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#include <shared/flags.h>
#include <shared/syscalls.h>
#include <user/lib/elf.h>
#include <user/lib/elfload.h>
void elf_execf(libc_file *f) {
const size_t cap = 0x60000;
size_t pos = 0;
void *buf = malloc(cap); // TODO a way to get file size
if (!buf) goto fail;
while (!f->eof) {
long ret = file_read(f, buf, cap - pos);
if (ret < 0) goto fail;
pos += ret;
if (pos >= cap) goto fail;
}
elf_exec(buf);
fail:
free(buf);
}
static bool valid_ehdr(const struct Elf64_Ehdr *h) {
return h->e_ident[0] == 0x7f
&& h->e_ident[1] == 'E'
&& h->e_ident[2] == 'L'
&& h->e_ident[3] == 'F'
&& h->e_machine == EM_X86_64
&& h->e_version == 1;
}
static bool load_phdr(const void *elf, void *exebase, size_t idx) {
const struct Elf64_Ehdr *ehdr = elf;
const struct Elf64_Phdr *phdr = elf + ehdr->e_phoff + idx * ehdr->e_phentsize;
if (phdr->p_type == PT_DYNAMIC) return true;
if (phdr->p_type != PT_LOAD) {
printf("unknown type %x\n", phdr->p_type);
return false;
}
// TODO overlap check
// TODO don't ignore flags
_syscall_memflag(exebase + phdr->p_vaddr, phdr->p_memsz, MEMFLAG_PRESENT);
// TODO check that filesz <= memsz
memcpy(exebase + phdr->p_vaddr, elf + phdr->p_offset, phdr->p_filesz);
return true;
}
static size_t elf_spread(const void *elf) {
const struct Elf64_Ehdr *ehdr = elf;
uintptr_t high = 0, low = ~0;
for (size_t phi = 0; phi < ehdr->e_phnum; phi++) {
const struct Elf64_Phdr *phdr = elf + ehdr->e_phoff + phi * ehdr->e_phentsize;
if (high < phdr->p_vaddr + phdr->p_memsz)
high = phdr->p_vaddr + phdr->p_memsz;
if (low > phdr->p_vaddr)
low = phdr->p_vaddr;
}
return high - low;
}
void elf_exec(void *base) {
struct Elf64_Ehdr *ehdr = base;
void *exebase;
if (!valid_ehdr(ehdr)) return;
switch (ehdr->e_type) {
case ET_EXEC:
exebase = (void*)0;
break;
case ET_DYN:
exebase = _syscall_memflag((void*)0x1000, elf_spread(base), MEMFLAG_FINDFREE);
if (!exebase) {
printf("elf: out of memory\n");
_syscall_exit(1);
}
break;
default:
return;
}
for (size_t phi = 0; phi < ehdr->e_phnum; phi++) {
if (!load_phdr(base, exebase, phi))
return;
}
// TODO free memory
((void(*)())exebase + ehdr->e_entry)();
_syscall_exit(1);
}
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