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postgres/src/backend/utils/adt/xml.c
Peter Eisentraut d3be7fae11 Add trailing zero byte in Unicode codepoint conversion.
2007-01-27 11:48:31 +00:00

1512 lines
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/*-------------------------------------------------------------------------
*
* xml.c
* XML data type support.
*
*
* Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/utils/adt/xml.c,v 1.23 2007/01/27 11:48:31 petere Exp $
*
*-------------------------------------------------------------------------
*/
/*
* Generally, XML type support is only available when libxml use was
* configured during the build. But even if that is not done, the
* type and all the functions are available, but most of them will
* fail. For one thing, this avoids having to manage variant catalog
* installations. But it also has nice effects such as that you can
* dump a database containing XML type data even if the server is not
* linked with libxml. Thus, make sure xml_out() works even if nothing
* else does.
*/
#include "postgres.h"
#ifdef USE_LIBXML
#include <libxml/chvalid.h>
#include <libxml/parser.h>
#include <libxml/tree.h>
#include <libxml/uri.h>
#include <libxml/xmlerror.h>
#include <libxml/xmlsave.h>
#include <libxml/xmlwriter.h>
#endif /* USE_LIBXML */
#include "catalog/pg_type.h"
#include "executor/executor.h"
#include "fmgr.h"
#include "libpq/pqformat.h"
#include "mb/pg_wchar.h"
#include "nodes/execnodes.h"
#include "parser/parse_expr.h"
#include "utils/array.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/memutils.h"
#include "utils/xml.h"
#ifdef USE_LIBXML
static StringInfo xml_err_buf = NULL;
static void xml_init(void);
#ifdef NOT_USED
static void *xml_palloc(size_t size);
static void *xml_repalloc(void *ptr, size_t size);
static void xml_pfree(void *ptr);
static char *xml_pstrdup(const char *string);
#endif
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);
static xmlChar *xml_text2xmlChar(text *in);
static int parse_xml_decl(const xmlChar *str, size_t *lenp, xmlChar **version, xmlChar **encoding, int *standalone);
static bool print_xml_decl(StringInfo buf, const xmlChar *version, pg_enc encoding, int standalone);
static xmlDocPtr xml_parse(text *data, bool is_document, bool preserve_whitespace, xmlChar *encoding);
#endif /* USE_LIBXML */
XmlBinaryType xmlbinary;
XmlOptionType xmloption;
#define NO_XML_SUPPORT() \
ereport(ERROR, \
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED), \
errmsg("no XML support in this installation")))
Datum
xml_in(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
char *s = PG_GETARG_CSTRING(0);
size_t len;
xmltype *vardata;
xmlDocPtr doc;
len = strlen(s);
vardata = palloc(len + VARHDRSZ);
VARATT_SIZEP(vardata) = len + VARHDRSZ;
memcpy(VARDATA(vardata), s, len);
/*
* Parse the data to check if it is well-formed XML data. Assume
* that ERROR occurred if parsing failed.
*/
doc = xml_parse(vardata, (xmloption == XMLOPTION_DOCUMENT), true, NULL);
xmlFreeDoc(doc);
PG_RETURN_XML_P(vardata);
#else
NO_XML_SUPPORT();
return 0;
#endif
}
#define PG_XML_DEFAULT_VERSION "1.0"
static char *
xml_out_internal(xmltype *x, pg_enc target_encoding)
{
char *str;
size_t len;
#ifdef USE_LIBXML
xmlChar *version;
xmlChar *encoding;
int standalone;
int res_code;
#endif
len = VARSIZE(x) - VARHDRSZ;
str = palloc(len + 1);
memcpy(str, VARDATA(x), len);
str[len] = '\0';
#ifdef USE_LIBXML
if ((res_code = parse_xml_decl((xmlChar *) str, &len, &version, &encoding, &standalone)) == 0)
{
StringInfoData buf;
initStringInfo(&buf);
if (!print_xml_decl(&buf, version, target_encoding, standalone))
{
/*
* If we are not going to produce an XML declaration, eat
* a single newline in the original string to prevent
* empty first lines in the output.
*/
if (*(str + len) == '\n')
len += 1;
}
appendStringInfoString(&buf, str + len);
return buf.data;
}
xml_ereport_by_code(WARNING, ERRCODE_INTERNAL_ERROR,
"could not parse XML declaration in stored value", res_code);
#endif
return str;
}
Datum
xml_out(PG_FUNCTION_ARGS)
{
xmltype *x = PG_GETARG_XML_P(0);
/*
* xml_out removes the encoding property in all cases. This is
* because we cannot control from here whether the datum will be
* converted to a different client encoding, so we'd do more harm
* than good by including it.
