add shToElf handler

src/handlers/index.ts

@@ -69,6 +69,7 @@ import chessjsHandler from "./chessjs.ts";
 import fenToJsonHandler from "./fenToJson.ts";
 import piskelHandler from "./piskel.ts";
 import xcursorHandler from "./xcursor.ts";
+import shToElfHandler from "./shToElf.ts";
 import cssHandler from "./css.ts";
 import TypstHandler from "./typst.ts";
 
@@ -146,6 +147,7 @@ try { handlers.push(new chessjsHandler()) } catch (_) { };
 try { handlers.push(new fenToJsonHandler()) } catch (_) { };
 try { handlers.push(new piskelHandler()) } catch (_) { };
 try { handlers.push(new xcursorHandler()) } catch (_) { };
+try { handlers.push(new shToElfHandler()) } catch (_) { };
 try { handlers.push(new cssHandler()) } catch (_) { };
 try { handlers.push(new TypstHandler()) } catch (_) { };
 

src/handlers/shToElf.ts

@@ -0,0 +1,71 @@
+// file: shToElf.ts
+
+import type { FileData, FileFormat, FormatHandler } from "../FormatHandler.ts";
+import CommonFormats, { Category } from "src/CommonFormats.ts";
+
+import elfUrl from "./shToElf/stub.elf?url";
+
+function replaceUint32LE(file: Buffer, from: number, to: number) {
+  const fromBytes = Buffer.alloc(4);
+  fromBytes.writeUint32LE(from, 0);
+
+  const toBytes = Buffer.alloc(4);
+  toBytes.writeUint32LE(to, 0);
+
+  const index = file.indexOf(fromBytes);
+  toBytes.copy(file, index);
+}
+
+class shToElfHandler implements FormatHandler {
+
+  public name: string = "shToElf";
+  public supportedFormats: FileFormat[] = [
+    CommonFormats.SH.builder("sh").allowFrom().markLossless(),
+    {
+      name: "x86-64 Linux Executable and Linkable Format",
+      format: "elf",
+      extension: "elf",
+      mime: "application/x-elf",
+      from: false,
+      to: true,
+      internal: "elf",
+      category: Category.CODE,
+    }
+  ];
+  public ready: boolean = false;
+
+  #binary?: Buffer;
+
+  async init () {
+    this.ready = true;
+    this.#binary = Buffer.from(await (await fetch(elfUrl)).bytes());
+  }
+
+  async doConvert (
+    inputFiles: FileData[],
+    inputFormat: FileFormat,
+    outputFormat: FileFormat
+  ): Promise<FileData[]> {
+    const outputFiles: FileData[] = [];
+
+    for (const inputFile of inputFiles) {
+      const binary = Buffer.from(new Uint8Array(this.#binary!));
+      replaceUint32LE(binary, 1273991571, inputFile.bytes.length);
+
+      let file = Buffer.concat([
+        binary,
+        inputFile.bytes
+      ]);
+
+      outputFiles.push({ 
+        name: inputFile.name.replace(/\.[^.]+$/, "") + ".elf",
+        bytes: file
+      });
+    }
+
+    return outputFiles;
+  }
+
+}
+
+export default shToElfHandler;

src/handlers/shToElf/stub.c

@@ -0,0 +1,21 @@
+// gcc -o stub.elf stub.c
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+// https://xkcd.com/221
+int cmd_size = 1273991571;
+
+int main() {
+  int fd = open("/proc/self/exe", O_RDONLY);
+  lseek(fd, -cmd_size, SEEK_END);
+
+  char *cmd = malloc(cmd_size + 1);
+  read(fd, cmd, cmd_size);
+  close(fd);
+
+  cmd[cmd_size] = '\0';
+  execl("/bin/bash", "bash", "-c", cmd, NULL);
+}