1/* Derived from the test case in
2 https://sourceware.org/bugzilla/show_bug.cgi?id=1078. */
3#include <stdio.h>
4#include <stdlib.h>
5#include <unistd.h>
6
7#define OUT_SIZE 10000
8
9
10static int fd;
11
12static void prepare (void);
13#define PREPARE(argc, argv) prepare ()
14
15static int do_test (void);
16#define TEST_FUNCTION do_test ()
17
18#include "../test-skeleton.c"
19
20
21static void
22prepare (void)
23{
24 fd = create_temp_file (base: "tst-fwrite.", NULL);
25 if (fd == -1)
26 {
27 puts (s: "cannot create temporary file");
28 exit (1);
29 }
30}
31
32
33static int
34do_test (void)
35{
36 FILE* f = fdopen (fd, "w+");
37 if (f == NULL) {
38 puts (s: "cannot create stream");
39 return 1;
40 }
41 puts (s: "Opened temp file");
42
43 if (fwrite ("a", 1, 1, f) != 1)
44 {
45 puts (s: "1st fwrite failed");
46 return 1;
47 }
48 puts (s: "Wrote a byte");
49 fflush (f);
50
51 char buffer[10000];
52 size_t i = fread (ptr: buffer, size: 1, n: sizeof (buffer), stream: f);
53 printf (format: "Read %zu bytes\n", i);
54
55 for (i = 0; i < OUT_SIZE; i++)
56 {
57 if (fwrite ("n", 1, 1, f) != 1)
58 {
59 printf (format: "fwrite in loop round %zu failed\n", i);
60 return 1;
61 }
62
63 if ((i + 1) % 1000 == 0)
64 printf (format: "wrote %zu bytes ...\n", i + 1);
65 }
66
67 printf (format: "Wrote %i bytes [done]\n", OUT_SIZE);
68
69 return 0;
70}
71

source code of glibc/stdio-common/tst-fwrite.c