X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Ffflush.c;h=ead4875498e760bc572310d49d02131a1d902573;hb=d1fb15ba12436afdd742eaff1ec46f75ee397bda;hp=4d2abc9cbc616fab16daeee05091560aea1c03a0;hpb=4a11bb6c20ff8285a95779dcdeb2c594940a98ed;p=gnulib.git diff --git a/lib/fflush.c b/lib/fflush.c index 4d2abc9cb..ead487549 100644 --- a/lib/fflush.c +++ b/lib/fflush.c @@ -1,5 +1,5 @@ /* fflush.c -- allow flushing input streams - Copyright (C) 2007-2008 Free Software Foundation, Inc. + Copyright (C) 2007-2010 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by @@ -25,18 +25,97 @@ #include #include "freading.h" -#include "fpurge.h" + +#include "stdio-impl.h" #undef fflush + +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ + +/* Clear the stream's ungetc buffer, preserving the value of ftello (fp). */ +static inline void +clear_ungetc_buffer_preserving_position (FILE *fp) +{ + if (fp->_flags & _IO_IN_BACKUP) + /* _IO_free_backup_area is a bit complicated. Simply call fseek. */ + fseeko (fp, 0, SEEK_CUR); +} + +#else + +/* Clear the stream's ungetc buffer. May modify the value of ftello (fp). */ +static inline void +clear_ungetc_buffer (FILE *fp) +{ +# if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ + if (HASUB (fp)) + { + fp_->_p += fp_->_r; + fp_->_r = 0; + } +# elif defined __EMX__ /* emx+gcc */ + if (fp->_ungetc_count > 0) + { + fp->_ungetc_count = 0; + fp->_rcount = - fp->_rcount; + } +# elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */ + /* Nothing to do. */ +# else /* other implementations */ + fseeko (fp, 0, SEEK_CUR); +# endif +} + +#endif + +#if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ + +static inline int +disable_seek_optimization (FILE *fp) +{ + int saved_flags = fp_->_flags & (__SOPT | __SNPT); + fp_->_flags = (fp_->_flags & ~__SOPT) | __SNPT; + return saved_flags; +} + +static inline void +restore_seek_optimization (FILE *fp, int saved_flags) +{ + fp_->_flags = (fp_->_flags & ~(__SOPT | __SNPT)) | saved_flags; +} + +#endif + +static inline void +update_fpos_cache (FILE *fp, off_t pos) +{ +#if defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ +# if defined __CYGWIN__ + /* fp_->_offset is typed as an integer. */ + fp_->_offset = pos; +# else + /* fp_->_offset is an fpos_t. */ + /* Use a union, since on NetBSD, the compilation flags determine + whether fpos_t is typedef'd to off_t or a struct containing a + single off_t member. */ + union + { + fpos_t f; + off_t o; + } u; + u.o = pos; + fp_->_offset = u.f; +# endif + fp_->_flags |= __SOFF; +#endif +} + /* Flush all pending data on STREAM according to POSIX rules. Both output and seekable input streams are supported. */ int rpl_fflush (FILE *stream) { - int result; - off_t pos; - /* When stream is NULL, POSIX and C99 only require flushing of "output streams and update streams in which the most recent operation was not input", and all implementations do this. @@ -59,91 +138,81 @@ rpl_fflush (FILE *stream) if (stream == NULL || ! freading (stream)) return fflush (stream); - /* Clear the ungetc buffer. - - This is needed before fetching the file-position indicator, because - 1) The file position indicator is incremented by fgetc() and decremented - by ungetc(): - - "... the fgetc() function shall ... advance the associated file - position indicator for the stream ..." - - "The file-position indicator is decremented by each successful - call to ungetc()..." - 2) says: - "The value of the file-position indicator for the stream after - reading or discarding all pushed-back bytes shall be the same - as it was before the bytes were pushed back." - 3) Here we are discarding all pushed-back bytes. - - Unfortunately it is impossible to implement this on platforms with - _IOERR, because an ungetc() on this platform prepends the pushed-back - bytes to the buffer without an indication of the limit between the - pushed-back bytes and the read-ahead bytes. */ -#if defined __sferror /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */ +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ + + clear_ungetc_buffer_preserving_position (stream); + + return fflush (stream); + +#else { -# if defined __NetBSD__ || defined __OpenBSD__ - struct __sfileext + /* Notes about the file-position indicator: + 1) The file position indicator is incremented by fgetc() and decremented + by ungetc(): + + "... the fgetc() function shall ... advance the associated file + position indicator for the stream ..." + + "The file-position indicator is decremented by each successful + call to ungetc()..." + 2) says: + "The value of the file-position indicator for the stream after + reading or discarding all pushed-back bytes shall be the same + as it was before the bytes were pushed back." + Here we are discarding all pushed-back bytes. But more specifically, + 3) says: + "[After fflush(),] the file offset of the underlying open file + description shall be set to the file position of the stream, and + any characters pushed back onto the stream by ungetc() ... shall + be discarded." */ + + /* POSIX does not specify fflush behavior for non-seekable input + streams. Some implementations purge unread data, some return + EBADF, some do nothing. */ + off_t pos = ftello (stream); + if (pos == -1) { - struct __sbuf _ub; /* ungetc buffer */ - /* More fields, not relevant here. */ - }; - if (((struct __sfileext *) stream->_ext._base)->_ub._base != NULL) -# else - if (stream->_ub._base != NULL) -# endif - { - stream->_p += stream->_r; - stream->_r = 0; + errno = EBADF; + return EOF; } - } -#endif - /* POSIX does not specify fflush behavior for non-seekable input - streams. Some implementations purge unread data, some return - EBADF, some do nothing. */ - pos = ftello (stream); - if (pos == -1) + /* Clear the ungetc buffer. */ + clear_ungetc_buffer (stream); + + /* To get here, we must be flushing a seekable input stream, so the + semantics of fpurge are now appropriate to clear the buffer. To + avoid losing data, the lseek is also necessary. */ { - errno = EBADF; - return EOF; + int result = fpurge (stream); + if (result != 0) + return result; } - /* To get here, we must be flushing a seekable input stream, so the - semantics of fpurge are now appropriate to clear the buffer. To - avoid losing data, the lseek is also necessary. */ - result = fpurge (stream); - if (result != 0) - return result; - -#if defined __sferror && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */ +# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ - { - /* Disable seek optimization for the next fseeko call. This tells the - following fseeko call to seek to the desired position directly, rather - than to seek to a block-aligned boundary. */ - int saved_flags = stream->_flags & (__SOPT | __SNPT); - stream->_flags = (stream->_flags & ~__SOPT) | __SNPT; + { + /* Disable seek optimization for the next fseeko call. This tells the + following fseeko call to seek to the desired position directly, rather + than to seek to a block-aligned boundary. */ + int saved_flags = disable_seek_optimization (stream); + int result = fseeko (stream, pos, SEEK_SET); + + restore_seek_optimization (stream, saved_flags); + return result; + } - result = fseeko (stream, pos, SEEK_SET); +# else - stream->_flags = (stream->_flags & ~(__SOPT | __SNPT)) | saved_flags; - } - return result; + pos = lseek (fileno (stream), pos, SEEK_SET); + if (pos == -1) + return EOF; + /* After a successful lseek, update the file descriptor's position cache + in the stream. */ + update_fpos_cache (stream, pos); -#else + return 0; - pos = lseek (fileno (stream), pos, SEEK_SET); - if (pos == -1) - return EOF; - /* After a successful lseek, update the file descriptor's position cache - in the stream. */ -# if defined __sferror /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */ - stream->_offset = pos; - stream->_flags |= __SOFF; # endif - - return 0; - + } #endif }