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#include <shared/flags.h>
#include <shared/mem.h>
#include <shared/syscalls.h>
#include <user/lib/elfload.h>
extern char _bss_start;
extern char _bss_end;
extern char _initrd;
static void *tar_find(void *tar, const char *path);
static int oct_parse(char *str, size_t len);
static void *tar_find(void *tar, const char *path) {
size_t path_len = strlen(path);
int size;
if (path_len > 100) return NULL;
for (size_t off = 0;;) {
if (0 != memcmp(tar + off + 257, "ustar", 5))
return NULL; // not a metadata sector, end of archive
_klogf("%s", tar + off);
size = oct_parse(tar + off + 124, 11);
if (0 == memcmp(tar + off, path, path_len) &&
*(char*)(tar + off + path_len) == '\0')
{
return tar + off + 512;
}
off += 512;
off += (size + 511) & ~511;
}
}
static int oct_parse(char *str, size_t len) {
int res = 0;
for (size_t i = 0; i < len; i++) {
res *= 8;
res += str[i] - '0'; // no format checking
}
return res;
}
__attribute__((section(".text.startup")))
int main(void) {
_syscall_memflag(&_bss_start, &_bss_end - &_bss_start, MEMFLAG_PRESENT);
void *init = tar_find(&_initrd, "init.elf");
if (!init) {
_klogf("couldn't find init.elf\n");
_syscall_exit(0);
}
void (*entry)(void*) = elf_partialexec(init);
if (entry) {
// TODO dynamically link initrd
entry(&_initrd);
} else {
_klogf("couldn't execute init.elf\n");
}
_syscall_exit(0);
}
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