Merge pull request commonmark#230 from github/fix-footnotes-plus-fix-fnref-label-and-backrefs

phillmv · web-flow · commit d7e50f07a8e8 · 2021-09-16T12:06:29.000-04:00
Fix footnotes plus fix footnote reference labels and backrefs
diff --git a/src/blocks.c b/src/blocks.c
@@ -484,6 +484,15 @@ static void process_footnotes(cmark_parser *parser) {
         if (!footnote->ix)
           footnote->ix = ++ix;
 
+        // store a reference to this footnote reference's footnote definition
+        // this is used by renderers when generating label ids
+        cur->parent_footnote_def = footnote->node;
+
+        // keep track of a) count of how many times this footnote def has been
+        // referenced, and b) which reference index this footnote ref is at.
+        // this is used by renderers when generating links and backreferences.
+        cur->footnote.ref_ix = ++footnote->node->footnote.def_count;
+
         char n[32];
         snprintf(n, sizeof(n), "%d", footnote->ix);
         cmark_chunk_free(parser->mem, &cur->as.literal);
diff --git a/src/commonmark.c b/src/commonmark.c
@@ -477,7 +477,13 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
   case CMARK_NODE_FOOTNOTE_REFERENCE:
     if (entering) {
       LIT("[^");
-      OUT(cmark_chunk_to_cstr(renderer->mem, &node->as.literal), false, LITERAL);
+
+      char *footnote_label = renderer->mem->calloc(node->parent_footnote_def->as.literal.len + 1, sizeof(char));
+      memmove(footnote_label, node->parent_footnote_def->as.literal.data, node->parent_footnote_def->as.literal.len);
+
+      OUT(footnote_label, false, LITERAL);
+      renderer->mem->free(footnote_label);
+
       LIT("]");
     }
     break;
@@ -486,9 +492,13 @@ static int S_render_node(cmark_renderer *renderer, cmark_node *node,
     if (entering) {
       renderer->footnote_ix += 1;
       LIT("[^");
-      char n[32];
-      snprintf(n, sizeof(n), "%d", renderer->footnote_ix);
-      OUT(n, false, LITERAL);
+
+      char *footnote_label = renderer->mem->calloc(node->as.literal.len + 1, sizeof(char));
+      memmove(footnote_label, node->as.literal.data, node->as.literal.len);
+
+      OUT(footnote_label, false, LITERAL);
+      renderer->mem->free(footnote_label);
+
       LIT("]:\n");
 
       cmark_strbuf_puts(renderer->prefix, "    ");
diff --git a/src/html.c b/src/html.c
@@ -59,17 +59,31 @@ static void filter_html_block(cmark_html_renderer *renderer, uint8_t *data, size
     cmark_strbuf_put(html, data, (bufsize_t)len);
 }
 
-static bool S_put_footnote_backref(cmark_html_renderer *renderer, cmark_strbuf *html) {
+static bool S_put_footnote_backref(cmark_html_renderer *renderer, cmark_strbuf *html, cmark_node *node) {
   if (renderer->written_footnote_ix >= renderer->footnote_ix)
     return false;
   renderer->written_footnote_ix = renderer->footnote_ix;
 
-  cmark_strbuf_puts(html, "<a href=\"#fnref");
-  char n[32];
-  snprintf(n, sizeof(n), "%d", renderer->footnote_ix);
-  cmark_strbuf_puts(html, n);
+  cmark_strbuf_puts(html, "<a href=\"#fnref-");
+  houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
   cmark_strbuf_puts(html, "\" class=\"footnote-backref\">↩</a>");
 
+  if (node->footnote.def_count > 1)
+  {
+    for(int i = 2; i <= node->footnote.def_count; i++) {
+      char n[32];
+      snprintf(n, sizeof(n), "%d", i);
+
+      cmark_strbuf_puts(html, " <a href=\"#fnref-");
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
+      cmark_strbuf_puts(html, "-");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "\" class=\"footnote-backref\">↩<sup class=\"footnote-ref\">");
+      cmark_strbuf_puts(html, n);
+      cmark_strbuf_puts(html, "</sup></a>");
+    }
+  }
+
   return true;
 }
 
