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Postgres FD Implementation
Commit 636a939f authored by Tom Lane's avatar Tom Lane
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Fix array_out's failure to backslash backslashes, per bug# 524. Also, 

remove brain-dead rule that double quotes are needed if and only if the
datatype is pass-by-reference; neither direction of the implication holds
water.  Instead, examine the actual data string to see if it contains
any characters that force us to quote it.
Add some documentation about quoting of array values, which was previously
explained nowhere AFAICT.
parent a4e8cd30
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Showing with 109 additions and 59 deletions
doc/src/sgml/array.sgml
View file @ 636a939f
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.17 2001/11/28 20:49:09 petere Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/array.sgml,v 1.18 2001/11/29 21:02:41 tgl Exp $ -->
<chapter id="arrays">
<title>Arrays</title>
......@@ -248,4 +248,36 @@ SELECT * FROM sal_emp WHERE pay_by_quarter **= 10000;
</para>
</note>
<formalpara>
<title>Quoting array elements.</title>
<para>
As shown above, when writing an array literal value you may write double
quotes around any individual array
element. You <emphasis>must</> do so if the element value would otherwise
confuse the array-value parser. For example, elements containing curly
braces, commas, double quotes, backslashes, or white space must be
double-quoted. To put a double quote or backslash in an array element
value, precede it with a backslash.
</para>
</formalpara>
<tip>
<para>
Remember that what you write in an SQL query will first be interpreted
as a string literal, and then as an array. This doubles the number of
backslashes you need. For example, to insert a <type>text</> array
value containing a backslash and a double quote, you'd need to write
<programlisting>
INSERT ... VALUES ('{"\\\\","\\""}');
</programlisting>
The string-literal processor removes one level of backslashes, so that
what arrives at the array-value parser looks like <literal>{"\\","\""}</>.
In turn, the strings fed to the <type>text</> datatype's input routine
become <literal>\</> and <literal>"</> respectively. (If we were working
with a datatype whose input routine also treated backslashes specially,
<type>bytea</> for example, we might need as many as eight backslashes
in the query to get one backslash into the stored array element.)
</para>
</tip>
</chapter>
src/backend/utils/adt/arrayfuncs.c
View file @ 636a939f
......@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.71 2001/10/25 05:49:43 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/utils/adt/arrayfuncs.c,v 1.72 2001/11/29 21:02:41 tgl Exp $
*
*-------------------------------------------------------------------------
*/
......@@ -346,6 +346,7 @@ ArrayCount(char *str, int *dim, int typdelim)
* If element type is pass-by-ref, the Datums point to palloc'd values.
* *nbytes is set to the amount of data space needed for the array,
* including alignment padding but not including array header overhead.
* CAUTION: the contents of "arrayStr" may be modified!
*---------------------------------------------------------------------------
*/
static Datum *
......@@ -564,16 +565,13 @@ array_out(PG_FUNCTION_ARGS)
char *p,
*tmp,
*retval,
**values,
delim[2];
**values;
bool *needquotes;
int nitems,
overall_length,
i,
j,
k,
#ifndef TCL_ARRAYS
l,
#endif
indx[MAXDIM];
int ndim,
*dim;
......@@ -581,26 +579,29 @@ array_out(PG_FUNCTION_ARGS)
system_cache_lookup(element_type, false, &typlen, &typbyval,
&typdelim, &typelem, &typoutput, &typalign);
fmgr_info(typoutput, &outputproc);
sprintf(delim, "%c", typdelim);
ndim = ARR_NDIM(v);
dim = ARR_DIMS(v);
nitems = ArrayGetNItems(ndim, dim);
if (nitems == 0)
{
retval = (char *) palloc(3);
retval[0] = '{';
retval[1] = '}';
retval[2] = '\0';
retval = pstrdup("{}");
PG_RETURN_CSTRING(retval);
}
/*
* Convert all values to string form, count total space needed
* (including any overhead such as escaping backslashes),
* and detect whether each item needs double quotes.
*/
values = (char **) palloc(nitems * sizeof(char *));
needquotes = (bool *) palloc(nitems * sizeof(bool));
p = ARR_DATA_PTR(v);
overall_length = 1; /* [TRH] don't forget to count \0 at end. */
values = (char **) palloc(nitems * sizeof(char *));
for (i = 0; i < nitems; i++)
{
Datum itemvalue;
bool nq;
itemvalue = fetch_att(p, typbyval, typlen);
values[i] = DatumGetCString(FunctionCall3(&outputproc,
......@@ -612,20 +613,32 @@ array_out(PG_FUNCTION_ARGS)
else
p += INTALIGN(*(int32 *) p);
/*
* For the pair of double quotes
*/
if (!typbyval)
overall_length += 2;
/* count data plus backslashes; detect chars needing quotes */
nq = (values[i][0] == '\0'); /* force quotes for empty string */
for (tmp = values[i]; *tmp; tmp++)
{
char ch = *tmp;
overall_length += 1;
if (ch == '"' || ch == '\\')
{
nq = true;
#ifndef TCL_ARRAYS
if (*tmp == '"')
overall_length += 1;
#endif
}
else if (ch == '{' || ch == '}' || ch == typdelim ||
isspace((unsigned char) ch))
nq = true;
}
needquotes[i] = nq;
/* Count the pair of double quotes, if needed */
if (nq)
overall_length += 2;
/* and the comma */
overall_length += 1;
}
......@@ -634,41 +647,41 @@ array_out(PG_FUNCTION_ARGS)
*/
for (i = j = 0, k = 1; i < ndim; k *= dim[i++], j += k);
p = (char *) palloc(overall_length + 2 * j);
retval = p;
retval = (char *) palloc(overall_length + 2 * j);
p = retval;
#define APPENDSTR(str) (strcpy(p, (str)), p += strlen(p))
#define APPENDCHAR(ch) (*p++ = (ch), *p = '\0')
strcpy(p, "{");
APPENDCHAR('{');
for (i = 0; i < ndim; indx[i++] = 0);
j = 0;
k = 0;
do
{
for (i = j; i < ndim - 1; i++)
strcat(p, "{");
APPENDCHAR('{');
/*
* Surround anything that is not passed by value in double quotes.
* See above for more details.
*/
if (!typbyval)
if (needquotes[k])
{
strcat(p, "\"");
APPENDCHAR('"');
#ifndef TCL_ARRAYS
l = strlen(p);
for (tmp = values[k]; *tmp; tmp++)
{
if (*tmp == '"')
p[l++] = '\\';
p[l++] = *tmp;
char ch = *tmp;
if (ch == '"' || ch == '\\')
*p++ = '\\';
*p++ = ch;
}
p[l] = '\0';
*p = '\0';
#else
strcat(p, values[k]);
APPENDSTR(values[k]);
#endif
strcat(p, "\"");
APPENDCHAR('"');
}
else
strcat(p, values[k]);
APPENDSTR(values[k]);
pfree(values[k++]);
for (i = ndim - 1; i >= 0; i--)
......@@ -676,16 +689,21 @@ array_out(PG_FUNCTION_ARGS)
indx[i] = (indx[i] + 1) % dim[i];
if (indx[i])
{
strcat(p, delim);
APPENDCHAR(typdelim);
break;
}
else
strcat(p, "}");
APPENDCHAR('}');
}
j = i;
} while (j != -1);
#undef APPENDSTR
#undef APPENDCHAR
pfree(values);
pfree(needquotes);
PG_RETURN_CSTRING(retval);
}
......
src/test/regress/expected/arrays.out
View file @ 636a939f
......@@ -28,11 +28,11 @@ INSERT INTO arrtest (a, b[2][2][1], c, d, e, f, g)
INSERT INTO arrtest (a, b[1][2][2], c, d[2][1])
VALUES ('{}', '{3,4}', '{foo,bar}', '{bar,foo}');
SELECT * FROM arrtest;
a | b | c | d | e | f | g
-------------+-----------------+---------------+-------------------+---------------+-------------------+-----------------
{1,2,3,4,5} | {{{0,0},{1,2}}} | {} | {} | | {} | {}
{11,12,23} | {{3,4},{4,5}} | {"foobar"} | {{"elt1","elt2"}} | {"3.4","6.7"} | {"abc ","abcde"} | {"abc","abcde"}
{} | {3,4} | {"foo","bar"} | {"bar","foo"} | | |
a | b | c | d | e | f | g
-------------+-----------------+-----------+---------------+-----------+-----------------+-------------
{1,2,3,4,5} | {{{0,0},{1,2}}} | {} | {} | | {} | {}
{11,12,23} | {{3,4},{4,5}} | {foobar} | {{elt1,elt2}} | {3.4,6.7} | {"abc ",abcde} | {abc,abcde}
{} | {3,4} | {foo,bar} | {bar,foo} | | |
(3 rows)
SELECT arrtest.a[1],
......@@ -62,11 +62,11 @@ SELECT a[1:3],
c[1:2],
d[1:1][1:2]
FROM arrtest;
a | b | c | d
------------+-----------------+---------------+-------------------
{1,2,3} | {{{0,0},{1,2}}} | |
{11,12,23} | | {"foobar"} | {{"elt1","elt2"}}
| | {"foo","bar"} |
a | b | c | d
------------+-----------------+-----------+---------------
{1,2,3} | {{{0,0},{1,2}}} | |
{11,12,23} | | {foobar} | {{elt1,elt2}}
| | {foo,bar} |
(3 rows)
SELECT array_dims(a) AS a,array_dims(b) AS b,array_dims(c) AS c
......@@ -98,11 +98,11 @@ UPDATE arrtest
SET c[2:2] = '{"new_word"}'
WHERE array_dims(c) is not null;
SELECT a,b,c FROM arrtest;
a | b | c
---------------+-----------------------+-----------------------
a | b | c
---------------+-----------------------+-------------------
{16,25,3,4,5} | {{{113,142},{1,147}}} | {}
{} | {3,4} | {"foo","new_word"}
{16,25,23} | {{3,4},{4,5}} | {"foobar","new_word"}
{} | {3,4} | {foo,new_word}
{16,25,23} | {{3,4},{4,5}} | {foobar,new_word}
(3 rows)
SELECT a[1:3],
......@@ -110,10 +110,10 @@ SELECT a[1:3],
c[1:2],
d[1:1][2:2]
FROM arrtest;
a | b | c | d
------------+-----------------------+-----------------------+------------
{16,25,3} | {{{113,142},{1,147}}} | |
| | {"foo","new_word"} |
{16,25,23} | | {"foobar","new_word"} | {{"elt2"}}
a | b | c | d
------------+-----------------------+-------------------+----------
{16,25,3} | {{{113,142},{1,147}}} | |
| | {foo,new_word} |
{16,25,23} | | {foobar,new_word} | {{elt2}}
(3 rows)
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