*/
PG_RETURN_CSTRING(xml_out_internal(x, 0));
}
Datum
xml_recv(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
StringInfo buf = (StringInfo) PG_GETARG_POINTER(0);
xmltype *result;
char *str;
char *newstr;
int nbytes;
xmlDocPtr doc;
xmlChar *encoding = NULL;
str = pq_getmsgtext(buf, buf->len - buf->cursor, &nbytes);
result = palloc(nbytes + VARHDRSZ);
VARATT_SIZEP(result) = nbytes + VARHDRSZ;
memcpy(VARDATA(result), str, nbytes);
parse_xml_decl((xmlChar *) str, NULL, NULL, &encoding, NULL);
/*
* Parse the data to check if it is well-formed XML data. Assume
* that ERROR occurred if parsing failed.
*/
doc = xml_parse(result, (xmloption == XMLOPTION_DOCUMENT), true, encoding);
xmlFreeDoc(doc);
newstr = (char *) pg_do_encoding_conversion((unsigned char *) str,
nbytes,
encoding ? pg_char_to_encoding((char *) encoding) : PG_UTF8,
GetDatabaseEncoding());
pfree(str);
if (newstr != str)
{
free(result);
nbytes = strlen(newstr);
result = palloc(nbytes + VARHDRSZ);
VARATT_SIZEP(result) = nbytes + VARHDRSZ;
memcpy(VARDATA(result), newstr, nbytes);
}
PG_RETURN_XML_P(result);
#else
NO_XML_SUPPORT();
return 0;
#endif
}
Datum
xml_send(PG_FUNCTION_ARGS)
{
xmltype *x = PG_GETARG_XML_P(0);
char *outval = xml_out_internal(x, pg_get_client_encoding());
StringInfoData buf;
pq_begintypsend(&buf);
pq_sendstring(&buf, outval);
PG_RETURN_BYTEA_P(pq_endtypsend(&buf));
}
#ifdef USE_LIBXML
static void
appendStringInfoText(StringInfo str, const text *t)
{
appendBinaryStringInfo(str, VARDATA(t), VARSIZE(t) - VARHDRSZ);
}
static xmltype *
stringinfo_to_xmltype(StringInfo buf)
{
int32 len;
xmltype *result;
len = buf->len + VARHDRSZ;
result = palloc(len);
VARATT_SIZEP(result) = len;
memcpy(VARDATA(result), buf->data, buf->len);
return result;
}
#ifdef NOT_USED
static xmltype *
cstring_to_xmltype(const char *string)
{
int32 len;
xmltype *result;
len = strlen(string) + VARHDRSZ;
result = palloc(len);
VARATT_SIZEP(result) = len;
memcpy(VARDATA(result), string, len - VARHDRSZ);
return result;
}
#endif
static xmltype *
xmlBuffer_to_xmltype(xmlBufferPtr buf)
{
int32 len;
xmltype *result;
len = xmlBufferLength(buf) + VARHDRSZ;
result = palloc(len);
VARATT_SIZEP(result) = len;
memcpy(VARDATA(result), xmlBufferContent(buf), len - VARHDRSZ);
return result;
}
#endif
Datum
xmlcomment(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
text *arg = PG_GETARG_TEXT_P(0);
int len = VARSIZE(arg) - VARHDRSZ;
StringInfoData buf;
int i;
/* check for "--" in string or "-" at the end */
for (i = 1; i < len; i++)
if ((VARDATA(arg)[i] == '-' && VARDATA(arg)[i - 1] == '-')
|| (VARDATA(arg)[i] == '-' && i == len - 1))
ereport(ERROR,
(errcode(ERRCODE_INVALID_XML_COMMENT),
errmsg("invalid XML comment")));
initStringInfo(&buf);
appendStringInfo(&buf, "<!--");
appendStringInfoText(&buf, arg);
appendStringInfo(&buf, "-->");
PG_RETURN_XML_P(stringinfo_to_xmltype(&buf));
#else
NO_XML_SUPPORT();
return 0;
#endif
}
/*
* TODO: xmlconcat needs to merge the notations and unparsed entities
* of the argument values. Not very important in practice, though.
