kvm_proc.c

早期freebsd实现

		 * kvm_close() will free it again.
		 */
		kd->procbase = 0;
	}
	if (ISALIVE(kd)) {
		size = 0;
		mib[0] = CTL_KERN;
		mib[1] = KERN_PROC;
		mib[2] = op;
		mib[3] = arg;
		st = sysctl(mib, 4, NULL, &size, NULL, 0);
		if (st == -1) {
			_kvm_syserr(kd, kd->program, "kvm_getprocs");
			return (0);
		}
		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
		if (kd->procbase == 0)
			return (0);
		st = sysctl(mib, 4, kd->procbase, &size, NULL, 0);
		if (st == -1) {
			_kvm_syserr(kd, kd->program, "kvm_getprocs");
			return (0);
		}
		if (size % sizeof(struct kinfo_proc) != 0) {
			_kvm_err(kd, kd->program,
				"proc size mismatch (%d total, %d chunks)",
				size, sizeof(struct kinfo_proc));
			return (0);
		}
		nprocs = size / sizeof(struct kinfo_proc);
	} else {
		struct nlist nl[4], *p;

		nl[0].n_name = "_nprocs";
		nl[1].n_name = "_allproc";
		nl[2].n_name = "_zombproc";
		nl[3].n_name = 0;

		if (kvm_nlist(kd, nl) != 0) {
			for (p = nl; p->n_type != 0; ++p)
				;
			_kvm_err(kd, kd->program,
				 "%s: no such symbol", p->n_name);
			return (0);
		}
		if (KREAD(kd, nl[0].n_value, &nprocs)) {
			_kvm_err(kd, kd->program, "can't read nprocs");
			return (0);
		}
		size = nprocs * sizeof(struct kinfo_proc);
		kd->procbase = (struct kinfo_proc *)_kvm_malloc(kd, size);
		if (kd->procbase == 0)
			return (0);

		nprocs = kvm_deadprocs(kd, op, arg, nl[1].n_value,
				      nl[2].n_value, nprocs);
#ifdef notdef
		size = nprocs * sizeof(struct kinfo_proc);
		(void)realloc(kd->procbase, size);
#endif
	}
	*cnt = nprocs;
	return (kd->procbase);
}

void
_kvm_freeprocs(kd)
	kvm_t *kd;
{
	if (kd->procbase) {
		free(kd->procbase);
		kd->procbase = 0;
	}
}

void *
_kvm_realloc(kd, p, n)
	kvm_t *kd;
	void *p;
	size_t n;
{
	void *np = (void *)realloc(p, n);

	if (np == 0)
		_kvm_err(kd, kd->program, "out of memory");
	return (np);
}

#ifndef MAX
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#endif

/*
 * Read in an argument vector from the user address space of process p.
 * addr if the user-space base address of narg null-terminated contiguous 
 * strings.  This is used to read in both the command arguments and
 * environment strings.  Read at most maxcnt characters of strings.
 */
static char **
kvm_argv(kd, p, addr, narg, maxcnt)
	kvm_t *kd;
	struct proc *p;
	register u_long addr;
	register int narg;
	register int maxcnt;
{
	register char *cp;
	register int len, cc;
	register char **argv;

	/*
	 * Check that there aren't an unreasonable number of agruments,
	 * and that the address is in user space.
	 */
	if (narg > 512 || addr < VM_MIN_ADDRESS || addr >= VM_MAXUSER_ADDRESS)
		return (0);

	if (kd->argv == 0) {
		/*
		 * Try to avoid reallocs.
		 */
		kd->argc = MAX(narg + 1, 32);
		kd->argv = (char **)_kvm_malloc(kd, kd->argc * 
						sizeof(*kd->argv));
		if (kd->argv == 0)
			return (0);
	} else if (narg + 1 > kd->argc) {
		kd->argc = MAX(2 * kd->argc, narg + 1);
		kd->argv = (char **)_kvm_realloc(kd, kd->argv, kd->argc * 
						sizeof(*kd->argv));
		if (kd->argv == 0)
			return (0);
	}
	if (kd->argspc == 0) {
		kd->argspc = (char *)_kvm_malloc(kd, NBPG);
		if (kd->argspc == 0)
			return (0);
		kd->arglen = NBPG;
	}
	cp = kd->argspc;
	argv = kd->argv;
	*argv = cp;
	len = 0;
	/*
	 * Loop over pages, filling in the argument vector.
	 */
	while (addr < VM_MAXUSER_ADDRESS) {
		cc = NBPG - (addr & PGOFSET);
		if (maxcnt > 0 && cc > maxcnt - len)
			cc = maxcnt - len;;
		if (len + cc > kd->arglen) {
			register int off;
			register char **pp;
			register char *op = kd->argspc;

