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03f1bdd260
libxml2/xpointer.c
Nick Wellnhofer 5d36664fc9 memory: Deprecate xmlGcMemSetup
2024-07-16 17:42:10 +02:00

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/*
* xpointer.c : Code to handle XML Pointer
*
* Base implementation was made accordingly to
* W3C Candidate Recommendation 7 June 2000
* http://www.w3.org/TR/2000/CR-xptr-20000607
*
* Added support for the element() scheme described in:
* W3C Proposed Recommendation 13 November 2002
* http://www.w3.org/TR/2002/PR-xptr-element-20021113/
*
* See Copyright for the status of this software.
*
* daniel@veillard.com
*/
/* To avoid EBCDIC trouble when parsing on zOS */
#if defined(__MVS__)
#pragma convert("ISO8859-1")
#endif
#define IN_LIBXML
#include "libxml.h"
/*
* TODO: better handling of error cases, the full expression should
* be parsed beforehand instead of a progressive evaluation
* TODO: Access into entities references are not supported now ...
* need a start to be able to pop out of entities refs since
* parent is the entity declaration, not the ref.
*/
#include <string.h>
#include <libxml/xpointer.h>
#include <libxml/xmlmemory.h>
#include <libxml/parserInternals.h>
#include <libxml/uri.h>
#include <libxml/xpath.h>
#include <libxml/xpathInternals.h>
#include <libxml/xmlerror.h>
#ifdef LIBXML_XPTR_ENABLED
/* Add support of the xmlns() xpointer scheme to initialize the namespaces */
#define XPTR_XMLNS_SCHEME
#include "private/error.h"
#include "private/xpath.h"
/************************************************************************
* *
* Some factorized error routines *
* *
************************************************************************/
/**
* xmlXPtrErr:
* @ctxt: an XPTR evaluation context
* @extra: extra information
*
* Handle an XPointer error
*/
static void LIBXML_ATTR_FORMAT(3,0)
xmlXPtrErr(xmlXPathParserContextPtr ctxt, int code,
const char * msg, const xmlChar *extra)
{
xmlStructuredErrorFunc serror = NULL;
void *data = NULL;
xmlNodePtr node = NULL;
int res;
if (ctxt == NULL)
return;
/* Only report the first error */
if (ctxt->error != 0)
return;
ctxt->error = code;
if (ctxt->context != NULL) {
xmlErrorPtr err = &ctxt->context->lastError;
/* cleanup current last error */
xmlResetError(err);
err->domain = XML_FROM_XPOINTER;
err->code = code;
err->level = XML_ERR_ERROR;
err->str1 = (char *) xmlStrdup(ctxt->base);
if (err->str1 == NULL) {
xmlXPathPErrMemory(ctxt);
return;
}
err->int1 = ctxt->cur - ctxt->base;
err->node = ctxt->context->debugNode;
serror = ctxt->context->error;
data = ctxt->context->userData;
node = ctxt->context->debugNode;
}
res = xmlRaiseError(serror, NULL, data, NULL, node,
XML_FROM_XPOINTER, code, XML_ERR_ERROR, NULL, 0,
(const char *) extra, (const char *) ctxt->base,
NULL, ctxt->cur - ctxt->base, 0,
msg, extra);
if (res < 0)
xmlXPathPErrMemory(ctxt);
}
/************************************************************************
* *
* A few helper functions for child sequences *
* *
************************************************************************/
/**
* xmlXPtrGetNthChild:
* @cur: the node
* @no: the child number
*
* Returns the @no'th element child of @cur or NULL
*/
static xmlNodePtr
xmlXPtrGetNthChild(xmlNodePtr cur, int no) {
int i;
if ((cur == NULL) || (cur->type == XML_NAMESPACE_DECL))
return(cur);
cur = cur->children;
for (i = 0;i <= no;cur = cur->next) {
if (cur == NULL)
return(cur);
if ((cur->type == XML_ELEMENT_NODE) ||
(cur->type == XML_DOCUMENT_NODE) ||
(cur->type == XML_HTML_DOCUMENT_NODE)) {
i++;
if (i == no)
break;
}
}
return(cur);
}
/************************************************************************
* *
* The parser *
* *
************************************************************************/
static void xmlXPtrEvalChildSeq(xmlXPathParserContextPtr ctxt, xmlChar *name);
/*
* Macros for accessing the content. Those should be used only by the parser,
* and not exported.
