将数据附加到可执行文件（Windows，Unix）

Question

I have a program which compiles and runs scripts.

To create a standalone version of the script, I reserve a large static buffer to hold the compiled script. The compiled script is copied into a copy of the program and it can then be run from that copy.

This works fine. It has some disadvantages however:

• the buffer is static and takes up space if there's no compiled program in it.
• if the script to be included exceeds the buffer's size, I need to build a new version with a larger buffer.

I'd like to add the compiled script to the end of the program, but naively doing so doesn't work as the exe loader chokes on the new file size.

Is there a way to manipulate the exe so it would be acceptable for the loaders (mind this is a cross platform program)?

Answer 1

would be acceptable for the loaders (mind this is a cross platform program)?

I would think that this is unlikely to be possible without being platform specific. Time for a common interface with different implementations (so the code that saves/loads the script is common, but the executable manipulation is specific).

On Windows you'll hit the problem that a running executable file is locked against modification. By working on copies this can be worked around (but the only way to rename back in a completely deterministic way it is perform the move on boot, but scheduling a job might be acceptable).

On Windows the easiest way to add data to an image (executable or dll) is using resources. Define a custom resource type and add into the image ( UpdateResource function) and later retrieve with LoadResource .

Answer 2

You said "script", so I suppose you have a separate file containing the script (a text file?). You could write a simple program that reads the script file and convert it in a compilable form (eg a C source containing the initialization of an array of byte). There are also tools you can use to convert an arbitrary file into a linkable object (.o or .obj). In the past I have used the command "objcopy" from GNU bimutils. In particular, on linux:

objcopy -I binary -O elf32-i386 mydata mydata.o

This command creates an object and three public symbols you can use to find the start, the end and the size of your data block:

_binary_mydata_start _binary_mydata_end _binary_mydata_size

Something similar may work also on Windows, provided that you install a Windows version of GNU binutils (eg cygwin).