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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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