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Commitfa09ee6

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Document the always-true-but-previously-undocumented fact that PQfnumber()
will downcase the supplied field name unless it is double-quoted. Also,upgrade the routine's handling of double quotes to match the backend,in particular support doubled double quotes within quoted identifiers.Per pgsql-interfaces discussion a couple weeks ago.
1 parentb833c3d commitfa09ee6

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2 files changed

+78
-13
lines changed

2 files changed

+78
-13
lines changed

‎doc/src/sgml/libpq.sgml

Lines changed: 20 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
<!--
2-
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.138 2003/10/03 18:26:14 tgl Exp $
2+
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.139 2003/10/04 21:05:20 tgl Exp $
33
-->
44

55
<chapter id="libpq">
@@ -1553,8 +1553,7 @@ NULL is returned if the column number is out of range.
15531553
<term><function>PQfnumber</function><indexterm><primary>PQfnumber</></></term>
15541554
<listitem>
15551555
<para>
1556-
Returns the column number
1557-
associated with the given column name.
1556+
Returns the column number associated with the given column name.
15581557
<synopsis>
15591558
int PQfnumber(const PGresult *res,
15601559
const char *column_name);
@@ -1564,6 +1563,24 @@ int PQfnumber(const PGresult *res,
15641563
<para>
15651564
-1 is returned if the given name does not match any column.
15661565
</para>
1566+
1567+
<para>
1568+
The given name is treated like an identifier in an SQL command,
1569+
that is, it is downcased unless double-quoted. For example,
1570+
given a query result generated from the SQL command
1571+
<programlisting>
1572+
select 1 as FOO, 2 as "BAR";
1573+
</programlisting>
1574+
we would have the results:
1575+
<programlisting>
1576+
PQfname(res, 0) <lineannotation>foo</lineannotation>
1577+
PQfname(res, 1) <lineannotation>BAR</lineannotation>
1578+
PQfnumber(res, "FOO") <lineannotation>0</lineannotation>
1579+
PQfnumber(res, "foo") <lineannotation>0</lineannotation>
1580+
PQfnumber(res, "BAR") <lineannotation>-1</lineannotation>
1581+
PQfnumber(res, "\"BAR\"") <lineannotation>1</lineannotation>
1582+
</programlisting>
1583+
</para>
15671584
</listitem>
15681585
</varlistentry>
15691586

‎src/interfaces/libpq/fe-exec.c

Lines changed: 58 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.150 2003/10/03 18:26:14 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.151 2003/10/04 21:05:21 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -1803,32 +1803,80 @@ PQfname(const PGresult *res, int field_num)
18031803
}
18041804

18051805
/*
1806-
* returns -1 on a bad field name
1806+
* PQfnumber: find column number given column name
1807+
*
1808+
* The column name is parsed as if it were in a SQL statement, including
1809+
* case-folding and double-quote processing. But note a possible gotcha:
1810+
* downcasing in the frontend might follow different locale rules than
1811+
* downcasing in the backend...
1812+
*
1813+
* Returns -1 if no match. In the present backend it is also possible
1814+
* to have multiple matches, in which case the first one is found.
18071815
*/
18081816
int
18091817
PQfnumber(constPGresult*res,constchar*field_name)
18101818
{
1811-
inti;
18121819
char*field_case;
1820+
boolin_quotes;
1821+
char*iptr;
1822+
char*optr;
1823+
inti;
18131824

18141825
if (!res)
18151826
return-1;
18161827

1828+
/*
1829+
* Note: it is correct to reject a zero-length input string; the proper
1830+
* input to match a zero-length field name would be "".
1831+
*/
18171832
if (field_name==NULL||
18181833
field_name[0]=='\0'||
18191834
res->attDescs==NULL)
18201835
return-1;
18211836

1837+
/*
1838+
* Note: this code will not reject partially quoted strings, eg
1839+
* foo"BAR"foo will become fooBARfoo when it probably ought to be
1840+
* an error condition.
1841+
*/
18221842
field_case=strdup(field_name);
1823-
if (*field_case=='"')
1843+
if (field_case==NULL)
1844+
return-1;/* grotty */
1845+
1846+
in_quotes= false;
1847+
optr=field_case;
1848+
for (iptr=field_case;*iptr;iptr++)
18241849
{
1825-
strcpy(field_case,field_case+1);
1826-
*(field_case+strlen(field_case)-1)='\0';
1850+
charc=*iptr;
1851+
1852+
if (in_quotes)
1853+
{
1854+
if (c=='"')
1855+
{
1856+
if (iptr[1]=='"')
1857+
{
1858+
/* doubled quotes become a single quote */
1859+
*optr++='"';
1860+
iptr++;
1861+
}
1862+
else
1863+
in_quotes= false;
1864+
}
1865+
else
1866+
*optr++=c;
1867+
}
1868+
elseif (c=='"')
1869+
{
1870+
in_quotes= true;
1871+
}
1872+
else
1873+
{
1874+
if (isupper((unsignedchar)c))
1875+
c=tolower((unsignedchar)c);
1876+
*optr++=c;
1877+
}
18271878
}
1828-
else
1829-
for (i=0;field_case[i];i++)
1830-
if (isupper((unsignedchar)field_case[i]))
1831-
field_case[i]=tolower((unsignedchar)field_case[i]);
1879+
*optr='\0';
18321880

18331881
for (i=0;i<res->numAttributes;i++)
18341882
{

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