1 | /* |
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2 | * read() - POSIX 1003.1b 6.4.1 - Read From a File |
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3 | * |
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4 | * COPYRIGHT (c) 1989-1998. |
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5 | * On-Line Applications Research Corporation (OAR). |
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6 | * Copyright assigned to U.S. Government, 1994. |
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7 | * |
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8 | * The license and distribution terms for this file may be |
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9 | * found in the file LICENSE in this distribution or at |
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10 | * http://www.OARcorp.com/rtems/license.html. |
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11 | * |
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12 | * $Id$ |
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13 | */ |
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14 | |
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15 | #include "libio_.h" |
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16 | |
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17 | ssize_t read( |
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18 | int fd, |
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19 | void *buffer, |
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20 | size_t count |
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21 | ) |
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22 | { |
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23 | int rc; /* XXX change to a size_t when prototype is fixed */ |
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24 | rtems_libio_t *iop; |
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25 | |
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26 | rtems_libio_check_fd( fd ); |
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27 | iop = rtems_libio_iop( fd ); |
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28 | rtems_libio_check_buffer( buffer ); |
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29 | rtems_libio_check_count( count ); |
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30 | rtems_libio_check_permissions( iop, LIBIO_FLAGS_READ ); |
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31 | |
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32 | /* |
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33 | * If this file descriptor is mapped to an external set of handlers, |
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34 | * then pass the request on to them. |
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35 | */ |
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36 | |
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37 | if ( iop->flags & LIBIO_FLAGS_HANDLER_MASK ) { |
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38 | rtems_libio_read_t fp; |
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39 | |
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40 | fp = rtems_libio_handlers[ |
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41 | (iop->flags >> LIBIO_FLAGS_HANDLER_SHIFT) - 1].read; |
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42 | if ( fp == NULL ) |
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43 | set_errno_and_return_minus_one( EBADF ); |
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44 | |
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45 | return (*fp)( fd, buffer, count ); |
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46 | } |
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47 | |
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48 | /* |
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49 | * Now process the read(). |
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50 | */ |
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51 | |
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52 | if ( !iop->handlers->read ) |
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53 | set_errno_and_return_minus_one( ENOTSUP ); |
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54 | |
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55 | rc = (*iop->handlers->read)( iop, buffer, count ); |
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56 | |
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57 | if ( rc > 0 ) |
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58 | iop->offset += rc; |
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59 | |
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60 | return rc; |
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61 | } |
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62 | |
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63 | /* |
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64 | * _read_r |
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65 | * |
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66 | * This is the Newlib dependent reentrant version of read(). |
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67 | */ |
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68 | |
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69 | #if defined(RTEMS_NEWLIB) |
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70 | |
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71 | #include <reent.h> |
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72 | |
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73 | _ssize_t _read_r( |
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74 | struct _reent *ptr, |
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75 | int fd, |
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76 | void *buf, |
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77 | size_t nbytes |
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78 | ) |
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79 | { |
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80 | return read( fd, buf, nbytes ); |
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81 | } |
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82 | #endif |
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