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Make a copy of program area when forking. 

Otherwise things go wrong if global variables are modified
between fork and execve.
This commit is contained in:
Andrius Štikonas 2024-01-14 11:50:46 +00:00
parent 5f7ebfd46c
commit a0cb7cd9a6
Signed by: andrius
GPG Key ID: 0C0331D5228A3B62
1 changed files with 13 additions and 0 deletions
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13
posix-runner/posix-runner.c
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@ -33,6 +33,7 @@ struct process {
void* stack;
void* saved_stack_pointer;
mem_block program;
mem_block saved_program;
mem_block saved_stack;
mem_block saved_memory;
int child_exit_code;
@ -217,6 +218,7 @@ int sys_fork(void, void, void, void, void, void)
current_process->saved_brk = current_process->brk;
current_process->saved_stack_pointer = get_stack();
current_process->forked = TRUE;
current_process->saved_stack.length = current_process->stack - current_process->saved_stack_pointer;
current_process->saved_stack.address = malloc(current_process->saved_stack.length);
if (current_process->saved_stack.address == NULL ) {
@ -224,6 +226,7 @@ int sys_fork(void, void, void, void, void, void)
exit(1);
}
memcpy(current_process->saved_stack.address, current_process->saved_stack_pointer, current_process->saved_stack.length);
current_process->saved_memory.length = current_process->brk - _brk;
current_process->saved_memory.address = malloc(current_process->saved_memory.length);
if (current_process->saved_stack.address == NULL ) {
@ -232,6 +235,14 @@ int sys_fork(void, void, void, void, void, void)
}
memcpy(current_process->saved_memory.address, _brk, current_process->saved_memory.length);
current_process->saved_program.length = current_process->program.length;
current_process->saved_program.address = malloc(current_process->saved_program.length);
if (current_process->saved_program.address == NULL ) {
fputs("Could not allocate memory for saved process.", stderr);
exit(1);
}
memcpy(current_process->saved_program.address, current_process->program.address, current_process->saved_program.length);
return 0; /* return as child */
}
@ -298,8 +309,10 @@ void sys_exit(unsigned value, void, void, void, void, void)
memcpy(current_process->saved_stack_pointer, current_process->saved_stack.address, current_process->saved_stack.length);
memcpy(_brk, current_process->saved_memory.address, current_process->saved_memory.length);
memcpy(current_process->program.address, current_process->saved_program.address, current_process->saved_program.length);
free(current_process->saved_stack.address);
free(current_process->saved_memory.address);
free(current_process->saved_program.address);
current_process->brk = current_process->saved_brk;
current_process->saved_stack_pointer;
/* Simulate return from sys_fork() */