-
+
<application>libpq</application> - C Library
+
+
Escaping Identifier for Inclusion in SQL Commands
+
+
+PQescapeIdentifier 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. PQescapeIdentifier performs this
+operation.
+
+
+
+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 SQL injection attacks wherein unwanted
+SQL commands are fed to your database.
+
+
+
+Note that it is still necessary to do escaping of identifiers when
+using functions that support parameterized queries such as PQexecParams or
+its sibling routines. Only literal values are automatically escaped
+using these functions, not identifiers.
+
+
+size_t PQescapeIdentifier (char *to, const char *from, size_t length);
+
+
+
+The parameter
from points to the first character of the+string that is to be escaped, and the
length parameter+gives the number of characters in this string. A terminating zero byte
+is not required, and should not be counted in
length. (If+a terminating zero byte is found before
length bytes are+processed, PQescapeIdentifier stops at the zero; the
+behavior is thus rather like
strncpy.) to+shall point to a buffer that is able to hold at least one more character
+than twice the value of
length, otherwise the behavior is+undefined. A call to PQescapeIdentifier writes an escaped
+version of the
from string to the to buffer,+replacing special characters so that they cannot cause any harm, and
+adding a terminating zero byte. The double quotes that may surround
+
PostgreSQL identifiers are not included in the result+string; they should be provided in the SQL command that the result is
+inserted into.
+
+PQescapeIdentifier returns the number of characters written
+to
to, not including the terminating zero byte.+
+Behavior is undefined if the
to and from+strings overlap.
+
+
Escaping Binary Strings for Inclusion in SQL Commands
-# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.11 2006/05/28 22:42:05 tgl Exp $
+# $PostgreSQL: pgsql/src/interfaces/libpq/exports.txt,v 1.12 2006/06/27 00:03:41 momjian Exp $
# Functions to be exported by libpq DLLs
PQconnectdb 1
PQsetdbLogin 2
PQencryptPassword 128
PQisthreadsafe 129
enlargePQExpBuffer 130
+PQescapeIdentifier 131
+
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.186 2006/05/28 21:13:54 tgl Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/fe-exec.c,v 1.187 2006/06/27 00:03:41 momjian Exp $
*
*-------------------------------------------------------------------------
*/
static_std_strings);
}
+/*
+ * Escaping arbitrary strings to get valid SQL identifier strings.
+ *
+ * Replaces " with "".
+ *
+ * length is the length of the source string. (Note: if a terminating NUL
+ * is encountered sooner, PQescapeIdentifier 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
+PQescapeIdentifier(char *to, const char *from, size_t length)
+{
+ const char *source = from;
+ char *target = to;
+ size_t remaining = length;
+
+ while (remaining > 0 && *source != '\0')
+ {
+ if (*source == '"')
+ *target++ = *source;
+ *target++ = *source++;
+ remaining--;
+ }
+
+ /* Write the terminating NUL character. */
+ *target = '\0';
+
+ return target - to;
+}
+
/*
* PQescapeBytea - converts from binary string to the
* minimal encoding necessary to include the string in an SQL
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.129 2006/05/23 22:13:19 momjian Exp $
+ * $PostgreSQL: pgsql/src/interfaces/libpq/libpq-fe.h,v 1.130 2006/06/27 00:03:42 momjian Exp $
*
*-------------------------------------------------------------------------
*/
size_t *to_length);
extern unsigned char *PQunescapeBytea(const unsigned char *strtext,
size_t *retbuflen);
+extern size_t PQescapeIdentifier(char *to, const char *from, size_t length);
+
/* These forms are deprecated! */
extern size_t PQescapeString(char *to, const char *from, size_t length);
extern unsigned char *PQescapeBytea(const unsigned char *from, size_t from_length,
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