56 lines
1.2 KiB
C
56 lines
1.2 KiB
C
/*
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* This file is part of the UCB release of Plan 9. It is subject to the license
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* terms in the LICENSE file found in the top-level directory of this
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* distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
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* part of the UCB release of Plan 9, including this file, may be copied,
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* modified, propagated, or distributed except according to the terms contained
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* in the LICENSE file.
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*/
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#include <u.h>
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#include <lib9.h>
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#include <bio.h>
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#include <ndb.h>
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/* replace a in t with b, the line structure in b is lost, c'est la vie */
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Ndbtuple*
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ndbsubstitute(Ndbtuple *t, Ndbtuple *a, Ndbtuple *b)
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{
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Ndbtuple *nt;
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if(a == b){
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ndbsetmalloctag(t, getcallerpc());
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return t;
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}
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if(b == nil){
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t = ndbdiscard(t, a);
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ndbsetmalloctag(t, getcallerpc());
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return t;
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}
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/* all pointers to a become pointers to b */
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for(nt = t; nt != nil; nt = nt->entry){
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if(nt->line == a)
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nt->line = b;
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if(nt->entry == a)
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nt->entry = b;
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}
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/* end of b chain points to a's successors */
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for(nt = b; nt->entry; nt = nt->entry)
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nt->line = nt->entry;
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nt->line = a->line;
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nt->entry = a->entry;
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a->entry = nil;
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ndbfree(a);
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if(a == t){
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ndbsetmalloctag(b, getcallerpc());
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return b;
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}else{
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ndbsetmalloctag(t, getcallerpc());
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return t;
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}
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}
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