forked from Imagelibrary/rtems
53da07e436
It is now the responsibility of the read() and write() handler to update the offset field of the IO descriptor (rtems_libio_t). This change makes it possible to protect the IO descriptor from concurrent access by per file locks.
118 lines
2.6 KiB
C
118 lines
2.6 KiB
C
/*
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* readv() - POSIX 1003.1 - Read a Vector
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*
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* OpenGroup URL:
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*
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* http://www.opengroup.org/onlinepubs/009695399/functions/readv.html
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*
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* COPYRIGHT (c) 1989-2011.
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* On-Line Applications Research Corporation (OAR).
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*
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* The license and distribution terms for this file may be
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* found in the file LICENSE in this distribution or at
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* http://www.rtems.com/license/LICENSE.
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*/
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#if HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <sys/types.h>
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#include <sys/uio.h>
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#include <rtems/libio_.h>
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#include <rtems/seterr.h>
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ssize_t readv(
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int fd,
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const struct iovec *iov,
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int iovcnt
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)
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{
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ssize_t total;
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int v;
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int bytes;
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rtems_libio_t *iop;
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bool all_zeros;
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rtems_libio_check_fd( fd );
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iop = rtems_libio_iop( fd );
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rtems_libio_check_is_open( iop );
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rtems_libio_check_permissions_with_error( iop, LIBIO_FLAGS_READ, EBADF );
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/*
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* Argument validation on IO vector
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*/
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if ( !iov )
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rtems_set_errno_and_return_minus_one( EINVAL );
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if ( iovcnt <= 0 )
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rtems_set_errno_and_return_minus_one( EINVAL );
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if ( iovcnt > IOV_MAX )
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rtems_set_errno_and_return_minus_one( EINVAL );
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/*
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* OpenGroup says that you are supposed to return EINVAL if the
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* sum of the iov_len values in the iov array would overflow a
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* ssize_t.
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*
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* Also we would like to ensure that no IO is performed if there
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* are obvious errors in the iovec. So this extra loop ensures
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* that we do not do anything if there is an argument error.
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*/
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all_zeros = true;
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for ( total=0, v=0 ; v < iovcnt ; v++ ) {
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ssize_t old;
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/*
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* iov[v].iov_len cannot be less than 0 because size_t is unsigned.
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* So we only check for zero.
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*/
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if ( iov[v].iov_base == 0 )
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rtems_set_errno_and_return_minus_one( EINVAL );
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/* check for wrap */
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old = total;
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total += iov[v].iov_len;
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if ( total < old )
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rtems_set_errno_and_return_minus_one( EINVAL );
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if ( iov[v].iov_len )
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all_zeros = false;
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}
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/*
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* A readv with all zeros logically has no effect. Even though
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* OpenGroup didn't address this case as they did with writev(),
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* we will handle it the same way for symmetry.
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*/
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if ( all_zeros == true ) {
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return 0;
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}
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/*
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* Now process the readv().
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*/
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for ( total=0, v=0 ; v < iovcnt ; v++ ) {
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bytes = (*iop->pathinfo.handlers->read_h)(
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iop,
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iov[v].iov_base,
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iov[v].iov_len
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);
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if ( bytes < 0 )
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return -1;
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if ( bytes > 0 ) {
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total += bytes;
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}
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if (bytes != iov[ v ].iov_len)
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break;
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}
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return total;
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}
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