*/
xmltype *
xmlconcat(List *args)
{
#ifdef USE_LIBXML
StringInfoData buf;
ListCell *v;
int global_standalone = 1;
xmlChar *global_version = NULL;
bool global_version_no_value = false;
initStringInfo(&buf);
foreach(v, args)
{
size_t len;
xmlChar *version;
int standalone;
xmltype *x = DatumGetXmlP(PointerGetDatum(lfirst(v)));
char *str;
len = VARSIZE(x) - VARHDRSZ;
str = palloc(len + 1);
memcpy(str, VARDATA(x), len);
str[len] = '\0';
parse_xml_decl((xmlChar *) str, &len, &version, NULL, &standalone);
if (standalone == 0 && global_standalone == 1)
global_standalone = 0;
if (standalone < 0)
global_standalone = -1;
if (!version)
global_version_no_value = true;
else if (!global_version)
global_version = xmlStrdup(version);
else if (xmlStrcmp(version, global_version) != 0)
global_version_no_value = true;
appendStringInfoString(&buf, str + len);
pfree(str);
}
if (!global_version_no_value || global_standalone >= 0)
{
StringInfoData buf2;
initStringInfo(&buf2);
print_xml_decl(&buf2,
(!global_version_no_value && global_version) ? global_version : NULL,
0,
global_standalone);
appendStringInfoString(&buf2, buf.data);
buf = buf2;
}
return stringinfo_to_xmltype(&buf);
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
/*
* XMLAGG support
*/
Datum
xmlconcat2(PG_FUNCTION_ARGS)
{
if (PG_ARGISNULL(0))
{
if (PG_ARGISNULL(1))
PG_RETURN_NULL();
else
PG_RETURN_XML_P(PG_GETARG_XML_P(1));
}
else if (PG_ARGISNULL(1))
PG_RETURN_XML_P(PG_GETARG_XML_P(0));
else
PG_RETURN_XML_P(xmlconcat(list_make2(PG_GETARG_XML_P(0), PG_GETARG_XML_P(1))));
}
Datum
texttoxml(PG_FUNCTION_ARGS)
{
text *data = PG_GETARG_TEXT_P(0);
PG_RETURN_XML_P(xmlparse(data, (xmloption == XMLOPTION_DOCUMENT), true));
}
xmltype *
xmlelement(XmlExprState *xmlExpr, ExprContext *econtext)
{
#ifdef USE_LIBXML
XmlExpr *xexpr = (XmlExpr *) xmlExpr->xprstate.expr;
int i;
ListCell *arg;
ListCell *narg;
bool isnull;
xmltype *result;
Datum value;
char *str;
xmlBufferPtr buf;
xmlTextWriterPtr writer;
buf = xmlBufferCreate();
writer = xmlNewTextWriterMemory(buf, 0);
xmlTextWriterStartElement(writer, (xmlChar *) xexpr->name);
i = 0;
forboth(arg, xmlExpr->named_args, narg, xexpr->arg_names)
{
ExprState *e = (ExprState *) lfirst(arg);
char *argname = strVal(lfirst(narg));
value = ExecEvalExpr(e, econtext, &isnull, NULL);
if (!isnull)
{
str = OutputFunctionCall(&xmlExpr->named_outfuncs[i], value);
xmlTextWriterWriteAttribute(writer, (xmlChar *) argname, (xmlChar *) str);
pfree(str);
}
i++;
}
foreach(arg, xmlExpr->args)
{
ExprState *e = (ExprState *) lfirst(arg);
value = ExecEvalExpr(e, econtext, &isnull, NULL);
if (!isnull)
xmlTextWriterWriteRaw(writer, (xmlChar *) map_sql_value_to_xml_value(value, exprType((Node *) e->expr)));
}
xmlTextWriterEndElement(writer);
xmlFreeTextWriter(writer);
result = xmlBuffer_to_xmltype(buf);
xmlBufferFree(buf);
return result;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlparse(text *data, bool is_document, bool preserve_whitespace)
{
#ifdef USE_LIBXML
xmlDocPtr doc;
doc = xml_parse(data, is_document, preserve_whitespace, NULL);
xmlFreeDoc(doc);
return (xmltype *) data;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlpi(char *target, text *arg, bool arg_is_null, bool *result_is_null)
{
#ifdef USE_LIBXML
xmltype *result;
StringInfoData buf;
if (pg_strncasecmp(target, "xml", 3) == 0)
ereport(ERROR,
(errcode(ERRCODE_SYNTAX_ERROR), /* really */
errmsg("invalid XML processing instruction"),
errdetail("XML processing instruction target name cannot start with \"xml\".")));
/*
* Following the SQL standard, the null check comes after the
* syntax check above.
