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Diffstat (limited to 'wcsmbs/tst-fgetwc-after-eof.c')
| -rw-r--r-- | wcsmbs/tst-fgetwc-after-eof.c | 114 |
1 files changed, 114 insertions, 0 deletions
diff --git a/wcsmbs/tst-fgetwc-after-eof.c b/wcsmbs/tst-fgetwc-after-eof.c new file mode 100644 index 0000000000..9103529246 --- /dev/null +++ b/wcsmbs/tst-fgetwc-after-eof.c @@ -0,0 +1,114 @@ +/* Bug 1190: EOF conditions are supposed to be sticky. + Copyright (C) 2018 Free Software Foundation. + Copying and distribution of this file, with or without modification, + are permitted in any medium without royalty provided the copyright + notice and this notice are preserved. This file is offered as-is, + without any warranty. */ + +/* ISO C1999 specification of fgetwc: + + #include <stdio.h> + #include <wchar.h> + wint_t fgetwc (FILE *stream); + + Description + + If the end-of-file indicator for the input stream pointed to by + stream is not set and a next wide character is present, the + fgetwc function obtains that wide character as a wchar_t + converted to a wint_t and advances the associated file position + indicator for the stream (if defined). + + Returns + + If the end-of-file indicator for the stream is set, or if the + stream is at end-of-file, the end- of-file indicator for the + stream is set and the fgetwc function returns WEOF. Otherwise, + the fgetwc function returns the next wide character from the + input stream pointed to by stream. If a read error occurs, the + error indicator for the stream is set and the fgetwc function + returns WEOF. If an encoding error occurs (including too few + bytes), the value of the macro EILSEQ is stored in errno and the + fgetwc function returns WEOF. + + The requirement to return WEOF "if the end-of-file indicator for the + stream is set" was new in C99; the language in the 1995 edition of + the standard was ambiguous. Historically, BSD-derived Unix always + had the C99 behavior, whereas in System V fgetwc would attempt to + call read() again before returning EOF again. Prior to version 2.28, + glibc followed the System V behavior even though this does not + comply with C99. + + See + <https://sourceware.org/bugzilla/show_bug.cgi?id=1190>, + <https://sourceware.org/bugzilla/show_bug.cgi?id=19476>, + and the thread at + <https://sourceware.org/ml/libc-alpha/2012-09/msg00343.html> + for more detail. */ + +#include <support/tty.h> +#include <support/check.h> + +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <wchar.h> + +#define XWRITE(fd, s, msg) do { \ + if (write (fd, s, sizeof s - 1) != sizeof s - 1) \ + { \ + perror ("write " msg); \ + return 1; \ + } \ + } while (0) + +int +do_test (void) +{ + /* The easiest way to set up the conditions under which you can + notice whether the end-of-file indicator is sticky, is with a + pseudo-tty. This is also the case which applications are most + likely to care about. And it avoids any question of whether and + how it is legitimate to access the same physical file with two + independent FILE objects. */ + int outer_fd, inner_fd; + FILE *fp; + + support_openpty (&outer_fd, &inner_fd, 0, 0, 0); + fp = fdopen (inner_fd, "r+"); + if (!fp) + { + perror ("fdopen"); + return 1; + } + + XWRITE (outer_fd, "abc\n\004", "first line + EOF"); + TEST_COMPARE (fgetwc (fp), L'a'); + TEST_COMPARE (fgetwc (fp), L'b'); + TEST_COMPARE (fgetwc (fp), L'c'); + TEST_COMPARE (fgetwc (fp), L'\n'); + TEST_COMPARE (fgetwc (fp), WEOF); + + TEST_VERIFY_EXIT (feof (fp)); + TEST_VERIFY_EXIT (!ferror (fp)); + + XWRITE (outer_fd, "d\n", "second line"); + + /* At this point, there is a new full line of input waiting in the + kernelside input buffer, but we should still observe EOF from + stdio, because the end-of-file indicator has not been cleared. */ + TEST_COMPARE (fgetwc (fp), WEOF); + + /* Clearing EOF should reveal the next line of input. */ + clearerr (fp); + TEST_COMPARE (fgetwc (fp), L'd'); + TEST_COMPARE (fgetwc (fp), L'\n'); + + fclose (fp); + close (outer_fd); + return 0; +} + +#include <support/test-driver.c> |