*
* Dirty macros, i.e. one need to make assumption on the context to use them
*
* CUR returns the current xmlChar value, i.e. a 8 bit value
* in ISO-Latin or UTF-8.
* This should be used internally by the parser
* only to compare to ASCII values otherwise it would break when
* running with UTF-8 encoding.
* NXT(n) returns the n'th next xmlChar. Same as CUR is should be used only
* to compare on ASCII based substring.
* SKIP(n) Skip n xmlChar, and must also be used only to skip ASCII defined
* strings within the parser.
* CURRENT Returns the current char value, with the full decoding of
* UTF-8 if we are using this mode. It returns an int.
* NEXT Skip to the next character, this does the proper decoding
* in UTF-8 mode. It also pop-up unfinished entities on the fly.
* It returns the pointer to the current xmlChar.
*/
#define CUR (*ctxt->cur)
#define SKIP(val) ctxt->cur += (val)
#define NXT(val) ctxt->cur[(val)]
#define SKIP_BLANKS \
while (IS_BLANK_CH(*(ctxt->cur))) NEXT
#define CURRENT (*ctxt->cur)
#define NEXT ((*ctxt->cur) ? ctxt->cur++: ctxt->cur)
/*
* xmlXPtrGetChildNo:
* @ctxt: the XPointer Parser context
* @index: the child number
*
* Move the current node of the nodeset on the stack to the
* given child if found
*/
static void
xmlXPtrGetChildNo(xmlXPathParserContextPtr ctxt, int indx) {
xmlNodePtr cur = NULL;
xmlXPathObjectPtr obj;
xmlNodeSetPtr oldset;
CHECK_TYPE(XPATH_NODESET);
obj = valuePop(ctxt);
oldset = obj->nodesetval;
if ((indx <= 0) || (oldset == NULL) || (oldset->nodeNr != 1)) {
xmlXPathFreeObject(obj);
valuePush(ctxt, xmlXPathNewNodeSet(NULL));
return;
}
cur = xmlXPtrGetNthChild(oldset->nodeTab[0], indx);
if (cur == NULL) {
xmlXPathFreeObject(obj);
valuePush(ctxt, xmlXPathNewNodeSet(NULL));
return;
}
oldset->nodeTab[0] = cur;
valuePush(ctxt, obj);
}
/**
* xmlXPtrEvalXPtrPart:
* @ctxt: the XPointer Parser context
* @name: the preparsed Scheme for the XPtrPart
*
* XPtrPart ::= 'xpointer' '(' XPtrExpr ')'
* | Scheme '(' SchemeSpecificExpr ')'
*
* Scheme ::= NCName - 'xpointer' [VC: Non-XPointer schemes]
*
* SchemeSpecificExpr ::= StringWithBalancedParens
*
* StringWithBalancedParens ::=
* [^()]* ('(' StringWithBalancedParens ')' [^()]*)*
* [VC: Parenthesis escaping]
*
* XPtrExpr ::= Expr [VC: Parenthesis escaping]
*
* VC: Parenthesis escaping:
* The end of an XPointer part is signaled by the right parenthesis ")"
* character that is balanced with the left parenthesis "(" character
* that began the part. Any unbalanced parenthesis character inside the
* expression, even within literals, must be escaped with a circumflex (^)
* character preceding it. If the expression contains any literal
* occurrences of the circumflex, each must be escaped with an additional
* circumflex (that is, ^^). If the unescaped parentheses in the expression
* are not balanced, a syntax error results.
*
* Parse and evaluate an XPtrPart. Basically it generates the unescaped
* string and if the scheme is 'xpointer' it will call the XPath interpreter.