@@ -273,7 +287,7 @@ static int S_render_node(cmark_html_renderer *renderer, cmark_node *node,
       } else {
         if (parent->type == CMARK_NODE_FOOTNOTE_DEFINITION && node->next == NULL) {
           cmark_strbuf_putc(html, ' ');
-          S_put_footnote_backref(renderer, html);
+          S_put_footnote_backref(renderer, html, parent);
         }
         cmark_strbuf_puts(html, "</p>\n");
       }
@@ -395,13 +409,12 @@ static int S_render_node(cmark_html_renderer *renderer, cmark_node *node,
         cmark_strbuf_puts(html, "<section class=\"footnotes\">\n<ol>\n");
       }
       ++renderer->footnote_ix;
-      cmark_strbuf_puts(html, "<li id=\"fn");
-      char n[32];
-      snprintf(n, sizeof(n), "%d", renderer->footnote_ix);
-      cmark_strbuf_puts(html, n);
+
+      cmark_strbuf_puts(html, "<li id=\"fn-");
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
       cmark_strbuf_puts(html, "\">\n");
     } else {
-      if (S_put_footnote_backref(renderer, html)) {
+      if (S_put_footnote_backref(renderer, html, node)) {
         cmark_strbuf_putc(html, '\n');
       }
       cmark_strbuf_puts(html, "</li>\n");
@@ -410,12 +423,20 @@ static int S_render_node(cmark_html_renderer *renderer, cmark_node *node,
 
   case CMARK_NODE_FOOTNOTE_REFERENCE:
     if (entering) {
-      cmark_strbuf_puts(html, "<sup class=\"footnote-ref\"><a href=\"#fn");
-      cmark_strbuf_put(html, node->as.literal.data, node->as.literal.len);
-      cmark_strbuf_puts(html, "\" id=\"fnref");
-      cmark_strbuf_put(html, node->as.literal.data, node->as.literal.len);
+      cmark_strbuf_puts(html, "<sup class=\"footnote-ref\"><a href=\"#fn-");
+      houdini_escape_href(html, node->parent_footnote_def->as.literal.data, node->parent_footnote_def->as.literal.len);
+      cmark_strbuf_puts(html, "\" id=\"fnref-");
+      houdini_escape_href(html, node->parent_footnote_def->as.literal.data, node->parent_footnote_def->as.literal.len);
+
+      if (node->footnote.ref_ix > 1) {
+        char n[32];
+        snprintf(n, sizeof(n), "%d", node->footnote.ref_ix);
+        cmark_strbuf_puts(html, "-");
+        cmark_strbuf_puts(html, n);
+      }
+
       cmark_strbuf_puts(html, "\">");
-      cmark_strbuf_put(html, node->as.literal.data, node->as.literal.len);
+      houdini_escape_href(html, node->as.literal.data, node->as.literal.len);
       cmark_strbuf_puts(html, "</a></sup>");
     }
     break;
diff --git a/src/node.h b/src/node.h
@@ -76,6 +76,13 @@ struct cmark_node {
 
   cmark_syntax_extension *extension;
 
+  union {
+    int ref_ix;
+    int def_count;
+  } footnote;
+
+  cmark_node *parent_footnote_def;
+
   union {
     cmark_chunk literal;
     cmark_list list;
diff --git a/test/extensions.txt b/test/extensions.txt
@@ -672,31 +672,68 @@ Hi!
 
