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Remove support for version-0 calling conventions.

Browse Source 
The V0 convention is failure prone because we've so far assumed that a
function is V0 if PG_FUNCTION_INFO_V1 is missing, leading to crashes
if a function was coded against the V1 interface.  V0 doesn't allow
proper NULL, SRF and toast handling.  V0 doesn't offer features that
V1 doesn't.

Thus remove V0 support and obsolete fmgr README contents relating to
it.

Author: Andres Freund, with contributions by Peter Eisentraut & Craig Ringer
Reviewed-By: Peter Eisentraut, Craig Ringer
Discussion: https://postgr.es/m/20161208213441.k3mbno4twhg2qf7g@alap3.anarazel.de
pull/3/merge
Andres Freund 8 years ago
parent 389bb2818f
commit 5ded4bd214
10 changed files with 106 additions and 911 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 22
      contrib/earthdistance/earthdistance.c
  2. 269
      doc/src/sgml/xfunc.sgml
  3. 254
      src/backend/utils/fmgr/README
  4. 375
      src/backend/utils/fmgr/fmgr.c
  5. 8
      src/include/fmgr.h
  6. 5
      src/test/regress/input/create_function_2.source
  7. 13
      src/test/regress/input/misc.source
  8. 4
      src/test/regress/output/create_function_2.source
  9. 18
      src/test/regress/output/misc.source
  10. 45
      src/test/regress/regress.c

22
contrib/earthdistance/earthdistance.c
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@ -88,16 +88,8 @@ geo_distance_internal(Point *pt1, Point *pt2)
* *
* returns: float8 * returns: float8
* distance between the points in miles on earth's surface * distance between the points in miles on earth's surface
*
* If float8 is passed-by-value, the oldstyle version-0 calling convention
* is unportable, so we use version-1. However, if it's passed-by-reference,
* continue to use oldstyle. This is just because we'd like earthdistance
* to serve as a canary for any unintentional breakage of version-0 functions
* with float8 results.
******************************************************/ ******************************************************/
#ifdef USE_FLOAT8_BYVAL
PG_FUNCTION_INFO_V1(geo_distance); PG_FUNCTION_INFO_V1(geo_distance);
Datum Datum
@ -110,17 +102,3 @@ geo_distance(PG_FUNCTION_ARGS)
result = geo_distance_internal(pt1, pt2); result = geo_distance_internal(pt1, pt2);
PG_RETURN_FLOAT8(result); PG_RETURN_FLOAT8(result);
} }
#else /* !USE_FLOAT8_BYVAL */
double *geo_distance(Point *pt1, Point *pt2);
double *
geo_distance(Point *pt1, Point *pt2)
{
double *resultp = palloc(sizeof(double));
*resultp = geo_distance_internal(pt1, pt2);
return resultp;
}
#endif /* USE_FLOAT8_BYVAL */

