Add support for SubRip

internal/magic/magic_test.go

@@ -112,3 +112,15 @@ func TestDropLastLine(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkSrt(b *testing.B) {
+	const subtitle = `1
+00:02:16,612 --> 00:02:19,376
+Senator, we're making
+our final approach into Coruscant.
+
+`
+	for i := 0; i < b.N; i++ {
+		Srt([]byte(subtitle), 0)
+	}
+}

internal/magic/text.go

@@ -3,6 +3,8 @@ package magic
 import (
 	"bufio"
 	"bytes"
+	"strings"
+	"time"
 
 	"github.com/gabriel-vasile/mimetype/internal/charset"
 	"github.com/gabriel-vasile/mimetype/internal/json"
@@ -297,3 +299,52 @@ func HAR(raw []byte, limit uint32) bool {
 func Svg(raw []byte, limit uint32) bool {
 	return bytes.Contains(raw, []byte("<svg"))
 }
+
+// Srt matches a SubRip file.
+func Srt(in []byte, _ uint32) bool {
+	s := bufio.NewScanner(bytes.NewReader(in))
+	if !s.Scan() {
+		return false
+	}
+	// First line must be 1.
+	if s.Text() != "1" {
+		return false
+	}
+
+	if !s.Scan() {
+		return false
+	}
+	secondLine := s.Text()
+	// Timestamp format (e.g: 00:02:16,612 --> 00:02:19,376) limits secondLine
+	// length to exactly 29 characters.
+	if len(secondLine) != 29 {
+		return false
+	}
+	// Decimal separator of fractional seconds in the timestamps must be a
+	// comma, not a period.
+	if strings.Contains(secondLine, ".") {
+		return false
+	}
+	// For Go <1.17, comma is not recognised as a decimal separator by `time.Parse`.
+	secondLine = strings.ReplaceAll(secondLine, ",", ".")
+	// Second line must be a time range.
+	ts := strings.Split(secondLine, " --> ")
+	if len(ts) != 2 {
+		return false
+	}
+	const layout = "15:04:05.000"
+	t0, err := time.Parse(layout, ts[0])
+	if err != nil {
+		return false
+	}
+	t1, err := time.Parse(layout, ts[1])
+	if err != nil {
+		return false
+	}
+	if t0.After(t1) {
+		return false
+	}
+
+	// A third line must exist and not be empty. This is the actual subtitle text.
+	return s.Scan() && len(s.Bytes()) != 0
+}

