[libxml2] Remove unnecessary calls to xmlPopInput

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 453dff1e3b6f7aa724c4996a375c51df6d95abc4
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Mon Jun 19 17:55:20 2017 +0200

    Remove unnecessary calls to xmlPopInput
    
    It's enough if xmlPopInput is called from xmlSkipBlankChars. Since the
    replacement text of a parameter entity is surrounded with space
    characters, that's the only place where the replacement can end in a
    well-formed document.
    
    This is also required to get rid of the "blanks wrapper" hack.

 parser.c          |   98 +++++++++++------------------------------------------
 parserInternals.c |   11 +-----
 2 files changed, 22 insertions(+), 87 deletions(-)
---
diff --git a/parser.c b/parser.c
index e7efdce..bf7ebc4 100644
--- a/parser.c
+++ b/parser.c
@@ -2043,9 +2043,8 @@ static int spacePop(xmlParserCtxtPtr ctxt) {
 
 #define SKIP(val) do {                                                 \
     ctxt->nbChars += (val),ctxt->input->cur += (val),ctxt->input->col+=(val);                  \
-    if ((*ctxt->input->cur == 0) &&                                    \
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))           \
-           xmlPopInput(ctxt);                                          \
+    if (*ctxt->input->cur == 0)                                                \
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);                  \
   } while (0)
 
 #define SKIPL(val) do {                                                        \
@@ -2057,9 +2056,8 @@ static int spacePop(xmlParserCtxtPtr ctxt) {
        ctxt->nbChars++;                                                \
        ctxt->input->cur++;                                             \
     }                                                                  \
-    if ((*ctxt->input->cur == 0) &&                                    \
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))           \
-           xmlPopInput(ctxt);                                          \
+    if (*ctxt->input->cur == 0)                                                \
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);                  \
   } while (0)
 
 #define SHRINK if ((ctxt->progressive == 0) &&                         \
@@ -2069,10 +2067,9 @@ static int spacePop(xmlParserCtxtPtr ctxt) {
 
 static void xmlSHRINK (xmlParserCtxtPtr ctxt) {
     xmlParserInputShrink(ctxt->input);
-    if ((*ctxt->input->cur == 0) &&
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))
-           xmlPopInput(ctxt);
-  }
+    if (*ctxt->input->cur == 0)
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
+}
 
 #define GROW if ((ctxt->progressive == 0) &&                           \
                 (ctxt->input->end - ctxt->input->cur < INPUT_CHUNK))   \
@@ -2097,9 +2094,8 @@ static void xmlGROW (xmlParserCtxtPtr ctxt) {
         xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR, "cur index out of bound");
        return;
     }
-    if ((ctxt->input->cur != NULL) && (*ctxt->input->cur == 0) &&
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))
-           xmlPopInput(ctxt);
+    if ((ctxt->input->cur != NULL) && (*ctxt->input->cur == 0))
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
 }
 
 #define SKIP_BLANKS xmlSkipBlankChars(ctxt)
@@ -2219,9 +2215,8 @@ xmlPopInput(xmlParserCtxtPtr ctxt) {
         xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR,
                     "Unfinished entity outside the DTD");
     xmlFreeInputStream(inputPop(ctxt));
-    if ((*ctxt->input->cur == 0) &&
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))
-           return(xmlPopInput(ctxt));
+    if (*ctxt->input->cur == 0)
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
     return(CUR);
 }
 
@@ -3808,11 +3803,6 @@ xmlParseEntityValue(xmlParserCtxtPtr ctxt, xmlChar **orig) {
        }
        COPY_BUF(l,buf,len,c);
        NEXTL(l);
-       /*
-        * Pop-up of finished entities.
-        */
-       while ((RAW == 0) && (ctxt->inputNr > 1)) /* non input consuming */
-           xmlPopInput(ctxt);
 