269
doc/src/sgml/xfunc.sgml
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@ -1610,14 +1610,10 @@ CREATE FUNCTION square_root(double precision) RETURNS double precision
</para> </para>
<para> <para>
Two different calling conventions are currently used for C functions. Currently only one calling convention is used for C functions
The newer <quote>version 1</quote> calling convention is indicated by writing (<quote>version 1</quote>). Support for that calling convention is
a <literal>PG_FUNCTION_INFO_V1()</literal> macro call for the function, indicated by writing a <literal>PG_FUNCTION_INFO_V1()</literal> macro
as illustrated below. Lack of such a macro indicates an old-style call for the function, as illustrated below.
(<quote>version 0</quote>) function. The language name specified in <command>CREATE FUNCTION</command>
is <literal>C</literal> in either case. Old-style functions are now deprecated
because of portability problems and lack of functionality, but they
are still supported for compatibility reasons.
</para> </para>
<sect2 id="xfunc-c-dynload"> <sect2 id="xfunc-c-dynload">
@ -2137,160 +2133,6 @@ memcpy(destination->data, buffer, 40);
</para> </para>
</sect2> </sect2>
<sect2>
<title>Version 0 Calling Conventions</title>
<para>
We present the <quote>old style</quote> calling convention first &mdash; although
this approach is now deprecated, it's easier to get a handle on
initially. In the version-0 method, the arguments and result
of the C function are just declared in normal C style, but being
careful to use the C representation of each SQL data type as shown
above.
</para>
<para>
Here are some examples:
<programlisting><![CDATA[
#include "postgres.h"
#include <string.h>
#include "utils/geo_decls.h"
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
/* by value */
int
add_one(int arg)
{
return arg + 1;
}
/* by reference, fixed length */
float8 *
add_one_float8(float8 *arg)
{
float8 *result = (float8 *) palloc(sizeof(float8));
*result = *arg + 1.0;
return result;
}
Point *
makepoint(Point *pointx, Point *pointy)
{
Point *new_point = (Point *) palloc(sizeof(Point));
new_point->x = pointx->x;
new_point->y = pointy->y;
return new_point;
}
/* by reference, variable length */
text *
copytext(text *t)
{
/*
* VARSIZE is the total size of the struct in bytes.
*/
text *new_t = (text *) palloc(VARSIZE(t));
SET_VARSIZE(new_t, VARSIZE(t));
/*
* VARDATA is a pointer to the data region of the struct.
*/
memcpy((void *) VARDATA(new_t), /* destination */
(void *) VARDATA(t), /* source */
VARSIZE(t) - VARHDRSZ); /* how many bytes */
return new_t;
}
text *
concat_text(text *arg1, text *arg2)
{
int32 new_text_size = VARSIZE(arg1) + VARSIZE(arg2) - VARHDRSZ;
text *new_text = (text *) palloc(new_text_size);
SET_VARSIZE(new_text, new_text_size);
memcpy(VARDATA(new_text), VARDATA(arg1), VARSIZE(arg1) - VARHDRSZ);
memcpy(VARDATA(new_text) + (VARSIZE(arg1) - VARHDRSZ),
VARDATA(arg2), VARSIZE(arg2) - VARHDRSZ);
return new_text;
}
]]>
</programlisting>
</para>
<para>
Supposing that the above code has been prepared in file
<filename>funcs.c</filename> and compiled into a shared object,
we could define the functions to <productname>PostgreSQL</productname>
with commands like this:
<programlisting>
CREATE FUNCTION add_one(integer) RETURNS integer
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'add_one'
LANGUAGE C STRICT;
-- note overloading of SQL function name "add_one"
CREATE FUNCTION add_one(double precision) RETURNS double precision
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'add_one_float8'
LANGUAGE C STRICT;
CREATE FUNCTION makepoint(point, point) RETURNS point
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'makepoint'
LANGUAGE C STRICT;
CREATE FUNCTION copytext(text) RETURNS text
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'copytext'
LANGUAGE C STRICT;
CREATE FUNCTION concat_text(text, text) RETURNS text
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'concat_text'
LANGUAGE C STRICT;
</programlisting>
</para>
<para>
Here, <replaceable>DIRECTORY</replaceable> stands for the
directory of the shared library file (for instance the
<productname>PostgreSQL</productname> tutorial directory, which
contains the code for the examples used in this section).
(Better style would be to use just <literal>'funcs'</> in the
<literal>AS</> clause, after having added
<replaceable>DIRECTORY</replaceable> to the search path. In any
case, we can omit the system-specific extension for a shared
library, commonly <literal>.so</literal> or
<literal>.sl</literal>.)
</para>
<para>
Notice that we have specified the functions as <quote>strict</quote>,
meaning that
the system should automatically assume a null result if any input
value is null. By doing this, we avoid having to check for null inputs
in the function code. Without this, we'd have to check for null values
explicitly, by checking for a null pointer for each
pass-by-reference argument. (For pass-by-value arguments, we don't
even have a way to check!)
</para>
<para>
Although this calling convention is simple to use,
it is not very portable; on some architectures there are problems
with passing data types that are smaller than <type>int</type> this way. Also, there is
no simple way to return a null result, nor to cope with null arguments
in any way other than making the function strict. The version-1
convention, presented next, overcomes these objections.
</para>
</sect2>
<sect2> <sect2>
<title>Version 1 Calling Conventions</title> <title>Version 1 Calling Conventions</title>
@ -2316,8 +2158,10 @@ PG_FUNCTION_INFO_V1(funcname);
<para> <para>
In a version-1 function, each actual argument is fetched using a In a version-1 function, each actual argument is fetched using a
<function>PG_GETARG_<replaceable>xxx</replaceable>()</function> <function>PG_GETARG_<replaceable>xxx</replaceable>()</function>
macro that corresponds to the argument's data type, and the macro that corresponds to the argument's data type. In non-strict
result is returned using a functions there needs to be a previous check about argument null-ness
using <function>PG_ARGNULL_<replaceable>xxx</replaceable>()</function>.
The result is returned using a
