qsort.c: prevent undefined behavior

Mark Milliard has detected a case of undefined behavior with the LLVM
UBSAN. The mandoc program called qsort with a==NULL and n==0, which is
allowed by the POSIX

qsort.c: prevent undefined behavior

Mark Milliard has detected a case of undefined behavior with the LLVM
UBSAN. The mandoc program called qsort with a==NULL and n==0, which is
allowed by the POSIX standard. The qsort() in FreeBSD did not attempt
to perform any accesses using the passed pointer for n==0, but it did
add an offset to the pointer value, which is undefined behavior in
case of a NULL pointer. This operation has no adverse effects on any
achitecture supported by FreeBSD, but could be caught in more strict
environments.

After some discussion in the freebsd-current mail list, it was
concluded that the case of a==NULL and n!=0 should still be caught by
UBSAN (or cause a program abort due to an illegal access) in order to
not hide errors in programs incorrectly invoking qsort().

Only the the case of a==NULL and n==0 should be fixed to not perform
the undefined operation on a NULL pointer.

This commit makes qsort() exit before reaching the point of
potentially undefined behvior for the case n==0, but does not test
the value of a, since the result will not depend on whether this
pointer is NULL or an actual pointer to an array if n==0.

The issue found by Mark Milliard in the whatis command has been
reported to the upstream (OpenBSD) and has already been patched
there.

(cherry picked from commit d106f982a54cd299671ccad58bc456138a22ae7b)

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libc/qsort: Don't allow interposing recursive calls

This causes problems when using ASAN with a runtime older than 12.0 since
the intercept does not expect qsort() to call itself using an interposab

libc/qsort: Don't allow interposing recursive calls

This causes problems when using ASAN with a runtime older than 12.0 since
the intercept does not expect qsort() to call itself using an interposable
function call. This results in infinite recursion and stack exhaustion
when a binary compiled with -fsanitize=address calls qsort.
See also https://bugs.llvm.org/show_bug.cgi?id=46832 and
https://reviews.llvm.org/D84509 (ASAN runtime patch).

To prevent this problem, this patch uses a static helper function
for the actual qsort() implementation. This prevents interposition and
allows for direct calls. As a nice side-effect, we can also move the
qsort_s checks to the top-level function and out of the recursive calls.

Reviewed By: kib
Differential Revision: https://reviews.freebsd.org/D28133

(cherry picked from commit cbcfe28f9d5f975f97b7fb4a0d72bc9780eb0c46)

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Add qsort_s(3). Apart from the constraints, it also makes it easier
to port software written for Linux variant of qsort_r(3).

Reviewed by: kib, arichardson
MFC after: 2 weeks
Relnotes: yes
Sponsore

Add qsort_s(3). Apart from the constraints, it also makes it easier
to port software written for Linux variant of qsort_r(3).

Reviewed by: kib, arichardson
MFC after: 2 weeks
Relnotes: yes
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D23174

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libc qsort(3): stop aliasing.

Qsort swap code aliases the sorted array elements to ints and longs in
order to do swap by machine words. Unfortunately this breaks with the
full code optimization, e.

libc qsort(3): stop aliasing.

Qsort swap code aliases the sorted array elements to ints and longs in
order to do swap by machine words. Unfortunately this breaks with the
full code optimization, e.g. LTO.

See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83201 which seems to
reference code directly copied from libc/stdlib/qsort.c.

PR: 228780
Reported by: [email protected]
Reviewed by: brooks
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks
Differential revision: https://reviews.freebsd.org/D15714

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General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier f

General further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 3-Clause license.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Special thanks to Wind River for providing access to "The Duke of
Highlander" tool: an older (2014) run over FreeBSD tree was useful as a
starting point.

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The current qsort(3) implementation ignores the sizes of partitions, and
always perform recursion on the left partition, then use a tail call to
handle the right partition. In the worst case this co

The current qsort(3) implementation ignores the sizes of partitions, and
always perform recursion on the left partition, then use a tail call to
handle the right partition. In the worst case this could require O(N)
levels of recursions.

Reduce the possible recursion level to log2(N) by always recursing on the
smaller partition instead.

Obtained from: PostgreSQL 9d6077abf9d6efd992a59f05ef5aba981ea32096

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Use size_t.

Inspired by: OpenBSD src/lib/libc/stdlib/qsort.c,v 1.11

Use ANSI C prototypes. Eliminates -Wold-style-definition warnings.

qsort(3): small style(9) cleanups.

Basically spaces vs. tabs.
No functional change.

qsort(3): enhance to handle 32-bit aligned data on 64-bit systems

Implement a small enhancement to the original qsort implementation:
If the data is 32 bit aligned we can side-step the long type
ver

qsort(3): enhance to handle 32-bit aligned data on 64-bit systems

Implement a small enhancement to the original qsort implementation:
If the data is 32 bit aligned we can side-step the long type
version and use int instead.

The change brings a modest but significant improvement in
32 bit workloads.

Relnotes: yes

PR: 135718
Taken from: ache

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Renumber clauses to reduce diffs to other versions

NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3,
so follow suit to make comparison easier.

Changing 'r' to a size_t in the previous commit turned quicksort
into slowsort for some sequences because different parts of the
code used 'r' to store two different things, one of which was
signed.

Changing 'r' to a size_t in the previous commit turned quicksort
into slowsort for some sequences because different parts of the
code used 'r' to store two different things, one of which was
signed. Clean things up by splitting 'r' into two variables, and
use a more meaningful name.

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Use size_t to avoid overflow when sorting arrays larger than 2 GB.

PR: 111085
MFC after: 2 weeks

Per Regents of the University of Calfornia letter, remove advertising
clause.

# If I've done so improperly on a file, please let me know.

Implement C99's _Exit() interface.
Implement a version of qsort that provides a thunk to the comparison function.

Update manual pages.

Fix the style of the SCM ID's.
I believe have made all of libc .c's as consistent as possible.

Remove __P() usage.

Remove 'register' keyword.

$Id$ -> $FreeBSD$

Revert $FreeBSD$ to $Id$

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so

Make the long-awaited change from $Id$ to $FreeBSD$

This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.

Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.

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Don't depend in the kernel on the gcc feature of doing arithmetic on
pointers of type `void *'. Warn about this in future.

Don't include <sys/types.h> when it isn't used.

This commit covers most of the ANSI library functions. Many others only
need <sys/types.h> because they use u_xxx.

Added prototypes.

Remove trailing whitespace.