kernel: Add binary format for shebang scripts

base/etc/init/00-home

@@ -1,4 +1,4 @@
 Name=mount-home
 Description=Mount the user's home directory on a writable filesystem.
-Script=/etc/startup/mount-home.sh
+Command=/etc/startup/mount-home.sh
 Wait=true

base/etc/startup/mount-home.sh

@@ -1,2 +1,3 @@
+#!/bin/sh
 mount -t tmpfs tmpfs /home/selene
 chown selene:selene /home/selene

kernel/CMakeLists.txt

@@ -62,6 +62,7 @@ set(SOURCES
     src/fs/InitRD.cpp
     src/binfmt/ELF.cpp
     src/binfmt/BinaryFormat.cpp
+    src/binfmt/Script.cpp
 )
 
 if("${LUNA_ARCH}" MATCHES "x86_64")

kernel/src/binfmt/BinaryFormat.cpp

@@ -1,5 +1,6 @@
 #include "binfmt/BinaryFormat.h"
 #include "binfmt/ELF.h"
+#include "binfmt/Script.h"
 
 struct BinaryFormatDescriptor
 {
@@ -12,6 +13,7 @@ Vector<BinaryFormatDescriptor> g_binary_formats;
 Result<void> BinaryFormat::init()
 {
     TRY(register_binary_format(ELFLoader::create, nullptr));
+    TRY(register_binary_format(ScriptLoader::create, nullptr));
 
     return {};
 }

kernel/src/binfmt/BinaryFormat.h

@@ -10,7 +10,7 @@ class BinaryFormatLoader : public Shareable
 
     virtual StringView format() const = 0;
 
-    virtual Result<Vector<String>> cmdline(const String& path, Vector<String> args) = 0;
+    virtual Result<Vector<String>> cmdline(Vector<String> args) = 0;
 
     virtual ~BinaryFormatLoader() = default;
 

kernel/src/binfmt/ELF.cpp

@@ -132,7 +132,7 @@ Result<u64> ELFLoader::load(AddressSpace* space)
     return elf_header.e_entry;
 }
 
-Result<Vector<String>> ELFLoader::cmdline(const String&, Vector<String> args)
+Result<Vector<String>> ELFLoader::cmdline(Vector<String> args)
 {
     return args;
 }

kernel/src/binfmt/ELF.h

@@ -55,7 +55,7 @@ class ELFLoader : public BinaryFormatLoader
     Result<bool> sniff() override;
     Result<u64> load(AddressSpace* space) override;
 
-    Result<Vector<String>> cmdline(const String& path, Vector<String> args) override;
+    Result<Vector<String>> cmdline(Vector<String> args) override;
 
     StringView format() const override
     {

kernel/src/binfmt/Script.cpp

@@ -0,0 +1,61 @@
+#include "binfmt/Script.h"
+#include "binfmt/ELF.h"
+#include "thread/Scheduler.h"
+
+#define SHEBANG "#!"
+
+Result<bool> ScriptLoader::sniff()
+{
+    u8 buf[2];
+    usize nread = TRY(m_inode->read(buf, 0, sizeof buf));
+    if (nread < 2) return false;
+
+    return !memcmp(buf, SHEBANG, 2);
+}
+
+Result<u64> ScriptLoader::load(AddressSpace* space)
+{
+    u8 buf[256];
+    usize nread = TRY(m_inode->read(buf, 2, 255));
+    if (!nread) return err(ENOEXEC);
+    for (usize i = 0; i < nread; i++)
+    {
+        if (buf[i] == '\n') buf[i] = '\0';
+        else if (buf[i] == '\r' && (i + 1) < nread && buf[i + 1] == '\n')
+            buf[i] = buf[i + 1] = '\0';
+        else
+            continue;
+        break;
+    }
+
+    auto view = StringView { (const char*)buf };
+    m_interpreter_cmdline = TRY(view.split(" "));
+    if (!m_interpreter_cmdline.size()) return err(ENOEXEC);
+
+    auto& interpreter_path = m_interpreter_cmdline[0];
+    auto* current = Scheduler::current();
+
+    auto interpreter =
+        TRY(VFS::resolve_path(interpreter_path.chars(), current->auth, current->current_directory, true));
+    if (!VFS::can_execute(interpreter, current->auth)) return err(EACCES);
+
+    auto loader = TRY(ELFLoader::create(interpreter, nullptr));
+    return loader->load(space);
+}
+
+Result<Vector<String>> ScriptLoader::cmdline(Vector<String> args)
+{
+    Vector<String> new_args;
+    for (auto& arg : m_interpreter_cmdline) { TRY(new_args.try_append(move(arg))); }
+    for (auto& arg : args) { TRY(new_args.try_append(move(arg))); }
+    return new_args;
+}
+
+ScriptLoader::ScriptLoader(SharedPtr<VFS::Inode> inode) : BinaryFormatLoader(inode)
+{
+}
+
+Result<SharedPtr<BinaryFormatLoader>> ScriptLoader::create(SharedPtr<VFS::Inode> inode, void*)
+{
+    return (SharedPtr<BinaryFormatLoader>)TRY(make_shared<ScriptLoader>(inode));
+}

kernel/src/binfmt/Script.h

@@ -0,0 +1,25 @@
+#pragma once
+#include "binfmt/BinaryFormat.h"
+#include "fs/VFS.h"
+#include "memory/AddressSpace.h"
+
+class ScriptLoader : public BinaryFormatLoader
+{
+  public:
+    Result<bool> sniff() override;
+    Result<u64> load(AddressSpace* space) override;
+
+    Result<Vector<String>> cmdline(Vector<String> args) override;
+
+    StringView format() const override
+    {
+        return "script";
+    }
+
+    ScriptLoader(SharedPtr<VFS::Inode> inode);
+
+    static Result<SharedPtr<BinaryFormatLoader>> create(SharedPtr<VFS::Inode> inode, void*);
+
+  private:
+    Vector<String> m_interpreter_cmdline;
+};

kernel/src/sys/exec.cpp

@@ -80,7 +80,7 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
 
     auto image = TRY(ThreadImage::try_load_from_binary(loader));
 
-    argv = TRY(loader->cmdline(move(path), move(argv)));
+    argv = TRY(loader->cmdline(move(argv)));
 
     u64 user_argv = TRY(image->push_string_vector_on_stack(argv));
     usize user_argc = argv.size();