<function>PG_RETURN_<replaceable>xxx</replaceable>()</function> <function>PG_RETURN_<replaceable>xxx</replaceable>()</function>
macro for the return type. macro for the return type.
<function>PG_GETARG_<replaceable>xxx</replaceable>()</function> <function>PG_GETARG_<replaceable>xxx</replaceable>()</function>
@ -2328,7 +2172,7 @@ PG_FUNCTION_INFO_V1(funcname);
</para> </para>
<para> <para>
Here we show the same functions as above, coded in version-1 style: Here are some examples using the version-1 calling convention:
<programlisting><![CDATA[ <programlisting><![CDATA[
#include "postgres.h" #include "postgres.h"
@ -2427,27 +2271,67 @@ concat_text(PG_FUNCTION_ARGS)
} }
]]> ]]>
</programlisting> </programlisting>
<para>
Supposing that the above code has been prepared in file
<filename>funcs.c</filename> and compiled into a shared object,
we could define the functions to <productname>PostgreSQL</productname>
with commands like this:
<programlisting>
CREATE FUNCTION add_one(integer) RETURNS integer
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'add_one'
LANGUAGE C STRICT;
-- note overloading of SQL function name "add_one"
CREATE FUNCTION add_one(double precision) RETURNS double precision
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'add_one_float8'
LANGUAGE C STRICT;
CREATE FUNCTION makepoint(point, point) RETURNS point
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'makepoint'
LANGUAGE C STRICT;
CREATE FUNCTION copytext(text) RETURNS text
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'copytext'
LANGUAGE C STRICT;
CREATE FUNCTION concat_text(text, text) RETURNS text
AS '<replaceable>DIRECTORY</replaceable>/funcs', 'concat_text'
LANGUAGE C STRICT;
</programlisting>
<para>
Here, <replaceable>DIRECTORY</replaceable> stands for the
directory of the shared library file (for instance the
<productname>PostgreSQL</productname> tutorial directory, which
contains the code for the examples used in this section).
(Better style would be to use just <literal>'funcs'</> in the
<literal>AS</> clause, after having added
<replaceable>DIRECTORY</replaceable> to the search path. In any
case, we can omit the system-specific extension for a shared
library, commonly <literal>.so</literal>.)
</para> </para>
<para> <para>
The <command>CREATE FUNCTION</command> commands are the same as Notice that we have specified the functions as <quote>strict</quote>,
for the version-0 equivalents. meaning that
the system should automatically assume a null result if any input
value is null. By doing this, we avoid having to check for null inputs
in the function code. Without this, we'd have to check for null values
explicitly, using PG_ARGISNULL().
</para> </para>
<para> <para>
At first glance, the version-1 coding conventions might appear to At first glance, the version-1 coding conventions might appear to be just
be just pointless obscurantism. They do, however, offer a number pointless obscurantism, over using plain <literal>C</> calling
of improvements, because the macros can hide unnecessary detail. conventions. They do however allow to deal with <literal>NULL</>able
An example is that in coding <function>add_one_float8</>, we no longer need to arguments/return values, and <quote>toasted</quote> (compressed or
be aware that <type>float8</type> is a pass-by-reference type. Another
example is that the <literal>GETARG</> macros for variable-length types allow
for more efficient fetching of <quote>toasted</quote> (compressed or
out-of-line) values. out-of-line) values.
</para> </para>
<para> <para>
One big improvement in version-1 functions is better handling of null The macro <function>PG_ARGISNULL(<replaceable>n</>)</function>
inputs and results. The macro <function>PG_ARGISNULL(<replaceable>n</>)</function>
allows a function to test whether each input is null. (Of course, doing allows a function to test whether each input is null. (Of course, doing
this is only necessary in functions not declared <quote>strict</>.) this is only necessary in functions not declared <quote>strict</>.)
As with the As with the
@ -2461,7 +2345,7 @@ concat_text(PG_FUNCTION_ARGS)
</para> </para>
<para> <para>
Other options provided in the new-style interface are two Other options provided by the version-1 interface are two
variants of the variants of the
<function>PG_GETARG_<replaceable>xxx</replaceable>()</function> <function>PG_GETARG_<replaceable>xxx</replaceable>()</function>
macros. The first of these, macros. The first of these,
@ -2493,9 +2377,7 @@ concat_text(PG_FUNCTION_ARGS)
to return set results (<xref linkend="xfunc-c-return-set">) and to return set results (<xref linkend="xfunc-c-return-set">) and
implement trigger functions (<xref linkend="triggers">) and implement trigger functions (<xref linkend="triggers">) and
procedural-language call handlers (<xref procedural-language call handlers (<xref
linkend="plhandler">). Version-1 code is also more linkend="plhandler">). For more details
portable than version-0, because it does not break restrictions
on function call protocol in the C standard. For more details
see <filename>src/backend/utils/fmgr/README</filename> in the see <filename>src/backend/utils/fmgr/README</filename> in the
source distribution. source distribution.
</para> </para>
@ -2630,7 +2512,7 @@ SELECT name, c_overpaid(emp, 1500) AS overpaid
WHERE name = 'Bill' OR name = 'Sam'; WHERE name = 'Bill' OR name = 'Sam';
</programlisting> </programlisting>
Using call conventions version 0, we can define Using the version-1 calling conventions, we can define
<function>c_overpaid</> as: <function>c_overpaid</> as:
<programlisting><![CDATA[ <programlisting><![CDATA[
@ -2641,31 +2523,6 @@ SELECT name, c_overpaid(emp, 1500) AS overpaid
PG_MODULE_MAGIC; PG_MODULE_MAGIC;
#endif #endif
bool
c_overpaid(HeapTupleHeader t, /* the current row of emp */
int32 limit)
{
bool isnull;
int32 salary;
salary = DatumGetInt32(GetAttributeByName(t, "salary", &isnull));
if (isnull)
return false;
return salary > limit;
}
]]>
</programlisting>
In version-1 coding, the above would look like this:
<programlisting><![CDATA[
#include "postgres.h"
#include "executor/executor.h" /* for GetAttributeByName() */
#ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC;
#endif
PG_FUNCTION_INFO_V1(c_overpaid); PG_FUNCTION_INFO_V1(c_overpaid);
Datum Datum

