From 0386be537b3e0e8097e30b0792589ad8b6819cba Mon Sep 17 00:00:00 2001
From: tjpcc <tjp@ctrl-c.club>
Date: Mon, 9 Oct 2023 08:55:10 -0600
Subject: improves filetype detection

---
 contrib/fs/file.go | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

(limited to 'contrib/fs/file.go')

diff --git a/contrib/fs/file.go b/contrib/fs/file.go
index 7690a62..9f11f4f 100644
--- a/contrib/fs/file.go
+++ b/contrib/fs/file.go
@@ -2,7 +2,9 @@ package fs
 
 import (
 	"mime"
+	"os"
 	"strings"
+	"unicode/utf8"
 )
 
 func mediaType(filePath string) string {
@@ -21,6 +23,9 @@ func mediaType(filePath string) string {
 
 	mtype := mime.TypeByExtension(ext)
 	if mtype == "" {
+		if contentsAreText(filePath) {
+			return "text/plain"
+		}
 		return "application/octet-stream"
 	}
 	return mtype
@@ -34,3 +39,28 @@ func isPrivate(fullpath string) bool {
 	}
 	return false
 }
+
+func contentsAreText(filepath string) bool {
+	f, err := os.Open(filepath)
+	if err != nil {
+		return false
+	}
+	defer func() { _ = f.Close() }()
+
+	var buf [1024]byte
+	n, err := f.Read(buf[:])
+	if err != nil {
+		return false
+	}
+
+	for i, c := range string(buf[:n]) {
+		if i+utf8.UTFMax > n {
+			// incomplete last char
+			break
+		}
+		if c == 0xFFFD || c < ' ' && c != '\n' && c != '\t' && c != '\f' {
+			return false
+		}
+	}
+	return true
+}
-- 
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