 [^unused]: This is unused.
 .
-<p>This is some text!<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup>. Other text.<sup class="footnote-ref"><a href="#fn2" id="fnref2">2</a></sup>.</p>
-<p>Here's a thing<sup class="footnote-ref"><a href="#fn3" id="fnref3">3</a></sup>.</p>
-<p>And another thing<sup class="footnote-ref"><a href="#fn4" id="fnref4">4</a></sup>.</p>
+<p>This is some text!<sup class="footnote-ref"><a href="#fn-1" id="fnref-1">1</a></sup>. Other text.<sup class="footnote-ref"><a href="#fn-footnote" id="fnref-footnote">2</a></sup>.</p>
+<p>Here's a thing<sup class="footnote-ref"><a href="#fn-other-note" id="fnref-other-note">3</a></sup>.</p>
+<p>And another thing<sup class="footnote-ref"><a href="#fn-codeblock-note" id="fnref-codeblock-note">4</a></sup>.</p>
 <p>This doesn't have a referent[^nope].</p>
 <p>Hi!</p>
 <section class="footnotes">
 <ol>
-<li id="fn1">
-<p>Some <em>bolded</em> footnote definition. <a href="#fnref1" class="footnote-backref">↩</a></p>
+<li id="fn-1">
+<p>Some <em>bolded</em> footnote definition. <a href="#fnref-1" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn2">
+<li id="fn-footnote">
 <blockquote>
 <p>Blockquotes can be in a footnote.</p>
 </blockquote>
 <pre><code>as well as code blocks
 </code></pre>
-<p>or, naturally, simple paragraphs. <a href="#fnref2" class="footnote-backref">↩</a></p>
+<p>or, naturally, simple paragraphs. <a href="#fnref-footnote" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn3">
-<p>no code block here (spaces are stripped away) <a href="#fnref3" class="footnote-backref">↩</a></p>
+<li id="fn-other-note">
+<p>no code block here (spaces are stripped away) <a href="#fnref-other-note" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn4">
+<li id="fn-codeblock-note">
 <pre><code>this is now a code block (8 spaces indentation)
 </code></pre>
-<a href="#fnref4" class="footnote-backref">↩</a>
+<a href="#fnref-codeblock-note" class="footnote-backref">↩</a>
+</li>
+</ol>
+</section>
+````````````````````````````````
+
+## When a footnote is used multiple times, we insert multiple backrefs.
+
+```````````````````````````````` example
+This is some text. It has a footnote[^a-footnote].
+
+This footnote is referenced[^a-footnote] multiple times, in lots of different places.[^a-footnote]
+
+[^a-footnote]: This footnote definition should have three backrefs.
+.
+<p>This is some text. It has a footnote<sup class="footnote-ref"><a href="#fn-a-footnote" id="fnref-a-footnote">1</a></sup>.</p>
+<p>This footnote is referenced<sup class="footnote-ref"><a href="#fn-a-footnote" id="fnref-a-footnote-2">1</a></sup> multiple times, in lots of different places.<sup class="footnote-ref"><a href="#fn-a-footnote" id="fnref-a-footnote-3">1</a></sup></p>
+<section class="footnotes">
+<ol>
+<li id="fn-a-footnote">
+<p>This footnote definition should have three backrefs. <a href="#fnref-a-footnote" class="footnote-backref">↩</a> <a href="#fnref-a-footnote-2" class="footnote-backref">↩<sup class="footnote-ref">2</sup></a> <a href="#fnref-a-footnote-3" class="footnote-backref">↩<sup class="footnote-ref">3</sup></a></p>
+</li>
+</ol>
+</section>
+````````````````````````````````
+
+## Footnote reference labels are href escaped
+
+```````````````````````````````` example
+Hello[^"><script>alert(1)</script>]
+
+[^"><script>alert(1)</script>]: pwned
+.
+<p>Hello<sup class="footnote-ref"><a href="#fn-%22%3E%3Cscript%3Ealert(1)%3C/script%3E" id="fnref-%22%3E%3Cscript%3Ealert(1)%3C/script%3E">1</a></sup></p>
+<section class="footnotes">
+<ol>
+<li id="fn-%22%3E%3Cscript%3Ealert(1)%3C/script%3E">
+<p>pwned <a href="#fnref-%22%3E%3Cscript%3Ealert(1)%3C/script%3E" class="footnote-backref">↩</a></p>
 </li>
 </ol>
 </section>
diff --git a/test/regression.txt b/test/regression.txt
@@ -175,7 +175,7 @@ A footnote in a paragraph[^1]
 
 [^1]: a footnote
 .
-<p>A footnote in a paragraph<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup></p>
+<p>A footnote in a paragraph<sup class="footnote-ref"><a href="#fn-1" id="fnref-1">1</a></sup></p>
 <table>
 <thead>
 <tr>
@@ -185,15 +185,15 @@ A footnote in a paragraph[^1]
 </thead>
 <tbody>
 <tr>
-<td>foot <sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup></td>
+<td>foot <sup class="footnote-ref"><a href="#fn-1" id="fnref-1-2">1</a></sup></td>
 <td>note</td>
 </tr>
 </tbody>
 </table>
 <section class="footnotes">
 <ol>
-<li id="fn1">
-<p>a footnote <a href="#fnref1" class="footnote-backref">↩</a></p>
+<li id="fn-1">
+<p>a footnote <a href="#fnref-1" class="footnote-backref">↩</a> <a href="#fnref-1-2" class="footnote-backref">↩<sup class="footnote-ref">2</sup></a></p>
 </li>
 </ol>
 </section>
@@ -279,14 +279,14 @@ This is some text. It has a citation.[^citation]
 