254
src/backend/utils/fmgr/README
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@ -3,62 +3,19 @@ src/backend/utils/fmgr/README
Function Manager Function Manager
================ ================
Proposal For Function-Manager Redesign 19-Nov-2000 [This file originally explained the transition from the V0 to the V1
-------------------------------------- interface. Now it just explains some internals and rationale for the V1
interface, while the V0 interface has been removed.]
We know that the existing mechanism for calling Postgres functions needs
to be redesigned. It has portability problems because it makes The V1 Function-Manager Interface
assumptions about parameter passing that violate ANSI C; it fails to ---------------------------------
handle NULL arguments and results cleanly; and "function handlers" that
support a class of functions (such as fmgr_pl) can only be done via a The core of the design is data structures for representing the result of a
really ugly, non-reentrant kluge. (Global variable set during every function lookup and for representing the parameters passed to a specific
function call, forsooth.) Here is a proposal for fixing these problems. function invocation. (We want to keep function lookup separate from
function call, since many parts of the system apply the same function over
In the past, the major objections to redoing the function-manager and over; the lookup overhead should be paid once per query, not once per
interface have been (a) it'll be quite tedious to implement, since every tuple.)
built-in function and everyplace that calls such functions will need to
be touched; (b) such wide-ranging changes will be difficult to make in
parallel with other development work; (c) it will break existing
user-written loadable modules that define "C language" functions. While
I have no solution to the "tedium" aspect, I believe I see an answer to
the other problems: by use of function handlers, we can support both old
and new interfaces in parallel for both callers and callees, at some
small efficiency cost for the old styles. That way, most of the changes
can be done on an incremental file-by-file basis --- we won't need a
"big bang" where everything changes at once. Support for callees
written in the old style can be left in place indefinitely, to provide
backward compatibility for user-written C functions.
Changes In pg_proc (System Data About a Function)
-------------------------------------------------
A new column "proisstrict" will be added to the system pg_proc table.
This is a boolean value which will be TRUE if the function is "strict",
that is it always returns NULL when any of its inputs are NULL. The
function manager will check this field and skip calling the function when
it's TRUE and there are NULL inputs. This allows us to remove explicit
NULL-value tests from many functions that currently need them (not to
mention fixing many more that need them but don't have them). A function
that is not marked "strict" is responsible for checking whether its inputs
are NULL or not. Most builtin functions will be marked "strict".
An optional WITH parameter will be added to CREATE FUNCTION to allow
specification of whether user-defined functions are strict or not. I am
inclined to make the default be "not strict", since that seems to be the
more useful case for functions expressed in SQL or a PL language, but
am open to arguments for the other choice.
The New Function-Manager Interface
----------------------------------
The core of the new design is revised data structures for representing
the result of a function lookup and for representing the parameters
passed to a specific function invocation. (We want to keep function
lookup separate from function call, since many parts of the system apply
the same function over and over; the lookup overhead should be paid once
per query, not once per tuple.)
When a function is looked up in pg_proc, the result is represented as When a function is looked up in pg_proc, the result is represented as
@ -183,50 +140,6 @@ should have no portability or optimization problems.
Function Coding Conventions Function Coding Conventions
--------------------------- ---------------------------
As an example, int4 addition goes from old-style
int32
int4pl(int32 arg1, int32 arg2)
{
return arg1 + arg2;
}
to new-style
Datum
int4pl(FunctionCallInfo fcinfo)
{
/* we assume the function is marked "strict", so we can ignore
* NULL-value handling */
return Int32GetDatum(DatumGetInt32(fcinfo->arg[0]) +
DatumGetInt32(fcinfo->arg[1]));
}
This is, of course, much uglier than the old-style code, but we can
improve matters with some well-chosen macros for the boilerplate parts.
I propose below macros that would make the code look like
Datum
int4pl(PG_FUNCTION_ARGS)
{
int32 arg1 = PG_GETARG_INT32(0);
int32 arg2 = PG_GETARG_INT32(1);
PG_RETURN_INT32( arg1 + arg2 );
}
This is still more code than before, but it's fairly readable, and it's
also amenable to machine processing --- for example, we could probably
write a script that scans code like this and extracts argument and result
type info for comparison to the pg_proc table.
For the standard data types float4, float8, and int8, these macros should hide
whether the types are pass-by-value or pass-by reference, by incorporating
indirection and space allocation if needed. This will offer a considerable
gain in readability, and it also opens up the opportunity to make these types
be pass-by-value on machines where it's feasible to do so.
Here are the proposed macros and coding conventions: Here are the proposed macros and coding conventions:
The definition of an fmgr-callable function will always look like The definition of an fmgr-callable function will always look like
@ -291,67 +204,6 @@ fields of FunctionCallInfo, it should just do it. I doubt that providing
syntactic-sugar macros for these cases is useful. syntactic-sugar macros for these cases is useful.
Call-Site Coding Conventions
----------------------------
There are many places in the system that call either a specific function
(for example, the parser invokes "textin" by name in places) or a
particular group of functions that have a common argument list (for
example, the optimizer invokes selectivity estimation functions with
a fixed argument list). These places will need to change, but we should
try to avoid making them significantly uglier than before.
Places that invoke an arbitrary function with an arbitrary argument list
can simply be changed to fill a FunctionCallInfoData structure directly;
that'll be no worse and possibly cleaner than what they do now.
When invoking a specific built-in function by name, we have generally
just written something like
result = textin ( ... args ... )
which will not work after textin() is converted to the new call style.
I suggest that code like this be converted to use "helper" functions
that will create and fill in a FunctionCallInfoData struct. For
example, if textin is being called with one argument, it'd look
something like
result = DirectFunctionCall1(textin, PointerGetDatum(argument));
These helper routines will have declarations like
Datum DirectFunctionCall2(PGFunction func, Datum arg1, Datum arg2);
Note it will be the caller's responsibility to convert to and from
Datum; appropriate conversion macros should be used.
The DirectFunctionCallN routines will not bother to fill in
fcinfo->flinfo (indeed cannot, since they have no idea about an OID for
the target function); they will just set it NULL. This is unlikely to
bother any built-in function that could be called this way. Note also
that this style of coding cannot pass a NULL input value nor cope with
a NULL result (it couldn't before, either!). We can make the helper
routines ereport an error if they see that the function returns a NULL.
When invoking a function that has a known argument signature, we have
usually written either
result = fmgr(targetfuncOid, ... args ... );
or
result = fmgr_ptr(FmgrInfo *finfo, ... args ... );
depending on whether an FmgrInfo lookup has been done yet or not.
This kind of code can be recast using helper routines, in the same
style as above:
result = OidFunctionCall1(funcOid, PointerGetDatum(argument));
result = FunctionCall2(funcCallInfo,
PointerGetDatum(argument),
Int32GetDatum(argument));
Again, this style of coding does not allow for expressing NULL inputs
or receiving a NULL result.
As with the callee-side situation, I propose adding argument conversion
macros that hide whether int8, float4, and float8 are pass-by-value or
pass-by-reference.
The existing helper functions fmgr(), fmgr_c(), etc will be left in
place until all uses of them are gone. Of course their internals will
have to change in the first step of implementation, but they can
continue to support the same external appearance.
Support for TOAST-Able Data Types Support for TOAST-Able Data Types
--------------------------------- ---------------------------------
@ -474,83 +326,3 @@ context. fn_mcxt normally points at the context that was
CurrentMemoryContext at the time the FmgrInfo structure was created; CurrentMemoryContext at the time the FmgrInfo structure was created;
in any case it is required to be a context at least as long-lived as the in any case it is required to be a context at least as long-lived as the
FmgrInfo itself. FmgrInfo itself.
Telling the Difference Between Old- and New-Style Functions
-----------------------------------------------------------
During the conversion process, we carried two different pg_language
entries, "internal" and "newinternal", for internal functions. The
function manager used the language code to distinguish which calling
convention to use. (Old-style internal functions were supported via
a function handler.) As of Nov. 2000, no old-style internal functions
remain, so we can drop support for them. We will remove the old "internal"
pg_language entry and rename "newinternal" to "internal".
The interim solution for dynamically-loaded compiled functions has been
similar: two pg_language entries "C" and "newC". This naming convention
is not desirable for the long run, and yet we cannot stop supporting
old-style user functions. Instead, it seems better to use just one
pg_language entry "C", and require the dynamically-loaded library to
provide additional information that identifies new-style functions.
This avoids compatibility problems --- for example, existing dump
scripts will identify PL language handlers as being in language "C",
which would be wrong under the "newC" convention. Also, this approach
should generalize more conveniently for future extensions to the function
interface specification.
Given a dynamically loaded function named "foo" (note that the name being
considered here is the link-symbol name, not the SQL-level function name),
the function manager will look for another function in the same dynamically
loaded library named "pg_finfo_foo". If this second function does not
exist, then foo is assumed to be called old-style, thus ensuring backwards
compatibility with existing libraries. If the info function does exist,
it is expected to have the signature
Pg_finfo_record * pg_finfo_foo (void);
The info function will be called by the fmgr, and must return a pointer
to a Pg_finfo_record struct. (The returned struct will typically be a
statically allocated constant in the dynamic-link library.) The current
definition of the struct is just
typedef struct {
int api_version;
} Pg_finfo_record;
where api_version is 0 to indicate old-style or 1 to indicate new-style
calling convention. In future releases, additional fields may be defined
after api_version, but these additional fields will only be used if
api_version is greater than 1.
These details will be hidden from the author of a dynamically loaded
function by using a macro. To define a new-style dynamically loaded
function named foo, write
PG_FUNCTION_INFO_V1(foo);
Datum
foo(PG_FUNCTION_ARGS)
{
...
}
The function itself is written using the same conventions as for new-style
internal functions; you just need to add the PG_FUNCTION_INFO_V1() macro.
Note that old-style and new-style functions can be intermixed in the same
library, depending on whether or not you write a PG_FUNCTION_INFO_V1() for
each one.
The SQL declaration for a dynamically-loaded function is CREATE FUNCTION
foo ... LANGUAGE C regardless of whether it is old- or new-style.
New-style dynamic functions will be invoked directly by fmgr, and will
therefore have the same performance as internal functions after the initial
pg_proc lookup overhead. Old-style dynamic functions will be invoked via
a handler, and will therefore have a small performance penalty.
To allow old-style dynamic functions to work safely on toastable datatypes,
the handler for old-style functions will automatically detoast toastable
arguments before passing them to the old-style function. A new-style
function is expected to take care of toasted arguments by using the
standard argument access macros defined above.

