1 | /** |
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2 | * @file |
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3 | * |
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4 | * @brief FIFO/Pipe Support |
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5 | * @ingroup FIFO_PIPE |
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6 | */ |
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7 | |
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8 | /* |
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9 | * Author: Wei Shen <cquark@gmail.com> |
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10 | * |
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11 | * The license and distribution terms for this file may be |
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12 | * found in the file LICENSE in this distribution or at |
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13 | * http://www.rtems.org/license/LICENSE. |
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14 | */ |
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15 | |
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16 | |
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17 | #if HAVE_CONFIG_H |
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18 | #include "config.h" |
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19 | #endif |
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20 | |
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21 | #include <sys/param.h> |
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22 | #include <errno.h> |
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23 | #include <stdlib.h> |
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24 | #include <string.h> |
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25 | |
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26 | #include <rtems.h> |
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27 | #include <rtems/libio_.h> |
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28 | #include <rtems/rtems/barrierimpl.h> |
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29 | #include <rtems/score/statesimpl.h> |
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30 | |
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31 | #include "pipe.h" |
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32 | |
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33 | #define LIBIO_ACCMODE(_iop) ((_iop)->flags & LIBIO_FLAGS_READ_WRITE) |
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34 | #define LIBIO_NODELAY(_iop) ((_iop)->flags & LIBIO_FLAGS_NO_DELAY) |
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35 | |
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36 | static rtems_id pipe_semaphore = RTEMS_ID_NONE; |
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37 | |
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38 | |
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39 | #define PIPE_EMPTY(_pipe) (_pipe->Length == 0) |
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40 | #define PIPE_FULL(_pipe) (_pipe->Length == _pipe->Size) |
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41 | #define PIPE_SPACE(_pipe) (_pipe->Size - _pipe->Length) |
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42 | #define PIPE_WSTART(_pipe) ((_pipe->Start + _pipe->Length) % _pipe->Size) |
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43 | |
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44 | #define PIPE_LOCK(_pipe) \ |
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45 | ( rtems_semaphore_obtain(_pipe->Semaphore, RTEMS_WAIT, RTEMS_NO_TIMEOUT) \ |
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46 | == RTEMS_SUCCESSFUL ) |
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47 | |
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48 | #define PIPE_UNLOCK(_pipe) rtems_semaphore_release(_pipe->Semaphore) |
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49 | |
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50 | #define PIPE_READWAIT(_pipe) \ |
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51 | ( rtems_barrier_wait(_pipe->readBarrier, RTEMS_NO_TIMEOUT) \ |
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52 | == RTEMS_SUCCESSFUL) |
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53 | |
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54 | #define PIPE_WRITEWAIT(_pipe) \ |
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55 | ( rtems_barrier_wait(_pipe->writeBarrier, RTEMS_NO_TIMEOUT) \ |
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56 | == RTEMS_SUCCESSFUL) |
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57 | |
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58 | #define PIPE_WAKEUPREADERS(_pipe) \ |
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59 | do {uint32_t n; rtems_barrier_release(_pipe->readBarrier, &n); } while(0) |
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60 | |
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61 | #define PIPE_WAKEUPWRITERS(_pipe) \ |
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62 | do {uint32_t n; rtems_barrier_release(_pipe->writeBarrier, &n); } while(0) |
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63 | |
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64 | /* |
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65 | * Alloc pipe control structure, buffer, and resources. |
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66 | * Called with pipe_semaphore held. |
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67 | */ |
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68 | static int pipe_alloc( |
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69 | pipe_control_t **pipep |
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70 | ) |
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71 | { |
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72 | static char c = 'a'; |
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73 | pipe_control_t *pipe; |
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74 | int err = -ENOMEM; |
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75 | |
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76 | pipe = malloc(sizeof(pipe_control_t)); |
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77 | if (pipe == NULL) |
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78 | return err; |
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79 | memset(pipe, 0, sizeof(pipe_control_t)); |
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80 | |
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81 | pipe->Size = PIPE_BUF; |
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82 | pipe->Buffer = malloc(pipe->Size); |
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83 | if (! pipe->Buffer) |
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84 | goto err_buf; |
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85 | |
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86 | err = -ENOMEM; |
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87 | |
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88 | if (rtems_barrier_create( |
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89 | rtems_build_name ('P', 'I', 'r', c), |
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90 | RTEMS_BARRIER_MANUAL_RELEASE, 0, |
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91 | &pipe->readBarrier) != RTEMS_SUCCESSFUL) |
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92 | goto err_rbar; |
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93 | if (rtems_barrier_create( |
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94 | rtems_build_name ('P', 'I', 'w', c), |
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95 | RTEMS_BARRIER_MANUAL_RELEASE, 0, |
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96 | &pipe->writeBarrier) != RTEMS_SUCCESSFUL) |
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97 | goto err_wbar; |
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98 | if (rtems_semaphore_create( |
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99 | rtems_build_name ('P', 'I', 's', c), 1, |
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100 | RTEMS_BINARY_SEMAPHORE | RTEMS_PRIORITY | RTEMS_INHERIT_PRIORITY, |
