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1 //
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2 // File descriptors
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3 //
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4
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5 #include "types.h"
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6 #include "defs.h"
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7 #include "param.h"
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8 #include "fs.h"
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9 #include "file.h"
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10 #include "spinlock.h"
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11
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12 struct devsw devsw[NDEV];
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27
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13 struct cbc_devsw cbc_devsw[NDEV];
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14
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0
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15 struct {
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16 struct spinlock lock;
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17 struct file file[NFILE];
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18 } ftable;
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19
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20 void fileinit (void)
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21 {
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22 initlock(&ftable.lock, "ftable");
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23 }
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24
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25 // Allocate a file structure.
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26 struct file* filealloc (void)
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27 {
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28 struct file *f;
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29
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30 acquire(&ftable.lock);
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31
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32 for (f = ftable.file; f < ftable.file + NFILE; f++) {
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33 if (f->ref == 0) {
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34 f->ref = 1;
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35 release(&ftable.lock);
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36 return f;
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37 }
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38 }
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39
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40 release(&ftable.lock);
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41 return 0;
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42 }
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43
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44 // Increment ref count for file f.
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45 struct file* filedup (struct file *f)
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46 {
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47 acquire(&ftable.lock);
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48
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49 if (f->ref < 1) {
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50 panic("filedup");
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51 }
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52
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53 f->ref++;
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54 release(&ftable.lock);
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55 return f;
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56 }
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57
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58 // Close file f. (Decrement ref count, close when reaches 0.)
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59 void fileclose (struct file *f)
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60 {
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61 struct file ff;
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62
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63 acquire(&ftable.lock);
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64
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65 if (f->ref < 1) {
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66 panic("fileclose");
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67 }
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68
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69 if (--f->ref > 0) {
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70 release(&ftable.lock);
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71 return;
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72 }
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73
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74 ff = *f;
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75 f->ref = 0;
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76 f->type = FD_NONE;
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77 release(&ftable.lock);
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78
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79 if (ff.type == FD_PIPE) {
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80 pipeclose(ff.pipe, ff.writable);
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81
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82 } else if (ff.type == FD_INODE) {
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83 begin_trans();
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84 iput(ff.ip);
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85 commit_trans();
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86 }
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87 }
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88
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89 // Get metadata about file f.
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90 int filestat (struct file *f, struct stat *st)
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91 {
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92 if (f->type == FD_INODE) {
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93 ilock(f->ip);
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94 stati(f->ip, st);
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95 iunlock(f->ip);
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96
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97 return 0;
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98 }
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99
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100 return -1;
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101 }
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102
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103 __code cbc_fileread1 (int r, struct file *f, char *addr, int n, __code (*next)(int ret))
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104 {
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105 if (r > 0)
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106 f->off += r;
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107 iunlock(f->ip);
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108 goto next(r);
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109 }
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110
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111 __code cbc_fileread (struct file *f, char *addr, int n, __code (*next)(int ret))
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112 {
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113 int r;
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114
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115 if (f->readable == 0) {
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116 goto next(-1);
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117 }
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118
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119 if (f->type == FD_PIPE) {
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120 //goto cbc_piperead(f->pipe, addr, n, next);
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121 goto next(-1);
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122 }
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123
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124 if (f->type == FD_INODE) {
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125 ilock(f->ip);
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126
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127 goto cbc_readi(f->ip, addr, f->off, n, next);
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128 }
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129
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130 goto cbc_panic("fileread");
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131 }
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132
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133 // Read from file f.
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134 int fileread (struct file *f, char *addr, int n)
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135 {
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136 int r;
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137
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138 if (f->readable == 0) {
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139 return -1;
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140 }
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141
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142 if (f->type == FD_PIPE) {
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143 return piperead(f->pipe, addr, n);
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144 }
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145
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146 if (f->type == FD_INODE) {
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147 ilock(f->ip);
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148
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149 if ((r = readi(f->ip, addr, f->off, n)) > 0) {
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150 f->off += r;
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151 }
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152
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153 iunlock(f->ip);
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154
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155 return r;
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156 }
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157
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158 panic("fileread");
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159 }
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160
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161 //PAGEBREAK!
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162 // Write to file f.
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163 int filewrite (struct file *f, char *addr, int n)
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164 {
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165 int r;
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166 int i;
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167 int max;
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168 int n1;
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169
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170 if (f->writable == 0) {
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171 return -1;
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172 }
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173
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174 if (f->type == FD_PIPE) {
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175 return pipewrite(f->pipe, addr, n);
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176 }
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177
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178 if (f->type == FD_INODE) {
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179 // write a few blocks at a time to avoid exceeding
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180 // the maximum log transaction size, including
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181 // i-node, indirect block, allocation blocks,
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182 // and 2 blocks of slop for non-aligned writes.
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183 // this really belongs lower down, since writei()
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184 // might be writing a device like the console.
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185 max = ((LOGSIZE - 1 - 1 - 2) / 2) * 512;
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186 i = 0;
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187
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188 while (i < n) {
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189 n1 = n - i;
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190
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191 if (n1 > max) {
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192 n1 = max;
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193 }
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194
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195 begin_trans();
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196 ilock(f->ip);
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197
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198 if ((r = writei(f->ip, addr + i, f->off, n1)) > 0) {
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199 f->off += r;
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200 }
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201
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202 iunlock(f->ip);
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203 commit_trans();
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204
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205 if (r < 0) {
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206 break;
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207 }
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208
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209 if (r != n1) {
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210 panic("short filewrite");
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211 }
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212
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213 i += r;
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214 }
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215
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216 return i == n ? n : -1;
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217 }
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218
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219 panic("filewrite");
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220 }
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221
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