375
src/backend/utils/fmgr/fmgr.c
Unescape View File

@ -36,37 +36,6 @@
PGDLLIMPORT needs_fmgr_hook_type needs_fmgr_hook = NULL; PGDLLIMPORT needs_fmgr_hook_type needs_fmgr_hook = NULL;
PGDLLIMPORT fmgr_hook_type fmgr_hook = NULL; PGDLLIMPORT fmgr_hook_type fmgr_hook = NULL;
/*
* Declaration for old-style function pointer type. This is now used only
* in fmgr_oldstyle() and is no longer exported.
*
* The m68k SVR4 ABI defines that pointers are returned in %a0 instead of
* %d0. So if a function pointer is declared to return a pointer, the
* compiler may look only into %a0, but if the called function was declared
* to return an integer type, it puts its value only into %d0. So the
* caller doesn't pick up the correct return value. The solution is to
* declare the function pointer to return int, so the compiler picks up the
* return value from %d0. (Functions returning pointers put their value
* *additionally* into %d0 for compatibility.) The price is that there are
* some warnings about int->pointer conversions ... which we can suppress
* with suitably ugly casts in fmgr_oldstyle().
*/
#if (defined(__mc68000__) || (defined(__m68k__))) && defined(__ELF__)
typedef int32 (*func_ptr) ();
#else
typedef char *(*func_ptr) ();
#endif
/*
* For an oldstyle function, fn_extra points to a record like this:
*/
typedef struct
{
func_ptr func; /* Address of the oldstyle function */
bool arg_toastable[FUNC_MAX_ARGS]; /* is n'th arg of a toastable
* datatype? */
} Oldstyle_fnextra;
/* /*
* Hashtable for fast lookup of external C functions * Hashtable for fast lookup of external C functions
*/ */
@ -90,7 +59,6 @@ static void fmgr_info_other_lang(Oid functionId, FmgrInfo *finfo, HeapTuple proc
static CFuncHashTabEntry *lookup_C_func(HeapTuple procedureTuple); static CFuncHashTabEntry *lookup_C_func(HeapTuple procedureTuple);
static void record_C_func(HeapTuple procedureTuple, static void record_C_func(HeapTuple procedureTuple,
PGFunction user_fn, const Pg_finfo_record *inforec); PGFunction user_fn, const Pg_finfo_record *inforec);
static Datum fmgr_oldstyle(PG_FUNCTION_ARGS);
static Datum fmgr_security_definer(PG_FUNCTION_ARGS); static Datum fmgr_security_definer(PG_FUNCTION_ARGS);
@ -304,13 +272,10 @@ fmgr_info_cxt_security(Oid functionId, FmgrInfo *finfo, MemoryContext mcxt,
static void static void
fmgr_info_C_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple) fmgr_info_C_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
{ {
Form_pg_proc procedureStruct = (Form_pg_proc) GETSTRUCT(procedureTuple);
CFuncHashTabEntry *hashentry; CFuncHashTabEntry *hashentry;
PGFunction user_fn; PGFunction user_fn;
const Pg_finfo_record *inforec; const Pg_finfo_record *inforec;
Oldstyle_fnextra *fnextra;
bool isnull; bool isnull;
int i;
/* /*
* See if we have the function address cached already * See if we have the function address cached already
@ -362,20 +327,6 @@ fmgr_info_C_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
switch (inforec->api_version) switch (inforec->api_version)
{ {
case 0:
/* Old style: need to use a handler */
finfo->fn_addr = fmgr_oldstyle;
fnextra = (Oldstyle_fnextra *)
MemoryContextAllocZero(finfo->fn_mcxt,
sizeof(Oldstyle_fnextra));
finfo->fn_extra = (void *) fnextra;
fnextra->func = (func_ptr) user_fn;
for (i = 0; i < procedureStruct->pronargs; i++)
{
fnextra->arg_toastable[i] =
TypeIsToastable(procedureStruct->proargtypes.values[i]);
}
break;
case 1: case 1:
/* New style: call directly */ /* New style: call directly */
finfo->fn_addr = user_fn; finfo->fn_addr = user_fn;
@ -415,14 +366,6 @@ fmgr_info_other_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
CurrentMemoryContext, true); CurrentMemoryContext, true);
finfo->fn_addr = plfinfo.fn_addr; finfo->fn_addr = plfinfo.fn_addr;
/*
* If lookup of the PL handler function produced nonnull fn_extra,
* complain --- it must be an oldstyle function! We no longer support
* oldstyle PL handlers.
*/
if (plfinfo.fn_extra != NULL)
elog(ERROR, "language %u has old-style handler", language);
ReleaseSysCache(languageTuple); ReleaseSysCache(languageTuple);
} }
@ -431,10 +374,7 @@ fmgr_info_other_lang(Oid functionId, FmgrInfo *finfo, HeapTuple procedureTuple)
* The function is specified by a handle for the containing library * The function is specified by a handle for the containing library
* (obtained from load_external_function) as well as the function name. * (obtained from load_external_function) as well as the function name.
* *
* If no info function exists for the given name, it is not an error. * If no info function exists for the given name an error is raised.
* Instead we return a default info record for a version-0 function.
* We want to raise an error here only if the info function returns
* something bogus.
* *
* This function is broken out of fmgr_info_C_lang so that fmgr_c_validator * This function is broken out of fmgr_info_C_lang so that fmgr_c_validator
* can validate the information record for a function not yet entered into * can validate the information record for a function not yet entered into
@ -446,7 +386,6 @@ fetch_finfo_record(void *filehandle, char *funcname)
char *infofuncname; char *infofuncname;
PGFInfoFunction infofunc; PGFInfoFunction infofunc;
const Pg_finfo_record *inforec; const Pg_finfo_record *inforec;
static Pg_finfo_record default_inforec = {0};
infofuncname = psprintf("pg_finfo_%s", funcname); infofuncname = psprintf("pg_finfo_%s", funcname);
@ -455,9 +394,12 @@ fetch_finfo_record(void *filehandle, char *funcname)
infofuncname); infofuncname);
if (infofunc == NULL) if (infofunc == NULL)
{ {
/* Not found --- assume version 0 */ ereport(ERROR,
pfree(infofuncname); (errcode(ERRCODE_UNDEFINED_FUNCTION),
return &default_inforec; errmsg("could not find function information for function \"%s\"",
funcname),
errhint("SQL-callable functions need an accompanying PG_FUNCTION_INFO_V1(funcname).")));
return NULL; /* silence compiler */
} }
/* Found, so call it */ /* Found, so call it */
@ -468,7 +410,6 @@ fetch_finfo_record(void *filehandle, char *funcname)
elog(ERROR, "null result from info function \"%s\"", infofuncname); elog(ERROR, "null result from info function \"%s\"", infofuncname);
