/*      $NetBSD: sys_generic.c,v 1.134 2022/07/10 23:12:12 riastradh Exp $      */

/*-
* Copyright (c) 2007, 2008, 2009 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Andrew Doran.
*
* 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.
*/

/*
* Copyright (c) 1982, 1986, 1989, 1993
*      The Regents of the University of California.  All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
*    may be used to endorse or promote products derived from this software
*    without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
*      @(#)sys_generic.c       8.9 (Berkeley) 2/14/95
*/

/*
* System calls relating to files.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: sys_generic.c,v 1.134 2022/07/10 23:12:12 riastradh Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/filedesc.h>
#include <sys/ioctl.h>
#include <sys/file.h>
#include <sys/proc.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/uio.h>
#include <sys/kernel.h>
#include <sys/stat.h>
#include <sys/kmem.h>
#include <sys/poll.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <sys/ktrace.h>
#include <sys/atomic.h>
#include <sys/disklabel.h>

/*
* Read system call.
*/
/* ARGSUSED */
int
sys_read(struct lwp *l, const struct sys_read_args *uap, register_t *retval)
{
       /* {
               syscallarg(int)         fd;
               syscallarg(void *)      buf;
               syscallarg(size_t)      nbyte;
       } */
       file_t *fp;
       int fd;

       fd = SCARG(uap, fd);

       if ((fp = fd_getfile(fd)) == NULL)
               return (EBADF);

       if ((fp->f_flag & FREAD) == 0) {
               fd_putfile(fd);
               return (EBADF);
       }

       /* dofileread() will unuse the descriptor for us */
       return (dofileread(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
           &fp->f_offset, FOF_UPDATE_OFFSET, retval));
}

int
dofileread(int fd, struct file *fp, void *buf, size_t nbyte,
       off_t *offset, int flags, register_t *retval)
{
       struct iovec aiov;
       struct uio auio;
       size_t cnt;
       int error;
       lwp_t *l;

       l = curlwp;

       aiov.iov_base = (void *)buf;
       aiov.iov_len = nbyte;
       auio.uio_iov = &aiov;
       auio.uio_iovcnt = 1;
       auio.uio_resid = nbyte;
       auio.uio_rw = UIO_READ;
       auio.uio_vmspace = l->l_proc->p_vmspace;

       /*
        * Reads return ssize_t because -1 is returned on error.  Therefore
        * we must restrict the length to SSIZE_MAX to avoid garbage return
        * values.
        */
       if (auio.uio_resid > SSIZE_MAX) {
               error = EINVAL;
               goto out;
       }

       cnt = auio.uio_resid;
       error = (*fp->f_ops->fo_read)(fp, offset, &auio, fp->f_cred, flags);
       if (error)
               if (auio.uio_resid != cnt && (error == ERESTART ||
                   error == EINTR || error == EWOULDBLOCK))
                       error = 0;
       cnt -= auio.uio_resid;
       ktrgenio(fd, UIO_READ, buf, cnt, error);
       *retval = cnt;
out:
       fd_putfile(fd);
       return (error);
}

/*
* Scatter read system call.
*/
int
sys_readv(struct lwp *l, const struct sys_readv_args *uap, register_t *retval)
{
       /* {
               syscallarg(int)                         fd;
               syscallarg(const struct iovec *)        iovp;
               syscallarg(int)                         iovcnt;
       } */

       return do_filereadv(SCARG(uap, fd), SCARG(uap, iovp),
           SCARG(uap, iovcnt), NULL, FOF_UPDATE_OFFSET, retval);
}

int
do_filereadv(int fd, const struct iovec *iovp, int iovcnt,
   off_t *offset, int flags, register_t *retval)
{
       struct uio      auio;
       struct iovec    *iov, *needfree = NULL, aiov[UIO_SMALLIOV];
       int             i, error;
       size_t          cnt;
       u_int           iovlen;
       struct file     *fp;
       struct iovec    *ktriov = NULL;

       if (iovcnt == 0)
               return EINVAL;

       if ((fp = fd_getfile(fd)) == NULL)
               return EBADF;

