1 | #include "stdio_impl.h"
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2 | #include <errno.h>
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3 | #include <string.h>
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4 | #include <inttypes.h>
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5 |
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6 | struct cookie {
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7 | size_t pos, len, size;
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8 | unsigned char *buf;
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9 | int mode;
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10 | };
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11 |
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12 | static off_t mseek(FILE *f, off_t off, int whence)
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13 | {
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14 | ssize_t base;
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15 | struct cookie *c = f->cookie;
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16 | if (whence>2U) {
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17 | fail:
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18 | errno = EINVAL;
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19 | return -1;
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20 | }
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21 | base = (size_t [3]){0, c->pos, c->len}[whence];
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22 | if (off < -base || off > (ssize_t)c->size-base) goto fail;
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23 | return c->pos = base+off;
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24 | }
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25 |
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26 | static size_t mread(FILE *f, unsigned char *buf, size_t len)
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27 | {
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28 | struct cookie *c = f->cookie;
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29 | size_t rem = c->len - c->pos;
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30 | if (c->pos > c->len) rem = 0;
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31 | if (len > rem) {
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32 | len = rem;
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33 | f->flags |= F_EOF;
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34 | }
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35 | memcpy(buf, c->buf+c->pos, len);
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36 | c->pos += len;
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37 | rem -= len;
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38 | if (rem > f->buf_size) rem = f->buf_size;
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39 | f->rpos = f->buf;
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40 | f->rend = f->buf + rem;
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41 | memcpy(f->rpos, c->buf+c->pos, rem);
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42 | c->pos += rem;
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43 | return len;
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44 | }
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45 |
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46 | static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
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47 | {
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48 | struct cookie *c = f->cookie;
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49 | size_t rem;
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50 | size_t len2 = f->wpos - f->wbase;
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51 | if (len2) {
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52 | f->wpos = f->wbase;
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53 | if (mwrite(f, f->wpos, len2) < len2) return 0;
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54 | }
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55 | if (c->mode == 'a') c->pos = c->len;
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56 | rem = c->size - c->pos;
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57 | if (len > rem) len = rem;
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58 | memcpy(c->buf+c->pos, buf, len);
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59 | c->pos += len;
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60 | if (c->pos > c->len) {
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61 | c->len = c->pos;
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62 | if (c->len < c->size) c->buf[c->len] = 0;
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63 | else if ((f->flags&F_NORD) && c->size) c->buf[c->size-1] = 0;
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64 | }
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65 | return len;
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66 | }
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67 |
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68 | static int mclose(FILE *m)
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69 | {
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70 | return 0;
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71 | }
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72 |
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73 | FILE *fmemopen(void *restrict buf, size_t size, const char *restrict mode)
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74 | {
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75 | FILE *f;
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76 | struct cookie *c;
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77 | int plus = !!strchr(mode, '+');
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78 |
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79 | if (!size || !strchr("rwa", *mode)) {
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80 | errno = EINVAL;
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81 | return 0;
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82 | }
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83 |
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84 | if (!buf && size > SIZE_MAX-sizeof(FILE)-BUFSIZ-UNGET) {
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85 | errno = ENOMEM;
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86 | return 0;
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87 | }
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88 |
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89 | f = calloc(sizeof *f + sizeof *c + UNGET + BUFSIZ + (buf?0:size), 1);
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90 | if (!f) return 0;
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91 | f->cookie = c = (void *)(f+1);
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92 | f->fd = -1;
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93 | f->lbf = EOF;
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94 | f->buf = (unsigned char *)(c+1) + UNGET;
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95 | f->buf_size = BUFSIZ;
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96 | if (!buf) buf = f->buf + BUFSIZ;
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97 |
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98 | c->buf = buf;
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99 | c->size = size;
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100 | c->mode = *mode;
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101 |
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102 | if (!plus) f->flags = (*mode == 'r') ? F_NOWR : F_NORD;
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103 | if (*mode == 'r') c->len = size;
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104 | else if (*mode == 'a') c->len = c->pos = strnlen(buf, size);
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105 |
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106 | f->read = mread;
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107 | f->write = mwrite;
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108 | f->seek = mseek;
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109 | f->close = mclose;
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110 |
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111 | if (!libc.threaded) f->lock = -1;
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112 |
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113 | return __ofl_add(f);
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114 | }
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