switch (inforec->api_version) switch (inforec->api_version)
{ {
case 0:
case 1: case 1:
/* OK, no additional fields to validate */ /* OK, no additional fields to validate */
break; break;
@ -585,17 +526,6 @@ fmgr_info_copy(FmgrInfo *dstinfo, FmgrInfo *srcinfo,
{ {
memcpy(dstinfo, srcinfo, sizeof(FmgrInfo)); memcpy(dstinfo, srcinfo, sizeof(FmgrInfo));
dstinfo->fn_mcxt = destcxt; dstinfo->fn_mcxt = destcxt;
if (dstinfo->fn_addr == fmgr_oldstyle)
{
/* For oldstyle functions we must copy fn_extra */
Oldstyle_fnextra *fnextra;
fnextra = (Oldstyle_fnextra *)
MemoryContextAlloc(destcxt, sizeof(Oldstyle_fnextra));
memcpy(fnextra, srcinfo->fn_extra, sizeof(Oldstyle_fnextra));
dstinfo->fn_extra = (void *) fnextra;
}
else
dstinfo->fn_extra = NULL; dstinfo->fn_extra = NULL;
} }
@ -616,245 +546,6 @@ fmgr_internal_function(const char *proname)
} }
/*
* Handler for old-style "C" language functions
*/
static Datum
fmgr_oldstyle(PG_FUNCTION_ARGS)
{
Oldstyle_fnextra *fnextra;
int n_arguments = fcinfo->nargs;
int i;
bool isnull;
func_ptr user_fn;
char *returnValue;
if (fcinfo->flinfo == NULL || fcinfo->flinfo->fn_extra == NULL)
elog(ERROR, "fmgr_oldstyle received NULL pointer");
fnextra = (Oldstyle_fnextra *) fcinfo->flinfo->fn_extra;
/*
* Result is NULL if any argument is NULL, but we still call the function
* (peculiar, but that's the way it worked before, and after all this is a
* backwards-compatibility wrapper). Note, however, that we'll never get
* here with NULL arguments if the function is marked strict.
*
* We also need to detoast any TOAST-ed inputs, since it's unlikely that
* an old-style function knows about TOASTing.
*/
isnull = false;
for (i = 0; i < n_arguments; i++)
{
if (PG_ARGISNULL(i))
isnull = true;
else if (fnextra->arg_toastable[i])
fcinfo->arg[i] = PointerGetDatum(PG_DETOAST_DATUM(fcinfo->arg[i]));
}
fcinfo->isnull = isnull;
user_fn = fnextra->func;
switch (n_arguments)
{
case 0:
returnValue = (char *) (*user_fn) ();
break;
case 1:
/*
* nullvalue() used to use isNull to check if arg is NULL; perhaps
* there are other functions still out there that also rely on
* this undocumented hack?
*/
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
&fcinfo->isnull);
break;
case 2:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1]);
break;
case 3:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2]);
break;
case 4:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3]);
break;
case 5:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4]);
break;
case 6:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5]);
break;
case 7:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6]);
break;
case 8:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7]);
break;
case 9:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8]);
break;
case 10:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9]);
break;
case 11:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10]);
break;
case 12:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10],
fcinfo->arg[11]);
break;
case 13:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10],
fcinfo->arg[11],
fcinfo->arg[12]);
break;
case 14:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10],
fcinfo->arg[11],
fcinfo->arg[12],
fcinfo->arg[13]);
break;
case 15:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10],
fcinfo->arg[11],
fcinfo->arg[12],
fcinfo->arg[13],
fcinfo->arg[14]);
break;
case 16:
returnValue = (char *) (*user_fn) (fcinfo->arg[0],
fcinfo->arg[1],
fcinfo->arg[2],
fcinfo->arg[3],
fcinfo->arg[4],
fcinfo->arg[5],
fcinfo->arg[6],
fcinfo->arg[7],
fcinfo->arg[8],
fcinfo->arg[9],
fcinfo->arg[10],
fcinfo->arg[11],
fcinfo->arg[12],
fcinfo->arg[13],
fcinfo->arg[14],
fcinfo->arg[15]);
break;
default:
/*
* Increasing FUNC_MAX_ARGS doesn't automatically add cases to the
* above code, so mention the actual value in this error not
* FUNC_MAX_ARGS. You could add cases to the above if you needed
* to support old-style functions with many arguments, but making
* 'em be new-style is probably a better idea.
*/
ereport(ERROR,
(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
errmsg("function %u has too many arguments (%d, maximum is %d)",
fcinfo->flinfo->fn_oid, n_arguments, 16)));
returnValue = NULL; /* keep compiler quiet */
break;
}
return PointerGetDatum(returnValue);
}
/* /*
* Support for security-definer and proconfig-using functions. We support * Support for security-definer and proconfig-using functions. We support
* both of these features using the same call handler, because they are * both of these features using the same call handler, because they are
@ -2081,58 +1772,6 @@ OidSendFunctionCall(Oid functionId, Datum val)
} }
/*
* !!! OLD INTERFACE !!!
*
* fmgr() is the only remaining vestige of the old-style caller support
* functions. It's no longer used anywhere in the Postgres distribution,
* but we should leave it around for a release or two to ease the transition
* for user-supplied C functions. OidFunctionCallN() replaces it for new
* code.
*
* DEPRECATED, DO NOT USE IN NEW CODE
*/
char *
fmgr(Oid procedureId,...)
{
FmgrInfo flinfo;
FunctionCallInfoData fcinfo;
int n_arguments;
Datum result;
fmgr_info(procedureId, &flinfo);
MemSet(&fcinfo, 0, sizeof(fcinfo));
fcinfo.flinfo = &flinfo;
fcinfo.nargs = flinfo.fn_nargs;
n_arguments = fcinfo.nargs;
if (n_arguments > 0)
{
va_list pvar;
int i;
if (n_arguments > FUNC_MAX_ARGS)
ereport(ERROR,
(errcode(ERRCODE_TOO_MANY_ARGUMENTS),
errmsg("function %u has too many arguments (%d, maximum is %d)",
flinfo.fn_oid, n_arguments, FUNC_MAX_ARGS)));
va_start(pvar, procedureId);
for (i = 0; i < n_arguments; i++)
fcinfo.arg[i] = PointerGetDatum(va_arg(pvar, char *));
va_end(pvar);
}
result = FunctionCallInvoke(&fcinfo);
/* Check for null result, since caller is clearly not expecting one */
if (fcinfo.isnull)
elog(ERROR, "function %u returned NULL", flinfo.fn_oid);
return DatumGetPointer(result);
}
/*------------------------------------------------------------------------- /*-------------------------------------------------------------------------
* Support routines for standard maybe-pass-by-reference datatypes * Support routines for standard maybe-pass-by-reference datatypes
* *

