Added ELF extractor. You can now specific which categories to search for in file type operations.

src/core/lib/FileSignatures.mjs

@@ -678,7 +678,7 @@ export const FILE_SIGNATURES = {
                 2: 0x4c,
                 3: 0x46
             },
-            extractor: null
+            extractor: extractELF
         },
         {
             name: "Adobe Flash",
@@ -1474,6 +1474,50 @@ export function extractZlib(bytes, offset) {
 }
 
 
+/**
+ * ELF extractor.
+ *
+ * @param {Uint8Array} bytes
+ * @param {number} offset
+ * @returns {Uint8Array}
+ */
+export function extractELF(bytes, offset) {
+    const stream = new Stream(bytes.slice(offset));
+
+    // Skip over magic number
+    stream.moveForwardsBy(4);
+
+    // Read architecture (x86 == 1, x64 == 2)
+    const x86 = stream.readInt(1) === 1;
+
+    // Read endianness (1 == little, 2 == big)
+    const endian = stream.readInt(1) === 1 ? "le" : "be";
+
+    // Skip over header values
+    stream.moveForwardsBy(x86 ? 26 : 34);
+
+    // Read section header table offset
+    const shoff = x86 ? stream.readInt(4, endian) : stream.readInt(8, endian);
+
+    // Skip over flags, header size and program header size and entries
+    stream.moveForwardsBy(10);
+
+    // Read section header table entry size
+    const shentsize = stream.readInt(2, endian);
+
+    // Read number of entries in the section header table
+    const shnum = stream.readInt(2, endian);
+
+    // Jump to section header table
+    stream.moveTo(shoff);
+
+    // Move past each section header
+    stream.moveForwardsBy(shentsize * shnum);
+
+    return stream.carve();
+}
+
+
 /**
  * Steps through a DEFLATE stream
  *

src/core/lib/FileType.mjs

@@ -75,22 +75,29 @@ function bytesMatch(sig, buf, offset=0) {
  * extension and mime type.
  *
  * @param {Uint8Array} buf
+ * @param {string[]} [categories=All] - Which categories of file to look for
  * @returns {Object[]} types
  * @returns {string} type.name - Name of file type
  * @returns {string} type.ext - File extension
  * @returns {string} type.mime - Mime type
  * @returns {string} [type.desc] - Description
  */
-export function detectFileType(buf) {
+export function detectFileType(buf, categories=Object.keys(FILE_SIGNATURES)) {
     if (!(buf && buf.length > 1)) {
         return [];
     }
 
     const matchingFiles = [];
+    const signatures = {};
 
-    // TODO allow user to select which categories to check
     for (const cat in FILE_SIGNATURES) {
-        const category = FILE_SIGNATURES[cat];
+        if (categories.includes(cat)) {
+            signatures[cat] = FILE_SIGNATURES[cat];
+        }
+    }
+
+    for (const cat in signatures) {
+        const category = signatures[cat];
 
         category.forEach(filetype => {
             if (signatureMatches(filetype.signature, buf)) {
@@ -107,6 +114,7 @@ export function detectFileType(buf) {
  * the extensions and mime types.
  *
  * @param {Uint8Array} buf
+ * @param {string[]} [categories=All] - Which categories of file to look for
  * @returns {Object[]} foundFiles
  * @returns {number} foundFiles.offset - The position in the buffer at which this file was found
  * @returns {Object} foundFiles.fileDetails
@@ -115,16 +123,22 @@ export function detectFileType(buf) {
  * @returns {string} foundFiles.fileDetails.mime - Mime type
  * @returns {string} [foundFiles.fileDetails.desc] - Description
  */
-export function scanForFileTypes(buf) {
+export function scanForFileTypes(buf, categories=Object.keys(FILE_SIGNATURES)) {
     if (!(buf && buf.length > 1)) {
         return [];
     }
 
     const foundFiles = [];
+    const signatures = {};
 
-    // TODO allow user to select which categories to check
     for (const cat in FILE_SIGNATURES) {
-        const category = FILE_SIGNATURES[cat];
+        if (categories.includes(cat)) {
+            signatures[cat] = FILE_SIGNATURES[cat];
+        }
+    }
+
+    for (const cat in signatures) {
+        const category = signatures[cat];
 
         for (let i = 0; i < category.length; i++) {
             const filetype = category[i];