X-Git-Url: https://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Ffflush.c;h=fa6f389fb94cb7cb5acc5c76f5a59c88e9a2000b;hb=e1baaf8d7c7da5c45041f3ecaf227dfd03c01891;hp=f143247f67df93559c4b91602e6799128c7390ff;hpb=284866a44c1115e8786a23c7a50d3e710fc75afd;p=gnulib.git diff --git a/lib/fflush.c b/lib/fflush.c index f143247f6..fa6f389fb 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) 2007-2012 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 @@ -25,24 +25,52 @@ #include #include "freading.h" -#include "fpurge.h" #include "stdio-impl.h" +#include "unused-parameter.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 defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ if (HASUB (fp)) { fp_->_p += fp_->_r; fp_->_r = 0; } -#endif +# elif defined __EMX__ /* emx+gcc */ + if (fp->_ungetc_count > 0) + { + fp->_ungetc_count = 0; + fp->_rcount = - fp->_rcount; + } +# elif defined _IOERR /* Minix, AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw, NonStop Kernel */ + /* 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 @@ -62,10 +90,26 @@ restore_seek_optimization (FILE *fp, int saved_flags) #endif static inline void -update_fpos_cache (FILE *fp) +update_fpos_cache (FILE *fp _GL_UNUSED_PARAMETER, + off_t pos _GL_UNUSED_PARAMETER) { #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 } @@ -75,9 +119,6 @@ update_fpos_cache (FILE *fp) 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. @@ -100,70 +141,81 @@ 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. */ - clear_ungetc_buffer (stream); - - /* 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) - { - errno = EBADF; - return EOF; - } +#if defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Haiku, Linux libc5 */ - /* 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; + clear_ungetc_buffer_preserving_position (stream); -#if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ + return fflush (stream); +#else { - /* 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); + /* 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) + { + errno = EBADF; + return EOF; + } + + /* 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. */ + { + int result = fpurge (stream); + if (result != 0) + return result; + } - result = fseeko (stream, pos, SEEK_SET); +# if (defined __sferror || defined __DragonFly__) && defined __SNPT /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */ - restore_seek_optimization (stream, saved_flags); - } - return result; + { + /* 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; + } -#else +# else - 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 = 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); - return 0; + return 0; +# endif + } #endif }