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101 | 0, &pipe->Semaphore) != RTEMS_SUCCESSFUL) |
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102 | goto err_sem; |
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103 | |
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104 | *pipep = pipe; |
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105 | if (c ++ == 'z') |
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106 | c = 'a'; |
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107 | return 0; |
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108 | |
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109 | err_sem: |
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110 | rtems_barrier_delete(pipe->writeBarrier); |
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111 | err_wbar: |
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112 | rtems_barrier_delete(pipe->readBarrier); |
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113 | err_rbar: |
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114 | free(pipe->Buffer); |
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115 | err_buf: |
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116 | free(pipe); |
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117 | return err; |
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118 | } |
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119 | |
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120 | /* Called with pipe_semaphore held. */ |
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121 | static inline void pipe_free( |
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122 | pipe_control_t *pipe |
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123 | ) |
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124 | { |
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125 | rtems_barrier_delete(pipe->readBarrier); |
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126 | rtems_barrier_delete(pipe->writeBarrier); |
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127 | rtems_semaphore_delete(pipe->Semaphore); |
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128 | free(pipe->Buffer); |
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129 | free(pipe); |
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130 | } |
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131 | |
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132 | static int pipe_lock(void) |
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133 | { |
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134 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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135 | |
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136 | if (pipe_semaphore == RTEMS_ID_NONE) { |
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137 | rtems_libio_lock(); |
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138 | |
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139 | if (pipe_semaphore == RTEMS_ID_NONE) { |
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140 | sc = rtems_semaphore_create( |
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141 | rtems_build_name('P', 'I', 'P', 'E'), |
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142 | 1, |
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143 | RTEMS_BINARY_SEMAPHORE | RTEMS_INHERIT_PRIORITY | RTEMS_PRIORITY, |
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144 | RTEMS_NO_PRIORITY, |
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145 | &pipe_semaphore |
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146 | ); |
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147 | } |
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148 | |
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149 | rtems_libio_unlock(); |
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150 | } |
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151 | |
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152 | if (sc == RTEMS_SUCCESSFUL) { |
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153 | sc = rtems_semaphore_obtain(pipe_semaphore, RTEMS_WAIT, RTEMS_NO_TIMEOUT); |
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154 | } |
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155 | |
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156 | if (sc == RTEMS_SUCCESSFUL) { |
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157 | return 0; |
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158 | } else { |
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159 | return -ENOMEM; |
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160 | } |
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161 | } |
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162 | |
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163 | static void pipe_unlock(void) |
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164 | { |
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165 | #ifdef RTEMS_DEBUG |
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166 | rtems_status_code sc = RTEMS_SUCCESSFUL; |
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167 | |
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168 | sc = |
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169 | #endif |
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170 | rtems_semaphore_release(pipe_semaphore); |
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171 | #ifdef RTEMS_DEBUG |
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172 | if (sc != RTEMS_SUCCESSFUL) { |
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173 | rtems_fatal_error_occurred(0xdeadbeef); |
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174 | } |
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175 | #endif |
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176 | } |
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177 | |
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178 | /* |
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179 | * If called with *pipep = NULL, pipe_new will call pipe_alloc to allocate a |
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180 | * pipe control structure and set *pipep to its address. |
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181 | * pipe is locked, when pipe_new returns with no error. |
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182 | */ |
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183 | static int pipe_new( |
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184 | pipe_control_t **pipep |
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185 | ) |
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186 | { |
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187 | pipe_control_t *pipe; |
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188 | int err = 0; |
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189 | |
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190 | _Assert( pipep ); |
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191 | err = pipe_lock(); |
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192 | if (err) |
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193 | return err; |
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194 | |
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195 | pipe = *pipep; |
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196 | if (pipe == NULL) { |
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197 | err = pipe_alloc(&pipe); |
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198 | if (err) |
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199 | goto out; |
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200 | } |
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201 | |
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202 | if (!PIPE_LOCK(pipe)) |
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203 | err = -EINTR; |
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204 | |
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205 | if (*pipep == NULL) { |
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206 | if (err) |
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207 | pipe_free(pipe); |
