1 | /* zio.c (simulation of non-standard low-level i/o functions) */ |
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2 | |
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3 | /* Written by Andrew Makhorin <mao@gnu.org>, April 2011 |
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4 | * For conditions of distribution and use, see copyright notice in |
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5 | * zlib.h */ |
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6 | |
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7 | /* (reserved for copyright notice) */ |
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8 | |
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9 | #include <assert.h> |
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10 | #include <stdio.h> |
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11 | #include "zio.h" |
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12 | |
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13 | static FILE *file[FOPEN_MAX]; |
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14 | static int initialized = 0; |
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15 | |
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16 | static void initialize(void) |
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17 | { int fd; |
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18 | assert(!initialized); |
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19 | file[0] = stdin; |
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20 | file[1] = stdout; |
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21 | file[2] = stderr; |
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22 | for (fd = 3; fd < FOPEN_MAX; fd++) |
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23 | file[fd] = NULL; |
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24 | initialized = 1; |
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25 | return; |
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26 | } |
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27 | |
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28 | int open(const char *path, int oflag, ...) |
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29 | { FILE *fp; |
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30 | int fd; |
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31 | if (!initialized) initialize(); |
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32 | /* see file gzlib.c, function gz_open */ |
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33 | if (oflag == O_RDONLY) |
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34 | fp = fopen(path, "rb"); |
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35 | else if (oflag == (O_WRONLY | O_CREAT | O_TRUNC)) |
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36 | fp = fopen(path, "wb"); |
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37 | else if (oflag == (O_WRONLY | O_CREAT | O_APPEND)) |
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38 | fp = fopen(path, "ab"); |
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39 | else |
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40 | assert(oflag != oflag); |
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41 | if (fp == NULL) |
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42 | return -1; |
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43 | for (fd = 0; fd < FOPEN_MAX; fd++) |
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44 | if (file[fd] == NULL) break; |
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45 | assert(fd < FOPEN_MAX); |
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46 | file[fd] = fp; |
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47 | return fd; |
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48 | } |
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49 | |
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50 | long read(int fd, void *buf, unsigned long nbyte) |
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51 | { unsigned long count; |
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52 | if (!initialized) initialize(); |
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53 | assert(0 <= fd && fd < FOPEN_MAX); |
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54 | assert(file[fd] != NULL); |
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55 | count = fread(buf, 1, nbyte, file[fd]); |
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56 | if (ferror(file[fd])) |
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57 | return -1; |
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58 | return count; |
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59 | } |
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60 | |
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61 | long write(int fd, const void *buf, unsigned long nbyte) |
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62 | { unsigned long count; |
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63 | if (!initialized) initialize(); |
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64 | assert(0 <= fd && fd < FOPEN_MAX); |
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65 | assert(file[fd] != NULL); |
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66 | count = fwrite(buf, 1, nbyte, file[fd]); |
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67 | if (count != nbyte) |
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68 | return -1; |
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69 | if (fflush(file[fd]) != 0) |
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70 | return -1; |
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71 | return count; |
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72 | } |
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73 | |
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74 | long lseek(int fd, long offset, int whence) |
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75 | { if (!initialized) initialize(); |
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76 | assert(0 <= fd && fd < FOPEN_MAX); |
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77 | assert(file[fd] != NULL); |
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78 | if (fseek(file[fd], offset, whence) != 0) |
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79 | return -1; |
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80 | return ftell(file[fd]); |
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81 | } |
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82 | |
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83 | int close(int fd) |
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84 | { if (!initialized) initialize(); |
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85 | assert(0 <= fd && fd < FOPEN_MAX); |
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86 | assert(file[fd] != NULL); |
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87 | fclose(file[fd]); |
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88 | file[fd] = NULL; |
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89 | return 0; |
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90 | } |
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91 | |
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92 | /* eof */ |
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