From 0b727ed4d605d9318cb0d323c88abb0d5a441a9b Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Thu, 13 Jul 2017 16:43:24 -0300 Subject: libio: Flush stream at freopen (BZ#21037) As POSIX states [1] a freopen call should first flush the stream as if by a call fflush. C99 (n1256) and C11 (n1570) only states the function should first close any file associated with the specific stream. Although current implementation only follow C specification, current BSD and other libc implementation (musl) are in sync with POSIX and fflush the stream. This patch change freopen{64} to fflush the stream before actually reopening it (or returning if the stream does not support reopen). It also changes the Linux implementation to avoid a dynamic allocation on 'fd_to_filename'. Checked on x86_64-linux-gnu. [BZ #21037] * libio/Makefile (tests): Add tst-memstream4 and tst-wmemstream4. * libio/freopen.c (freopen): Sync stream before reopen and adjust to new fd_to_filename interface. * libio/freopen64.c (freopen64): Likewise. * libio/tst-memstream.h: New file. * libio/tst-memstream4.c: Likewise. * libio/tst-wmemstream4.c: Likewise. * sysdeps/generic/fd_to_filename.h (fd_to_filename): Change signature. * sysdeps/unix/sysv/linux/fd_to_filename.h (fd_to_filename): Likewise and remove internal dynamic allocation. [1] http://pubs.opengroup.org/onlinepubs/9699919799/ --- libio/freopen.c | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) (limited to 'libio/freopen.c') diff --git a/libio/freopen.c b/libio/freopen.c index abf19e96f1..6ce74ae449 100644 --- a/libio/freopen.c +++ b/libio/freopen.c @@ -24,28 +24,34 @@ This exception applies to code released by its copyright holders in files containing the exception. */ -#include "libioP.h" -#include "stdio.h" +#include #include #include #include -#include +#include #include - -#include +#include FILE * freopen (const char *filename, const char *mode, FILE *fp) { - FILE *result; + FILE *result = NULL; + char fdfilename[FD_TO_FILENAME_SIZE]; + CHECK_FILE (fp, NULL); - if (!(fp->_flags & _IO_IS_FILEBUF)) - return NULL; + _IO_acquire_lock (fp); + /* First flush the stream (failure should be ignored). */ + _IO_SYNC (fp); + + if (!(fp->_flags & _IO_IS_FILEBUF)) + goto end; + int fd = _IO_fileno (fp); - const char *gfilename = (filename == NULL && fd >= 0 - ? fd_to_filename (fd) : filename); + const char *gfilename + = filename != NULL ? filename : fd_to_filename (fd, fdfilename); + fp->_flags2 |= _IO_FLAGS2_NOCLOSE; #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1) if (&_IO_stdin_used == NULL) @@ -101,9 +107,6 @@ freopen (const char *filename, const char *mode, FILE *fp) __close (fd); end: - if (filename == NULL) - free ((char *) gfilename); - _IO_release_lock (fp); return result; } -- cgit v1.2.1