8
src/include/fmgr.h
Unescape View File

@ -336,10 +336,10 @@ extern struct varlena *pg_detoast_datum_packed(struct varlena * datum);
/*------------------------------------------------------------------------- /*-------------------------------------------------------------------------
* Support for detecting call convention of dynamically-loaded functions * Support for detecting call convention of dynamically-loaded functions
* *
* Dynamically loaded functions may use either the version-1 ("new style") * Dynamically loaded functions currently can only use the version-1 ("new
* or version-0 ("old style") calling convention. Version 1 is the call * style") calling convention. Version-0 ("old style") is not supported
* convention defined in this header file; version 0 is the old "plain C" * anymore. Version 1 is the call convention defined in this header file, and
* convention. A version-1 function must be accompanied by the macro call * must be accompanied by the macro call
* *
* PG_FUNCTION_INFO_V1(function_name); * PG_FUNCTION_INFO_V1(function_name);
* *

5
src/test/regress/input/create_function_2.source
Unescape View File

@ -87,11 +87,6 @@ CREATE FUNCTION reverse_name(name)
AS '@libdir@/regress@DLSUFFIX@' AS '@libdir@/regress@DLSUFFIX@'
LANGUAGE C STRICT; LANGUAGE C STRICT;
CREATE FUNCTION oldstyle_length(int4, text)
RETURNS int4
AS '@libdir@/regress@DLSUFFIX@'
LANGUAGE C; -- intentionally not strict
-- --
-- Function dynamic loading -- Function dynamic loading
-- --