 [^citation]: This is a long winded parapgraph that also has another citation.[^another-citation]
 .
-<p>This is some text. It has a citation.<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup></p>
+<p>This is some text. It has a citation.<sup class="footnote-ref"><a href="#fn-citation" id="fnref-citation">1</a></sup></p>
 <section class="footnotes">
 <ol>
-<li id="fn1">
-<p>This is a long winded parapgraph that also has another citation.<sup class="footnote-ref"><a href="#fn2" id="fnref2">2</a></sup> <a href="#fnref1" class="footnote-backref">↩</a></p>
+<li id="fn-citation">
+<p>This is a long winded parapgraph that also has another citation.<sup class="footnote-ref"><a href="#fn-another-citation" id="fnref-another-citation">2</a></sup> <a href="#fnref-citation" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn2">
-<p>My second citation. <a href="#fnref2" class="footnote-backref">↩</a></p>
+<li id="fn-another-citation">
+<p>My second citation. <a href="#fnref-another-citation" class="footnote-backref">↩</a></p>
 </li>
 </ol>
 </section>
@@ -301,14 +301,14 @@ This is some text. It has two footnotes references, side-by-side without any spa
 
 [^footnote2]: Goodbye.
 .
-<p>This is some text. It has two footnotes references, side-by-side without any spaces,<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup><sup class="footnote-ref"><a href="#fn2" id="fnref2">2</a></sup> which are definitely not link references.</p>
+<p>This is some text. It has two footnotes references, side-by-side without any spaces,<sup class="footnote-ref"><a href="#fn-footnote1" id="fnref-footnote1">1</a></sup><sup class="footnote-ref"><a href="#fn-footnote2" id="fnref-footnote2">2</a></sup> which are definitely not link references.</p>
 <section class="footnotes">
 <ol>
-<li id="fn1">
-<p>Hello. <a href="#fnref1" class="footnote-backref">↩</a></p>
+<li id="fn-footnote1">
+<p>Hello. <a href="#fnref-footnote1" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn2">
-<p>Goodbye. <a href="#fnref2" class="footnote-backref">↩</a></p>
+<li id="fn-footnote2">
+<p>Goodbye. <a href="#fnref-footnote2" class="footnote-backref">↩</a></p>
 </li>
 </ol>
 </section>
@@ -325,15 +325,15 @@ It has another footnote that contains many different characters (the autolinker
 
 [^widely-cited]: this renders properly.
 .
-<p>This is some text. Sometimes the autolinker splits up text into multiple nodes, hoping it will find a hyperlink, so this text has a footnote whose reference label begins with a <code>w</code>.<sup class="footnote-ref"><a href="#fn1" id="fnref1">1</a></sup></p>
-<p>It has another footnote that contains many different characters (the autolinker was also breaking on <code>_</code>).<sup class="footnote-ref"><a href="#fn2" id="fnref2">2</a></sup></p>
+<p>This is some text. Sometimes the autolinker splits up text into multiple nodes, hoping it will find a hyperlink, so this text has a footnote whose reference label begins with a <code>w</code>.<sup class="footnote-ref"><a href="#fn-widely-cited" id="fnref-widely-cited">1</a></sup></p>
+<p>It has another footnote that contains many different characters (the autolinker was also breaking on <code>_</code>).<sup class="footnote-ref"><a href="#fn-sphinx-of-black-quartz_judge-my-vow-0123456789" id="fnref-sphinx-of-black-quartz_judge-my-vow-0123456789">2</a></sup></p>
 <section class="footnotes">
 <ol>
-<li id="fn1">
-<p>this renders properly. <a href="#fnref1" class="footnote-backref">↩</a></p>
+<li id="fn-widely-cited">
+<p>this renders properly. <a href="#fnref-widely-cited" class="footnote-backref">↩</a></p>
 </li>
-<li id="fn2">
-<p>so does this. <a href="#fnref2" class="footnote-backref">↩</a></p>
+<li id="fn-sphinx-of-black-quartz_judge-my-vow-0123456789">
+<p>so does this. <a href="#fnref-sphinx-of-black-quartz_judge-my-vow-0123456789" class="footnote-backref">↩</a></p>
 </li>
 </ol>
 </section>