*
* TODO: there is no new scheme registration mechanism
*/
static void
xmlXPtrEvalXPtrPart(xmlXPathParserContextPtr ctxt, xmlChar *name) {
xmlChar *buffer, *cur;
int len;
int level;
if (name == NULL)
name = xmlXPathParseName(ctxt);
if (name == NULL)
XP_ERROR(XPATH_EXPR_ERROR);
if (CUR != '(') {
xmlFree(name);
XP_ERROR(XPATH_EXPR_ERROR);
}
NEXT;
level = 1;
len = xmlStrlen(ctxt->cur);
len++;
buffer = xmlMalloc(len);
if (buffer == NULL) {
xmlXPathPErrMemory(ctxt);
xmlFree(name);
return;
}
cur = buffer;
while (CUR != 0) {
if (CUR == ')') {
level--;
if (level == 0) {
NEXT;
break;
}
} else if (CUR == '(') {
level++;
} else if (CUR == '^') {
if ((NXT(1) == ')') || (NXT(1) == '(') || (NXT(1) == '^')) {
NEXT;
}
}
*cur++ = CUR;
NEXT;
}
*cur = 0;
if ((level != 0) && (CUR == 0)) {
xmlFree(name);
xmlFree(buffer);
XP_ERROR(XPTR_SYNTAX_ERROR);
}
if (xmlStrEqual(name, (xmlChar *) "xpointer") ||
xmlStrEqual(name, (xmlChar *) "xpath1")) {
const xmlChar *oldBase = ctxt->base;
const xmlChar *oldCur = ctxt->cur;
ctxt->cur = ctxt->base = buffer;
/*
* To evaluate an xpointer scheme element (4.3) we need:
* context initialized to the root
* context position initialized to 1
* context size initialized to 1
*/
ctxt->context->node = (xmlNodePtr)ctxt->context->doc;
ctxt->context->proximityPosition = 1;
ctxt->context->contextSize = 1;
xmlXPathEvalExpr(ctxt);
ctxt->base = oldBase;
ctxt->cur = oldCur;
} else if (xmlStrEqual(name, (xmlChar *) "element")) {
const xmlChar *oldBase = ctxt->base;
const xmlChar *oldCur = ctxt->cur;
xmlChar *name2;
ctxt->cur = ctxt->base = buffer;
if (buffer[0] == '/') {
xmlXPathRoot(ctxt);
xmlXPtrEvalChildSeq(ctxt, NULL);
} else {
name2 = xmlXPathParseName(ctxt);
if (name2 == NULL) {
ctxt->base = oldBase;
ctxt->cur = oldCur;
xmlFree(buffer);
xmlFree(name);
XP_ERROR(XPATH_EXPR_ERROR);
}
xmlXPtrEvalChildSeq(ctxt, name2);
}
ctxt->base = oldBase;
ctxt->cur = oldCur;
#ifdef XPTR_XMLNS_SCHEME
} else if (xmlStrEqual(name, (xmlChar *) "xmlns")) {
const xmlChar *oldBase = ctxt->base;
const xmlChar *oldCur = ctxt->cur;
xmlChar *prefix;
ctxt->cur = ctxt->base = buffer;
prefix = xmlXPathParseNCName(ctxt);
if (prefix == NULL) {
ctxt->base = oldBase;
ctxt->cur = oldCur;
xmlFree(buffer);
xmlFree(name);
XP_ERROR(XPTR_SYNTAX_ERROR);
}
SKIP_BLANKS;
if (CUR != '=') {
ctxt->base = oldBase;
ctxt->cur = oldCur;
xmlFree(prefix);
xmlFree(buffer);
xmlFree(name);
XP_ERROR(XPTR_SYNTAX_ERROR);
}
NEXT;
SKIP_BLANKS;
if (xmlXPathRegisterNs(ctxt->context, prefix, ctxt->cur) < 0)
xmlXPathPErrMemory(ctxt);
ctxt->base = oldBase;
ctxt->cur = oldCur;
xmlFree(prefix);
#endif /* XPTR_XMLNS_SCHEME */
} else {
xmlXPtrErr(ctxt, XML_XPTR_UNKNOWN_SCHEME,
"unsupported scheme '%s'\n", name);
}
xmlFree(buffer);
xmlFree(name);
}
/**
* xmlXPtrEvalFullXPtr:
* @ctxt: the XPointer Parser context
* @name: the preparsed Scheme for the first XPtrPart
*
* FullXPtr ::= XPtrPart (S? XPtrPart)*
*
* As the specs says:
* -----------
* When multiple XPtrParts are provided, they must be evaluated in
* left-to-right order. If evaluation of one part fails, the nexti
* is evaluated. The following conditions cause XPointer part failure:
*
* - An unknown scheme
* - A scheme that does not locate any sub-resource present in the resource
* - A scheme that is not applicable to the media type of the resource
*
* The XPointer application must consume a failed XPointer part and
* attempt to evaluate the next one, if any. The result of the first
* XPointer part whose evaluation succeeds is taken to be the fragment
* located by the XPointer as a whole. If all the parts fail, the result
* for the XPointer as a whole is a sub-resource error.
