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Top Forums Programming Timed action after fork() in parent process Post 302510825 by disaster on Tuesday 5th of April 2011 05:31:56 AM
Old 04-05-2011
Timed action after fork() in parent process

Assume you have such a piece of (more or less pseudo-)code:

Code:
if(fork() == 0) {// childprocess
     chmod(someProgram, 00777);
     exec(someProgram);
} else { // assume it never fails and this is the parent
     chmod(someProgram, 00000); // should be executed as soon as possible after the exec call of the child
}

What do I want to achieve: Assume a non executable program someProgram. I want to execute this program in such a way, that it gets executable rights, execute it in a child process via fork, and then take away the executable rights as soon as possible after the exec call.
Is there any way to do this?
 

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FORK(2) 							System Calls Manual							   FORK(2)

NAME
fork - spawn new process SYNOPSIS
fork( ) DESCRIPTION
Fork is the only way new processes are created. The new process's core image is a copy of that of the caller of fork. The only distinc- tion is the fact that the value returned in the old (parent) process contains the process ID of the new (child) process, while the value returned in the child is 0. Process ID's range from 1 to 30,000. This process ID is used by wait(2). Files open before the fork are shared, and have a common read-write pointer. In particular, this is the way that standard input and output files are passed and also how pipes are set up. SEE ALSO
wait(2), exec(2) DIAGNOSTICS
Returns -1 and fails to create a process if: there is inadequate swap space, the user is not super-user and has too many processes, or the system's process table is full. Only the super-user can take the last process-table slot. ASSEMBLER
(fork = 2.) sys fork (new process return) (old process return, new process ID in r0) The return locations in the old and new process differ by one word. The C-bit is set in the old process if a new process could not be cre- ated. FORK(2)
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