       if ((fp->f_flag & FREAD) == 0) {
               fd_putfile(fd);
               return EBADF;
       }

       if (offset == NULL)
               offset = &fp->f_offset;
       else {
               /*
                * Caller must not specify &fp->f_offset -- we can't
                * safely dereference it for the call to fo_seek
                * without holding some underlying object lock.
                */
               KASSERT(offset != &fp->f_offset);
               if (fp->f_ops->fo_seek == NULL) {
                       error = ESPIPE;
                       goto out;
               }
               error = (*fp->f_ops->fo_seek)(fp, *offset, SEEK_SET, NULL,
                   0);
               if (error != 0)
                       goto out;
       }

       iovlen = iovcnt * sizeof(struct iovec);
       if (flags & FOF_IOV_SYSSPACE)
               iov = __UNCONST(iovp);
       else {
               iov = aiov;
               if ((u_int)iovcnt > UIO_SMALLIOV) {
                       if ((u_int)iovcnt > IOV_MAX) {
                               error = EINVAL;
                               goto out;
                       }
                       iov = kmem_alloc(iovlen, KM_SLEEP);
                       needfree = iov;
               }
               error = copyin(iovp, iov, iovlen);
               if (error)
                       goto done;
       }

       auio.uio_iov = iov;
       auio.uio_iovcnt = iovcnt;
       auio.uio_rw = UIO_READ;
       auio.uio_vmspace = curproc->p_vmspace;

       auio.uio_resid = 0;
       for (i = 0; i < iovcnt; i++, iov++) {
               auio.uio_resid += iov->iov_len;
               /*
                * Reads return ssize_t because -1 is returned on error.
                * Therefore we must restrict the length to SSIZE_MAX to
                * avoid garbage return values.
                */
               if (iov->iov_len > SSIZE_MAX ||
                   auio.uio_resid > SSIZE_MAX - iov->iov_len) {
                       error = EINVAL;
                       goto done;
               }
       }

       /*
        * if tracing, save a copy of iovec
        */
       if (ktrpoint(KTR_GENIO))  {
               ktriov = kmem_alloc(iovlen, KM_SLEEP);
               memcpy(ktriov, auio.uio_iov, iovlen);
       }

       cnt = auio.uio_resid;
       error = (*fp->f_ops->fo_read)(fp, offset, &auio, fp->f_cred, flags);
       if (error)
               if (auio.uio_resid != cnt && (error == ERESTART ||
                   error == EINTR || error == EWOULDBLOCK))
                       error = 0;
       cnt -= auio.uio_resid;
       *retval = cnt;

       if (ktriov != NULL) {
               ktrgeniov(fd, UIO_READ, ktriov, cnt, error);
               kmem_free(ktriov, iovlen);
       }

done:
       if (needfree)
               kmem_free(needfree, iovlen);
out:
       fd_putfile(fd);
       return (error);
}

/*
* Write system call
*/
int
sys_write(struct lwp *l, const struct sys_write_args *uap, register_t *retval)
{
       /* {
               syscallarg(int)                 fd;
               syscallarg(const void *)        buf;
               syscallarg(size_t)              nbyte;
       } */
       file_t *fp;
       int fd;

       fd = SCARG(uap, fd);

       if ((fp = fd_getfile(fd)) == NULL)
               return (EBADF);

       if ((fp->f_flag & FWRITE) == 0) {
               fd_putfile(fd);
               return (EBADF);
       }

       /* dofilewrite() will unuse the descriptor for us */
       return (dofilewrite(fd, fp, SCARG(uap, buf), SCARG(uap, nbyte),
           &fp->f_offset, FOF_UPDATE_OFFSET, retval));
}

int
dofilewrite(int fd, struct file *fp, const void *buf,
       size_t nbyte, off_t *offset, int flags, register_t *retval)
{
       struct iovec aiov;
       struct uio auio;
       size_t cnt;
       int error;

       aiov.iov_base = __UNCONST(buf);         /* XXXUNCONST kills const */
       aiov.iov_len = nbyte;
       auio.uio_iov = &aiov;
       auio.uio_iovcnt = 1;
       auio.uio_resid = nbyte;
       auio.uio_rw = UIO_WRITE;
       auio.uio_vmspace = curproc->p_vmspace;

