src,doc: Experimental support for SEA

- add strategy as discussed in next-10 mini-summit
  - https://github.com/nodejs/next-10/blob/main/meetings/summit-nov-2021.md#single-executable-applications
- add initial support single executable application support for linux

Signed-off-by: Michael Dawson <[email protected]>

doc/contributing/maintaining-single-executable-application-support.md

@@ -0,0 +1,110 @@
+# Maintaining Single Executable Applications support
+
+Support for [single executable applications](https://github.com/nodejs/node/blob/master/doc/contributing/technical-priorities.md#single-executable-applications)
+is on of the key technical priorities identified for the success of Node.js.
+
+## High level strategy
+
+From the [next-10 discussions](https://github.com/nodejs/next-10/blob/main/meetings/summit-nov-2021.md#single-executable-applications)
+there are 2 approaches the projects believes are important to support:
+
+* Compile with node into executable (boxnode approach)
+* Bundled onto exising Node.js exe (pkg approach)
+
+### Compile with node into executable
+
+No specific code within the Node.js project is needed to support the
+option of compiling a bundled application along with Node.js into a single
+executable application.
+
+### Bundled onto Existing Node.js
+
+The project does not plan to provide the complete solution but instead the key
+elements which are required in the Node.js executable in order to enabling
+bundling with the shipping Node.js binaries. This includes:
+
+* Looking for a segment within the executable that holds bundled code.
+* Running the bundled code when such a segement is found.
+
+It is left up to external tools/solutions to:
+
+* Bundled code into a single script that can be executed with -e on
+  the command line.
+* Generating a command line with appropriate options, including -e to
+  run the bundle script.
+* adding a segment to the existing Node.js executable which contains
+  the command line and appropriate headers.
+* re-generating or removing signatures on the resulting executable
+* providing a virtual file system, and hooking it in if needed to
+  support native modules or reading file contents.
+
+## Maintaining
+
+### Compile with node into executable
+
+There are not special consideration needed.
+
+### Bundled onto Existing Node.js
+
+The following header must be included in a segment in order to have it run
+as a single executable application:
+
+JSCODEVVVVVVVVFFFFFFFFF
+
+where:
+
+* VVVVVVVV string representing the version to be used to interpret the section,
+  for example `00000001`.
+* FFFFFFFF string representing the flags to be used in the process of starting
+  the bundled application. Currently this must be `00000000` to indicate that
+  no flags are set.
+
+The characters in both `VVVVVVVV` and `FFFFFFFF` are restricted to being
+between the characters "0" and "F" such that they can each be converted to
+a 32 bit integer.
+
+The string following the header is treated as a set of command line options
+that are used as a prefix to any additional command line options passed when
+the executable was started. For example, for a simple single hello world
+for version `00000001`could be:
+
+```text
+JSCODE0000000100000000-e \"console.log('Hello from single binary');\"
+```
+
+Support for bundling onto existing Node.js binaries is maintained
+in `src/node_single_binary.*`.
+
+Currently only POSIX compliant platform are suppported. The goal
+is to expand this to include Windows and MacOS as well.
+
+If a breaking change is required to the content after the header, the version
+`VVVVVVVV` should be incremented. Support for a new format
+may be introduced as a SemVer minor provided that older versions
+are still supported. Removing support for a version is SemVer major.
+
+The `FFFFFFFF` are a set of flags that are used to control the
+process of starting the application. For example they might indicate
+that some set of arguments should be suppressed on the command line.
+Currently no flags are in use.
+
+For test purposes \[LIFE}(<https://github.com/lief-project/LIEF>) can
+be used to add a section in the required format. The following is a
+simple example for doing so on Linux. It can be improved as it
+currently replaces an existing section instead of adding a new
+one:
+
+```text
+#!/usr/bin/env python
+import lief
+binary = lief.parse('node')
+
+segment = lief.ELF.Segment()
+segment.type = lief.ELF.SEGMENT_TYPES.LOAD
+segment.flags = lief.ELF.SEGMENT_FLAGS.R
+stringContent = "JSCODE0000000100000000-e \"console.log('Hello from single binary');\""
+segment.content = bytearray(stringContent.encode())
+segment = binary.replace(segment, binary[lief.ELF.SEGMENT_TYPES.NOTE])
+
+binary.write("hello")
+```

node.gyp

@@ -506,6 +506,7 @@
         'src/node_report_module.cc',
         'src/node_report_utils.cc',
         'src/node_serdes.cc',
+        'src/node_single_binary.cc',
         'src/node_snapshotable.cc',
         'src/node_sockaddr.cc',
         'src/node_stat_watcher.cc',

src/node.cc

@@ -40,6 +40,7 @@
 #include "node_revert.h"
 #include "node_v8_platform-inl.h"
 #include "node_version.h"
+#include "node_single_binary.h"
 
