apio
f8b3567042
Very bare-bones for now. Doesn't support arguments or environment (we don't have that stuff right now), and the executable is not a valid ELF, it terminates the task. But it's a start!
67 lines
2.1 KiB
C++
67 lines
2.1 KiB
C++
#define MODULE "exec"
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#include "assert.h"
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#include "errno.h"
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#include "interrupts/Interrupts.h"
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#include "memory/MemoryManager.h"
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#include "sys/elf/ELFLoader.h"
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#include "thread/Scheduler.h"
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void sys_exec(Context* context, const char* pathname)
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{
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if (!pathname)
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{
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context->rax = -EINVAL; // FIXME: This should probably return EFAULT.
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return;
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}
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kinfoln("exec(): executing %s", pathname);
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VFS::Node* program = VFS::resolve_path(pathname);
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if (!program)
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{
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context->rax = -ENOENT;
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return;
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}
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uint64_t allocated_stack = (uint64_t)MemoryManager::get_pages(TASK_PAGES_IN_STACK, MAP_READ_WRITE | MAP_USER);
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if (!allocated_stack)
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{
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context->rax = -ENOMEM;
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return;
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}
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// FIXME: This should be done later, but since there is a very high chance that loading the executed program's ELF
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// image will overwrite ours, we have to do it here.
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ELFLoader::release_elf_image(Scheduler::current_task()->image);
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// FIXME: Check the ELF image is valid before loading it into memory. This will allow us to first check, then free
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// the previous image, then load, which should reduce the chances of loading failing to almost zero.
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ELFImage* image = ELFLoader::load_elf_from_filesystem(pathname);
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if (!image)
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{
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MemoryManager::release_pages((void*)allocated_stack, TASK_PAGES_IN_STACK);
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Scheduler::current_task()->image = nullptr;
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kwarnln("exec(): ERROR: Failed to load program. Previous program has already been freed, thus cannot "
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"return to it.");
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return Scheduler::task_exit(context, -255);
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}
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Interrupts::disable();
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ASSERT(!Interrupts::are_enabled()); // This part is pretty sensitive.
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Task* task = Scheduler::current_task();
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ASSERT(task);
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// At this point, pretty much nothing can fail.
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MemoryManager::release_pages((void*)task->allocated_stack, TASK_PAGES_IN_STACK);
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task->allocated_stack = allocated_stack;
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Scheduler::reset_task(task, image);
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set_context_from_task(*task, context);
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return;
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} |