       /*
        * Writes return ssize_t because -1 is returned on error.  Therefore
        * we must restrict the length to SSIZE_MAX to avoid garbage return
        * values.
        */
       if (auio.uio_resid > SSIZE_MAX) {
               error = EINVAL;
               goto out;
       }

       cnt = auio.uio_resid;
       error = (*fp->f_ops->fo_write)(fp, offset, &auio, fp->f_cred, flags);
       if (error) {
               if (auio.uio_resid != cnt && (error == ERESTART ||
                   error == EINTR || error == EWOULDBLOCK))
                       error = 0;
               if (error == EPIPE && !(fp->f_flag & FNOSIGPIPE)) {
                       mutex_enter(&proc_lock);
                       psignal(curproc, SIGPIPE);
                       mutex_exit(&proc_lock);
               }
       }
       cnt -= auio.uio_resid;
       ktrgenio(fd, UIO_WRITE, buf, cnt, error);
       *retval = cnt;
out:
       fd_putfile(fd);
       return (error);
}

/*
* Gather write system call
*/
int
sys_writev(struct lwp *l, const struct sys_writev_args *uap, register_t *retval)
{
       /* {
               syscallarg(int)                         fd;
               syscallarg(const struct iovec *)        iovp;
               syscallarg(int)                         iovcnt;
       } */

       return do_filewritev(SCARG(uap, fd), SCARG(uap, iovp),
           SCARG(uap, iovcnt), NULL, FOF_UPDATE_OFFSET, retval);
}

int
do_filewritev(int fd, const struct iovec *iovp, int iovcnt,
   off_t *offset, int flags, register_t *retval)
{
       struct uio      auio;
       struct iovec    *iov, *needfree = NULL, aiov[UIO_SMALLIOV];
       int             i, error;
       size_t          cnt;
       u_int           iovlen;
       struct file     *fp;
       struct iovec    *ktriov = NULL;

       if (iovcnt == 0)
               return EINVAL;

       if ((fp = fd_getfile(fd)) == NULL)
               return EBADF;

       if ((fp->f_flag & FWRITE) == 0) {
               fd_putfile(fd);
               return EBADF;
       }

       if (offset == NULL)
               offset = &fp->f_offset;
       else {
               /*
                * Caller must not specify &fp->f_offset -- we can't
                * safely dereference it for the call to fo_seek
                * without holding some underlying object lock.
                */
               KASSERT(offset != &fp->f_offset);
               if (fp->f_ops->fo_seek == NULL) {
                       error = ESPIPE;
                       goto out;
               }
               error = (*fp->f_ops->fo_seek)(fp, *offset, SEEK_SET, NULL,
                   0);
               if (error != 0)
                       goto out;
       }

       iovlen = iovcnt * sizeof(struct iovec);
       if (flags & FOF_IOV_SYSSPACE)
               iov = __UNCONST(iovp);
       else {
               iov = aiov;
               if ((u_int)iovcnt > UIO_SMALLIOV) {
                       if ((u_int)iovcnt > IOV_MAX) {
                               error = EINVAL;
                               goto out;
                       }
                       iov = kmem_alloc(iovlen, KM_SLEEP);
                       needfree = iov;
               }
               error = copyin(iovp, iov, iovlen);
               if (error)
                       goto done;
       }

       auio.uio_iov = iov;
       auio.uio_iovcnt = iovcnt;
       auio.uio_rw = UIO_WRITE;
       auio.uio_vmspace = curproc->p_vmspace;

       auio.uio_resid = 0;
       for (i = 0; i < iovcnt; i++, iov++) {
               auio.uio_resid += iov->iov_len;
               /*
                * Writes return ssize_t because -1 is returned on error.
                * Therefore we must restrict the length to SSIZE_MAX to
                * avoid garbage return values.
                */
               if (iov->iov_len > SSIZE_MAX ||
                   auio.uio_resid > SSIZE_MAX - iov->iov_len) {
                       error = EINVAL;
                       goto done;
               }
       }

