Export xml.c's libxml-error-handling support so that contrib/xml2 can use it

too, instead of duplicating the functionality (badly).

I renamed xml_init to pg_xml_init, because the former seemed just a bit too
generic to be safe as a global symbol.  I considered likewise renaming
xml_ereport to pg_xml_ereport, but felt that the reference to ereport probably
made it sufficiently PG-centric already.

diff --git a/src/backend/utils/adt/xml.c b/src/backend/utils/adt/xml.c
index b32d03f90f74a8b745d3811c942def184c30dd2d..3719e3715e703016eb2d9cdea405aedc4b22c6d4 100644 (file)
--- a/src/backend/utils/adt/xml.c
+++ b/src/backend/utils/adt/xml.c
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.96 2010/02/14 18:42:17 rhaas Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.97 2010/03/03 17:29:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -86,7 +86,6 @@ int                   xmloption;
 
 static StringInfo xml_err_buf = NULL;
 
-static void xml_ereport(int level, int sqlcode, const char *msg);
 static void xml_errorHandler(void *ctxt, const char *msg,...);
 static void xml_ereport_by_code(int level, int sqlcode,
                                        const char *msg, int errcode);
@@ -102,7 +101,6 @@ static void xml_pfree(void *ptr);
 static char *xml_pstrdup(const char *string);
 #endif   /* USE_LIBXMLCONTEXT */
 
-static void xml_init(void);
 static xmlChar *xml_text2xmlChar(text *in);
 static int parse_xml_decl(const xmlChar *str, size_t *lenp,
                           xmlChar **version, xmlChar **encoding, int *standalone);
@@ -599,7 +597,7 @@ xmlelement(XmlExprState *xmlExpr, ExprContext *econtext)
        }
 
        /* now safe to run libxml */
-       xml_init();
+       pg_xml_init();
 
        PG_TRY();
        {
@@ -845,14 +843,23 @@ xml_is_document(xmltype *arg)
 #ifdef USE_LIBXML
 
 /*
- * Set up for use of libxml --- this should be called by each function that
- * is about to use libxml facilities.
+ * pg_xml_init --- set up for use of libxml
+ *
+ * This should be called by each function that is about to use libxml
+ * facilities.  It has two responsibilities: verify compatibility with the
+ * loaded libxml version (done on first call in a session) and establish
+ * or re-establish our libxml error handler.  The latter needs to be done
+ * anytime we might have passed control to add-on modules (eg libperl) which
+ * might have set their own error handler for libxml.
+ *
+ * This is exported for use by contrib/xml2, as well as other code that might
+ * wish to share use of this module's libxml error handler.
  *
  * TODO: xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and
  * check)
  */
-static void
-xml_init(void)
+void
+pg_xml_init(void)
 {
        static bool first_time = true;
 
@@ -962,7 +969,7 @@ parse_xml_decl(const xmlChar *str, size_t *lenp,
        int                     utf8char;
        int                     utf8len;
 
-       xml_init();
+       pg_xml_init();
 
        /* Initialize output arguments to "not present" */
        if (version)
@@ -1114,7 +1121,7 @@ static bool
 print_xml_decl(StringInfo buf, const xmlChar *version,
                           pg_enc encoding, int standalone)
 {
-       xml_init();                                     /* why is this here? */
+       pg_xml_init();                                  /* why is this here? */
 
        if ((version && strcmp((char *) version, PG_XML_DEFAULT_VERSION) != 0)
                || (encoding && encoding != PG_UTF8)
@@ -1178,7 +1185,7 @@ xml_parse(text *data, XmlOptionType xmloption_arg, bool preserve_whitespace,
                                                                                   PG_UTF8);
 
        /* Start up libxml and its parser (no-ops if already done) */
-       xml_init();
+       pg_xml_init();
        xmlInitParser();
 
        ctxt = xmlNewParserCtxt();
@@ -1314,16 +1321,26 @@ xml_pstrdup(const char *string)
 
 
 /*
- * Wrapper for "ereport" function for XML-related errors.  The "msg"
- * is the SQL-level message; some can be adopted from the SQL/XML
- * standard.  This function adds libxml's native error messages, if
- * any, as detail.
+ * xml_ereport --- report an XML-related error
+ *
+ * The "msg" is the SQL-level message; some can be adopted from the SQL/XML
+ * standard.  This function adds libxml's native error message, if any, as
+ * detail.
+ *
+ * This is exported for modules that want to share the core libxml error
+ * handler.  Note that pg_xml_init() *must* have been called previously.
  */
-static void
+void
 xml_ereport(int level, int sqlcode, const char *msg)
 {
        char       *detail;
 
+       /*
+        * It might seem that we should just pass xml_err_buf->data directly to
+        * errdetail.  However, we want to clean out xml_err_buf before throwing
+        * error, in case there is another function using libxml further down
+        * the call stack.
+        */
        if (xml_err_buf->len > 0)
        {
                detail = pstrdup(xml_err_buf->data);
@@ -1332,11 +1349,11 @@ xml_ereport(int level, int sqlcode, const char *msg)
        else
                detail = NULL;
 
-       /* libxml error messages end in '\n'; get rid of it */
        if (detail)
        {
                size_t          len;
 
+               /* libxml error messages end in '\n'; get rid of it */
                len = strlen(detail);
                if (len > 0 && detail[len - 1] == '\n')
                        detail[len - 1] = '\0';
@@ -1738,7 +1755,7 @@ map_sql_value_to_xml_value(Datum value, Oid type, bool xml_escape_strings)
                                        xmlTextWriterPtr writer = NULL;
                                        char       *result;
 
-                                       xml_init();
+                                       pg_xml_init();
 
                                        PG_TRY();
                                        {
@@ -3367,7 +3384,7 @@ xpath(PG_FUNCTION_ARGS)
        memcpy(xpath_expr, VARDATA(xpath_expr_text), xpath_len);
        xpath_expr[xpath_len] = '\0';
 
-       xml_init();
+       pg_xml_init();
        xmlInitParser();
 
        PG_TRY();

diff --git a/src/include/utils/xml.h b/src/include/utils/xml.h
index a5dc673ad0ea30b1af76cd609c7250a4054bdc2d..7543cbb6ee481b57ab7511e65471e9bf94a4bd94 100644 (file)
--- a/src/include/utils/xml.h
+++ b/src/include/utils/xml.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2010, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/xml.h,v 1.30 2010/01/02 16:58:10 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/utils/xml.h,v 1.31 2010/03/03 17:29:45 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -63,6 +63,8 @@ typedef enum
        XML_STANDALONE_OMITTED
 } XmlStandaloneType;
 
+extern void pg_xml_init(void);
+extern void xml_ereport(int level, int sqlcode, const char *msg);
 extern xmltype *xmlconcat(List *args);
 extern xmltype *xmlelement(XmlExprState *xmlExpr, ExprContext *econtext);
 extern xmltype *xmlparse(text *data, XmlOptionType xmloption, bool preserve_whitespace);