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208 | else |
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209 | *pipep = pipe; |
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210 | } |
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211 | |
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212 | out: |
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213 | pipe_unlock(); |
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214 | return err; |
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215 | } |
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216 | |
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217 | void pipe_release( |
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218 | pipe_control_t **pipep, |
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219 | rtems_libio_t *iop |
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220 | ) |
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221 | { |
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222 | pipe_control_t *pipe = *pipep; |
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223 | uint32_t mode; |
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224 | |
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225 | #if defined(RTEMS_DEBUG) |
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226 | /* WARN pipe not freed and pipep not set to NULL! */ |
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227 | if (pipe_lock()) |
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228 | rtems_fatal_error_occurred(0xdeadbeef); |
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229 | |
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230 | /* WARN pipe not released! */ |
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231 | if (!PIPE_LOCK(pipe)) |
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232 | rtems_fatal_error_occurred(0xdeadbeef); |
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233 | #endif |
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234 | |
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235 | mode = LIBIO_ACCMODE(iop); |
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236 | if (mode & LIBIO_FLAGS_READ) |
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237 | pipe->Readers --; |
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238 | if (mode & LIBIO_FLAGS_WRITE) |
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239 | pipe->Writers --; |
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240 | |
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241 | PIPE_UNLOCK(pipe); |
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242 | |
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243 | if (pipe->Readers == 0 && pipe->Writers == 0) { |
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244 | #if 0 |
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245 | /* To delete an anonymous pipe file when all users closed it */ |
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246 | if (pipe->Anonymous) |
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247 | delfile = TRUE; |
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248 | #endif |
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249 | pipe_free(pipe); |
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250 | *pipep = NULL; |
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251 | } |
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252 | else if (pipe->Readers == 0 && mode != LIBIO_FLAGS_WRITE) |
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253 | /* Notify waiting Writers that all their partners left */ |
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254 | PIPE_WAKEUPWRITERS(pipe); |
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255 | else if (pipe->Writers == 0 && mode != LIBIO_FLAGS_READ) |
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256 | PIPE_WAKEUPREADERS(pipe); |
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257 | |
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258 | pipe_unlock(); |
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259 | |
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260 | #if 0 |
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261 | if (! delfile) |
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262 | return; |
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263 | if (iop->pathinfo.ops->unlink_h == NULL) |
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264 | return; |
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265 | |
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266 | /* This is safe for IMFS, but how about other FSes? */ |
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267 | iop->flags &= ~LIBIO_FLAGS_OPEN; |
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268 | if(iop->pathinfo.ops->unlink_h(&iop->pathinfo)) |
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269 | return; |
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270 | #endif |
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271 | |
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272 | } |
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273 | |
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274 | int fifo_open( |
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275 | pipe_control_t **pipep, |
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276 | rtems_libio_t *iop |
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277 | ) |
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278 | { |
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279 | pipe_control_t *pipe; |
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280 | unsigned int prevCounter; |
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281 | int err; |
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282 | |
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283 | err = pipe_new(pipep); |
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284 | if (err) |
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285 | return err; |
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286 | pipe = *pipep; |
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287 | |
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288 | switch (LIBIO_ACCMODE(iop)) { |
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289 | case LIBIO_FLAGS_READ: |
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290 | pipe->readerCounter ++; |
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291 | if (pipe->Readers ++ == 0) |
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292 | PIPE_WAKEUPWRITERS(pipe); |
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293 | |
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294 | if (pipe->Writers == 0) { |
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295 | /* Not an error */ |
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296 | if (LIBIO_NODELAY(iop)) |
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297 | break; |
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298 | |
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299 | prevCounter = pipe->writerCounter; |
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300 | err = -EINTR; |
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301 | /* Wait until a writer opens the pipe */ |
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302 | do { |
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303 | PIPE_UNLOCK(pipe); |
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304 | if (! PIPE_READWAIT(pipe)) |
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305 | goto out_error; |
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306 | if (! PIPE_LOCK(pipe)) |
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307 | goto out_error; |
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308 | } while (prevCounter == pipe->writerCounter); |
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309 | } |
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310 | break; |
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311 | |
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312 | case LIBIO_FLAGS_WRITE: |
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313 | pipe->writerCounter ++; |
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314 | |
