feat: provide bundled API

Node.js core doesn't support relative require calls, so this change
provides a bundles API for Postject, so that it can be used easily
in Node.js. Undici too follows the same strategy.

Refs: nodejs/undici#1183
Signed-off-by: Darshan Sen <raisinten@gmail.com>

CMakeLists.txt

@@ -20,7 +20,7 @@ endif()
 add_subdirectory(vendor/lief)
 
 add_executable(postject src/postject.cpp)
-set_target_properties(postject PROPERTIES LINK_FLAGS "-sMODULARIZE=1 -sALLOW_MEMORY_GROWTH -sINITIAL_MEMORY=268435456 -sMAXIMUM_MEMORY=4294967296 --bind")
+set_target_properties(postject PROPERTIES LINK_FLAGS "-sSINGLE_FILE -sMODULARIZE=1 -sALLOW_MEMORY_GROWTH -sINITIAL_MEMORY=268435456 -sMAXIMUM_MEMORY=4294967296 --bind")
 
 if(MSVC)
   set_property(TARGET postject PROPERTY LINK_FLAGS /NODEFAULTLIB:MSVCRT)

README.markdown

@@ -14,6 +14,8 @@ npm i -g postject
 
 ## Usage
 
+### Command line utility
+
 ```sh
 $ postject -h
 Usage: postject [options] <filename> <resource_name> <resource>
@@ -32,6 +34,14 @@ Options:
   -h, --help                           display help for command
 ```
 
+### Using Programatically
+
+```js
+const { inject } = require('postject');
+
+await inject('a.out', 'lol', Buffer.from('Hello, world!'));
+```
+
 ## Building
 
 ### Prerequisites