mimetype_test.go

@@ -171,47 +171,53 @@ var files = map[string]string{
 	"shx.shx":            "application/octet-stream",
 	"so.so":              "application/x-sharedlib",
 	"sqlite.sqlite":      "application/vnd.sqlite3",
-	"svg.1.svg":          "image/svg+xml",
-	"svg.svg":            "image/svg+xml",
-	"swf.swf":            "application/x-shockwave-flash",
-	"tar.tar":            "application/x-tar",
-	"tcl.tcl":            "text/x-tcl",
-	"tcx.tcx":            "application/vnd.garmin.tcx+xml",
-	"tiff.tiff":          "image/tiff",
-	"torrent.torrent":    "application/x-bittorrent",
-	"tsv.tsv":            "text/tab-separated-values",
-	"ttf.ttf":            "font/ttf",
-	"tzfile":             "application/tzif",
-	"utf16bebom.txt":     "text/plain; charset=utf-16be",
-	"utf16lebom.txt":     "text/plain; charset=utf-16le",
-	"utf32bebom.txt":     "text/plain; charset=utf-32be",
-	"utf32lebom.txt":     "text/plain; charset=utf-32le",
-	"utf8.txt":           "text/plain; charset=utf-8",
-	"utf8ctrlchars":      "application/octet-stream",
-	"vcf.dos.vcf":        "text/vcard",
-	"vcf.vcf":            "text/vcard",
-	"voc.voc":            "audio/x-unknown",
-	"warc.warc":          "application/warc",
-	"wasm.wasm":          "application/wasm",
-	"wav.wav":            "audio/wav",
-	"webm.webm":          "video/webm",
-	"webp.webp":          "image/webp",
-	"woff.woff":          "font/woff",
-	"woff2.woff2":        "font/woff2",
-	"x3d.x3d":            "model/x3d+xml",
-	"xar.xar":            "application/x-xar",
-	"xcf.xcf":            "image/x-xcf",
-	"xfdf.xfdf":          "application/vnd.adobe.xfdf",
-	"xlf.xlf":            "application/x-xliff+xml",
-	"xls.xls":            "application/vnd.ms-excel",
-	"xlsx.1.xlsx":        "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
-	"xlsx.2.xlsx":        "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
-	"xlsx.xlsx":          "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
-	"xml.xml":            "text/xml; charset=utf-8",
-	"xml.withbr.xml":     "text/xml; charset=utf-8",
-	"xz.xz":              "application/x-xz",
-	"zip.zip":            "application/zip",
-	"zst.zst":            "application/zstd",
+	"srt.srt":            "text/x-subrip",
+	// not.srt.txt uses periods instead of commas for the decimal separators of
+	// the timestamps.
+	"not.srt.txt": "text/plain; charset=utf-8",
+	// not.srt.2.txt does not specify milliseconds.
+	"not.srt.2.txt":   "text/plain; charset=utf-8",
+	"svg.1.svg":       "image/svg+xml",
+	"svg.svg":         "image/svg+xml",
+	"swf.swf":         "application/x-shockwave-flash",
+	"tar.tar":         "application/x-tar",
+	"tcl.tcl":         "text/x-tcl",
+	"tcx.tcx":         "application/vnd.garmin.tcx+xml",
+	"tiff.tiff":       "image/tiff",
+	"torrent.torrent": "application/x-bittorrent",
+	"tsv.tsv":         "text/tab-separated-values",
+	"ttf.ttf":         "font/ttf",
+	"tzfile":          "application/tzif",
+	"utf16bebom.txt":  "text/plain; charset=utf-16be",
+	"utf16lebom.txt":  "text/plain; charset=utf-16le",
+	"utf32bebom.txt":  "text/plain; charset=utf-32be",
+	"utf32lebom.txt":  "text/plain; charset=utf-32le",
+	"utf8.txt":        "text/plain; charset=utf-8",
+	"utf8ctrlchars":   "application/octet-stream",
+	"vcf.dos.vcf":     "text/vcard",
+	"vcf.vcf":         "text/vcard",
+	"voc.voc":         "audio/x-unknown",
+	"warc.warc":       "application/warc",
+	"wasm.wasm":       "application/wasm",
+	"wav.wav":         "audio/wav",
+	"webm.webm":       "video/webm",
+	"webp.webp":       "image/webp",
+	"woff.woff":       "font/woff",
+	"woff2.woff2":     "font/woff2",
+	"x3d.x3d":         "model/x3d+xml",
+	"xar.xar":         "application/x-xar",
+	"xcf.xcf":         "image/x-xcf",
+	"xfdf.xfdf":       "application/vnd.adobe.xfdf",
+	"xlf.xlf":         "application/x-xliff+xml",
+	"xls.xls":         "application/vnd.ms-excel",
+	"xlsx.1.xlsx":     "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+	"xlsx.2.xlsx":     "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+	"xlsx.xlsx":       "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+	"xml.xml":         "text/xml; charset=utf-8",
+	"xml.withbr.xml":  "text/xml; charset=utf-8",
+	"xz.xz":           "application/x-xz",
+	"zip.zip":         "application/zip",
+	"zst.zst":         "application/zstd",
 }
 
 func TestDetect(t *testing.T) {

supported_mimes.md

@@ -1,4 +1,4 @@
-## 166 Supported MIME types
+## 167 Supported MIME types
 This file is automatically generated when running tests. Do not edit manually.
 