*/
*result_is_null = arg_is_null;
if (*result_is_null)
return NULL;
initStringInfo(&buf);
appendStringInfo(&buf, "<?%s", target);
if (arg != NULL)
{
char *string;
string = DatumGetCString(DirectFunctionCall1(textout,
PointerGetDatum(arg)));
if (strstr(string, "?>") != NULL)
ereport(ERROR,
(errcode(ERRCODE_INVALID_XML_PROCESSING_INSTRUCTION),
errmsg("invalid XML processing instruction"),
errdetail("XML processing instruction cannot contain \"?>\".")));
appendStringInfoChar(&buf, ' ');
appendStringInfoString(&buf, string + strspn(string, " "));
pfree(string);
}
appendStringInfoString(&buf, "?>");
result = stringinfo_to_xmltype(&buf);
pfree(buf.data);
return result;
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
xmltype *
xmlroot(xmltype *data, text *version, int standalone)
{
#ifdef USE_LIBXML
char *str;
size_t len;
xmlChar *orig_version;
int orig_standalone;
StringInfoData buf;
len = VARSIZE(data) - VARHDRSZ;
str = palloc(len + 1);
memcpy(str, VARDATA(data), len);
str[len] = '\0';
parse_xml_decl((xmlChar *) str, &len, &orig_version, NULL, &orig_standalone);
if (version)
orig_version = xml_text2xmlChar(version);
else
orig_version = NULL;
switch (standalone)
{
case XML_STANDALONE_YES:
orig_standalone = 1;
break;
case XML_STANDALONE_NO:
orig_standalone = 0;
break;
case XML_STANDALONE_NO_VALUE:
orig_standalone = -1;
break;
case XML_STANDALONE_OMITTED:
/* leave original value */
break;
}
initStringInfo(&buf);
print_xml_decl(&buf, orig_version, 0, orig_standalone);
appendStringInfoString(&buf, str + len);
return stringinfo_to_xmltype(&buf);
#else
NO_XML_SUPPORT();
return NULL;
#endif
}
/*
* Validate document (given as string) against DTD (given as external link)
* TODO !!! use text instead of cstring for second arg
* TODO allow passing DTD as a string value (not only as an URI)
* TODO redesign (see comment with '!!!' below)
*/
Datum
xmlvalidate(PG_FUNCTION_ARGS)
{
#ifdef USE_LIBXML
text *data = PG_GETARG_TEXT_P(0);
text *dtdOrUri = PG_GETARG_TEXT_P(1);
bool result = false;
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
xmlDtdPtr dtd = NULL;
xml_init();
/* We use a PG_TRY block to ensure libxml is cleaned up on error */
PG_TRY();
{
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not allocate parser context");
doc = xmlCtxtReadMemory(ctxt, (char *) VARDATA(data),
VARSIZE(data) - VARHDRSZ,
NULL, NULL, 0);
if (doc == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not parse XML data");
#if 0
uri = xmlCreateURI();
elog(NOTICE, "dtd - %s", dtdOrUri);
dtd = palloc(sizeof(xmlDtdPtr));
uri = xmlParseURI(dtdOrUri);
if (uri == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"not implemented yet... (TODO)");
else
#endif
dtd = xmlParseDTD(NULL, xml_text2xmlChar(dtdOrUri));
if (dtd == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"could not load DTD");
if (xmlValidateDtd(xmlNewValidCtxt(), doc, dtd) == 1)
result = true;
if (!result)
xml_ereport(NOTICE, ERRCODE_INVALID_XML_DOCUMENT,
"validation against DTD failed");
#if 0
if (uri)
xmlFreeURI(uri);
#endif
if (dtd)
xmlFreeDtd(dtd);
if (doc)
xmlFreeDoc(doc);
if (ctxt)
xmlFreeParserCtxt(ctxt);
xmlCleanupParser();
}
PG_CATCH();
{
#if 0
if (uri)
xmlFreeURI(uri);
#endif
if (dtd)
xmlFreeDtd(dtd);
if (doc)
xmlFreeDoc(doc);
if (ctxt)
xmlFreeParserCtxt(ctxt);
xmlCleanupParser();
PG_RE_THROW();
}
PG_END_TRY();
PG_RETURN_BOOL(result);
#else /* not USE_LIBXML */
NO_XML_SUPPORT();
return 0;
#endif /* not USE_LIBXML */
}
bool
xml_is_document(xmltype *arg)
{
#ifdef USE_LIBXML
bool result;
xmlDocPtr doc = NULL;
MemoryContext ccxt = CurrentMemoryContext;
PG_TRY();
{
doc = xml_parse((text *) arg, true, true, NULL);
result = true;
}
PG_CATCH();
{
ErrorData *errdata;
MemoryContext ecxt;
ecxt = MemoryContextSwitchTo(ccxt);
errdata = CopyErrorData();
if (errdata->sqlerrcode == ERRCODE_INVALID_XML_DOCUMENT)
{
FlushErrorState();
result = false;
}
else
{
MemoryContextSwitchTo(ecxt);
PG_RE_THROW();
}
}
PG_END_TRY();
if (doc)
xmlFreeDoc(doc);
return result;
#else /* not USE_LIBXML */
NO_XML_SUPPORT();
return false;
#endif /* not USE_LIBXML */
}
#ifdef USE_LIBXML
/*
* Container for some init stuff (not good design!)
* TODO xmlChar is utf8-char, make proper tuning (initdb with enc!=utf8 and check)
*/
static void
xml_init(void)
{
/*
* Currently, we have no pure UTF-8 support for internals -- check
* if we can work.