       /*
        * if tracing, save a copy of iovec
        */
       if (ktrpoint(KTR_GENIO))  {
               ktriov = kmem_alloc(iovlen, KM_SLEEP);
               memcpy(ktriov, auio.uio_iov, iovlen);
       }

       cnt = auio.uio_resid;
       error = (*fp->f_ops->fo_write)(fp, offset, &auio, fp->f_cred, flags);
       if (error) {
               if (auio.uio_resid != cnt && (error == ERESTART ||
                   error == EINTR || error == EWOULDBLOCK))
                       error = 0;
               if (error == EPIPE && !(fp->f_flag & FNOSIGPIPE)) {
                       mutex_enter(&proc_lock);
                       psignal(curproc, SIGPIPE);
                       mutex_exit(&proc_lock);
               }
       }
       cnt -= auio.uio_resid;
       *retval = cnt;

       if (ktriov != NULL) {
               ktrgeniov(fd, UIO_WRITE, ktriov, cnt, error);
               kmem_free(ktriov, iovlen);
       }

done:
       if (needfree)
               kmem_free(needfree, iovlen);
out:
       fd_putfile(fd);
       return (error);
}

/*
* Ioctl system call
*/
/* ARGSUSED */
int
sys_ioctl(struct lwp *l, const struct sys_ioctl_args *uap, register_t *retval)
{
       /* {
               syscallarg(int)         fd;
               syscallarg(u_long)      com;
               syscallarg(void *)      data;
       } */
       struct file     *fp;
       proc_t          *p;
       u_long          com;
       int             error;
       size_t          size, alloc_size;
       void            *data, *memp;
#define STK_PARAMS      128
       u_long          stkbuf[STK_PARAMS/sizeof(u_long)];
#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
       size_t          zero_last = 0;
#define zero_size(SZ)   ((SZ)+zero_last)
#else
#define zero_size(SZ)   (SZ)
#endif

       memp = NULL;
       alloc_size = 0;
       error = 0;
       p = l->l_proc;

       if ((fp = fd_getfile(SCARG(uap, fd))) == NULL)
               return (EBADF);

       if ((fp->f_flag & (FREAD | FWRITE)) == 0) {
               error = EBADF;
               com = 0;
               goto out;
       }

       switch (com = SCARG(uap, com)) {
       case FIONCLEX:
       case FIOCLEX:
               fd_set_exclose(l, SCARG(uap, fd), com == FIOCLEX);
               goto out;
       }

       /*
        * Interpret high order word to find amount of data to be
        * copied to/from the user's address space.
        */
       size = IOCPARM_LEN(com);
       alloc_size = size;

       /*
        * The disklabel is now padded to a multiple of 8 bytes however the old
        * disklabel on 32bit platforms wasn't.  This leaves a difference in
        * size of 4 bytes between the two but are otherwise identical.
        * To deal with this, we allocate enough space for the new disklabel
        * but only copyin/out the smaller amount.
        */
       if (IOCGROUP(com) == 'd') {
#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
               u_long ocom = com;
#endif
               u_long ncom = com ^ (DIOCGDINFO ^ DIOCGDINFO32);

#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
       /*
        * Userland might use struct disklabel that is bigger than the
        * the kernel version (historic accident) - alloc userland
        * size and zero unused part on copyout.
        */
#define DISKLABELLENDIFF        (sizeof(struct partition)       \
                                      *(__TMPBIGMAXPARTITIONS-MAXPARTITIONS))
#define IOCFIXUP(NIOC)  ((NIOC&~(IOCPARM_MASK<<IOCPARM_SHIFT))  | \
                          (IOCPARM_LEN(NIOC)-DISKLABELLENDIFF)<<IOCPARM_SHIFT)

