Recent gcc versions have started to trigger false positive
maybe-uninitialized warnings. Let's make sure we initialize
variables annotated with _cleanup_ to avoid these.
This improves the performance of parsing the file and reduces memory pressure.
Running 'fuzz-etc-hosts timeout-strv' with valgrind,
Before:
total heap usage: 321,020 allocs, 321,020 frees, 15,820,387,193 bytes allocated
real 0m23.531s
user 0m21.458s
sys 0m1.961s
After:
total heap usage: 112,408 allocs, 112,408 frees, 7,297,480 bytes allocated
real 0m8.664s
user 0m8.545s
sys 0m0.065s
Hopefully fixes oss-fuzz#47708 (https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=47708).
Same idea as 03677889f0.
No functional change intended. The type of the iterator is generally changed to
be 'const char*' instead of 'char*'. Despite the type commonly used, modifying
the string was not allowed.
I adjusted the naming of some short variables for clarity and reduced the scope
of some variable declarations in code that was being touched anyway.
We recently started making more use of malloc_usable_size() and rely on
it (see the string_erase() story). Given that we don't really support
sytems where malloc_usable_size() cannot be trusted beyond statistics
anyway, let's go fully in and rework GREEDY_REALLOC() on top of it:
instead of passing around and maintaining the currenly allocated size
everywhere, let's just derive it automatically from
malloc_usable_size().
I am mostly after this for the simplicity this brings. It also brings
minor efficiency improvements I guess, but things become so much nicer
to look at if we can avoid these allocation size variables everywhere.
Note that the malloc_usable_size() man page says relying on it wasn't
"good programming practice", but I think it does this for reasons that
don't apply here: the greedy realloc logic specifically doesn't rely on
the returned extra size, beyond the fact that it is equal or larger than
what was requested.
(This commit was supposed to be a quick patch btw, but apparently we use
the greedy realloc stuff quite a bit across the codebase, so this ends
up touching *a*lot* of code.)
https://tools.ietf.org/html/draft-knodel-terminology-02https://lwn.net/Articles/823224/
This gets rid of most but not occasions of these loaded terms:
1. scsi_id and friends are something that is supposed to be removed from
our tree (see #7594)
2. The test suite defines an API used by the ubuntu CI. We can remove
this too later, but this needs to be done in sync with the ubuntu CI.
3. In some cases the terms are part of APIs we call or where we expose
concepts the kernel names the way it names them. (In particular all
remaining uses of the word "slave" in our codebase are like this,
it's used by the POSIX PTY layer, by the network subsystem, the mount
API and the block device subsystem). Getting rid of the term in these
contexts would mean doing some major fixes of the kernel ABI first.
Regarding the replacements: when whitelist/blacklist is used as noun we
replace with with allow list/deny list, and when used as verb with
allow-list/deny-list.
https://tools.ietf.org/html/rfc1035#section-2.3.1 says (approximately)
that only letters, numbers, and non-leading non-trailing dashes are allowed
(for entries with A/AAAA records). We set no restrictions.
hosts(5) says:
> Host names may contain only alphanumeric characters, minus signs ("-"), and
> periods ("."). They must begin with an alphabetic character and end with an
> alphanumeric character.
nss-files follows those rules, and will ignore names in /etc/hosts that do not
follow this rule.
Let's follow the documented rules for /etc/hosts. In particular, this makes us
consitent with nss-files, reducing surprises for the user.
I'm pretty sure we should apply stricter filtering to names received over DNS
and LLMNR and MDNS, but it's a bigger project, because the rules differ
depepending on which level the label appears (rules for top-level names are
stricter), and this patch takes the minimalistic approach and only changes
behaviour for /etc/hosts.
Escape syntax is also disallowed in /etc/hosts, even if the resulting character
would be allowed. Other tools that parse /etc/hosts do not support this, and
there is no need to use it because no allowed characters benefit from escaping.
Do not treat various errors (missing hostname, invalid address) as fatal,
just warn and continue. /etc/hosts is written by humans and we should not
reject the whole file just because a singly entry is not to our liking.
Handle comments as described in hosts(5):
everything from the comment character until the end of the line should be
ignored.
Fixes#10779.
Add tests.
If file "/etc/hosts" does not exist, fopen fails and sets errno to ENOENT
("No such file or directory"). So errno should be compared with ENOENT.
This mistake causes test test-resolved-etc-hosts to fail when run on Debian
image built with mkosi.debian included in the repo. The image does not include
"/etc/hosts" file as it is not created by debootstrap, see debootstrap manpage
https://manpages.debian.org/stretch/debootstrap/debootstrap.8.en.html.
This splits out a bunch of functions from fileio.c that have to do with
temporary files. Simply to make the header files a bit shorter, and to
group things more nicely.
No code changes, just some rearranging of source files.
We'd store every 0.0.0.0 and ::0 entry as a structure without any addresses
allocated. This is a somewhat common use case, let's optimize it a bit.
This gives some memory savings and a bit faster response time too:
'time build/test-resolved-etc-hosts hosts' goes from 7.7s to 5.6s, and
memory use as reported by valgrind for ~10000 hosts is reduced
==18097== total heap usage: 29,902 allocs, 29,902 frees, 2,136,437 bytes allocated
==18240== total heap usage: 19,955 allocs, 19,955 frees, 1,556,021 bytes allocated
Also rename 'suppress' to 'found' (with reverse meaning). I think this makes
the intent clearer.
Dmitry V. Levin
Daan De Meyer
Yu Watanabe
Zbigniew Jędrzejewski-Szmek
Jan Janssen
Lennart Poettering
Alexey Bogdanenko