13
src/test/regress/input/misc.source
Unescape View File

@ -249,19 +249,6 @@ SELECT *, name(equipment(h.*)) FROM hobbies_r h;
SELECT *, (equipment(CAST((h.*) AS hobbies_r))).name FROM hobbies_r h; SELECT *, (equipment(CAST((h.*) AS hobbies_r))).name FROM hobbies_r h;
--
-- check that old-style C functions work properly with TOASTed values
--
create table oldstyle_test(i int4, t text);
insert into oldstyle_test values(null,null);
insert into oldstyle_test values(0,'12');
insert into oldstyle_test values(1000,'12');
insert into oldstyle_test values(0, repeat('x', 50000));
select i, length(t), octet_length(t), oldstyle_length(i,t) from oldstyle_test;
drop table oldstyle_test;
-- --
-- functional joins -- functional joins
-- --

4
src/test/regress/output/create_function_2.source
Unescape View File

@ -67,10 +67,6 @@ CREATE FUNCTION reverse_name(name)
RETURNS name RETURNS name
AS '@libdir@/regress@DLSUFFIX@' AS '@libdir@/regress@DLSUFFIX@'
LANGUAGE C STRICT; LANGUAGE C STRICT;
CREATE FUNCTION oldstyle_length(int4, text)
RETURNS int4
AS '@libdir@/regress@DLSUFFIX@'
LANGUAGE C; -- intentionally not strict
-- --
-- Function dynamic loading -- Function dynamic loading
-- --

18
src/test/regress/output/misc.source
Unescape View File

@ -681,24 +681,6 @@ SELECT *, (equipment(CAST((h.*) AS hobbies_r))).name FROM hobbies_r h;
skywalking | | guts skywalking | | guts
(7 rows) (7 rows)
--
-- check that old-style C functions work properly with TOASTed values
--
create table oldstyle_test(i int4, t text);
insert into oldstyle_test values(null,null);
insert into oldstyle_test values(0,'12');
insert into oldstyle_test values(1000,'12');
insert into oldstyle_test values(0, repeat('x', 50000));
select i, length(t), octet_length(t), oldstyle_length(i,t) from oldstyle_test;
i | length | octet_length | oldstyle_length
------+--------+--------------+-----------------
| | |
0 | 2 | 2 | 2
1000 | 2 | 2 | 1002
0 | 50000 | 50000 | 50000
(4 rows)
drop table oldstyle_test;
-- --
-- functional joins -- functional joins
-- --

45
src/test/regress/regress.c
Unescape View File

@ -45,8 +45,6 @@
extern PATH *poly2path(POLYGON *poly); extern PATH *poly2path(POLYGON *poly);
extern void regress_lseg_construct(LSEG *lseg, Point *pt1, Point *pt2); extern void regress_lseg_construct(LSEG *lseg, Point *pt1, Point *pt2);
extern char *reverse_name(char *string);
extern int oldstyle_length(int n, text *t);
#ifdef PG_MODULE_MAGIC #ifdef PG_MODULE_MAGIC
PG_MODULE_MAGIC; PG_MODULE_MAGIC;
@ -240,14 +238,15 @@ typedef struct
double radius; double radius;
} WIDGET; } WIDGET;
WIDGET *widget_in(char *str); PG_FUNCTION_INFO_V1(widget_in);
char *widget_out(WIDGET *widget); PG_FUNCTION_INFO_V1(widget_out);
#define NARGS 3 #define NARGS 3
WIDGET * Datum
widget_in(char *str) widget_in(PG_FUNCTION_ARGS)
{ {
char *str = PG_GETARG_CSTRING(0);
char *p, char *p,
*coord[NARGS]; *coord[NARGS];
int i; int i;
@ -270,14 +269,16 @@ widget_in(char *str)
result->center.y = atof(coord[1]); result->center.y = atof(coord[1]);
result->radius = atof(coord[2]); result->radius = atof(coord[2]);
return result; PG_RETURN_POINTER(result);
} }
char * Datum
widget_out(WIDGET *widget) widget_out(PG_FUNCTION_ARGS)
{ {
return psprintf("(%g,%g,%g)", WIDGET *widget = (WIDGET *) PG_GETARG_POINTER(0);
char *str = psprintf("(%g,%g,%g)",
widget->center.x, widget->center.y, widget->radius); widget->center.x, widget->center.y, widget->radius);
PG_RETURN_CSTRING(str);
} }
PG_FUNCTION_INFO_V1(pt_in_widget); PG_FUNCTION_INFO_V1(pt_in_widget);
@ -305,9 +306,12 @@ boxarea(PG_FUNCTION_ARGS)
PG_RETURN_FLOAT8(width * height); PG_RETURN_FLOAT8(width * height);
} }
char * PG_FUNCTION_INFO_V1(reverse_name);
reverse_name(char *string)
Datum
reverse_name(PG_FUNCTION_ARGS)
{ {
char *string = PG_GETARG_CSTRING(0);
int i; int i;
int len; int len;
char *new_string; char *new_string;
@ -320,22 +324,7 @@ reverse_name(char *string)
len = i; len = i;
for (; i >= 0; --i) for (; i >= 0; --i)
new_string[len - i] = string[i]; new_string[len - i] = string[i];
return new_string; PG_RETURN_CSTRING(new_string);
}
/*
* This rather silly function is just to test that oldstyle functions
* work correctly on toast-able inputs.
*/
int
oldstyle_length(int n, text *t)
{
int len = 0;
if (t)
len = VARSIZE(t) - VARHDRSZ;
return n + len;
} }

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