- Use a replacement for PQunescapeBytea so that linking against a pre-7.3

libpq is possible.  This is exactly what ext/pgsql currently does.

# I hope this is an acceptable improvement.

ext/pdo_pgsql/pgsql_statement.c

@@ -208,6 +208,110 @@ static int pgsql_stmt_describe(pdo_stmt_t *stmt, int colno TSRMLS_DC)
 	return 1;
 }
 
+/* PQunescapeBytea() from PostgreSQL 7.3 to provide bytea unescape feature to 7.2 users.
+   Renamed to php_pgsql_unescape_bytea() */
+/*
+ *		PQunescapeBytea - converts the null terminated string representation
+ *		of a bytea, strtext, into binary, filling a buffer. It returns a
+ *		pointer to the buffer which is NULL on error, and the size of the
+ *		buffer in retbuflen. The pointer may subsequently be used as an
+ *		argument to the function free(3). It is the reverse of PQescapeBytea.
+ *
+ *		The following transformations are reversed:
+ *		'\0' == ASCII  0 == \000
+ *		'\'' == ASCII 39 == \'
+ *		'\\' == ASCII 92 == \\
+ *
+ *		States:
+ *		0	normal		0->1->2->3->4
+ *		1	\			   1->5
+ *		2	\0			   1->6
+ *		3	\00
+ *		4	\000
+ *		5	\'
+ *		6	\\
+ */
+static unsigned char * php_pgsql_unescape_bytea(unsigned char *strtext, size_t *retbuflen)
+{
+	size_t		buflen;
+	unsigned char *buffer,
+			   *sp,
+			   *bp;
+	unsigned int state = 0;
+
+	if (strtext == NULL)
+		return NULL;
+	buflen = strlen(strtext);	/* will shrink, also we discover if
+								 * strtext */
+	buffer = (unsigned char *) emalloc(buflen);	/* isn't NULL terminated */
+	for (bp = buffer, sp = strtext; *sp != '\0'; bp++, sp++)
+	{
+		switch (state)
+		{
+			case 0:
+				if (*sp == '\\')
+					state = 1;
+				*bp = *sp;
+				break;
+			case 1:
+				if (*sp == '\'')	/* state=5 */
+				{				/* replace \' with 39 */
+					bp--;
+					*bp = '\'';
+					buflen--;
+					state = 0;
+				}
+				else if (*sp == '\\')	/* state=6 */
+				{				/* replace \\ with 92 */
+					bp--;
+					*bp = '\\';
+					buflen--;
+					state = 0;
+				}
+				else
+				{
+					if (isdigit(*sp))
+						state = 2;
+					else
+						state = 0;
+					*bp = *sp;
+				}
+				break;
+			case 2:
+				if (isdigit(*sp))
+					state = 3;
+				else
+					state = 0;
+				*bp = *sp;
+				break;
+			case 3:
+				if (isdigit(*sp))		/* state=4 */
+				{
+					unsigned char *start, *end, buf[4]; /* 000 + '\0' */
+					
+					bp -= 3;
+					memcpy(buf, sp-2, 3);
+					buf[3] = '\0';
+					start = buf;
+ 					*bp = (unsigned char)strtoul(start, (char **)&end, 8);
+					buflen -= 3;
+					state = 0;
+				}
+				else
+				{
+					*bp = *sp;
+					state = 0;
+				}
+				break;
+		}
+	}
+	buffer = erealloc(buffer, buflen+1);
+	buffer[buflen] = '\0';
+
+	*retbuflen = buflen;
+	return buffer;
+}
+
 static int pgsql_stmt_get_col(pdo_stmt_t *stmt, int colno, char **ptr, unsigned long *len, int *caller_frees  TSRMLS_DC)
 {
 	pdo_pgsql_stmt *S = (pdo_pgsql_stmt*)stmt->driver_data;
@@ -242,7 +346,7 @@ static int pgsql_stmt_get_col(pdo_stmt_t *stmt, int colno, char **ptr, unsigned
 				break;
 				
 			case PDO_PARAM_LOB:
-				tmp_ptr = PQunescapeBytea(*ptr, &tmp_len);
+				tmp_ptr = php_pgsql_unescape_bytea(*ptr, &tmp_len);
 				*ptr = estrndup(tmp_ptr, tmp_len);
 				*len = tmp_len;
 				*caller_frees = 1;