*/
if (sizeof (char) != sizeof (xmlChar))
ereport(ERROR,
(errmsg("could not initialize XML library"),
errdetail("libxml2 has incompatible char type: sizeof(char)=%u, sizeof(xmlChar)=%u.",
(int) sizeof(char), (int) sizeof(xmlChar))));
if (xml_err_buf == NULL)
{
/* First time through: create error buffer in permanent context */
MemoryContext oldcontext;
oldcontext = MemoryContextSwitchTo(TopMemoryContext);
xml_err_buf = makeStringInfo();
MemoryContextSwitchTo(oldcontext);
}
else
{
/* Reset pre-existing buffer to empty */
xml_err_buf->data[0] = '\0';
xml_err_buf->len = 0;
}
/* Now that xml_err_buf exists, safe to call xml_errorHandler */
xmlSetGenericErrorFunc(NULL, xml_errorHandler);
#ifdef NOT_USED
/*
* FIXME: This doesn't work because libxml assumes that whatever
* libxml allocates, only libxml will free, so we can't just drop
* memory contexts behind it. This needs to be refined.
*/
xmlMemSetup(xml_pfree, xml_palloc, xml_repalloc, xml_pstrdup);
#endif
xmlInitParser();
LIBXML_TEST_VERSION;
}
/*
* SQL/XML allows storing "XML documents" or "XML content". "XML
* documents" are specified by the XML specification and are parsed
* easily by libxml. "XML content" is specified by SQL/XML as the
* production "XMLDecl? content". But libxml can only parse the
* "content" part, so we have to parse the XML declaration ourselves
* to complete this.
*/
#define CHECK_XML_SPACE(p) if (!xmlIsBlank_ch(*(p))) return XML_ERR_SPACE_REQUIRED
#define SKIP_XML_SPACE(p) while (xmlIsBlank_ch(*(p))) (p)++
static int
parse_xml_decl(const xmlChar *str, size_t *lenp, xmlChar **version, xmlChar **encoding, int *standalone)
{
const xmlChar *p;
const xmlChar *save_p;
size_t len;
p = str;
if (version)
*version = NULL;
if (encoding)
*encoding = NULL;
if (standalone)
*standalone = -1;
if (xmlStrncmp(p, (xmlChar *)"<?xml", 5) != 0)
goto finished;
p += 5;
/* version */
CHECK_XML_SPACE(p);
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *)"version", 7) != 0)
return XML_ERR_VERSION_MISSING;
p += 7;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_VERSION_MISSING;
p += 1;
SKIP_XML_SPACE(p);
if (*p == '\'' || *p == '"')
{
const xmlChar *q;
q = xmlStrchr(p + 1, *p);
if (!q)
return XML_ERR_VERSION_MISSING;
if (version)
*version = xmlStrndup(p + 1, q - p - 1);
p = q + 1;
}
else
return XML_ERR_VERSION_MISSING;
/* encoding */
save_p = p;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *)"encoding", 8) == 0)
{
CHECK_XML_SPACE(save_p);
p += 8;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_MISSING_ENCODING;
p += 1;
SKIP_XML_SPACE(p);
if (*p == '\'' || *p == '"')
{
const xmlChar *q;
q = xmlStrchr(p + 1, *p);
if (!q)
return XML_ERR_MISSING_ENCODING;
if (encoding)
*encoding = xmlStrndup(p + 1, q - p - 1);
p = q + 1;
}
else
return XML_ERR_MISSING_ENCODING;
}
else
{
p = save_p;
}
/* standalone */
save_p = p;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *)"standalone", 10) == 0)
{
CHECK_XML_SPACE(save_p);
p += 10;
SKIP_XML_SPACE(p);
if (*p != '=')
return XML_ERR_STANDALONE_VALUE;
p += 1;
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *)"'yes'", 5) == 0 || xmlStrncmp(p, (xmlChar *)"\"yes\"", 5) == 0)
{
*standalone = 1;
p += 5;
}
else if (xmlStrncmp(p, (xmlChar *)"'no'", 4) == 0 || xmlStrncmp(p, (xmlChar *)"\"no\"", 4) == 0)
{
*standalone = 0;
p += 4;
}
else
return XML_ERR_STANDALONE_VALUE;
}
else
{
p = save_p;
}
SKIP_XML_SPACE(p);
if (xmlStrncmp(p, (xmlChar *)"?>", 2) != 0)
return XML_ERR_XMLDECL_NOT_FINISHED;
p += 2;
finished:
len = p - str;
for (p = str; p < str + len; p++)
if (*p > 127)
return XML_ERR_INVALID_CHAR;
if (lenp)
*lenp = len;
return XML_ERR_OK;
}
/*
* Write an XML declaration. On output, we adjust the XML declaration
* as follows. (These rules are the moral equivalent of the clause
* "Serialization of an XML value" in the SQL standard.)