* -----------
*
* Parse and evaluate a Full XPtr i.e. possibly a cascade of XPath based
* expressions or other schemes.
*/
static void
xmlXPtrEvalFullXPtr(xmlXPathParserContextPtr ctxt, xmlChar *name) {
if (name == NULL)
name = xmlXPathParseName(ctxt);
if (name == NULL)
XP_ERROR(XPATH_EXPR_ERROR);
while (name != NULL) {
ctxt->error = XPATH_EXPRESSION_OK;
xmlXPtrEvalXPtrPart(ctxt, name);
/* in case of syntax error, break here */
if ((ctxt->error != XPATH_EXPRESSION_OK) &&
(ctxt->error != XML_XPTR_UNKNOWN_SCHEME))
return;
/*
* If the returned value is a non-empty nodeset
* or location set, return here.
*/
if (ctxt->value != NULL) {
xmlXPathObjectPtr obj = ctxt->value;
switch (obj->type) {
case XPATH_NODESET: {
xmlNodeSetPtr loc = ctxt->value->nodesetval;
if ((loc != NULL) && (loc->nodeNr > 0))
return;
break;
}
default:
break;
}
/*
* Evaluating to improper values is equivalent to
* a sub-resource error, clean-up the stack
*/
do {
obj = valuePop(ctxt);
if (obj != NULL) {
xmlXPathFreeObject(obj);
}
} while (obj != NULL);
}
/*
* Is there another XPointer part.
*/
SKIP_BLANKS;
name = xmlXPathParseName(ctxt);
}
}
/**
* xmlXPtrEvalChildSeq:
* @ctxt: the XPointer Parser context
* @name: a possible ID name of the child sequence
*
* ChildSeq ::= '/1' ('/' [0-9]*)*
* | Name ('/' [0-9]*)+
*
* Parse and evaluate a Child Sequence. This routine also handle the
* case of a Bare Name used to get a document ID.
*/
static void
xmlXPtrEvalChildSeq(xmlXPathParserContextPtr ctxt, xmlChar *name) {
/*
* XPointer don't allow by syntax to address in multirooted trees
* this might prove useful in some cases, warn about it.