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315 | if (pipe->Writers ++ == 0) |
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316 | PIPE_WAKEUPREADERS(pipe); |
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317 | |
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318 | if (pipe->Readers == 0 && LIBIO_NODELAY(iop)) { |
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319 | PIPE_UNLOCK(pipe); |
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320 | err = -ENXIO; |
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321 | goto out_error; |
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322 | } |
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323 | |
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324 | if (pipe->Readers == 0) { |
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325 | prevCounter = pipe->readerCounter; |
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326 | err = -EINTR; |
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327 | do { |
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328 | PIPE_UNLOCK(pipe); |
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329 | if (! PIPE_WRITEWAIT(pipe)) |
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330 | goto out_error; |
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331 | if (! PIPE_LOCK(pipe)) |
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332 | goto out_error; |
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333 | } while (prevCounter == pipe->readerCounter); |
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334 | } |
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335 | break; |
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336 | |
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337 | case LIBIO_FLAGS_READ_WRITE: |
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338 | pipe->readerCounter ++; |
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339 | if (pipe->Readers ++ == 0) |
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340 | PIPE_WAKEUPWRITERS(pipe); |
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341 | pipe->writerCounter ++; |
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342 | if (pipe->Writers ++ == 0) |
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343 | PIPE_WAKEUPREADERS(pipe); |
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344 | break; |
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345 | } |
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346 | |
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347 | PIPE_UNLOCK(pipe); |
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348 | return 0; |
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349 | |
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350 | out_error: |
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351 | pipe_release(pipep, iop); |
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352 | return err; |
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353 | } |
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354 | |
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355 | ssize_t pipe_read( |
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356 | pipe_control_t *pipe, |
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357 | void *buffer, |
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358 | size_t count, |
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359 | rtems_libio_t *iop |
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360 | ) |
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361 | { |
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362 | int chunk, chunk1, read = 0, ret = 0; |
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363 | |
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364 | if (! PIPE_LOCK(pipe)) |
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365 | return -EINTR; |
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366 | |
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367 | while (PIPE_EMPTY(pipe)) { |
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368 | /* Not an error */ |
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369 | if (pipe->Writers == 0) |
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370 | goto out_locked; |
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371 | |
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372 | if (LIBIO_NODELAY(iop)) { |
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373 | ret = -EAGAIN; |
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374 | goto out_locked; |
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375 | } |
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376 | |
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377 | /* Wait until pipe is no more empty or no writer exists */ |
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378 | pipe->waitingReaders ++; |
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379 | PIPE_UNLOCK(pipe); |
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380 | if (! PIPE_READWAIT(pipe)) |
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381 | ret = -EINTR; |
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382 | if (! PIPE_LOCK(pipe)) { |
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383 | /* WARN waitingReaders not restored! */ |
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384 | ret = -EINTR; |
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385 | goto out_nolock; |
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386 | } |
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387 | pipe->waitingReaders --; |
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388 | if (ret != 0) |
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389 | goto out_locked; |
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390 | } |
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391 | |
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392 | /* Read chunk bytes */ |
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393 | chunk = MIN(count - read, pipe->Length); |
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394 | chunk1 = pipe->Size - pipe->Start; |
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395 | if (chunk > chunk1) { |
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396 | memcpy(buffer + read, pipe->Buffer + pipe->Start, chunk1); |
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397 | memcpy(buffer + read + chunk1, pipe->Buffer, chunk - chunk1); |
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398 | } |
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399 | else |
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400 | memcpy(buffer + read, pipe->Buffer + pipe->Start, chunk); |
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401 | |
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402 | pipe->Start += chunk; |
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403 | pipe->Start %= pipe->Size; |
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404 | pipe->Length -= chunk; |
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405 | /* For buffering optimization */ |
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406 | if (PIPE_EMPTY(pipe)) |
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407 | pipe->Start = 0; |
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408 | |
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409 | if (pipe->waitingWriters > 0) |
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410 | PIPE_WAKEUPWRITERS(pipe); |
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411 | read += chunk; |
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412 | |
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413 | out_locked: |
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414 | PIPE_UNLOCK(pipe); |
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415 | |
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416 | out_nolock: |
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417 | if (read > 0) |
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418 | return read; |
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419 | return ret; |
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420 | } |