*
* We try to avoid generating an XML declaration if possible. This is
* so that you don't get trivial things like xml '<foo/>' resulting in
* '<?xml version="1.0"?><foo/>', which would surely be annoying. We
* must provide a declaration if the standalone property is specified
* or if we include an encoding declaration. If we have a
* declaration, we must specify a version (XML requires this).
* Otherwise we only make a declaration if the version is not "1.0",
* which is the default version specified in SQL:2003.
*/
static bool
print_xml_decl(StringInfo buf, const xmlChar *version, pg_enc encoding, int standalone)
{
if ((version && strcmp((char *) version, PG_XML_DEFAULT_VERSION) != 0)
|| (encoding && encoding != PG_UTF8)
|| standalone != -1)
{
appendStringInfoString(buf, "<?xml");
if (version)
appendStringInfo(buf, " version=\"%s\"", version);
else
appendStringInfo(buf, " version=\"%s\"", PG_XML_DEFAULT_VERSION);
if (encoding && encoding != PG_UTF8)
/* XXX might be useful to convert this to IANA names
* (ISO-8859-1 instead of LATIN1 etc.); needs field
* experience */
appendStringInfo(buf, " encoding=\"%s\"", pg_encoding_to_char(encoding));
if (standalone == 1)
appendStringInfoString(buf, " standalone=\"yes\"");
else if (standalone == 0)
appendStringInfoString(buf, " standalone=\"no\"");
appendStringInfoString(buf, "?>");
return true;
}
else
return false;
}
/*
* Convert a C string to XML internal representation
*
* TODO maybe, libxml2's xmlreader is better? (do not construct DOM, yet do not use SAX - see xml_reader.c)
*/
static xmlDocPtr
xml_parse(text *data, bool is_document, bool preserve_whitespace, xmlChar *encoding)
{
int32 len;
xmlChar *string;
xmlChar *utf8string;
xmlParserCtxtPtr ctxt = NULL;
xmlDocPtr doc = NULL;
len = VARSIZE(data) - VARHDRSZ; /* will be useful later */
string = xml_text2xmlChar(data);
utf8string = pg_do_encoding_conversion(string,
len,
encoding
? pg_char_to_encoding((char *) encoding)
: GetDatabaseEncoding(),
PG_UTF8);
xml_init();
/* We use a PG_TRY block to ensure libxml is cleaned up on error */
PG_TRY();
{
ctxt = xmlNewParserCtxt();
if (ctxt == NULL)
xml_ereport(ERROR, ERRCODE_INTERNAL_ERROR,
"could not allocate parser context");
if (is_document)
{
/*
* Note, that here we try to apply DTD defaults
* (XML_PARSE_DTDATTR) according to SQL/XML:10.16.7.d:
* 'Default valies defined by internal DTD are applied'.
* As for external DTDs, we try to support them too, (see
* SQL/XML:10.16.7.e)
*/
doc = xmlCtxtReadDoc(ctxt, utf8string,
NULL,
"UTF-8",
XML_PARSE_NOENT | XML_PARSE_DTDATTR
| (preserve_whitespace ? 0 : XML_PARSE_NOBLANKS));
if (doc == NULL)
xml_ereport(ERROR, ERRCODE_INVALID_XML_DOCUMENT,
"invalid XML document");
}
else
{
int res_code;
size_t count;
xmlChar *version = NULL;
int standalone = -1;
doc = xmlNewDoc(NULL);
res_code = parse_xml_decl(utf8string, &count, &version, NULL, &standalone);
if (res_code != 0)
xml_ereport_by_code(ERROR, ERRCODE_INVALID_XML_CONTENT,
"invalid XML content: invalid XML declaration", res_code);
res_code = xmlParseBalancedChunkMemory(doc, NULL, NULL, 0, utf8string + count, NULL);
if (res_code != 0)
xml_ereport(ERROR, ERRCODE_INVALID_XML_CONTENT,
"invalid XML content");
doc->version = xmlStrdup(version);
doc->encoding = xmlStrdup((xmlChar *) "UTF-8");
doc->standalone = standalone;
}
if (ctxt)
xmlFreeParserCtxt(ctxt);
xmlCleanupParser();
}
PG_CATCH();
{
if (doc)
xmlFreeDoc(doc);
doc = NULL;
if (ctxt)
xmlFreeParserCtxt(ctxt);
xmlCleanupParser();
PG_RE_THROW();
}
PG_END_TRY();
return doc;
}
/*
* xmlChar<->text convertions
*/
static xmlChar *
xml_text2xmlChar(text *in)
{
int32 len = VARSIZE(in) - VARHDRSZ;
xmlChar *res;
res = palloc(len + 1);
memcpy(res, VARDATA(in), len);
res[len] = '\0';
return(res);
}
#ifdef NOT_USED
/*
* Wrappers for memory management functions
*/
static void *
xml_palloc(size_t size)
{
return palloc(size);
}
static void *
xml_repalloc(void *ptr, size_t size)
{
return repalloc(ptr, size);
}
static void
xml_pfree(void *ptr)
{
pfree(ptr);
}
static char *
xml_pstrdup(const char *string)
{
return pstrdup(string);
}
#endif /* NOT_USED */
/*
* 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.
