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 (a_outer: &outer_fd, a_inner: &inner_fd, a_name: 0, termp: 0, winp: 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 (stream: fp); |
106 | TEST_COMPARE (fgetwc (fp), L'd'); |
107 | TEST_COMPARE (fgetwc (fp), L'\n'); |
108 | |
109 | fclose (fp); |
110 | close (fd: outer_fd); |
111 | return 0; |
112 | } |
113 | |
114 | #include <support/test-driver.c> |
115 | |