[libxml2] Store per-element parser state in a struct

[Nick Wellnhofer <nwellnhof src gnome org>]

commit ce00c36e654f0a5291d48bc437e807daecbd8449
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Sat May 8 21:20:05 2021 +0200

    Store per-element parser state in a struct
    
    Make the parser context's "pushTab" point to an array of structs
    instead of void pointers. This avoids casting unrelated types to void
    pointers, improving readability and portability, and allows for more
    efficient packing. Ultimately, the struct could be extended to include
    the contents of "nameTab" and "spaceTab", further simplifying the code.
    
    Historically, "pushTab" was only used by the push parser (hence the
    name), so the change to the public headers should be safe.
    
    Also remove an unused parameter from xmlParseEndTag2.

 include/libxml/parser.h |  4 ++-
 parser.c                | 83 +++++++++++++++++++------------------------------
 2 files changed, 35 insertions(+), 52 deletions(-)
---
diff --git a/include/libxml/parser.h b/include/libxml/parser.h
index 1c86a97c..0ba1c387 100644
--- a/include/libxml/parser.h
+++ b/include/libxml/parser.h
@@ -169,6 +169,8 @@ typedef enum {
     XML_PARSE_READER = 5
 } xmlParserMode;
 
+typedef struct _xmlStartTag xmlStartTag;
+
 /**
  * xmlParserCtxt:
  *
@@ -280,7 +282,7 @@ struct _xmlParserCtxt {
     int                nsMax;         /* the size of the arrays */
     const xmlChar *   *nsTab;         /* the array of prefix/namespace name */
     int               *attallocs;     /* which attribute were allocated */
-    void *            *pushTab;       /* array of data for push */
+    xmlStartTag       *pushTab;       /* array of data for push */
     xmlHashTablePtr    attsDefault;   /* defaulted attributes if any */
     xmlHashTablePtr    attsSpecial;   /* non-CDATA attributes if any */
     int                nsWellFormed;  /* is the document XML Namespace okay */
diff --git a/parser.c b/parser.c
index dd582826..9bda9458 100644
--- a/parser.c
+++ b/parser.c
@@ -87,6 +87,13 @@
 #include "buf.h"
 #include "enc.h"
 
+struct _xmlStartTag {
+    const xmlChar *prefix;
+    const xmlChar *URI;
+    int line;
+    int nsNr;
+};
+
 static void
 xmlFatalErr(xmlParserCtxtPtr ctxt, xmlParserErrors error, const char *info);
 
@@ -1849,9 +1856,11 @@ static int
 nameNsPush(xmlParserCtxtPtr ctxt, const xmlChar * value,
            const xmlChar *prefix, const xmlChar *URI, int line, int nsNr)
 {
+    xmlStartTag *tag;
+
     if (ctxt->nameNr >= ctxt->nameMax) {
         const xmlChar * *tmp;
-        void **tmp2;
+        xmlStartTag *tmp2;
         ctxt->nameMax *= 2;
         tmp = (const xmlChar * *) xmlRealloc((xmlChar * *)ctxt->nameTab,
                                     ctxt->nameMax *
@@ -1861,8 +1870,8 @@ nameNsPush(xmlParserCtxtPtr ctxt, const xmlChar * value,
            goto mem_error;
         }
        ctxt->nameTab = tmp;
-        tmp2 = (void **) xmlRealloc((void * *)ctxt->pushTab,
-                                    ctxt->nameMax * 4 *
+        tmp2 = (xmlStartTag *) xmlRealloc((void * *)ctxt->pushTab,
+                                    ctxt->nameMax *
                                     sizeof(ctxt->pushTab[0]));
         if (tmp2 == NULL) {
            ctxt->nameMax /= 2;
@@ -1870,17 +1879,18 @@ nameNsPush(xmlParserCtxtPtr ctxt, const xmlChar * value,
         }
        ctxt->pushTab = tmp2;
     } else if (ctxt->pushTab == NULL) {
-        ctxt->pushTab = (void **) xmlMalloc(ctxt->nameMax * 4 *
+        ctxt->pushTab = (xmlStartTag *) xmlMalloc(ctxt->nameMax *
                                             sizeof(ctxt->pushTab[0]));
         if (ctxt->pushTab == NULL)
             goto mem_error;
     }
     ctxt->nameTab[ctxt->nameNr] = value;
     ctxt->name = value;
-    ctxt->pushTab[ctxt->nameNr * 4] = (void *) prefix;
-    ctxt->pushTab[ctxt->nameNr * 4 + 1] = (void *) URI;
-    ctxt->pushTab[ctxt->nameNr * 4 + 2] = (void *) (ptrdiff_t) line;
-    ctxt->pushTab[ctxt->nameNr * 4 + 3] = (void *) (ptrdiff_t) nsNr;
+    tag = &ctxt->pushTab[ctxt->nameNr];
+    tag->prefix = prefix;
+    tag->URI = URI;
+    tag->line = line;
+    tag->nsNr = nsNr;
     return (ctxt->nameNr++);
 mem_error:
     xmlErrMemory(ctxt, NULL);
@@ -9652,10 +9662,8 @@ done:
  */
 
 static void
-xmlParseEndTag2(xmlParserCtxtPtr ctxt, const xmlChar *prefix,
-                const xmlChar *URI, int line, int nsNr, int tlen) {
+xmlParseEndTag2(xmlParserCtxtPtr ctxt, const xmlStartTag *tag) {
     const xmlChar *name;
-    size_t curLength;
 
     GROW;
     if ((RAW != '<') || (NXT(1) != '/')) {
@@ -9664,24 +9672,10 @@ xmlParseEndTag2(xmlParserCtxtPtr ctxt, const xmlChar *prefix,
     }
     SKIP(2);
 
