Reported-by: Andrew Micallef <andrew.micallef@live.com.au>
Reported-by: Walter Harms <wharms@bfs.de>
Reviewed-by: Andrew Micallef <andrew.micallef@live.com.au>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
* man3/strftime.3 (%C): Describe the meaning of %EC conversion
specification.
(%E): Mention the concept of "era" in description.
(%O): Mention that alternative format is related to numeric
representation.
(%y): Describe the meaning of %Ey conversion specification.
(%Y): Describe the meaning of %EY conversion specification.
(.SH DESCRIPTION): Mention that the behaviour of %E modifier is governed
by ERA locale element and provide ja_JP locale as an example.
Signed-off-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
As it wasn't clear before where this kind of information can be
obtained from.
* man3/strftime.3 (%a, %A, %b, %B, %c, %p, %r, %x, %X): Add information
about the locale elements that can be used to retrieve the relevant
information using nl_langinfo() library call.
Signed-off-by: Eugene Syromyatnikov <evgsyr@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In many cases, these don't improve readability, and (when stacked)
they sometimes have the side effect of sometimes forcing text
to be justified within a narrow column range.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
One might be tempted to think that realloc() always requests a new
allocation before moving the contents over (at least in the case
where the new size is bigger than the original). This is not the
case; for example, on my system the following program:
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
void *x = malloc(15);
void *y = malloc(32);
printf("x = %p\n", x);
printf("y = %p\n", y);
printf("usable_size(x) = %lu\n", malloc_usable_size(x));
void *z = realloc(x, 24);
printf("z = %p\n", z);
return 0;
}
prints:
x = 0x1b3a010
y = 0x1b3a030
usable_size(x) = 24
z = 0x1b3a010
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Admittedly, the POSIX specification for exit() also uses octal.
However, 0xFF immediately indicates the lowest 8 bits to me
whereas I had to think a bit about the octal mask.
Cowritten-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
From an email by Rich Felker:
It came to my attention while reviewing possible breakage with
move to 64-bit time_t that some applications are dereferencing
data in socket control messages (particularly SCM_TIMESTAMP*)
in-place as the message type, rather than memcpy'ing it to
appropriate storage. This necessarily does not work and is not
supportable if the message contains data with greater alignment
requirement than the header. In particular, on 32-bit archs,
cmsghdr has size 12 and alignment 4, but struct timeval and
timespec may have alignment requirement 8.
I found at least ptpd, socat, and ssmping doing this via Debian
Code Search:
https://sources.debian.org/src/ptpd/2.3.1-debian1-4/src/dep/net.c/?hl=1578#L1578https://sources.debian.org/src/socat/1.7.3.3-2/xio-socket.c/?hl=1839#L1839https://sources.debian.org/src/ssmping/0.9.1-3/ssmpngcl.c/?hl=307#L307
and I suspect there are a good deal more out there. On most archs
they won't break, or will visibly break with SIGBUS, but in theory
it's possible that they silently read wrong data and this might
happen on some older and more tiny-embedded-oriented archs.
I think it's clear to someone who understands alignment and who's
thought about it that applications just can't do this, but it
doesn't seem to be documented, and an example in cmsg(3) even
shows access to int payload via *(int *)CMSG_DATA(cmsg) (of course
int is safe because its alignment is <= header alignment, but this
is not mentioned).
Could we add text, and perhaps change the example, to indicate
that in general memcpy needs to be used to copy the payload
to/from a suitable object?
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This patch is a minor wording fix in getcwd.3 that changes "In the case getcwd()" to "In the case of getcwd()". This patch should apply cleanly to the master branch of the git repository.
Regards,
Mike Salvatore
From 3b68ad225dbaada2b1b55153dc57807b04531cd6 Mon Sep 17 00:00:00 2001
From: Mike Salvatore <mike.salvatore@canonical.com>
Date: Thu, 16 Jan 2020 16:08:08 -0500
Subject: [PATCH] getcwd.3: wfix
Signed-off-by: Mike Salvatore <mike.salvatore@canonical.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Fixes: d8d701003 ("malloc.3: Since glibc 2.29, realloc() is exposed by
defining _DEFAULT_SOURCE")
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The glibc implementation of getpt has actually never been setting
O_NOCTTY when opening /dev/ptmx or BSD ptys.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk