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Cause PQescapeString to stop processing at a null character, rather

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than generating an invalid output string.  Per observation and patch
from Igor Shevchenko.  Further code cleanup and documentation by
Tom Lane.
This commit is contained in:
Tom Lane 2003-10-03 18:26:14 +00:00
parent 3b4c142030
commit 251033186f
2 changed files with 29 additions and 26 deletions
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13
doc/src/sgml/libpq.sgml
View File

@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.137 2003/09/20 20:12:05 tgl Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.138 2003/10/03 18:26:14 tgl Exp $
-->
<chapter id="libpq">
@ -1972,10 +1972,13 @@ size_t PQescapeString (char *to, const char *from, size_t length);
<para>
The parameter <parameter>from</> points to the first character of the string
that
is to be escaped, and the <parameter>length</> parameter gives the
number of characters in this string. (A terminating zero byte is
neither necessary nor counted.) <parameter>to</> shall point to a
that is to be escaped, and the <parameter>length</> parameter gives the
number of characters in this string. A terminating zero byte is not
required, and should not be counted in <parameter>length</>. (If
a terminating zero byte is found before <parameter>length</> bytes are
processed, <function>PQescapeString</> stops at the zero; the behavior
is thus rather like <function>strncpy</>.)
<parameter>to</> shall point to a
buffer that is able to hold at least one more character than twice
the value of <parameter>length</>, otherwise the behavior is
undefined. A call to <function>PQescapeString</> writes an escaped

42
src/interfaces/libpq/fe-exec.c
View File

@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.149 2003/10/02 14:47:44 tgl Exp $
* $Header: /cvsroot/pgsql/src/interfaces/libpq/fe-exec.c,v 1.150 2003/10/03 18:26:14 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -2143,47 +2143,47 @@ PQfreeNotify(PGnotify *notify)
}
/* ---------------
* Escaping arbitrary strings to get valid SQL strings/identifiers.
/*
* Escaping arbitrary strings to get valid SQL literal strings.
*
* Replaces "\\" with "\\\\" and "'" with "''".
* length is the length of the buffer pointed to by
* from. The buffer at to must be at least 2*length + 1 characters
* long. A terminating NUL character is written.
* ---------------
*
* length is the length of the source string. (Note: if a terminating NUL
* is encountered sooner, PQescapeString stops short of "length"; the behavior
* is thus rather like strncpy.)
*
* For safety the buffer at "to" must be at least 2*length + 1 bytes long.
* A terminating NUL character is added to the output string, whether the
* input is NUL-terminated or not.
*
* Returns the actual length of the output (not counting the terminating NUL).
*/
size_t
PQescapeString(char *to, const char *from, size_t length)
{
const char *source = from;
char *target = to;
unsigned int remaining = length;
size_t remaining = length;
while (remaining > 0)
while (remaining > 0 && *source != '\0')
{
switch (*source)
{
case '\\':
*target = '\\';
target++;
*target = '\\';
/* target and remaining are updated below. */
*target++ = '\\';
*target++ = '\\';
break;
case '\'':
*target = '\'';
target++;
*target = '\'';
/* target and remaining are updated below. */
*target++ = '\'';
*target++ = '\'';
break;
default:
*target = *source;
/* target and remaining are updated below. */
*target++ = *source;
break;
}
source++;
target++;
remaining--;
}