*/
static void
xml_ereport(int level, int sqlcode,
const char *msg)
{
char *detail;
if (xml_err_buf->len > 0)
{
detail = pstrdup(xml_err_buf->data);
xml_err_buf->data[0] = '\0';
xml_err_buf->len = 0;
}
else
detail = NULL;
/* libxml error messages end in '\n'; get rid of it */
if (detail)
{
size_t len;
len = strlen(detail);
if (len > 0 && detail[len-1] == '\n')
detail[len-1] = '\0';
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg),
errdetail("%s", detail)));
}
else
{
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg)));
}
}
/*
* Error handler for libxml error messages
*/
static void
xml_errorHandler(void *ctxt, const char *msg,...)
{
/* Append the formatted text to xml_err_buf */
for (;;)
{
va_list args;
bool success;
/* Try to format the data. */
va_start(args, msg);
success = appendStringInfoVA(xml_err_buf, msg, args);
va_end(args);
if (success)
break;
/* Double the buffer size and try again. */
enlargeStringInfo(xml_err_buf, xml_err_buf->maxlen);
}
}
/*
* 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 uses "code" to create a textual detail
* message. At the moment, we only need to cover those codes that we
* may raise in this file.
*/
static void
xml_ereport_by_code(int level, int sqlcode,
const char *msg, int code)
{
const char *det;
switch (code)
{
case XML_ERR_INVALID_CHAR:
det = "Invalid character value";
break;
case XML_ERR_SPACE_REQUIRED:
det = "Space required";
break;
case XML_ERR_STANDALONE_VALUE:
det = "standalone accepts only 'yes' or 'no'";
break;
case XML_ERR_VERSION_MISSING:
det = "Malformed declaration expecting version";
break;
case XML_ERR_MISSING_ENCODING:
det = "Missing encoding in text declaration";
break;
case XML_ERR_XMLDECL_NOT_FINISHED:
det = "Parsing XML declaration: '?>' expected";
break;
default:
det = "Unrecognized libxml error code: %d";
break;
}
ereport(level,
(errcode(sqlcode),
errmsg("%s", msg),
errdetail(det, code)));
}
/*
* Convert one char in the current server encoding to a Unicode codepoint.
*/
static pg_wchar
sqlchar_to_unicode(char *s)
{
char *utf8string;
pg_wchar ret[2]; /* need space for trailing zero */
utf8string = (char *) pg_do_encoding_conversion((unsigned char *) s,
pg_mblen(s),
GetDatabaseEncoding(),
PG_UTF8);
pg_encoding_mb2wchar_with_len(PG_UTF8, utf8string, ret, pg_mblen(s));
return ret[0];
}
static bool
is_valid_xml_namefirst(pg_wchar c)
{
/* (Letter | '_' | ':') */
return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
|| c == '_' || c == ':');
}
static bool
is_valid_xml_namechar(pg_wchar c)
{
/* Letter | Digit | '.' | '-' | '_' | ':' | CombiningChar | Extender */
return (xmlIsBaseCharQ(c) || xmlIsIdeographicQ(c)
|| xmlIsDigitQ(c)
|| c == '.' || c == '-' || c == '_' || c == ':'
|| xmlIsCombiningQ(c)
|| xmlIsExtenderQ(c));
}
#endif /* USE_LIBXML */
/*
* Map SQL identifier to XML name; see SQL/XML:2003 section 9.1.
*/
char *
map_sql_identifier_to_xml_name(char *ident, bool fully_escaped)
{
#ifdef USE_LIBXML
StringInfoData buf;
char *p;
initStringInfo(&buf);
for (p = ident; *p; p += pg_mblen(p))
{
if (*p == ':' && (p == ident || fully_escaped))
appendStringInfo(&buf, "_x003A_");
else if (*p == '_' && *(p+1) == 'x')
appendStringInfo(&buf, "_x005F_");
else if (fully_escaped && p == ident &&
pg_strncasecmp(p, "xml", 3) == 0)
{
if (*p == 'x')
appendStringInfo(&buf, "_x0078_");
else
appendStringInfo(&buf, "_x0058_");
}
else
{
pg_wchar u = sqlchar_to_unicode(p);
if ((p == ident)
? !is_valid_xml_namefirst(u)
: !is_valid_xml_namechar(u))
appendStringInfo(&buf, "_x%04X_", (unsigned int) u);
else
appendBinaryStringInfo(&buf, p, pg_mblen(p));
}
}
return buf.data;
#else /* not USE_LIBXML */
NO_XML_SUPPORT();
return NULL;
#endif /* not USE_LIBXML */
}
/*
* Map a Unicode codepoint into the current server encoding.
