qsort_r.c File Reference

Context-free sorting function. More...

#include "config.h"
#include <stddef.h>
#include <stdlib.h>
#include "qsort_r.h"
#include <assert.h>

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Typedefs
typedef int(*	qsort_compar_t) (const void *a, const void *b)
	Prototype for generic comparison function, compatible with qsort() More...

Functions
static int	relay_compar (const void *a, const void *b)
	Shim to pass context through to real comparator. More...
void	mutt_qsort_r (void *base, size_t nmemb, size_t size, qsort_r_compar_t compar, void *arg)
	Sort an array, where the comparator has access to opaque data rather than requiring global variables. More...

Variables
static qsort_r_compar_t	global_compar = NULL
	Original comparator in fallback implementation. More...
static void *	global_data = NULL
	Original opaque data in fallback implementation. More...

Detailed Description

Context-free sorting function.

Authors

• Eric Blake

Copyright

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see http://www.gnu.org/licenses/.

Definition in file qsort_r.c.

Typedef Documentation

qsort_compar_t

typedef int(* qsort_compar_t) (const void *a, const void *b)

Prototype for generic comparison function, compatible with qsort()

Parameters

a	First item
b	Second item

Return values

<0	a precedes b
0	a and b are identical
>0	b precedes a

Definition at line 42 of file qsort_r.c.

Function Documentation

relay_compar()

static int relay_compar ( const void *  a, const void *  b  )

static

Shim to pass context through to real comparator.

Parameters

a	First item to be compared
b	Second item to be compared

Return values

<0	a sorts before b
0	a and b sort equally (sort stability not guaranteed)
>0	a sorts after b

Definition at line 59 of file qsort_r.c.

{
  return global_compar(a, b, global_data);
}

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mutt_qsort_r()

void mutt_qsort_r	(	void *	base,
		size_t	nmemb,
		size_t	size,
		qsort_r_compar_t	compar,
		void *	arg
	)

Sort an array, where the comparator has access to opaque data rather than requiring global variables.

Parameters

base	Start of the array to be sorted
nmemb	Number of elements in the array
size	Size of each array element
compar	Comparison function, return <0/0/>0 to compare two elements
arg	Opaque argument to pass to compar

Note

This implementation might not be re-entrant: signal handlers and compar must not call mutt_qsort_r().

Definition at line 76 of file qsort_r.c.

{
#ifdef HAVE_QSORT_S
  /* FreeBSD 13, where qsort_r had incompatible signature but qsort_s works */
  qsort_s(base, nmemb, size, compar, arg);
#elif defined(HAVE_QSORT_R)
  /* glibc, POSIX (https://www.austingroupbugs.net/view.php?id=900) */
  qsort_r(base, nmemb, size, compar, arg);
#else
  /* This fallback is not re-entrant. */
  assert((global_compar == NULL) && (global_data == NULL));
  global_compar = compar;
  global_data = arg;
  qsort(base, nmemb, size, relay_compar);
  global_compar = NULL;
  global_data = NULL;
#endif
}

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Variable Documentation

global_compar

qsort_r_compar_t global_compar = NULL

static

Original comparator in fallback implementation.

Definition at line 47 of file qsort_r.c.

global_data

void* global_data = NULL

static

Original opaque data in fallback implementation.

Definition at line 49 of file qsort_r.c.