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1 | /* Bug 1190: EOF conditions are supposed to be sticky. |
2 | Copyright (C) 2018 Free Software Foundation. | |
3 | Copying and distribution of this file, with or without modification, | |
4 | are permitted in any medium without royalty provided the copyright | |
5 | notice and this notice are preserved. This file is offered as-is, | |
6 | without any warranty. */ | |
7 | ||
8 | /* ISO C1999 specification of fgetwc: | |
9 | ||
10 | #include <stdio.h> | |
11 | #include <wchar.h> | |
12 | wint_t fgetwc (FILE *stream); | |
13 | ||
14 | Description | |
15 | ||
16 | If the end-of-file indicator for the input stream pointed to by | |
17 | stream is not set and a next wide character is present, the | |
18 | fgetwc function obtains that wide character as a wchar_t | |
19 | converted to a wint_t and advances the associated file position | |
20 | indicator for the stream (if defined). | |
21 | ||
22 | Returns | |
23 | ||
24 | If the end-of-file indicator for the stream is set, or if the | |
25 | stream is at end-of-file, the end- of-file indicator for the | |
26 | stream is set and the fgetwc function returns WEOF. Otherwise, | |
27 | the fgetwc function returns the next wide character from the | |
28 | input stream pointed to by stream. If a read error occurs, the | |
29 | error indicator for the stream is set and the fgetwc function | |
30 | returns WEOF. If an encoding error occurs (including too few | |
31 | bytes), the value of the macro EILSEQ is stored in errno and the | |
32 | fgetwc function returns WEOF. | |
33 | ||
34 | The requirement to return WEOF "if the end-of-file indicator for the | |
35 | stream is set" was new in C99; the language in the 1995 edition of | |
36 | the standard was ambiguous. Historically, BSD-derived Unix always | |
37 | had the C99 behavior, whereas in System V fgetwc would attempt to | |
38 | call read() again before returning EOF again. Prior to version 2.28, | |
39 | glibc followed the System V behavior even though this does not | |
40 | comply with C99. | |
41 | ||
42 | See | |
43 | <https://sourceware.org/bugzilla/show_bug.cgi?id=1190>, | |
44 | <https://sourceware.org/bugzilla/show_bug.cgi?id=19476>, | |
45 | and the thread at | |
46 | <https://sourceware.org/ml/libc-alpha/2012-09/msg00343.html> | |
47 | for more detail. */ | |
48 | ||
49 | #include <support/tty.h> | |
50 | #include <support/check.h> | |
51 | ||
52 | #include <fcntl.h> | |
53 | #include <stdio.h> | |
54 | #include <stdlib.h> | |
55 | #include <string.h> | |
56 | #include <unistd.h> | |
57 | #include <wchar.h> | |
58 | ||
59 | #define XWRITE(fd, s, msg) do { \ | |
60 | if (write (fd, s, sizeof s - 1) != sizeof s - 1) \ | |
61 | { \ | |
62 | perror ("write " msg); \ | |
63 | return 1; \ | |
64 | } \ | |
65 | } while (0) | |
66 | ||
67 | int | |
68 | do_test (void) | |
69 | { | |
70 | /* The easiest way to set up the conditions under which you can | |
71 | notice whether the end-of-file indicator is sticky, is with a | |
72 | pseudo-tty. This is also the case which applications are most | |
73 | likely to care about. And it avoids any question of whether and | |
74 | how it is legitimate to access the same physical file with two | |
75 | independent FILE objects. */ | |
76 | int outer_fd, inner_fd; | |
77 | FILE *fp; | |
78 | ||
79 | support_openpty (&outer_fd, &inner_fd, 0, 0, 0); | |
80 | fp = fdopen (inner_fd, "r+"); | |
81 | if (!fp) | |
82 | { | |
83 | perror ("fdopen"); | |
84 | return 1; | |
85 | } | |
86 | ||
87 | XWRITE (outer_fd, "abc\n\004", "first line + EOF"); | |
88 | TEST_COMPARE (fgetwc (fp), L'a'); | |
89 | TEST_COMPARE (fgetwc (fp), L'b'); | |
90 | TEST_COMPARE (fgetwc (fp), L'c'); | |
91 | TEST_COMPARE (fgetwc (fp), L'\n'); | |
92 | TEST_COMPARE (fgetwc (fp), WEOF); | |
93 | ||
94 | TEST_VERIFY_EXIT (feof (fp)); | |
95 | TEST_VERIFY_EXIT (!ferror (fp)); | |
96 | ||
97 | XWRITE (outer_fd, "d\n", "second line"); | |
98 | ||
99 | /* At this point, there is a new full line of input waiting in the | |
100 | kernelside input buffer, but we should still observe EOF from | |
101 | stdio, because the end-of-file indicator has not been cleared. */ | |
102 | TEST_COMPARE (fgetwc (fp), WEOF); | |
103 | ||
104 | /* Clearing EOF should reveal the next line of input. */ | |
105 | clearerr (fp); | |
106 | TEST_COMPARE (fgetwc (fp), L'd'); | |
107 | TEST_COMPARE (fgetwc (fp), L'\n'); | |
108 | ||
109 | fclose (fp); | |
110 | close (outer_fd); | |
111 | return 0; | |
112 | } | |
113 | ||
114 | #include <support/test-driver.c> |