| 1 | #define _GNU_SOURCE
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| 2 | #include <stdio.h>
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| 3 | #include <string.h>
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| 4 | #include <assert.h>
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| 5 |
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| 6 | #if __GLIBC__ == 2
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| 7 | # define fpurge(f) (__fpurge (f), 0)
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| 8 | extern void __fpurge (FILE *);
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| 9 | #endif
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| 10 |
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| 11 |
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| 12 | /* Preparations: printf 'foogarsh' > foo.tmp */
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| 13 |
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| 14 | int main ()
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| 15 | {
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| 16 | FILE *fp;
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| 17 |
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| 18 | /* Open it in read-only mode. */
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| 19 | fp = fopen ("foo.tmp", "r");
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| 20 | if (fp == NULL)
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| 21 | return 1;
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| 22 | /* Verify that the pending writes before the fpurge were really
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| 23 | discarded. */
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| 24 | {
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| 25 | char buf[8];
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| 26 | if (fread (buf, 1, 7, fp) < 7)
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| 27 | return 2;
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| 28 | assert (memcmp (buf, "foogars", 7) == 0);
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| 29 | }
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| 30 | /* Discard the buffered 'h'. */
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| 31 | assert (ftell (fp) == 7);
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| 32 | assert (fpurge (fp) == 0);
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| 33 | /* Verify that when discarding pending input, the file position is
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| 34 | advanced to match the end of the previously read input. */
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| 35 | printf ("ftell (fp) = %ld\n", ftell (fp));
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| 36 | assert (ftell (fp) == 8);
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| 37 | assert (getc (fp) == EOF);
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| 38 | assert (fclose (fp) == 0);
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| 39 | printf ("OK\n");
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| 40 | return 0;
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| 41 | }
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