			kd->arglen *= 2;
			kd->argspc = (char *)_kvm_realloc(kd, kd->argspc,
							  kd->arglen);
			if (kd->argspc == 0)
				return (0);
			cp = &kd->argspc[len];
			/*
			 * Adjust argv pointers in case realloc moved
			 * the string space.
			 */
			off = kd->argspc - op;
			for (pp = kd->argv; pp < argv; ++pp)
				*pp += off;
		}
		if (kvm_uread(kd, p, addr, cp, cc) != cc)
			/* XXX */
			return (0);
		len += cc;
		addr += cc;

		if (maxcnt == 0 && len > 16 * NBPG)
			/* sanity */
			return (0);

		while (--cc >= 0) {
			if (*cp++ == 0) {
				if (--narg <= 0) {
					*++argv = 0;
					return (kd->argv);
				} else
					*++argv = cp;
			}
		}
		if (maxcnt > 0 && len >= maxcnt) {
			/*
			 * We're stopping prematurely.  Terminate the
			 * argv and current string.
			 */
			*++argv = 0;
			*cp = 0;
			return (kd->argv);
		}
	}
}

static void
ps_str_a(p, addr, n)
	struct ps_strings *p;
	u_long *addr;
	int *n;
{
	*addr = (u_long)p->ps_argvstr;
	*n = p->ps_nargvstr;
}

static void
ps_str_e(p, addr, n)
	struct ps_strings *p;
	u_long *addr;
	int *n;
{
	*addr = (u_long)p->ps_envstr;
	*n = p->ps_nenvstr;
}

/*
 * Determine if the proc indicated by p is still active.
 * This test is not 100% foolproof in theory, but chances of
 * being wrong are very low.
 */
static int
proc_verify(kd, kernp, p)
	kvm_t *kd;
	u_long kernp;
	const struct proc *p;
{
	struct proc kernproc;

	/*
	 * Just read in the whole proc.  It's not that big relative
	 * to the cost of the read system call.
	 */
	if (kvm_read(kd, kernp, (char *)&kernproc, sizeof(kernproc)) != 
	    sizeof(kernproc))
		return (0);
	return (p->p_pid == kernproc.p_pid &&
		(kernproc.p_stat != SZOMB || p->p_stat == SZOMB));
}

static char **
kvm_doargv(kd, kp, nchr, info)
	kvm_t *kd;
	const struct kinfo_proc *kp;
	int nchr;
	int (*info)(struct ps_strings*, u_long *, int *);
{
	register const struct proc *p = &kp->kp_proc;
	register char **ap;
	u_long addr;
	int cnt;
	struct ps_strings arginfo;

	/*
	 * Pointers are stored at the top of the user stack.
	 */
	if (p->p_stat == SZOMB || 
	    kvm_uread(kd, p, USRSTACK - sizeof(arginfo), (char *)&arginfo,
		      sizeof(arginfo)) != sizeof(arginfo))
		return (0);

	(*info)(&arginfo, &addr, &cnt);
	ap = kvm_argv(kd, p, addr, cnt, nchr);
	/*
	 * For live kernels, make sure this process didn't go away.
	 */
	if (ap != 0 && ISALIVE(kd) &&
	    !proc_verify(kd, (u_long)kp->kp_eproc.e_paddr, p))
		ap = 0;
	return (ap);
}

/*
 * Get the command args.  This code is now machine independent.
 */
char **
kvm_getargv(kd, kp, nchr)
	kvm_t *kd;
	const struct kinfo_proc *kp;
	int nchr;
{
	return (kvm_doargv(kd, kp, nchr, ps_str_a));
}

char **
kvm_getenvv(kd, kp, nchr)
	kvm_t *kd;
	const struct kinfo_proc *kp;
	int nchr;
{
	return (kvm_doargv(kd, kp, nchr, ps_str_e));
}

/*
 * Read from user space.  The user context is given by p.
 */
ssize_t
kvm_uread(kd, p, uva, buf, len)
	kvm_t *kd;
	register struct proc *p;
	register u_long uva;
	register char *buf;
	register size_t len;
{
	register char *cp;

	cp = buf;
	while (len > 0) {
		u_long pa;
		register int cc;
		
		cc = _kvm_uvatop(kd, p, uva, &pa);
		if (cc > 0) {
			if (cc > len)
				cc = len;
			errno = 0;
			if (lseek(kd->pmfd, (off_t)pa, 0) == -1 && errno != 0) {
				_kvm_err(kd, 0, "invalid address (%x)", uva);
				break;
			}
			cc = read(kd->pmfd, cp, cc);
			if (cc < 0) {
				_kvm_syserr(kd, 0, _PATH_MEM);
				break;
			} else if (cc < len) {
				_kvm_err(kd, kd->program, "short read");
				break;
			}
		} else if (ISALIVE(kd)) {
			/* try swap */
			register char *dp;
			int cnt;

			dp = kvm_readswap(kd, p, uva, &cnt);
			if (dp == 0) {
				_kvm_err(kd, 0, "invalid address (%x)", uva);
				return (0);
			}
			cc = MIN(cnt, len);
			bcopy(dp, cp, cc);
		} else
			break;
		cp += cc;
		uva += cc;
		len -= cc;
	}
	return (ssize_t)(cp - buf);
}