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4ef9bd22ed
Back in 2015 when I reimplemented these functions to use an AVL tree, I was annoyed by the weakness of the typing of these functions. Both tree nodes and keys are represented by 'void *', meaning that things like the documentation for these functions are an absolute train wreck. To make things worse, users of these functions need to cast the return value of tfind()/tsearch() from 'void *' to 'type_of_key **' in order to access the key. Technically speaking such casts violate aliasing rules. I've observed actual breakages as a result of this by enabling features like LTO. I've filed a bug report at the Austin Group. Looking at the way the bug got resolved, they made a pretty good step in the right direction. A new type 'posix_tnode' has been added to correspond to tree nodes. It is still defined as 'void' for source-level compatibility, but in the very far future it could be replaced by a proper structure type containing a key pointer. MFC after: 1 month Differential Revision: https://reviews.freebsd.org/D8205
86 lines
1.7 KiB
C
86 lines
1.7 KiB
C
/*-
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* Written by J.T. Conklin <jtc@NetBSD.org>
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* Public domain.
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*
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* $NetBSD: search.h,v 1.16 2005/02/03 04:39:32 perry Exp $
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* $FreeBSD$
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*/
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#ifndef _SEARCH_H_
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#define _SEARCH_H_
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#include <sys/cdefs.h>
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#include <sys/_types.h>
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#ifndef _SIZE_T_DECLARED
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typedef __size_t size_t;
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#define _SIZE_T_DECLARED
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#endif
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typedef struct entry {
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char *key;
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void *data;
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} ENTRY;
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typedef enum {
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FIND, ENTER
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} ACTION;
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typedef enum {
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preorder,
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postorder,
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endorder,
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leaf
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} VISIT;
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#ifdef _SEARCH_PRIVATE
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typedef struct __posix_tnode {
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void *key;
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struct __posix_tnode *llink, *rlink;
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signed char balance;
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} posix_tnode;
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struct que_elem {
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struct que_elem *next;
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struct que_elem *prev;
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};
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#else
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typedef void posix_tnode;
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#endif
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#if __BSD_VISIBLE
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struct hsearch_data {
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struct __hsearch *__hsearch;
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};
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#endif
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__BEGIN_DECLS
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int hcreate(size_t);
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void hdestroy(void);
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ENTRY *hsearch(ENTRY, ACTION);
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void insque(void *, void *);
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void *lfind(const void *, const void *, size_t *, size_t,
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int (*)(const void *, const void *));
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void *lsearch(const void *, void *, size_t *, size_t,
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int (*)(const void *, const void *));
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void remque(void *);
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void *tdelete(const void * __restrict, posix_tnode ** __restrict,
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int (*)(const void *, const void *));
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posix_tnode *
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tfind(const void *, posix_tnode * const *,
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int (*)(const void *, const void *));
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posix_tnode *
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tsearch(const void *, posix_tnode **,
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int (*)(const void *, const void *));
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void twalk(const posix_tnode *, void (*)(const posix_tnode *, VISIT, int));
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#if __BSD_VISIBLE
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int hcreate_r(size_t, struct hsearch_data *);
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void hdestroy_r(struct hsearch_data *);
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int hsearch_r(ENTRY, ACTION, ENTRY **, struct hsearch_data *);
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#endif
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__END_DECLS
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#endif /* !_SEARCH_H_ */
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