Add PQescapeIdentifier() to libpq

Christopher Kings-Lynne

1 files changed, 63 insertions, 1 deletions

diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml
index 229e9d5a28f..7dec1214c83 100644
--- a/doc/src/sgml/libpq.sgml
+++ b/doc/src/sgml/libpq.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.211 2006/05/23 22:13:19 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.212 2006/06/27 00:03:41 momjian Exp $ -->
 
  <chapter id="libpq">
   <title><application>libpq</application> - C Library</title>
@@ -2279,6 +2279,68 @@ in favor of <function>PQescapeStringConn</>.
 </para>
 </sect2>
 
+<sect2 id="libpq-exec-escape-identifier">
+  <title>Escaping Identifier for Inclusion in SQL Commands</title>
+
+   <indexterm zone="libpq-exec-escape-identifier"><primary>PQescapeIdentifier</></>
+   <indexterm zone="libpq-exec-escape-identifier"><primary>escaping strings</></>
+
+<para>
+<function>PQescapeIdentifier</function> escapes a string for use 
+as an identifier name within an SQL command.  For example; table names,
+column names, view names and user names are all identifiers.
+Double quotes (") must be escaped to prevent them from being interpreted 
+specially by the SQL parser. <function>PQescapeIdentifier</> performs this 
+operation.
+</para>
+
+<tip>
+<para>
+It is especially important to do proper escaping when handling strings that
+were received from an untrustworthy source.  Otherwise there is a security
+risk: you are vulnerable to <quote>SQL injection</> attacks wherein unwanted
+SQL commands are fed to your database.
+</para>
+</tip>
+
+<para>
+Note that it is still necessary to do escaping of identifiers when
+using functions that support parameterized queries such as <function>PQexecParams</> or
+its sibling routines. Only literal values are automatically escaped
+using these functions, not identifiers.
+
+<synopsis>
+size_t PQescapeIdentifier (char *to, const char *from, size_t length);
+</synopsis>
+</para>
+
+<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 not required, and should not be counted in <parameter>length</>. (If
+a terminating zero byte is found before <parameter>length</> bytes are
+processed, <function>PQescapeIdentifier</> 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>PQescapeIdentifier</> writes an escaped
+version of the <parameter>from</> string to the <parameter>to</> buffer,
+replacing special characters so that they cannot cause any harm, and
+adding a terminating zero byte. The double quotes that may surround
+<productname>PostgreSQL</> identifiers are not included in the result
+string; they should be provided in the SQL command that the result is
+inserted into.
+</para>
+<para>
+<function>PQescapeIdentifier</> returns the number of characters written
+to <parameter>to</>, not including the terminating zero byte.
+</para>
+<para>
+Behavior is undefined if the <parameter>to</> and <parameter>from</>
+strings overlap.
+</para>
+</sect2>
 
  <sect2 id="libpq-exec-escape-bytea">
   <title>Escaping Binary Strings for Inclusion in SQL Commands</title>