*/
static char *
unicode_to_sqlchar(pg_wchar c)
{
static unsigned char utf8string[5]; /* need trailing zero */
if (c <= 0x7F)
{
utf8string[0] = c;
}
else if (c <= 0x7FF)
{
utf8string[0] = 0xC0 | ((c >> 6) & 0x1F);
utf8string[1] = 0x80 | (c & 0x3F);
}
else if (c <= 0xFFFF)
{
utf8string[0] = 0xE0 | ((c >> 12) & 0x0F);
utf8string[1] = 0x80 | ((c >> 6) & 0x3F);
utf8string[2] = 0x80 | (c & 0x3F);
}
else
{
utf8string[0] = 0xF0 | ((c >> 18) & 0x07);
utf8string[1] = 0x80 | ((c >> 12) & 0x3F);
utf8string[2] = 0x80 | ((c >> 6) & 0x3F);
utf8string[3] = 0x80 | (c & 0x3F);
}
return (char *) pg_do_encoding_conversion(utf8string,
pg_mblen((char *) utf8string),
PG_UTF8,
GetDatabaseEncoding());
}
/*
* Map XML name to SQL identifier; see SQL/XML:2003 section 9.17.
*/
char *
map_xml_name_to_sql_identifier(char *name)
{
StringInfoData buf;
char *p;
initStringInfo(&buf);
for (p = name; *p; p += pg_mblen(p))
{
if (*p == '_' && *(p+1) == 'x'
&& isxdigit((unsigned char) *(p+2))
&& isxdigit((unsigned char) *(p+3))
&& isxdigit((unsigned char) *(p+4))
&& isxdigit((unsigned char) *(p+5))
&& *(p+6) == '_')
{
unsigned int u;
sscanf(p + 2, "%X", &u);
appendStringInfoString(&buf, unicode_to_sqlchar(u));
p += 6;
}
else
appendBinaryStringInfo(&buf, p, pg_mblen(p));
}
return buf.data;
}
/*
* Map SQL value to XML value; see SQL/XML:2003 section 9.16.
*/
char *
map_sql_value_to_xml_value(Datum value, Oid type)
{
StringInfoData buf;
initStringInfo(&buf);
if (is_array_type(type))
{
int i;
ArrayType *array;
Oid elmtype;
int16 elmlen;
bool elmbyval;
char elmalign;
array = DatumGetArrayTypeP(value);
/* TODO: need some code-fu here to remove this limitation */
if (ARR_NDIM(array) != 1)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("only supported for one-dimensional array")));
elmtype = ARR_ELEMTYPE(array);
get_typlenbyvalalign(elmtype, &elmlen, &elmbyval, &elmalign);
for (i = ARR_LBOUND(array)[0];
i < ARR_LBOUND(array)[0] + ARR_DIMS(array)[0];
i++)
{
Datum subval;
bool isnull;
subval = array_ref(array, 1, &i, -1, elmlen, elmbyval, elmalign, &isnull);
appendStringInfoString(&buf, "<element>");
appendStringInfoString(&buf, map_sql_value_to_xml_value(subval, elmtype));
appendStringInfoString(&buf, "</element>");
}
}
else
{
Oid typeOut;
bool isvarlena;
char *p, *str;
getTypeOutputInfo(type, &typeOut, &isvarlena);
str = OidOutputFunctionCall(typeOut, value);
if (type == XMLOID)
return str;
#ifdef USE_LIBXML
if (type == BYTEAOID)
{
xmlBufferPtr buf;
xmlTextWriterPtr writer;
char *result;
buf = xmlBufferCreate();
writer = xmlNewTextWriterMemory(buf, 0);
if (xmlbinary == XMLBINARY_BASE64)
xmlTextWriterWriteBase64(writer, VARDATA(value), 0, VARSIZE(value) - VARHDRSZ);
else
xmlTextWriterWriteBinHex(writer, VARDATA(value), 0, VARSIZE(value) - VARHDRSZ);
xmlFreeTextWriter(writer);
result = pstrdup((const char *) xmlBufferContent(buf));
xmlBufferFree(buf);
return result;
}
#endif /* USE_LIBXML */
for (p = str; *p; p += pg_mblen(p))
{
switch (*p)
{
case '&':
appendStringInfo(&buf, "&amp;");
break;
case '<':
appendStringInfo(&buf, "&lt;");
break;
case '>':
appendStringInfo(&buf, "&gt;");
break;
case '\r':
appendStringInfo(&buf, "&#x0d;");
break;
default:
appendBinaryStringInfo(&buf, p, pg_mblen(p));
break;
}
}
}
return buf.data;
}
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