2016-12-02 17:29:01 +01:00
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/*-------------------------------------------------------------------------
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*
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* relptr.h
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* This file contains basic declarations for relative pointers.
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*
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2017-01-03 19:48:53 +01:00
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* Portions Copyright (c) 1996-2017, PostgreSQL Global Development Group
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2016-12-02 17:29:01 +01:00
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/include/utils/relptr.h
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*
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*-------------------------------------------------------------------------
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*/
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#ifndef RELPTR_H
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#define RELPTR_H
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/*
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* Relative pointers are intended to be used when storing an address that may
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2016-12-06 02:27:55 +01:00
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* be relative either to the base of the process's address space or some
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2016-12-02 17:29:01 +01:00
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* dynamic shared memory segment mapped therein.
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*
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* The idea here is that you declare a relative pointer as relptr(type)
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* and then use relptr_access to dereference it and relptr_store to change
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* it. The use of a union here is a hack, because what's stored in the
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* relptr is always a Size, never an actual pointer. But including a pointer
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* in the union allows us to use stupid macro tricks to provide some measure
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* of type-safety.
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*/
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#define relptr(type) union { type *relptr_type; Size relptr_off; }
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/*
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2016-12-06 02:27:55 +01:00
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* pgindent gets confused by declarations that use "relptr(type)" directly,
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* so preferred style is to write
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* typedef struct ... SomeStruct;
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* relptr_declare(SomeStruct, RelptrSomeStruct);
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* and then declare pointer variables as "RelptrSomeStruct someptr".
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2016-12-02 17:29:01 +01:00
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*/
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2016-12-06 02:27:55 +01:00
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#define relptr_declare(type, relptrtype) \
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typedef relptr(type) relptrtype
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2016-12-02 17:29:01 +01:00
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#ifdef HAVE__BUILTIN_TYPES_COMPATIBLE_P
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#define relptr_access(base, rp) \
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(AssertVariableIsOfTypeMacro(base, char *), \
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(__typeof__((rp).relptr_type)) ((rp).relptr_off == 0 ? NULL : \
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(base + (rp).relptr_off)))
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#else
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/*
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* If we don't have __builtin_types_compatible_p, assume we might not have
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* __typeof__ either.
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*/
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#define relptr_access(base, rp) \
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(AssertVariableIsOfTypeMacro(base, char *), \
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(void *) ((rp).relptr_off == 0 ? NULL : (base + (rp).relptr_off)))
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#endif
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#define relptr_is_null(rp) \
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((rp).relptr_off == 0)
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#ifdef HAVE__BUILTIN_TYPES_COMPATIBLE_P
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#define relptr_store(base, rp, val) \
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(AssertVariableIsOfTypeMacro(base, char *), \
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AssertVariableIsOfTypeMacro(val, __typeof__((rp).relptr_type)), \
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(rp).relptr_off = ((val) == NULL ? 0 : ((char *) (val)) - (base)))
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#else
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/*
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* If we don't have __builtin_types_compatible_p, assume we might not have
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* __typeof__ either.
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*/
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#define relptr_store(base, rp, val) \
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(AssertVariableIsOfTypeMacro(base, char *), \
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(rp).relptr_off = ((val) == NULL ? 0 : ((char *) (val)) - (base)))
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#endif
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#define relptr_copy(rp1, rp2) \
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((rp1).relptr_off = (rp2).relptr_off)
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Phase 2 of pgindent updates.
Change pg_bsd_indent to follow upstream rules for placement of comments
to the right of code, and remove pgindent hack that caused comments
following #endif to not obey the general rule.
Commit e3860ffa4dd0dad0dd9eea4be9cc1412373a8c89 wasn't actually using
the published version of pg_bsd_indent, but a hacked-up version that
tried to minimize the amount of movement of comments to the right of
code. The situation of interest is where such a comment has to be
moved to the right of its default placement at column 33 because there's
code there. BSD indent has always moved right in units of tab stops
in such cases --- but in the previous incarnation, indent was working
in 8-space tab stops, while now it knows we use 4-space tabs. So the
net result is that in about half the cases, such comments are placed
one tab stop left of before. This is better all around: it leaves
more room on the line for comment text, and it means that in such
cases the comment uniformly starts at the next 4-space tab stop after
the code, rather than sometimes one and sometimes two tabs after.
Also, ensure that comments following #endif are indented the same
as comments following other preprocessor commands such as #else.
That inconsistency turns out to have been self-inflicted damage
from a poorly-thought-through post-indent "fixup" in pgindent.
This patch is much less interesting than the first round of indent
changes, but also bulkier, so I thought it best to separate the effects.
Discussion: https://postgr.es/m/E1dAmxK-0006EE-1r@gemulon.postgresql.org
Discussion: https://postgr.es/m/30527.1495162840@sss.pgh.pa.us
2017-06-21 21:18:54 +02:00
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#endif /* RELPTR_H */
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