RAND_MAX is for rand(3). POSIX fixes random()'s range at 2^31-1;
RAND_MAX may be smaller on some platforms (even though with glibc
or musl on Linux they are the same).
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
In the few pages where this heading (which is "nonstandard" within
man-pages) is used, it always immediately follows CONFORMING TO
and generally contains information related to standards. Remove
the section heading, thus incorporating AVAILABILITY into
CONFORMING TO.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
EXAMPLES appears to be the wider majority usage across various
projects' manual pages, and is also what is used in the POSIX
manual pages.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The fact that an FE_UNDERFLOW exception is not raised for
"Range error: result underflow" is intended behavior.
See https://www.sourceware.org/bugzilla/show_bug.cgi?id=6806.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
The function make_message illustrates how to use vsnprintf to
determine the required amount of memory for a specific format and
its arguments.
If make_message is called with a format which will use exactly
INT_MAX characters (excluding '\0'), then the size++ calculation
will overflow the signed integer "size", which is an undefined
behaviour in C.
Since malloc and vsnprintf rightfully take a size_t argument, I
decided to use a size_t variable for size calculation. Therefore,
this patched code uses variables of the same data types as
expected by function arguments.
Proof of concept (tested on Linux/glibc amd64):
int main() { make_message("%647s%2147483000s", "", ""); }
If the code is compiled with address sanitizer (gcc
-fsanitize=address) you can see the following line, assuming that
a signed integer overflow simply leads to INT_MIN:
==3094==WARNING: AddressSanitizer failed to allocate 0xffffffff80000000 bytes
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Remove the text ("rare)" after a note from Vincent Lefèvre:
Subject: [Bug math/13932] dbl-64 pow unexpectedly slow for some inputs
Date: Sat, 23 May 2020 21:31:52 +0000
From: vincent-srcware at vinc17 dot net <sourceware-bugzilla@sourceware.org>
To: mtk.manpages@gmail.comhttps://sourceware.org/bugzilla/show_bug.cgi?id=13932
--- Comment #26 from Vincent Lefèvre <vincent-srcware at vinc17 dot net> ---
(In reply to Michael Kerrisk from comment #25)
> Fix documented for man-pages-5.07.
[...]
> -On 64-bits,
> +Before glibc 2.28,
> .\"
> .\" https://sourceware.org/bugzilla/show_bug.cgi?id=13932
> +on some architectures (e.g., x86-64)
> .BR pow ()
> may be more than 10,000 times slower for some (rare) inputs
> than for other nearby inputs.
[...]
The problematic values are uncommon, but not so rare, in the sense
that they are close to simple values, i.e. are likely to occur in
practice. An example given above: pow(0.999999999999999889, 1.5)
1 and 1.5 are very simple values, which are more likely to occur
in practice than some fixed random value. Then it suffices to have
a small rounding error on 1...
For instance, this is very different from hard-to-round cases of
exp, which are also very slow IMHO, but unless one writes a
specific program for them, no-one should notice the slowness
because such a case would typically occur only once among billions
(I don't remember the accuracy before the slowest path in this
library).
Reported-by: Vincent Lefèvre <vincent-srcware@vinc17.net>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Avoid implying that use of IFUNC is the only way to produce a
symbol with NULL value. Give more scenarios how a symbol may get
NULL value, but explain that in those scenarios dlsym() will fail
with Glibc's ld.so due to an implementation inconsistency.
Signed-off-by: Alexander Monakov <amonakov@ispras.ru>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This is a sequel to commit baf17bc4f2, addressing the
issues with missing commas in the middle of SEE ALSO lists that
emerged since.
The awk script from the original commit was not working and had to
be slightly modified (s/["]SEE ALSO["]/"?SEE ALSO/), otherwise it
works like a charm. Here's the fixed script and its output just
before this commit:
for f in man*/*; do
awk '
/^.SH "?SEE ALSO/ {
sa=1; print "== " FILENAME " =="; print; next
}
/^\.(PP|SH)/ {
sa=0; no=0; next
}
/^\.BR/ {
if (sa==1) {
print;
if (no == 1)
print "Missing comma in " FILENAME " +" FNR-1; no=0
}
}
/^\.BR .*)$/ {
if (sa==1)
no=1;
next
}
/\.\\"/ {next}
/.*/ {
if (sa==1) {
print; next
}
}
' $f; done | grep Missing
Missing comma in man1/memusage.1 +272
Missing comma in man2/adjtimex.2 +597
Missing comma in man2/adjtimex.2 +598
Missing comma in man2/mkdir.2 +252
Missing comma in man2/sigaction.2 +1045
Missing comma in man2/sigaction.2 +1047
Missing comma in man3/mbsnrtowcs.3 +198
Missing comma in man3/ntp_gettime.3 +142
Missing comma in man3/strcmp.3 +219
Missing comma in man3/strtol.3 +302
Missing comma in man3/wcstombs.3 +120
Missing comma in man7/user_namespaces.7 +1378
Missing comma in man7/xattr.7 +198
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
By way of a hint that the file descriptor returned by dirfd()
could usefully be fed to the *at() APIs.
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Both functions behave the same wrt return value, no need to describe
them separately.
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Michael Kerrisk