Magic operation now recognises useful operations such as 'Render Image' even though their output cannot be analysed

src/core/FlowControl.js

@@ -294,13 +294,14 @@ const FlowControl = {
             let language = "",
                 fileType = "",
                 matchingOps = "",
+                useful = "",
                 validUTF8 = option.isUTF8 ? "Valid UTF8\n" : "";
 
-            if (option.languageScores[0].probability > 0.00001) {
-                let likelyLangs = option.languageScores.filter(l => l.probability > 0.2);
+            if (option.languageScores[0].probability > 0) {
+                let likelyLangs = option.languageScores.filter(l => l.probability > 0);
                 if (likelyLangs.length < 1) likelyLangs = [option.languageScores[0]];
-                language = "Language:\n    " + likelyLangs.map(lang => {
-                    return `${Magic.codeToLanguage(lang.lang)} ${(lang.probability * 100).toFixed(2)}%`;
+                language = "Possible languages:\n    " + likelyLangs.map(lang => {
+                    return Magic.codeToLanguage(lang.lang);
                 }).join("\n    ") + "\n";
             }
 
@@ -312,10 +313,14 @@ const FlowControl = {
                 matchingOps = `Matching ops: ${[...new Set(option.matchingOps.map(op => op.op))].join(", ")}\n`;
             }
 
+            if (option.useful) {
+                useful = "Useful op detected\n";
+            }
+
             output += `<tr>
                 <td><a href="#${recipeURL}">${Utils.generatePrettyRecipe(option.recipe, true)}</a></td>
                 <td>${Utils.escapeHtml(Utils.printable(Utils.truncate(option.data, 99)))}</td>
-                <td>${language}${fileType}${matchingOps}${validUTF8}</td>
+                <td>${language}${fileType}${matchingOps}${useful}${validUTF8}</td>
             </tr>`;
         });
 

src/core/config/OperationConfig.js

@@ -4091,7 +4091,8 @@ const OperationConfig = {
             {
                 match: "^(?:\\xff\\xd8\\xff|\\x89\\x50\\x4e\\x47|\\x47\\x49\\x46|.{8}\\x57\\x45\\x42\\x50|\\x42\\x4d)",
                 flags: "",
-                args: ["Raw"]
+                args: ["Raw"],
+                useful: true
             },
         ]
     },

src/core/lib/Magic.js

@@ -58,6 +58,12 @@ class Magic {
      * @returns {Object[]}
      */
     detectLanguage(extLang = false) {
+        if (!this.inputBuffer.length) return [{
+            lang: "Unknown",
+            score: Math.MAX_VALUE,
+            probability: Math.MIN_VALUE
+        }];
+
         const inputFreq = this._freqDist();
         const langFreqs = extLang ? EXTENSIVE_LANG_FREQS : COMMON_LANG_FREQS;
         let chiSqrs = [];
@@ -212,9 +218,10 @@ class Magic {
      * @param {boolean} [intensive=false] - Run brute-forcing on each branch (significantly affects
      *                                      performance)
      * @param {Object[]} [recipeConfig=[]] - The recipe configuration up to this point
+     * @param {boolean} [useful=false] - Whether the current recipe should be scored highly
      * @returns {Object[]} - A sorted list of the recipes most likely to result in correct decoding
      */
-    async speculativeExecution(depth = 0, extLang = false, intensive = false, recipeConfig = []) {
+    async speculativeExecution(depth=0, extLang=false, intensive=false, recipeConfig=[], useful=false) {
         if (depth < 0) return [];
 
         // Find any operations that can be run on this data
@@ -229,7 +236,8 @@ class Magic {
             languageScores: this.detectLanguage(extLang),
             fileType: this.detectFileType(),
             isUTF8: this.isUTF8(),
-            matchingOps: matchingOps
+            matchingOps: matchingOps,
+            useful: useful
         });
 
         // Execute each of the matching operations, then recursively call the speculativeExecution()
@@ -250,7 +258,7 @@ class Magic {
 
             const magic = new Magic(dish.get(Dish.ARRAY_BUFFER), this.opPatterns),
                 speculativeResults = await magic.speculativeExecution(
-                        depth-1, extLang, intensive, [...recipeConfig, opConfig]);
+                        depth-1, extLang, intensive, [...recipeConfig, opConfig], op.useful);
 
             results = results.concat(speculativeResults);
         }));
@@ -273,7 +281,8 @@ class Magic {
                 r.languageScores[0].probability > 0 ||
                 r.fileType ||
                 r.isUTF8 ||
-                r.matchingOps.length);
+                r.matchingOps.length ||
+                r.useful);
 
         // Return a sorted list of possible recipes along with their properties
         return results.sort((a, b) => {
@@ -289,6 +298,10 @@ class Magic {
             if (a.isUTF8) aScore -= 100;
             if (b.isUTF8) bScore -= 100;
 
+            // If the option is marked useful, give it a good score
+            if (a.useful) aScore = 100;
+            if (b.useful) bScore = 100;
+
             return aScore - bScore;
         });
     }
@@ -332,7 +345,8 @@ class Magic {
                     op: op,
                     match: pattern.match,
                     flags: pattern.flags,
-                    args: pattern.args
+                    args: pattern.args,
+                    useful: pattern.useful || false
                 });
             });
         }