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421 | |
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422 | ssize_t pipe_write( |
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423 | pipe_control_t *pipe, |
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424 | const void *buffer, |
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425 | size_t count, |
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426 | rtems_libio_t *iop |
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427 | ) |
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428 | { |
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429 | int chunk, chunk1, written = 0, ret = 0; |
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430 | |
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431 | /* Write nothing */ |
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432 | if (count == 0) |
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433 | return 0; |
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434 | |
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435 | if (! PIPE_LOCK(pipe)) |
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436 | return -EINTR; |
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437 | |
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438 | if (pipe->Readers == 0) { |
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439 | ret = -EPIPE; |
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440 | goto out_locked; |
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441 | } |
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442 | |
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443 | /* Write of PIPE_BUF bytes or less shall not be interleaved */ |
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444 | chunk = count <= pipe->Size ? count : 1; |
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445 | |
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446 | while (written < count) { |
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447 | while (PIPE_SPACE(pipe) < chunk) { |
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448 | if (LIBIO_NODELAY(iop)) { |
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449 | ret = -EAGAIN; |
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450 | goto out_locked; |
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451 | } |
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452 | |
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453 | /* Wait until there is chunk bytes space or no reader exists */ |
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454 | pipe->waitingWriters ++; |
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455 | PIPE_UNLOCK(pipe); |
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456 | if (! PIPE_WRITEWAIT(pipe)) |
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457 | ret = -EINTR; |
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458 | if (! PIPE_LOCK(pipe)) { |
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459 | /* WARN waitingWriters not restored! */ |
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460 | ret = -EINTR; |
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461 | goto out_nolock; |
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462 | } |
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463 | pipe->waitingWriters --; |
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464 | if (ret != 0) |
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465 | goto out_locked; |
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466 | |
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467 | if (pipe->Readers == 0) { |
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468 | ret = -EPIPE; |
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469 | goto out_locked; |
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470 | } |
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471 | } |
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472 | |
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473 | chunk = MIN(count - written, PIPE_SPACE(pipe)); |
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474 | chunk1 = pipe->Size - PIPE_WSTART(pipe); |
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475 | if (chunk > chunk1) { |
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476 | memcpy(pipe->Buffer + PIPE_WSTART(pipe), buffer + written, chunk1); |
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477 | memcpy(pipe->Buffer, buffer + written + chunk1, chunk - chunk1); |
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478 | } |
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479 | else |
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480 | memcpy(pipe->Buffer + PIPE_WSTART(pipe), buffer + written, chunk); |
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481 | |
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482 | pipe->Length += chunk; |
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483 | if (pipe->waitingReaders > 0) |
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484 | PIPE_WAKEUPREADERS(pipe); |
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485 | written += chunk; |
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486 | /* Write of more than PIPE_BUF bytes can be interleaved */ |
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487 | chunk = 1; |
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488 | } |
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489 | |
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490 | out_locked: |
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491 | PIPE_UNLOCK(pipe); |
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492 | |
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493 | out_nolock: |
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494 | #ifdef RTEMS_POSIX_API |
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495 | /* Signal SIGPIPE */ |
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496 | if (ret == -EPIPE) |
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497 | kill(getpid(), SIGPIPE); |
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498 | #endif |
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499 | |
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500 | if (written > 0) |
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501 | return written; |
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502 | return ret; |
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503 | } |
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504 | |
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505 | int pipe_ioctl( |
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506 | pipe_control_t *pipe, |
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507 | ioctl_command_t cmd, |
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508 | void *buffer, |
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509 | rtems_libio_t *iop |
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510 | ) |
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511 | { |
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512 | if (cmd == FIONREAD) { |
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513 | if (buffer == NULL) |
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514 | return -EFAULT; |
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515 | |
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516 | if (! PIPE_LOCK(pipe)) |
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517 | return -EINTR; |
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518 | |
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519 | /* Return length of pipe */ |
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520 | *(unsigned int *)buffer = pipe->Length; |
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521 | PIPE_UNLOCK(pipe); |
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522 | return 0; |
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523 | } |
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524 | |
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525 | return -EINVAL; |
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526 | } |
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