/*	$NetBSD: procfs_cmdline.c,v 1.27 2008/04/28 20:24:08 martin Exp $	*/

/*
 * Copyright (c) 1999 Jaromir Dolecek <dolecek@ics.muni.cz>
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Jaromir Dolecek.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: procfs_cmdline.c,v 1.27 2008/04/28 20:24:08 martin Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/syslimits.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/malloc.h>
#include <miscfs/procfs/procfs.h>

#include <uvm/uvm_extern.h>

/*
 * code for returning process's command line arguments
 */
int
procfs_docmdline(
    struct lwp *curl,
    struct proc *p,
    struct pfsnode *pfs,
    struct uio *uio
)
{
	struct ps_strings pss;
	int count, error;
	size_t i, len, xlen, upper_bound;
	struct uio auio;
	struct iovec aiov;
	struct vmspace *vm;
	vaddr_t argv;
	char *arg;

	/* Don't allow writing. */
	if (uio->uio_rw != UIO_READ)
		return (EOPNOTSUPP);

	/*
	 * Allocate a temporary buffer to hold the arguments.
	 */
	arg = malloc(PAGE_SIZE, M_TEMP, M_WAITOK);

	/*
	 * Zombies don't have a stack, so we can't read their psstrings.
	 * System processes also don't have a user stack.  This is what
	 * ps(1) would display.
	 */
	if (P_ZOMBIE(p) || (p->p_flag & PK_SYSTEM) != 0) {
		len = snprintf(arg, PAGE_SIZE, "(%s)", p->p_comm) + 1;
		error = uiomove_frombuf(arg, len, uio);
		free(arg, M_TEMP);
		return (error);
	}

	/*
	 * NOTE: Don't bother doing a process_checkioperm() here
	 * because the psstrings info is available by using ps(1),
	 * so it's not like there's anything to protect here.
	 */

	/*
	 * Lock the process down in memory.
	 */
	if ((error = proc_vmspace_getref(p, &vm)) != 0) {
		free(arg, M_TEMP);
		return (error);
	}

	/*
	 * Read in the ps_strings structure.
	 */
	aiov.iov_base = &pss;
	aiov.iov_len = sizeof(pss);
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = (vaddr_t)p->p_psstr;
	auio.uio_resid = sizeof(pss);
	auio.uio_rw = UIO_READ;
	UIO_SETUP_SYSSPACE(&auio);
	error = uvm_io(&vm->vm_map, &auio);
	if (error)
		goto bad;

	/*
	 * Now read the address of the argument vector.
	 */
	aiov.iov_base = &argv;
	aiov.iov_len = sizeof(argv);
	auio.uio_iov = &aiov;
	auio.uio_iovcnt = 1;
	auio.uio_offset = (vaddr_t)pss.ps_argvstr;
	auio.uio_resid = sizeof(argv);
	auio.uio_rw = UIO_READ;
	UIO_SETUP_SYSSPACE(&auio);
	error = uvm_io(&vm->vm_map, &auio);
	if (error)
		goto bad;

	/*
	 * Now copy in the actual argument vector, one page at a time,
	 * since we don't know how long the vector is (though, we do
	 * know how many NUL-terminated strings are in the vector).
	 */
	len = 0;
	count = pss.ps_nargvstr;
	upper_bound = round_page(uio->uio_offset + uio->uio_resid);
	for (; count && len < upper_bound; len += xlen) {
		aiov.iov_base = arg;
		aiov.iov_len = PAGE_SIZE;
		auio.uio_iov = &aiov;
		auio.uio_iovcnt = 1;
		auio.uio_offset = argv + len;
		xlen = PAGE_SIZE - ((argv + len) & PAGE_MASK);
		auio.uio_resid = xlen;
		auio.uio_rw = UIO_READ;
		UIO_SETUP_SYSSPACE(&auio);
		error = uvm_io(&vm->vm_map, &auio);
		if (error)
			goto bad;

		for (i = 0; i < xlen && count != 0; i++) {
			if (arg[i] == '\0')
				count--;	/* one full string */
		}

		if (len + i > uio->uio_offset) {
			/* Have data in this page, copy it out */
			error = uiomove(arg + uio->uio_offset - len,
			    i + len - uio->uio_offset, uio);
			if (error || uio->uio_resid <= 0)
				break;
		}
	}

 bad:
	/*
	 * Release the process.
	 */
	uvmspace_free(vm);

	free(arg, M_TEMP);
	return (error);
}