#include <string.h>

#include <elf.h>


bool is_elf(fs_handle_t *f) {
	elf_ehdr_t h;
	if (file_read(f, 0, sizeof(elf_ehdr_t), (char*)&h) != sizeof(elf_ehdr_t)) return false;

	return (h.e_ident[0] == 0x7F && h.e_ident[1] == 'E'
		  && h.e_ident[2] == 'L' && h.e_ident[3] == 'F');
}

proc_entry_t elf_load(fs_handle_t *f, process_t* process) {
	if (!is_elf(f)) return 0;

	elf_ehdr_t ehdr;
	if (file_read(f, 0, sizeof(elf_ehdr_t), (char*)&ehdr) != sizeof(elf_ehdr_t)) return 0;

	elf_phdr_t phdr;
	int i;

	pagedir_t *r = get_current_pagedir();
	switch_pagedir(process->pd);

	// TODO : when we fail, free ressources ?

	for (i = 0; i < ehdr.e_phnum; i++) {
		size_t read_phdr_r = 
			file_read(f,
					ehdr.e_phoff + i * sizeof(elf_phdr_t),
					sizeof(elf_phdr_t),
					(char*)&phdr);
		if (read_phdr_r != sizeof(elf_phdr_t)) goto error;

		if (phdr.p_type == PT_LOAD) {
			if ((phdr.p_flags & PF_W) || !(f->mode & FM_MMAP)) {
				bool mmap_ok = mmap(process, (void*)phdr.p_vaddr, phdr.p_memsz,
						((phdr.p_flags & PF_R) ? MM_READ : 0) | MM_WRITE);
				if (!mmap_ok) goto error;

				size_t read_r = file_read(f, phdr.p_offset, phdr.p_filesz, (char*)phdr.p_vaddr);
				if (read_r != phdr.p_filesz) goto error;

				// no need to zero out extra portion, paging code does that for us

				if (!(phdr.p_flags & PF_W)) {
					bool mchmap_ok = mchmap(process, (void*)phdr.p_vaddr,
							((phdr.p_flags & PF_R) ? MM_READ : 0));
					if (!mchmap_ok) goto error;
				}
			} else {
				if (phdr.p_filesz != phdr.p_memsz) {
					dbg_printf("Strange ELF file...\n");
				}

				bool mmap_ok = mmap_file(process,
							f, phdr.p_offset,
							(void*)phdr.p_vaddr, phdr.p_memsz,
							((phdr.p_flags & PF_R) ? MM_READ : 0) | ((phdr.p_flags & PF_X) ? MM_EXEC : 0));
				if (!mmap_ok) goto error;
			}
		}
	}

	switch_pagedir(r);

	return (proc_entry_t)ehdr.e_entry;

error:
	switch_pagedir(r);
	return 0;
}

/* vim: set ts=4 sw=4 tw=0 noet :*/