CPU threads)
Kernel taint flags: TAINT_WARN, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8), LANGUAGE not set
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
Versions of packages apt-listchanges depends on:
ii apt 2.2.4
ii debconf [debconf-2.0] 1.5.77
ii python3 3.9.2-3
ii python3-apt 2.2.1
ii python3-debconf 1.5.77
ii sensible-utils 0.0.14
ii ucf 3.0043
apt-listchanges recommends no packages.
Versions of packages apt-listchanges suggests:
ii lynx [www-browser] 2.9.0dev.6-3~deb11u1
ii postfix [mail-transport-agent] 3.5.17-0+deb11u1
pn python3-gi <none>
pn x-terminal-emulator <none>
-- debconf information excluded