 Extension | MIME type | Aliases
@@ -163,6 +163,7 @@ Extension | MIME type | Aliases
 **.har** | application/json | -
 **.ndjson** | application/x-ndjson | -
 **.rtf** | text/rtf | -
+**.srt** | text/x-subrip | text/x-srt
 **.tcl** | text/x-tcl | application/x-tcl
 **.csv** | text/csv | -
 **.tsv** | text/tab-separated-values | -

testdata/not.srt.2.txt

@@ -0,0 +1,20 @@
+1
+00:02:16 --> 00:02:19
+Senator, we're making
+our final approach into Coruscant.
+
+2
+00:02:19 --> 00:02:21
+Very good, Lieutenant.
+
+3
+00:03:13 --> 00:03:15
+We made it.
+
+4
+00:03:18 --> 00:03:20
+I guess I was wrong.
+
+5
+00:03:20 --> 00:03:22
+There was no danger at all.

testdata/not.srt.txt

@@ -0,0 +1,20 @@
+1
+00:02:16.612 --> 00:02:19.376
+Senator, we're making
+our final approach into Coruscant.
+
+2
+00:02:19.482 --> 00:02:21.609
+Very good, Lieutenant.
+
+3
+00:03:13.336 --> 00:03:15.167
+We made it.
+
+4
+00:03:18.608 --> 00:03:20.371
+I guess I was wrong.
+
+5
+00:03:20.476 --> 00:03:22.671
+There was no danger at all.

testdata/srt.srt

@@ -0,0 +1,20 @@
+1
+00:02:16,612 --> 00:02:19,376
+Senator, we're making
+our final approach into Coruscant.
+
+2
+00:02:19,482 --> 00:02:21,609
+Very good, Lieutenant.
+
+3
+00:03:13,336 --> 00:03:15,167
+We made it.
+
+4
+00:03:18,608 --> 00:03:20,371
+I guess I was wrong.
+
+5
+00:03:20,476 --> 00:03:22,671
+There was no danger at all.

tree.go

@@ -76,7 +76,7 @@ var (
 		alias("application/x-ogg")
 	oggAudio = newMIME("audio/ogg", ".oga", magic.OggAudio)
 	oggVideo = newMIME("video/ogg", ".ogv", magic.OggVideo)
-	text     = newMIME("text/plain", ".txt", magic.Text, html, svg, xml, php, js, lua, perl, python, json, ndJSON, rtf, tcl, csv, tsv, vCard, iCalendar, warc)
+	text     = newMIME("text/plain", ".txt", magic.Text, html, svg, xml, php, js, lua, perl, python, json, ndJSON, rtf, srt, tcl, csv, tsv, vCard, iCalendar, warc)
 	xml      = newMIME("text/xml", ".xml", magic.XML, rss, atom, x3d, kml, xliff, collada, gml, gpx, tcx, amf, threemf, xfdf, owl2)
 	json     = newMIME("application/json", ".json", magic.JSON, geoJSON, har)
 	har      = newMIME("application/json", ".har", magic.HAR)
@@ -87,8 +87,10 @@ var (
 	html     = newMIME("text/html", ".html", magic.HTML)
 	php      = newMIME("text/x-php", ".php", magic.Php)
 	rtf      = newMIME("text/rtf", ".rtf", magic.Rtf)
-	js       = newMIME("application/javascript", ".js", magic.Js).
-			alias("application/x-javascript", "text/javascript")
+	srt      = newMIME("text/x-subrip", ".srt", magic.Srt).
+			alias("text/x-srt")
+	js = newMIME("application/javascript", ".js", magic.Js).
+		alias("application/x-javascript", "text/javascript")
 	lua    = newMIME("text/x-lua", ".lua", magic.Lua)
 	perl   = newMIME("text/x-perl", ".pl", magic.Perl)
 	python = newMIME("application/x-python", ".py", magic.Python)