GLIBC explicitly allows one to assign a new FILE pointer to stdout and other standard streams. printf and wprintf were honouring assignment to stdout and using the new value, but puts, putchar, and wide char variants did not. The stdout part is fixed here. The stdin part will be fixed in a followup.
* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
C99 specifies that the EOF condition on a file is "sticky": once EOF
has been encountered, all subsequent reads should continue to return
EOF until the file is closed or something clears the "end-of-file
indicator" (e.g. fseek, clearerr). This is arguably a change from
C89, where the wording was ambiguous; the BSDs always had sticky EOF,
but the System V lineage would attempt to read from the underlying fd
again. GNU libc has followed System V for as long as we've been
using libio, but nowadays C99 conformance and BSD compatibility are
more important than System V compatibility.
You might wonder if changing the _underflow impls is sufficient to
apply the C99 semantics to all of the many stdio functions that
perform input. It should be enough to cover all paths to _IO_SYSREAD,
and the only other functions that call _IO_SYSREAD are the _seekoff
impls, which is OK because seeking clears EOF, and the _xsgetn impls,
which, as far as I can tell, are unused within glibc.
The test programs in this patch use a pseudoterminal to set up the
necessary conditions. To facilitate this I added a new test-support
function that sets up a pair of pty file descriptors for you; it's
almost the same as BSD openpty, the only differences are that it
allocates the optionally-returned tty pathname with malloc, and that
it crashes if anything goes wrong.
[BZ #1190]
[BZ #19476]
* libio/fileops.c (_IO_new_file_underflow): Return EOF immediately
if the _IO_EOF_SEEN bit is already set; update commentary.
* libio/oldfileops.c (_IO_old_file_underflow): Likewise.
* libio/wfileops.c (_IO_wfile_underflow): Likewise.
* support/support_openpty.c, support/tty.h: New files.
* support/Makefile (libsupport-routines): Add support_openpty.
* libio/tst-fgetc-after-eof.c, wcsmbs/test-fgetwc-after-eof.c:
New test cases.
* libio/Makefile (tests): Add tst-fgetc-after-eof.
* wcsmbs/Makefile (tests): Add tst-fgetwc-after-eof.
This patch eliminates a number of #if 0 and #ifdef TODO blocks, macros that are never used, macros that provide portability to substrates that lack basic things like EINVAL and off_t, and other such debris. I preserved IO_DEBUG and CHECK_FILE, even though as far as I can tell IO_DEBUG is never defined and therefore CHECK_FILE never does anything, because it seems like we might actually want to turn it _on_. Installed stripped libraries and executables are unchanged, except, again, that the line number of an assertion changes (this time it's somewhere in fileops.c). * libio/libio.h (_IO_pos_BAD, _IO_pos_0, _IO_pos_adjust): Define here, unconditionally. * libio/iolibio.h (_IO_pos_BAD): Don't define here. * libio/libioP.h: Remove #if 0 blocks. (_IO_pos_BAD, _IO_pos_0, _IO_pos_adjust): Don't define here. (_IO_va_start, COERCE_FILE, MAYBE_SET_EINVAL): Don't define. (CHECK_FILE): Don't use MAYBE_SET_EINVAL or COERCE_FILE. Fix style. * libio/clearerr.c, libio/fputc.c, libio/getchar.c: Assume weak_alias is always defined. * libio/fileops.c, libio/genops.c, libio/oldfileops.c * libio/oldpclose.c, libio/pclose.c, libio/wfileops.c: Remove #if 0 and #ifdef TODO blocks. Assume text_set_element is always defined. * libio/iofdopen.c, libio/iogetdelim.c, libio/oldiofdopen.c Use __set_errno (EINVAL) instead of MAYBE_SET_EINVAL. * libio/tst-mmap-eofsync.c: Make #if 1 block unconditional.