*/
if ((name == NULL) && (CUR == '/') && (NXT(1) != '1')) {
xmlXPtrErr(ctxt, XML_XPTR_CHILDSEQ_START,
"warning: ChildSeq not starting by /1\n", NULL);
}
if (name != NULL) {
valuePush(ctxt, xmlXPathNewString(name));
xmlFree(name);
xmlXPathIdFunction(ctxt, 1);
CHECK_ERROR;
}
while (CUR == '/') {
int child = 0, overflow = 0;
NEXT;
while ((CUR >= '0') && (CUR <= '9')) {
int d = CUR - '0';
if (child > INT_MAX / 10)
overflow = 1;
else
child *= 10;
if (child > INT_MAX - d)
overflow = 1;
else
child += d;
NEXT;
}
if (overflow)
child = 0;
xmlXPtrGetChildNo(ctxt, child);
}
}
/**
* xmlXPtrEvalXPointer:
* @ctxt: the XPointer Parser context
*
* XPointer ::= Name
* | ChildSeq
* | FullXPtr
*
* Parse and evaluate an XPointer
*/
static void
xmlXPtrEvalXPointer(xmlXPathParserContextPtr ctxt) {
if (ctxt->valueTab == NULL) {
/* Allocate the value stack */
ctxt->valueTab = (xmlXPathObjectPtr *)
xmlMalloc(10 * sizeof(xmlXPathObjectPtr));
if (ctxt->valueTab == NULL) {
xmlXPathPErrMemory(ctxt);
return;
}
ctxt->valueNr = 0;
ctxt->valueMax = 10;
ctxt->value = NULL;
}
SKIP_BLANKS;
if (CUR == '/') {
xmlXPathRoot(ctxt);
xmlXPtrEvalChildSeq(ctxt, NULL);
} else {
xmlChar *name;
name = xmlXPathParseName(ctxt);
if (name == NULL)
XP_ERROR(XPATH_EXPR_ERROR);
if (CUR == '(') {
xmlXPtrEvalFullXPtr(ctxt, name);
/* Short evaluation */
return;
} else {
/* this handle both Bare Names and Child Sequences */
xmlXPtrEvalChildSeq(ctxt, name);
}
}
SKIP_BLANKS;
if (CUR != 0)
XP_ERROR(XPATH_EXPR_ERROR);
}
/************************************************************************
* *
* General routines *
* *
************************************************************************/
/**
* xmlXPtrNewContext:
* @doc: the XML document
* @here: the node that directly contains the XPointer being evaluated or NULL
* @origin: the element from which a user or program initiated traversal of
* the link, or NULL.
*
* Create a new XPointer context
*
* Returns the xmlXPathContext just allocated.
*/
xmlXPathContextPtr
xmlXPtrNewContext(xmlDocPtr doc, xmlNodePtr here, xmlNodePtr origin) {
xmlXPathContextPtr ret;
(void) here;
(void) origin;
ret = xmlXPathNewContext(doc);
if (ret == NULL)
return(ret);
return(ret);
}
/**
* xmlXPtrEval:
* @str: the XPointer expression
* @ctx: the XPointer context
*
* Evaluate the XPath Location Path in the given context.
*
* Returns the xmlXPathObjectPtr resulting from the evaluation or NULL.
* the caller has to free the object.
*/
xmlXPathObjectPtr
xmlXPtrEval(const xmlChar *str, xmlXPathContextPtr ctx) {
xmlXPathParserContextPtr ctxt;
xmlXPathObjectPtr res = NULL, tmp;
xmlXPathObjectPtr init = NULL;
int stack = 0;
xmlInitParser();
if ((ctx == NULL) || (str == NULL))
return(NULL);
xmlResetError(&ctx->lastError);
ctxt = xmlXPathNewParserContext(str, ctx);
if (ctxt == NULL) {
xmlXPathErrMemory(ctx);
return(NULL);
}
xmlXPtrEvalXPointer(ctxt);
if (ctx->lastError.code != XML_ERR_OK)
goto error;
if ((ctxt->value != NULL) &&
(ctxt->value->type != XPATH_NODESET)) {
xmlXPtrErr(ctxt, XML_XPTR_EVAL_FAILED,
"xmlXPtrEval: evaluation failed to return a node set\n",
NULL);
} else {
res = valuePop(ctxt);
}
do {
tmp = valuePop(ctxt);
if (tmp != NULL) {
if (tmp != init) {
if (tmp->type == XPATH_NODESET) {
/*
* Evaluation may push a root nodeset which is unused
*/
xmlNodeSetPtr set;
set = tmp->nodesetval;
if ((set == NULL) || (set->nodeNr != 1) ||
(set->nodeTab[0] != (xmlNodePtr) ctx->doc))
stack++;
} else
stack++;
}
xmlXPathFreeObject(tmp);
}
} while (tmp != NULL);
if (stack != 0) {
xmlXPtrErr(ctxt, XML_XPTR_EXTRA_OBJECTS,
"xmlXPtrEval: object(s) left on the eval stack\n",
NULL);
}
if (ctx->lastError.code != XML_ERR_OK) {
xmlXPathFreeObject(res);
res = NULL;
}
error:
xmlXPathFreeParserContext(ctxt);
return(res);
}
#endif
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