143 lines
3.5 KiB
C
143 lines
3.5 KiB
C
#include "types.h"
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#include "param.h"
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#include "memlayout.h"
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#include "mmu.h"
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#include "proc.h"
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#include "defs.h"
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#include "x86.h"
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#include "elf.h"
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void cleanupexec(pde_t * pgdir, struct inode *ip) {
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if (pgdir) {
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freevm(pgdir);
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}
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if (ip) {
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iunlockput(ip);
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end_op();
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}
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}
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int exec(char *path, char **argv) {
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char *s, *last;
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int i, off;
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uint argc, sz, sp, ustack[3 + MAXARG + 1];
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struct elfhdr elf;
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struct inode *ip;
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struct proghdr ph;
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pde_t *pgdir, *oldpgdir;
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struct proc *curproc = myproc();
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begin_op();
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if ((ip = namei(path)) == 0) {
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end_op();
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cprintf("exec: fail\n");
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return -1;
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}
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ilock(ip);
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pgdir = 0;
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// Check ELF header
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if (readi(ip, (char*)&elf, 0, sizeof(elf)) != sizeof(elf)) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if (elf.magic != ELF_MAGIC) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if ((pgdir = setupkvm()) == 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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// Load program into memory.
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sz = 0;
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for (i = 0, off = elf.phoff; i < elf.phnum; i++, off += sizeof(ph)) {
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if (readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph)) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if (ph.type != ELF_PROG_LOAD) {
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continue;
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}
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if (ph.memsz < ph.filesz) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if (ph.vaddr + ph.memsz < ph.vaddr) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if ((sz = allocuvm(pgdir, sz, ph.vaddr + ph.memsz)) == 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if (ph.vaddr % PGSIZE != 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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if (loaduvm(pgdir, (char*)ph.vaddr, ip, ph.off, ph.filesz) < 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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}
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iunlockput(ip);
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end_op();
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ip = 0;
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// Allocate two pages at the next page boundary.
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// Make the first inaccessible. Use the second as the user stack.
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sz = PGROUNDUP(sz);
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if ((sz = allocuvm(pgdir, sz, sz + 2 * PGSIZE)) == 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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clearpteu(pgdir, (char*)(sz - 2 * PGSIZE));
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sp = sz;
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// Push argument strings, prepare rest of stack in ustack.
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for (argc = 0; argv[argc]; argc++) {
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if (argc >= MAXARG) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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sp = (sp - (strlen(argv[argc]) + 1)) & ~3;
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if (copyout(pgdir, sp, argv[argc], strlen(argv[argc]) + 1) < 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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ustack[3 + argc] = sp;
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}
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ustack[3 + argc] = 0;
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ustack[0] = 0xffffffff; // fake return PC
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ustack[1] = argc;
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ustack[2] = sp - (argc + 1) * 4; // argv pointer
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sp -= (3 + argc + 1) * 4;
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if (copyout(pgdir, sp, ustack, (3 + argc + 1) * 4) < 0) {
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cleanupexec(pgdir, ip);
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return -1;
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}
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// Save program name for debugging.
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for (last = s = path; *s; s++) {
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if (*s == '/') {
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last = s + 1;
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}
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}
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safestrcpy(curproc->name, last, sizeof(curproc->name));
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// Commit to the user image.
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oldpgdir = curproc->pgdir;
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curproc->pgdir = pgdir;
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curproc->sz = sz;
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curproc->tf->eip = elf.entry; // main
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curproc->tf->esp = sp;
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switchuvm(curproc);
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freevm(oldpgdir);
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return 0;
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}
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