-    curLength = ctxt->input->end - ctxt->input->cur;
-    if ((tlen > 0) && (curLength >= (size_t)tlen) &&
-        (xmlStrncmp(ctxt->input->cur, ctxt->name, tlen) == 0)) {
-        if ((curLength >= (size_t)(tlen + 1)) &&
-           (ctxt->input->cur[tlen] == '>')) {
-           ctxt->input->cur += tlen + 1;
-           ctxt->input->col += tlen + 1;
-           goto done;
-       }
-       ctxt->input->cur += tlen;
-       ctxt->input->col += tlen;
-       name = (xmlChar*)1;
-    } else {
-       if (prefix == NULL)
-           name = xmlParseNameAndCompare(ctxt, ctxt->name);
-       else
-           name = xmlParseQNameAndCompare(ctxt, ctxt->name, prefix);
-    }
+    if (tag->prefix == NULL)
+        name = xmlParseNameAndCompare(ctxt, ctxt->name);
+    else
+        name = xmlParseQNameAndCompare(ctxt, ctxt->name, tag->prefix);
 
     /*
      * We should definitely be at the ending "S? '>'" part
@@ -9703,25 +9697,22 @@ xmlParseEndTag2(xmlParserCtxtPtr ctxt, const xmlChar *prefix,
      */
     if (name != (xmlChar*)1) {
         if (name == NULL) name = BAD_CAST "unparsable";
-        if ((line == 0) && (ctxt->node != NULL))
-            line = ctxt->node->line;
         xmlFatalErrMsgStrIntStr(ctxt, XML_ERR_TAG_NAME_MISMATCH,
                     "Opening and ending tag mismatch: %s line %d and %s\n",
-                               ctxt->name, line, name);
+                               ctxt->name, tag->line, name);
     }
 
     /*
      * SAX: End of Tag
      */
-done:
     if ((ctxt->sax != NULL) && (ctxt->sax->endElementNs != NULL) &&
        (!ctxt->disableSAX))
-       ctxt->sax->endElementNs(ctxt->userData, ctxt->name, prefix, URI);
+       ctxt->sax->endElementNs(ctxt->userData, ctxt->name, tag->prefix,
+                                tag->URI);
 
     spacePop(ctxt);
-    if (nsNr != 0)
-       nsPop(ctxt, nsNr);
-    return;
+    if (tag->nsNr != 0)
+       nsPop(ctxt, tag->nsNr);
 }
 
 /**
@@ -9937,7 +9928,7 @@ xmlParseContent(xmlParserCtxtPtr ctxt) {
 
     if ((ctxt->instate != XML_PARSER_EOF) && (ctxt->nameNr > nameNr)) {
         const xmlChar *name = ctxt->nameTab[ctxt->nameNr - 1];
-        int line = (ptrdiff_t) ctxt->pushTab[ctxt->nameNr * 4 - 2];
+        int line = ctxt->pushTab[ctxt->nameNr - 1].line;
         xmlFatalErrMsgStrIntStr(ctxt, XML_ERR_TAG_NOT_FINISHED,
                 "Premature end of data in tag %s line %d\n",
                name, line, NULL);
@@ -9969,7 +9960,7 @@ xmlParseElement(xmlParserCtxtPtr ctxt) {
 
     if (CUR == 0) {
         const xmlChar *name = ctxt->nameTab[ctxt->nameNr - 1];
-        int line = (ptrdiff_t) ctxt->pushTab[ctxt->nameNr * 4 - 2];
+        int line = ctxt->pushTab[ctxt->nameNr - 1].line;
         xmlFatalErrMsgStrIntStr(ctxt, XML_ERR_TAG_NOT_FINISHED,
                 "Premature end of data in tag %s line %d\n",
                name, line, NULL);
@@ -10132,11 +10123,7 @@ xmlParseElementEnd(xmlParserCtxtPtr ctxt) {
      * parse the end of tag: '</' should be here.
      */
     if (ctxt->sax2) {
-        const xmlChar *prefix = ctxt->pushTab[ctxt->nameNr * 4 - 4];
-        const xmlChar *URI = ctxt->pushTab[ctxt->nameNr * 4 - 3];
-        int line = (ptrdiff_t) ctxt->pushTab[ctxt->nameNr * 4 - 2];
-        int nsNr = (ptrdiff_t) ctxt->pushTab[ctxt->nameNr * 4 - 1];
-       xmlParseEndTag2(ctxt, prefix, URI, line, nsNr, 0);
+       xmlParseEndTag2(ctxt, &ctxt->pushTab[ctxt->nameNr - 1]);
        namePop(ctxt);
     }
 #ifdef LIBXML_SAX1_ENABLED
@@ -11632,13 +11619,7 @@ xmlParseTryOrFinish(xmlParserCtxtPtr ctxt, int terminate) {
                    }
                }
                if (ctxt->sax2) {
-                   xmlParseEndTag2(ctxt,
-                           (void *) ctxt->pushTab[ctxt->nameNr * 4 - 4],
-                           (void *) ctxt->pushTab[ctxt->nameNr * 4 - 3],
-                            (int) (ptrdiff_t)
-                                ctxt->pushTab[ctxt->nameNr * 4 - 2],
-                           (int) (ptrdiff_t)
-                                ctxt->pushTab[ctxt->nameNr * 4 - 1], 0);
+                   xmlParseEndTag2(ctxt, &ctxt->pushTab[ctxt->nameNr - 1]);
                    nameNsPop(ctxt);
                }
 #ifdef LIBXML_SAX1_ENABLED