               switch (IOCFIXUP(ocom)) {
               case DIOCGDINFO:
               case DIOCWDINFO:
               case DIOCSDINFO:
               case DIOCGDEFLABEL:
                       com = ncom = IOCFIXUP(ocom);
                       zero_last = DISKLABELLENDIFF;
                       size -= DISKLABELLENDIFF;
                       goto done;
               }
#endif

               switch (ncom) {
               case DIOCGDINFO:
               case DIOCWDINFO:
               case DIOCSDINFO:
               case DIOCGDEFLABEL:
                       com = ncom;
                       if (IOCPARM_LEN(DIOCGDINFO32) < IOCPARM_LEN(DIOCGDINFO))
                               alloc_size = IOCPARM_LEN(DIOCGDINFO);
                       break;
               }
#if  __TMPBIGMAXPARTITIONS > MAXPARTITIONS
               done: ;
#endif
       }
       if (size > IOCPARM_MAX) {
               error = ENOTTY;
               goto out;
       }
       memp = NULL;
       if ((com >> IOCPARM_SHIFT) == 0)  {
               /* UNIX-style ioctl. */
               data = SCARG(uap, data);
       } else {
               if (alloc_size > sizeof(stkbuf)) {
                       memp = kmem_alloc(alloc_size, KM_SLEEP);
                       data = memp;
               } else {
                       data = (void *)stkbuf;
               }
               if (com&IOC_IN) {
                       if (size) {
                               error = copyin(SCARG(uap, data), data, size);
                               if (error) {
                                       goto out;
                               }
                               /*
                                * The data between size and alloc_size has
                                * not been overwritten.  It shouldn't matter
                                * but let's clear that anyway.
                                */
                               if (__predict_false(size < alloc_size)) {
                                       memset((char *)data+size, 0,
                                           alloc_size - size);
                               }
                               ktrgenio(SCARG(uap, fd), UIO_WRITE,
                                   SCARG(uap, data), size, 0);
                       } else {
                               *(void **)data = SCARG(uap, data);
                       }
               } else if ((com&IOC_OUT) && size) {
                       /*
                        * Zero the buffer so the user always
                        * gets back something deterministic.
                        */
                       memset(data, 0, zero_size(size));
               } else if (com&IOC_VOID) {
                       *(void **)data = SCARG(uap, data);
               }
       }

       switch (com) {

       case FIONBIO:
               /* XXX Code block is not atomic */
               if (*(int *)data != 0)
                       atomic_or_uint(&fp->f_flag, FNONBLOCK);
               else
                       atomic_and_uint(&fp->f_flag, ~FNONBLOCK);
               error = (*fp->f_ops->fo_ioctl)(fp, FIONBIO, data);
               break;

       case FIOASYNC:
               /* XXX Code block is not atomic */
               if (*(int *)data != 0)
                       atomic_or_uint(&fp->f_flag, FASYNC);
               else
                       atomic_and_uint(&fp->f_flag, ~FASYNC);
               error = (*fp->f_ops->fo_ioctl)(fp, FIOASYNC, data);
               break;

       default:
               error = (*fp->f_ops->fo_ioctl)(fp, com, data);
               /*
                * Copy any data to user, size was
                * already set and checked above.
                */
               if (error == 0 && (com&IOC_OUT) && size) {
                       error = copyout(data, SCARG(uap, data),
                           zero_size(size));
                       ktrgenio(SCARG(uap, fd), UIO_READ, SCARG(uap, data),
                           size, error);
               }
               break;
       }
out:
       if (memp)
               kmem_free(memp, alloc_size);
       fd_putfile(SCARG(uap, fd));
       switch (error) {
       case -1:
               printf("sys_ioctl: _IO%s%s('%c', %lu, %lu) returned -1: "
                   "pid=%d comm=%s\n",
                   (com & IOC_IN) ? "W" : "", (com & IOC_OUT) ? "R" : "",
                   (char)IOCGROUP(com), (com & 0xff), IOCPARM_LEN(com),
                   p->p_pid, p->p_comm);
               /* FALLTHROUGH */
       case EPASSTHROUGH:
               error = ENOTTY;
               /* FALLTHROUGH */
       default:
               return (error);
       }
}

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