1 | #include "stdio_impl.h"
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2 | #include <errno.h>
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3 | #include <limits.h>
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4 | #include <string.h>
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5 |
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6 | struct cookie {
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7 | char **bufp;
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8 | size_t *sizep;
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9 | size_t pos;
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10 | char *buf;
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11 | size_t len;
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12 | size_t space;
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13 | };
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14 |
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15 | static off_t ms_seek(FILE *f, off_t off, int whence)
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16 | {
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17 | ssize_t base;
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18 | struct cookie *c = f->cookie;
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19 | if (whence>2U) {
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20 | fail:
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21 | errno = EINVAL;
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22 | return -1;
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23 | }
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24 | base = (size_t [3]){0, c->pos, c->len}[whence];
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25 | if (off < -base || off > SSIZE_MAX-base) goto fail;
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26 | return c->pos = base+off;
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27 | }
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28 |
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29 | static size_t ms_write(FILE *f, const unsigned char *buf, size_t len)
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30 | {
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31 | struct cookie *c = f->cookie;
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32 | size_t len2 = f->wpos - f->wbase;
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33 | char *newbuf;
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34 | if (len2) {
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35 | f->wpos = f->wbase;
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36 | if (ms_write(f, f->wbase, len2) < len2) return 0;
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37 | }
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38 | if (len + c->pos >= c->space) {
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39 | len2 = 2*c->space+1 | c->pos+len+1;
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40 | newbuf = realloc(c->buf, len2);
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41 | if (!newbuf) return 0;
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42 | *c->bufp = c->buf = newbuf;
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43 | memset(c->buf + c->space, 0, len2 - c->space);
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44 | c->space = len2;
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45 | }
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46 | memcpy(c->buf+c->pos, buf, len);
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47 | c->pos += len;
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48 | if (c->pos >= c->len) c->len = c->pos;
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49 | *c->sizep = c->pos;
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50 | return len;
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51 | }
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52 |
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53 | static int ms_close(FILE *f)
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54 | {
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55 | return 0;
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56 | }
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57 |
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58 | FILE *open_memstream(char **bufp, size_t *sizep)
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59 | {
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60 | FILE *f;
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61 | struct cookie *c;
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62 | char *buf;
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63 |
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64 | if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0;
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65 | if (!(buf=malloc(sizeof *buf))) {
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66 | free(f);
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67 | return 0;
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68 | }
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69 | memset(f, 0, sizeof *f + sizeof *c);
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70 | f->cookie = c = (void *)(f+1);
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71 |
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72 | c->bufp = bufp;
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73 | c->sizep = sizep;
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74 | c->pos = c->len = c->space = *sizep = 0;
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75 | c->buf = *bufp = buf;
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76 | *buf = 0;
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77 |
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78 | f->flags = F_NORD;
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79 | f->fd = -1;
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80 | f->buf = (void *)(c+1);
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81 | f->buf_size = BUFSIZ;
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82 | f->lbf = EOF;
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83 | f->write = ms_write;
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84 | f->seek = ms_seek;
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85 | f->close = ms_close;
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86 |
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87 | if (!libc.threaded) f->lock = -1;
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88 |
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89 | return __ofl_add(f);
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90 | }
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