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