 #if HAVE_OPENSSL
 #include "allocated_buffer-inl.h"  // Inlined functions needed by node_crypto.h
@@ -1148,7 +1149,15 @@ void TearDownOncePerProcess() {
 }
 
 int Start(int argc, char** argv) {
-  InitializationResult result = InitializeOncePerProcess(argc, argv);
+  node::single_binary::NewArgs* newArgs =
+     node::single_binary::checkForSingleBinary(argc, argv);
+
+  InitializationResult result;
+  if (!newArgs->singleBinary) {
+    result = InitializeOncePerProcess(argc, argv);
+  } else {
+    result = InitializeOncePerProcess(newArgs->argc, newArgs->argv);
+  }
   if (result.early_return) {
     return result.exit_code;
   }

src/node_single_binary.cc

@@ -0,0 +1,72 @@
+#include "node_single_binary.h"
+#if defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+#include <link.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wordexp.h>
+#endif  // defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+
+namespace node {
+namespace single_binary {
+
+#define MAGIC_HEADER "JSCODE"
+#define VERSION_CHARS "00000001"
+#define FLAG_CHARS "00000000"
+
+#if defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+static int
+callback(struct dl_phdr_info* info, size_t size, void* data) {
+  // look for the segment with the magic number
+  for (int index = 0; index < info->dlpi_phnum; index++) {
+     if (info->dlpi_phdr[index].p_type == PT_LOAD) {
+      char* content =
+        reinterpret_cast<char*>(info->dlpi_addr +
+                                info->dlpi_phdr[index].p_vaddr);
+      if (strncmp(MAGIC_HEADER,
+                  content,
+                  strlen(MAGIC_HEADER)) == 0) {
+        *(static_cast<char**>(data)) = content;
+        break;
+      }
+    }
+  }
+  return 0;
+}
+#endif  // defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+
+struct NewArgs* checkForSingleBinary(int argc, char** argv) {
+  struct NewArgs* newArgs = new NewArgs;
+  newArgs->singleBinary = false;
+
+#if defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+  char* singleBinaryData = nullptr;
+  dl_iterate_phdr(callback, static_cast<void*>(&singleBinaryData));
+  if (singleBinaryData != nullptr) {
+    wordexp_t parsedArgs;
+    wordexp(&(singleBinaryData[strlen(MAGIC_HEADER) +
+      strlen(VERSION_CHARS) +
+      strlen(FLAG_CHARS)]),
+      &parsedArgs, WRDE_NOCMD);
+    newArgs->argc = 0;
+    while (parsedArgs.we_wordv[newArgs->argc] != nullptr)
+      newArgs->argc++;
+    newArgs->argc = newArgs->argc + argc;
+    newArgs->argv = new char*[newArgs->argc];
+    newArgs->argv[0] = argv[0];
+    int index = 1;
+    while (parsedArgs.we_wordv[index-1] != nullptr) {
+      newArgs->argv[index] = parsedArgs.we_wordv[index-1];
+      index++;
+    }
+    for (int i = 1; i < argc; i++) {
+      newArgs->argv[index++] = argv[i];
+    }
+
+    newArgs->singleBinary = true;
+  }
+#endif  // defined(__POSIX__) && !defined(_AIX) && !defined(__APPLE__)
+  return newArgs;
+}
+
+}  // namespace single_binary
+}  // namespace node

src/node_single_binary.h

@@ -0,0 +1,22 @@
+#ifndef SRC_NODE_SINGLE_BINARY_H_
+#define SRC_NODE_SINGLE_BINARY_H_
+
+#if defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+
+namespace node {
+namespace single_binary {
+
+struct NewArgs {
+  bool singleBinary;
+  int argc;
+  char** argv;
+};
+
+NewArgs* checkForSingleBinary(int argc, char** argv);
+
+}  // namespace single_binary
+}  // namespace node
+
+#endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
+
+#endif  // SRC_NODE_SINGLE_BINARY_H_