C：不带main的exec二进制文件，带有exec *（）syscall

Question

I have a question about exec() and fork() syscalls. what I'm trying to get done: a little program where there are 3 "main" processes, one of them execute a fork() N times (user choice) and every child send messagges to the other 2 procs in order to sync and do some stuff.

So: main.c: creates queue, sem and other ipc stuff. Then fork (2 times) and exec(p1)/(p2). If everything is ok, it starts to fork N times, on user choice.

p1.c: attach to ipc created by main, wait for messagges from one of the child of "main.c"

p2.c: attach to ipc... wait for messagges from one of the child of "main.c" or form "p2.c"

What i'm doing right now: I wrote 3 C files, each one with a main function, the "first main" reserve all IPC structure and then fork and execute and execve() in order to start the other 2 program.

Everything seems ok, the first one run and fork correctly, the execve() runs the other 2 programs and these can attach to ipc structure created by first program. Wonderful, but I have 3 program, 3 main and of course I cannot build only one executable file.

So my question: how can I load (if is possible) a program with syscall exec without a main? If is not possibile, how should I write the structure of my program?

I hope is clear, if needed I can write the code, but right now there a few lines..

Thanks!!

Answer 1

用main_p1和main_p2替换main，然后简单地调用它们而不是调用exec。

Answer 2

exec* replaces the current process image with another new program. So those other programs must have a main if written in C.

You can fork your current process without calling exec* however. So you could link all three "programs" into one binary, and simply call into the other ones after forking.