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#include "types.h"
#include "stat.h"
#include "param.h"
#include "mmu.h"
#include "proc.h"
#include "defs.h"
#include "x86.h"
#include "traps.h"
#include "syscall.h"
#include "spinlock.h"
#include "buf.h"
#include "fs.h"
#include "fsvar.h"
#include "elf.h"
#include "file.h"
#include "fcntl.h"
int
exec(char *path, char **argv)
{
uint sz, sp, p1, p2;
int i, nargs, argbytes, len;
struct inode *ip;
struct elfhdr elf;
struct proghdr ph;
char *mem;
char *s, *last;
sz = 0;
mem = 0;
if((ip = namei(path)) == 0)
return -1;
if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
goto bad;
if(elf.magic != ELF_MAGIC)
goto bad;
for(i = 0; i < elf.phnum; i++){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
sizeof(ph)) != sizeof(ph))
goto bad;
if(ph.type != ELF_PROG_LOAD)
continue;
if(ph.memsz < ph.filesz)
goto bad;
sz += ph.memsz;
}
sz += 4096 - (sz % 4096);
sz += 4096;
mem = kalloc(sz);
if(mem == 0)
goto bad;
memset(mem, 0, sz);
argbytes = 0;
for(i = 0; argv[i]; i++){
len = strlen(argv[i]);
argbytes += len + 1;
}
nargs = i;
// argn\0
// ...
// arg0\0
// 0
// ptr to argn
// ...
// 12: ptr to arg0
// 8: argv (points to ptr to arg0)
// 4: argc
// 0: fake return pc
sp = sz - argbytes - (nargs+1)*4 - 4 - 4 - 4;
*(uint*)(mem + sp) = 0xffffffff;
*(uint*)(mem + sp + 4) = nargs;
*(uint*)(mem + sp + 8) = (uint)(sp + 12);
p1 = sp + 12;
p2 = sp + 12 + (nargs + 1) * 4;
for(i = 0; i < nargs; i++){
len = strlen(argv[i]);
memmove(mem + p2, argv[i], len + 1);
*(uint*)(mem + p1) = p2;
p1 += 4;
p2 += len + 1;
}
*(uint*)(mem + p1) = 0;
// Save name for debugging.
for(last=s=path; *s; s++)
if(*s == '/')
last = s+1;
safestrcpy(cp->name, last, sizeof cp->name);
// commit to the new image.
kfree(cp->mem, cp->sz);
cp->sz = sz;
cp->mem = mem;
mem = 0;
for(i = 0; i < elf.phnum; i++){
if(readi(ip, (char*)&ph, elf.phoff + i * sizeof(ph),
sizeof(ph)) != sizeof(ph))
goto bad2;
if(ph.type != ELF_PROG_LOAD)
continue;
if(ph.va + ph.memsz > sz)
goto bad2;
if(readi(ip, cp->mem + ph.va, ph.offset, ph.filesz) != ph.filesz)
goto bad2;
memset(cp->mem + ph.va + ph.filesz, 0, ph.memsz - ph.filesz);
}
iput(ip);
cp->tf->eip = elf.entry;
cp->tf->esp = sp;
setupsegs(cp);
return 0;
bad:
if(mem)
kfree(mem, sz);
iput(ip);
return -1;
bad2:
iput(ip);
proc_exit();
return 0;
}
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