Add support for APK; close #345 (#624)

Author: gabriel-vasile

internal/magic/zip.go

@@ -110,3 +110,22 @@ func zipContains(raw, sig []byte, msoCheck bool) bool {
 	}
 	return false
 }
+
+// APK matches an Android Package Archive.
+// The source of signatures is https://github.com/file/file/blob/1778642b8ba3d947a779a36fcd81f8e807220a19/magic/Magdir/archive#L1820-L1887
+func APK(raw []byte, _ uint32) bool {
+	apkSignatures := [][]byte{
+		[]byte("AndroidManifest.xml"),
+		[]byte("META-INF/com/android/build/gradle/app-metadata.properties"),
+		[]byte("classes.dex"),
+		[]byte("resources.arsc"),
+		[]byte("res/drawable"),
+	}
+	for _, sig := range apkSignatures {
+		if zipContains(raw, sig, false) {
+			return true
+		}
+	}
+
+	return false
+}

supported_mimes.md

@@ -1,4 +1,4 @@
-## 177 Supported MIME types
+## 178 Supported MIME types
 This file is automatically generated when running tests. Do not edit manually.
 
 Extension | MIME type | Aliases
@@ -11,6 +11,7 @@ Extension | MIME type | Aliases
 **.docx** | application/vnd.openxmlformats-officedocument.wordprocessingml.document | -
 **.pptx** | application/vnd.openxmlformats-officedocument.presentationml.presentation | -
 **.epub** | application/epub+zip | -
+**.apk** | application/vnd.android.package-archive | -
 **.jar** | application/jar | -
 **.odt** | application/vnd.oasis.opendocument.text | application/x-vnd.oasis.opendocument.text
 **.ott** | application/vnd.oasis.opendocument.text-template | application/x-vnd.oasis.opendocument.text-template

tree.go

@@ -44,7 +44,11 @@ var (
 		"application/gzip-compressed", "application/x-gzip-compressed",
 		"gzip/document")
 	sevenZ = newMIME("application/x-7z-compressed", ".7z", magic.SevenZ)
-	zip    = newMIME("application/zip", ".zip", magic.Zip, xlsx, docx, pptx, epub, jar, odt, ods, odp, odg, odf, odc, sxc).
+	// APK must be checked before JAR because APK is a subset of JAR.
+	// This means APK should be a child of JAR detector, but in practice,
+	// the decisive signature for JAR might be located at the end of the file
+	// and not reachable because of library readLimit.
+	zip = newMIME("application/zip", ".zip", magic.Zip, xlsx, docx, pptx, epub, apk, jar, odt, ods, odp, odg, odf, odc, sxc).
 		alias("application/x-zip", "application/x-zip-compressed")
 	tar = newMIME("application/x-tar", ".tar", magic.Tar)
 	xar = newMIME("application/x-xar", ".xar", magic.Xar)
@@ -57,6 +61,7 @@ var (
 	pptx = newMIME("application/vnd.openxmlformats-officedocument.presentationml.presentation", ".pptx", magic.Pptx)
 	epub = newMIME("application/epub+zip", ".epub", magic.Epub)
 	jar  = newMIME("application/jar", ".jar", magic.Jar)
+	apk  = newMIME("application/vnd.android.package-archive", ".apk", magic.APK)
 	ole  = newMIME("application/x-ole-storage", "", magic.Ole, msi, aaf, msg, xls, pub, ppt, doc)
 	msi  = newMIME("application/x-ms-installer", ".msi", magic.Msi).
 		alias("application/x-windows-installer", "application/x-msi")