This patch mechanically removes all remaining uses, and the definitions, of the following libio name aliases: name replaced with ---- ------------- _IO_FILE FILE _IO_fpos_t __fpos_t _IO_fpos64_t __fpos64_t _IO_size_t size_t _IO_ssize_t ssize_t or __ssize_t _IO_off_t off_t _IO_off64_t off64_t _IO_pid_t pid_t _IO_uid_t uid_t _IO_wint_t wint_t _IO_va_list va_list or __gnuc_va_list _IO_BUFSIZ BUFSIZ _IO_cookie_io_functions_t cookie_io_functions_t __io_read_fn cookie_read_function_t __io_write_fn cookie_write_function_t __io_seek_fn cookie_seek_function_t __io_close_fn cookie_close_function_t I used __fpos_t and __fpos64_t instead of fpos_t and fpos64_t because the definitions of fpos_t and fpos64_t depend on the largefile mode. I used __ssize_t and __gnuc_va_list in a handful of headers where namespace cleanliness might be relevant even though they're internal-use-only. In all other cases, I used the public-namespace name. There are a tiny handful of places where I left a use of 'struct _IO_FILE' alone, because it was being used together with 'struct _IO_FILE_plus' or 'struct _IO_FILE_complete' in the same arithmetic expression. Because this patch was almost entirely done with search and replace, I may have introduced indentation botches. I did proofread the diff, but I may have missed something. The ChangeLog below calls out all of the places where this was not a pure search-and-replace change. Installed stripped libraries and executables are unchanged by this patch, except that some assertions in vfscanf.c change line numbers. * libio/libio.h (_IO_FILE): Delete; all uses changed to FILE. (_IO_fpos_t): Delete; all uses changed to __fpos_t. (_IO_fpos64_t): Delete; all uses changed to __fpos64_t. (_IO_size_t): Delete; all uses changed to size_t. (_IO_ssize_t): Delete; all uses changed to ssize_t or __ssize_t. (_IO_off_t): Delete; all uses changed to off_t. (_IO_off64_t): Delete; all uses changed to off64_t. (_IO_pid_t): Delete; all uses changed to pid_t. (_IO_uid_t): Delete; all uses changed to uid_t. (_IO_wint_t): Delete; all uses changed to wint_t. (_IO_va_list): Delete; all uses changed to va_list or __gnuc_va_list. (_IO_BUFSIZ): Delete; all uses changed to BUFSIZ. (_IO_cookie_io_functions_t): Delete; all uses changed to cookie_io_functions_t. (__io_read_fn): Delete; all uses changed to cookie_read_function_t. (__io_write_fn): Delete; all uses changed to cookie_write_function_t. (__io_seek_fn): Delete; all uses changed to cookie_seek_function_t. (__io_close_fn): Delete: all uses changed to cookie_close_function_t. * libio/iofopncook.c: Remove unnecessary forward declarations. * libio/iolibio.h: Correct outdated commentary. * malloc/malloc.c (__malloc_stats): Remove unnecessary casts. * stdio-common/fxprintf.c (__fxprintf_nocancel): Remove unnecessary casts. * stdio-common/getline.c: Use _IO_getdelim directly. Don't redefine ssize_t. * stdio-common/printf_fp.c, stdio_common/printf_fphex.c * stdio-common/printf_size.c: Don't redefine size_t or FILE. Remove outdated comments. * stdio-common/vfscanf.c: Don't redefine va_list.
* All files with FSF copyright notices: Update copyright dates using scripts/update-copyrights. * locale/programs/charmap-kw.h: Regenerated. * locale/programs/locfile-kw.h: Likewise.
Some libio operations fail to correctly free the backup area (created
by _IO_{w}default_pbackfail on unget{w}c) resulting in either invalid
buffer free operations or memory leaks.
For instance, on the example provided by BZ#22415 a following
fputc after a fseek to rewind the stream issues an invalid free on
the buffer. It is because although _IO_file_overflow correctly
(from fputc) correctly calls _IO_free_backup_area, the
_IO_new_file_seekoff (called by fseek) updates the FILE internal
pointers without first free the backup area (resulting in invalid
values in the internal pointers).
The wide version also shows an issue, but instead of accessing invalid
pointers it leaks the backup memory on fseek/fputwc operation.
Checked on x86_64-linux-gnu and i686-linux-gnu.
* libio/Makefile (tests): Add tst-bz22415.
(tst-bz22415-ENV): New rule.
(generated): Add tst-bz22415.mtrace and tst-bz22415.check.
(tests-special): Add tst-bz22415-mem.out.
($(objpfx)tst-bz22415-mem.out): New rule.
* libio/fileops.c (_IO_new_file_seekoff): Call _IO_free_backup_area
in case of a successful seek operation.
* libio/wfileops.c (_IO_wfile_seekoff): Likewise.
(_IO_wfile_overflow): Call _IO_free_wbackup_area in case a write
buffer is required.
* libio/tst-bz22415.c: New test.
Do not define _POSIX_SOURCE.
This commit puts all libio vtables in a dedicated, read-only ELF section, so that they are consecutive in memory. Before any indirect jump, the vtable pointer is checked against the section boundaries, and the process is terminated if the vtable pointer does not fall into the special ELF section. To enable backwards compatibility, a special flag variable (_IO_accept_foreign_vtables), protected by the pointer guard, avoids process termination if libio stream object constructor functions have been called earlier. Such constructor functions are called by the GCC 2.95 libstdc++ library, and this mechanism ensures compatibility with old binaries. Existing callers inside glibc of these functions are adjusted to call the original functions, not the wrappers which enable vtable compatiblity. The compatibility mechanism is used to enable passing FILE * objects across a static dlopen boundary, too.