        GROW;
        c = CUR_CHAR(l);
@@ -6602,8 +6592,6 @@ xmlParseElementDecl(xmlParserCtxtPtr ctxt) {
                           "xmlParseElementDecl: no name for Element\n");
            return(-1);
        }
-       while ((RAW == 0) && (ctxt->inputNr > 1))
-           xmlPopInput(ctxt);
        if (!IS_BLANK_CH(CUR)) {
            xmlFatalErrMsg(ctxt, XML_ERR_SPACE_REQUIRED,
                           "Space required after the element name\n");
@@ -6640,12 +6628,6 @@ xmlParseElementDecl(xmlParserCtxtPtr ctxt) {
        }
 
        SKIP_BLANKS;
-       /*
-        * Pop-up of finished entities.
-        */
-       while ((RAW == 0) && (ctxt->inputNr > 1))
-           xmlPopInput(ctxt);
-       SKIP_BLANKS;
 
        if (RAW != '>') {
            xmlFatalErr(ctxt, XML_ERR_GT_REQUIRED, NULL);
@@ -6724,22 +6706,20 @@ xmlParseConditionalSections(xmlParserCtxtPtr ctxt) {
                    "Entering INCLUDE Conditional Section\n");
        }
 
+        SKIP_BLANKS;
+        GROW;
        while (((RAW != 0) && ((RAW != ']') || (NXT(1) != ']') ||
                (NXT(2) != '>'))) && (ctxt->instate != XML_PARSER_EOF)) {
            const xmlChar *check = CUR_PTR;
            unsigned int cons = ctxt->input->consumed;
 
-            SKIP_BLANKS;
            if ((RAW == '<') && (NXT(1) == '!') && (NXT(2) == '[')) {
                xmlParseConditionalSections(ctxt);
            } else
                xmlParseMarkupDecl(ctxt);
 
-           /*
-            * Pop-up of finished entities.
-            */
-           while ((RAW == 0) && (ctxt->inputNr > 1))
-               xmlPopInput(ctxt);
+            SKIP_BLANKS;
+            GROW;
 
            if ((CUR_PTR == check) && (cons == ctxt->input->consumed)) {
                xmlFatalErr(ctxt, XML_ERR_EXT_SUBSET_NOT_FINISHED, NULL);
@@ -7043,24 +7023,19 @@ xmlParseExternalSubset(xmlParserCtxtPtr ctxt, const xmlChar *ExternalID,
 
     ctxt->instate = XML_PARSER_DTD;
     ctxt->external = 1;
+    SKIP_BLANKS;
     while (((RAW == '<') && (NXT(1) == '?')) ||
            ((RAW == '<') && (NXT(1) == '!')) ||
-          (RAW == '%') || IS_BLANK_CH(CUR)) {
+          (RAW == '%')) {
        const xmlChar *check = CUR_PTR;
        unsigned int cons = ctxt->input->consumed;
 
-        SKIP_BLANKS;
        GROW;
         if ((RAW == '<') && (NXT(1) == '!') && (NXT(2) == '[')) {
            xmlParseConditionalSections(ctxt);
        } else
            xmlParseMarkupDecl(ctxt);
-
-       /*
-        * Pop-up of finished entities.
-        */
-       while ((RAW == 0) && (ctxt->inputNr > 1))
-           xmlPopInput(ctxt);
+        SKIP_BLANKS;
 
        if ((CUR_PTR == check) && (cons == ctxt->input->consumed)) {
            xmlFatalErr(ctxt, XML_ERR_EXT_SUBSET_NOT_FINISHED, NULL);
@@ -8368,7 +8343,8 @@ xmlParseInternalSubset(xmlParserCtxtPtr ctxt) {
         * PEReferences.
         * Subsequence (markupdecl | PEReference | S)*
         */
-       while ((RAW != ']') && (ctxt->instate != XML_PARSER_EOF)) {
+       while (((RAW != ']') || (ctxt->inputNr > 1)) &&
+               (ctxt->instate != XML_PARSER_EOF)) {
            const xmlChar *check = CUR_PTR;
            unsigned int cons = ctxt->input->consumed;
 
