replace-exe

A smol Zig library that lets a running executable replace (or delete) itself.

This can be used, for instance, in applications implementing a self update feature keeping the current installation path intact.

Only windows, linux, and unix like systems (macOS, *BSD) are supported.

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Usage

1. Add the library to your build.zig.zon:

zig fetch --save git+https://github.com/weezy20/replace-exe.git

1. Add it to your build.zig:

const exe = b.addExecutable(.{
    ...
});

// Add the replace_exe dependency
const libreplace_exe = b.dependency("replace_exe", .{});
exe.root_module.addImport("replace_exe", libreplace_exe.module("replace_exe"));

1. Call selfReplace or selfDelete from your code:

const re = @import("replace_exe");
// Replace current executable with a new one
try re.selfReplace(allocator, "path/to/new/executable");
// Warning: Deletes current executable
try re.selfDelete();

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Demo

Two demo applications are provided in the demo folder: demo.zig is version 1 and calls selfReplace to replace itself with demo2.zig

Build the demo applications with:

zig build -Ddemo

Then run the first demo exe:

./zig-out/bin/demo delete # self-delete
./zig-out/bin/demo replace ?</path/to/new/exe> # self-replace; default path is ./zig-out/bin/demo2

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C API

Building the library as a shared object or static library for use with C/C++:

# This builds a .so shared library like libreplace-exe.so that you can link against
zig build -Dcapi -Dso -Doptimization=ReleaseFast
# Or if you prefer a static library:
zig build -Dcapi -Doptimization=ReleaseFast

This will put the header file replace_exe.h and the shared or static library in the zig-out/include & zig-out/lib folders respectively.

Example usage in C (using dynamic library): See demo.c

1. Build your C app using either of the generated libraries:

gcc demo/demo.c -Izig-out/include -Lzig-out/lib -lreplace-exe -o test

1. Run the C demo:

LD_LIBRARY_PATH=zig-out/lib ./test /path/to/new/executable

1. Run again to verify replacement:

LD_LIBRARY_PATH=zig-out/lib ./test

Or if you prefer go (using cgo): See demo/main.go for an example.

1. Build your Go app linking libreplace-exe.a or libreplace-exe.so:

go build -o demo-go demo/main.go

1. Run the Go demo:

./demo-go replace /path/to/new/executable