fixes a bug in md4c where indentation would include nul bytes. Closes #5

src/md4c.c

@@ -26,7 +26,6 @@
 #include "md4c.h"
 
 #include <limits.h>
-// #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -4558,9 +4557,9 @@ md_process_verbatim_block_contents(MD_CTX* ctx, MD_TEXTTYPE text_type, const MD_
         MD_ASSERT(indent >= 0);
 
         /* Output code indentation. */
-        while(indent > (int) SIZEOF_ARRAY(indent_chunk_str)) {
+        while(indent >= indent_chunk_size) {
             MD_TEXT(text_type, indent_chunk_str, indent_chunk_size);
-            indent -= SIZEOF_ARRAY(indent_chunk_str);
+            indent -= indent_chunk_size;
         }
         if(indent > 0)
             MD_TEXT(text_type, indent_chunk_str, indent);

test/issue5.js

@@ -0,0 +1,96 @@
+// https://github.com/rsms/markdown-wasm/issues/5
+const libdir = process.argv.includes("-debug") ? "build/debug" : "dist"
+const md = require(`../${libdir}/markdown.node.js`)
+
+// this triggers the bug
+const input1 = Buffer.from(
+  "```\n" +
+  "                 |\n" +
+  "```"
+, "utf8")
+const expected1 = Buffer.from(
+  "<pre><code>" +
+  "                 |\n" +
+  "</code></pre>\n"
+, "utf8")
+
+// this does not (indent is 1 less space)
+const input2 = Buffer.from(
+  "```\n" +
+  "                |\n" +
+  "```"
+, "utf8")
+const expected2 = Buffer.from(
+  "<pre><code>" +
+  "                |\n" +
+  "</code></pre>\n"
+, "utf8")
+
+// this does not (indent is 1 more space)
+const input3 = Buffer.from(
+  "```\n" +
+  "                  |\n" +
+  "```"
+, "utf8")
+const expected3 = Buffer.from(
+  "<pre><code>" +
+  "                  |\n" +
+  "</code></pre>\n"
+, "utf8")
+
+let fails = 0
+check("test1", expected1, input1)
+check("test2", expected2, input2)
+check("test3", expected3, input3)
+
+
+function check(name, expected, inputData) {
+  const actual = Buffer.from(md.parse(inputData, { asMemoryView: true }))
+
+  if (expected.compare(actual) == 0) {
+    console.log(`${name} OK`)
+    return
+  }
+  fails++
+  const line = "——————————————————————————————————————————————————"
+  const wave = "~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~"
+  console.error(`${name} FAIL.`)
+
+  console.error(`\n\nExpected output:\n${line}`)
+  inspectBuf(expected, actual)
+  console.error(`${line}\n\nActual output:\n${line}`)
+  inspectBuf(actual, expected)
+  console.error(line)
+
+  function inspectBuf(buf, otherbuf) {
+    process.stderr.write(buf)
+    if (buf[buf.length-1] != 0x0a) {
+      process.stderr.write("<no-ending-line-break>\n")
+    }
+    console.error(wave)
+    const styleReset = "\x1b[22;39m"
+    const styleNone = s=>s
+    const styleDiff = process.stderr.isTTY ? s => "\x1b[1;33m"+s+styleReset : styleNone
+    const styleErr  = process.stderr.isTTY ? s => "\x1b[1;31m"+s+styleReset : styleNone
+
+    for (let i = 0; i < buf.length; i++) {
+      let b = buf[i]
+
+      let style = styleNone
+      if (b < 0x20 && b != 0x09 && b != 0x0A && b != 0x0D) {
+        // byte is unexpected control character (except TAB, CR, LF)
+        style = styleErr
+      } else if (otherbuf && otherbuf[i] != b) {
+        style = styleDiff
+      }
+
+      process.stderr.write(style(b.toString(16).padStart(2, '0')) + " ")
+
+      if (b == 0x0a) {
+        process.stderr.write("\n")
+      }
+    }
+  }
+}
+
+process.exit(fails > 0 ? 1 : 0)

test/test.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+set -euo pipefail
+cd "$(dirname "$0")"
+
+node issue5.js "$@"