@@ -8376,23 +8352,6 @@ xmlParseInternalSubset(xmlParserCtxtPtr ctxt) {
            xmlParseMarkupDecl(ctxt);
            xmlParsePEReference(ctxt);
 
-           /*
-            * Pop-up of finished entities.
-            */
-            while (ctxt->inputNr > 1) {
-                if (RAW == 0) {
-                   xmlPopInput(ctxt);
-                } else if (RAW == ']') {
-                    /*
-                     * Make sure not to return with unfinished entities.
-                     */
-                   xmlFatalErr(ctxt, XML_ERR_EXT_SUBSET_NOT_FINISHED, NULL);
-                    xmlPopInput(ctxt);
-                } else {
-                    break;
-                }
-            }
-
            if ((CUR_PTR == check) && (cons == ctxt->input->consumed)) {
                xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR,
             "xmlParseInternalSubset: error detected in Markup declaration\n");
@@ -9973,11 +9932,6 @@ xmlParseContent(xmlParserCtxtPtr ctxt) {
        }
 
        GROW;
-       /*
-        * Pop-up of finished entities.
-        */
-       while ((RAW == 0) && (ctxt->inputNr > 1))
-           xmlPopInput(ctxt);
        SHRINK;
 
        if ((cons == ctxt->input->consumed) && (test == CUR_PTR)) {
@@ -11272,13 +11226,6 @@ xmlParseTryOrFinish(xmlParserCtxtPtr ctxt, int terminate) {
        if ((ctxt->errNo != XML_ERR_OK) && (ctxt->disableSAX == 1))
            return(0);
 
-
-       /*
-        * Pop-up of finished entities.
-        */
-       while ((RAW == 0) && (ctxt->inputNr > 1))
-           xmlPopInput(ctxt);
-
        if (ctxt->input == NULL) break;
        if (ctxt->input->buf == NULL)
            avail = ctxt->input->length -
@@ -11629,11 +11576,6 @@ xmlParseTryOrFinish(xmlParserCtxtPtr ctxt, int terminate) {
                    ctxt->checkIndex = 0;
                    xmlParseCharData(ctxt, 0);
                }
-               /*
-                * Pop-up of finished entities.
-                */
-               while ((RAW == 0) && (ctxt->inputNr > 1))
-                   xmlPopInput(ctxt);
                if ((cons == ctxt->input->consumed) && (test == CUR_PTR)) {
                    xmlFatalErr(ctxt, XML_ERR_INTERNAL_ERROR,
                                "detected an error in element content\n");
diff --git a/parserInternals.c b/parserInternals.c
index 7593fc7..d98227c 100644
--- a/parserInternals.c
+++ b/parserInternals.c
@@ -435,8 +435,6 @@ xmlNextChar(xmlParserCtxtPtr ctxt)
 
     if ((*ctxt->input->cur == 0) &&
         (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0)) {
-        if ((ctxt->instate != XML_PARSER_COMMENT))
-            xmlPopInput(ctxt);
         return;
     }
 
@@ -523,8 +521,6 @@ xmlNextChar(xmlParserCtxtPtr ctxt)
             ctxt->input->cur++;
 
         ctxt->nbChars++;
-        if (*ctxt->input->cur == 0)
-            xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
     } else {
         /*
          * Assume it's a fixed length encoding (1) with
@@ -538,12 +534,9 @@ xmlNextChar(xmlParserCtxtPtr ctxt)
             ctxt->input->col++;
         ctxt->input->cur++;
         ctxt->nbChars++;
-        if (*ctxt->input->cur == 0)
-            xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
     }
-    if ((*ctxt->input->cur == 0) &&
-        (xmlParserInputGrow(ctxt->input, INPUT_CHUNK) <= 0))
-        xmlPopInput(ctxt);
+    if (*ctxt->input->cur == 0)
+        xmlParserInputGrow(ctxt->input, INPUT_CHUNK);
     return;
 encoding_error:
     /*