From 2d6c821261b3639c4f1aaa120844642e8f6f094e Mon Sep 17 00:00:00 2001
From: SheetJS <dev@sheetjs.com>
Date: Wed, 2 Oct 2024 01:04:56 -0400
Subject: [PATCH] Parse DIF-esque CSV (fixes #3230 h/t @lowkeyfish)

---
 CHANGELOG.md    |  1 +
 bits/40_harb.js | 14 ++++++++++++++
 bits/87_read.js |  2 +-
 3 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 350b601..633c350 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ changes may not be included if they are not expected to break existing code.
 * Sheet Visibility for ODS / FODS (h/t @edemaine)
 * HTML DOM ingress support formulae (`data-f`)
 * Proper handling of XLSX encoded entities (h/t @inreoh)
+* Proper handling of invalid DIF sheets that match heuristics (h/t @lowkeyfish)
 
 ## v0.20.3
 
diff --git a/bits/40_harb.js b/bits/40_harb.js
index 4ce011b..9be637a 100644
--- a/bits/40_harb.js
+++ b/bits/40_harb.js
@@ -1138,3 +1138,17 @@ function read_wb_ID(d, opts) {
 	}
 }
 
+function read_wb_TABL(d, opts) {
+	var o = opts || {}, OLD_WTF = !!o.WTF; o.WTF = true;
+	try {
+		var out = DIF.to_workbook(d, o);
+		if(!out || !out.Sheets) throw "DIF bad workbook";
+		var ws = out.Sheets[out.SheetNames[0]];
+		if(!ws || !ws["!ref"]) throw "DIF empty worksheet";
+		o.WTF = OLD_WTF;
+		return out;
+	} catch(e) {
+		o.WTF = OLD_WTF;
+		return PRN.to_workbook(d, opts);
+	}
+}
diff --git a/bits/87_read.js b/bits/87_read.js
index 4933c13..fe0e8eb 100644
--- a/bits/87_read.js
+++ b/bits/87_read.js
@@ -99,7 +99,7 @@ function readSync(data/*:RawData*/, opts/*:?ParseOpts*/)/*:Workbook*/ {
 			if(n[1] === 0x49 && n[2] === 0x2a && n[3] === 0x00) throw new Error("TIFF Image File is not a spreadsheet");
 			if(n[1] === 0x44) return read_wb_ID(d, o);
 			break;
-		case 0x54: if(n[1] === 0x41 && n[2] === 0x42 && n[3] === 0x4C) return DIF.to_workbook(d, o); break;
+		case 0x54: if(n[1] === 0x41 && n[2] === 0x42 && n[3] === 0x4C) return read_wb_TABL(d, o); break;
 		case 0x50: return (n[1] === 0x4B && n[2] < 0x09 && n[3] < 0x09) ? read_zip(d, o) : read_prn(data, d, o, str);
 		case 0xEF: return n[3] === 0x3C ? parse_xlml(d, o) : read_prn(data, d, o, str);
 		case 0xFF: