4 Commits

Author	SHA1	Message	Date
Zack Weinberg	03992356e6	Use C99-compliant scanf under _GNU_SOURCE with modern compilers. ... The only difference between noncompliant and C99-compliant scanf is that the former accepts the archaic GNU extension '%as' (also %aS and %a[...]) meaning to allocate space for the input string with malloc. This extension conflicts with C99's use of %a as a format _type_ meaning to read a floating-point number; POSIX.1-2008 standardized equivalent functionality using the modifier letter 'm' instead (%ms, %mS, %m[...]). The extension was already disabled in most conformance modes: specifically, any mode that doesn't involve _GNU_SOURCE and _does_ involve either strict conformance to C99 or loose conformance to both C99 and POSIX.1-2001 would get the C99-compliant scanf. With compilers new enough to use -std=gnu11 instead of -std=gnu89, or equivalent, that includes the default mode. With this patch, we now provide C99-compliant scanf in all configurations except when _GNU_SOURCE is defined *and* __STDC_VERSION__ or __cplusplus (whichever is relevant) indicates C89/C++98. This leaves the old scanf available under e.g. -std=c89 -D_GNU_SOURCE, but removes it from e.g. -std=gnu11 -D_GNU_SOURCE (it was already not present under -std=gnu11 without -D_GNU_SOURCE) and from -std=gnu89 without -D_GNU_SOURCE. There needs to be an internal override so we can compile the noncompliant scanf itself. This is the same problem we had when we removed 'gets' from _GNU_SOURCE and it's dealt with the same way: there's a new __GLIBC_USE symbol, DEPRECATED_SCANF, which defaults to off under the appropriate conditions for external code, but can be overridden by individual files within stdio. We also run into problems with PLT bypass for internal uses of sscanf, because libc_hidden_proto uses __REDIRECT and so does the logic in stdio.h for choosing which implementation of scanf to use; __REDIRECT isn't transitive, so include/stdio.h needs to bridge the gap with a macro. As far as I can tell, sscanf is the only function in this family that's internally called by unrelated code. Finally, there are several tests in stdio-common that use the extension. bug21.c is a regression test for a crash; it still exercises the relevant code when changed to use %ms instead of %as. scanf14.c through scanf17.c are more complicated since they are actually testing the subtleties of the extension - under what circumstances is 'a' treated as a modifier letter, etc. I changed all of them to use %ms instead of %as as well, but duplicated scanf14.c and scanf16.c as scanf14a.c and scanf16a.c. These still use %as and are compiled with -std=gnu89 to access the old extension. A bunch of diagnostic overrides and manual workarounds for the old stdio.h behavior become unnecessary. Yay! * include/features.h (__GLIBC_USE_DEPRECATED_SCANF): New __GLIBC_USE parameter. Only use deprecated scanf when __USE_GNU is defined and __STDC_VERSION__ is less than 199901L or __cplusplus is less than 201103L, whichever is relevant for the language being compiled. * libio/stdio.h, libio/bits/stdio-ldbl.h: Decide whether to redirect scanf, fscanf, sscanf, vscanf, vfscanf, and vsscanf to their __isoc99_ variants based only on __GLIBC_USE (DEPRECATED_SCANF). * wcsmbs/wchar.h: wcsmbs/bits/wchar-ldbl.h: Likewise for wscanf, fwscanf, swscanf, vwscanf, vfwscanf, and vswscanf. * libio/iovsscanf.c * libio/fwscanf.c * libio/iovswscanf.c * libio/swscanf.c * libio/vscanf.c * libio/vwscanf.c * libio/wscanf.c * stdio-common/fscanf.c * stdio-common/scanf.c * stdio-common/vfscanf.c * stdio-common/vfwscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-compat.c * sysdeps/ieee754/ldbl-opt/nldbl-fscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-fwscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-iovfscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-scanf.c * sysdeps/ieee754/ldbl-opt/nldbl-sscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-swscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vfscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vfwscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vsscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vswscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-vwscanf.c * sysdeps/ieee754/ldbl-opt/nldbl-wscanf.c: Override __GLIBC_USE_DEPRECATED_SCANF to 1. * stdio-common/sscanf.c: Likewise. Remove ldbl_hidden_def for __sscanf. * stdio-common/isoc99_sscanf.c: Add libc_hidden_def for __isoc99_sscanf. * include/stdio.h: Provide libc_hidden_proto for __isoc99_sscanf, not sscanf. [!__GLIBC_USE (DEPRECATED_SCANF)]: Define sscanf as __isoc99_scanf with a preprocessor macro. * stdio-common/bug21.c, stdio-common/scanf14.c: Use %ms instead of %as, %mS instead of %aS, %m[] instead of %a[]; remove DIAG_IGNORE_NEEDS_COMMENT for -Wformat. * stdio-common/scanf16.c: Likewise. Add __attribute__ ((format (scanf))) to xscanf, xfscanf, xsscanf. * stdio-common/scanf14a.c: New copy of scanf14.c which still uses %as, %aS, %a[]. Remove DIAG_IGNORE_NEEDS_COMMENT for -Wformat. * stdio-common/scanf16a.c: New copy of scanf16.c which still uses %as, %aS, %a[]. Add __attribute__ ((format (scanf))) to xscanf, xfscanf, xsscanf. * stdio-common/scanf15.c, stdio-common/scanf17.c: No need to override feature selection macros or provide definitions of u_char etc. * stdio-common/Makefile (tests): Add scanf14a and scanf16a. (CFLAGS-scanf15.c, CFLAGS-scanf17.c): Remove. (CFLAGS-scanf14a.c, CFLAGS-scanf16a.c): New. Compile these files with -std=gnu89.	2019-01-03 11:12:39 -05:00
Joseph Myers	acf0cb6f24	Don't include <bits/stdio-lock.h> from installed <libio.h>. ... Every so often someone gets confused by the fact that the installed <bits/stdio-lock.h> header includes the non-installed <lowlevellock.h> header. This inclusion is not in fact a bug, because <bits/stdio-lock.h> only gets included by any header that users should include directly if _IO_MTSAFE_IO is defined, and that's an internal define used when building libio, not a feature test macro it's valid for users to define. However, on general principles it's best to have as little as possible in the installed headers that is inapplicable for valid uses of the installed glibc. This patch moves the include of <bits/stdio-lock.h> to the internal header include/libio.h, so that even if someone defines _IO_MTSAFE_IO it won't get included. This is intended as preparation for stopping <bits/stdio-lock.h> and <bits/libc-lock.h> from being installed at all (after this patch they aren't used in any installed header; formally of course they don't need to be installed even before this patch, but stopping them being installed before removing the #include would just exacerbate the confusion described above), and then moving those out of the bits/ namespace in accordance with the principle that that namespace is only for installed headers. The tests scanf15.c and scanf17.c avoid the internal headers; after this patch that means they need to undefine _IO_MTSAFE_IO as well as _LIBC so as to get a working _IO_lock_t definition for libio.h. This brings them closer to using the headers as an installed program would, which clearly accords with the intent of those tests. Tested for x86_64 (testsuite, and that installed stripped shared libraries are unchanged by the patch). * libio/libio.h [_IO_MTSAFE_IO]: Remove include of <bits/stdio-lock.h> and commented-out include of <comthread.h>. * include/libio.h [!_ISOMAC && _IO_MTSAFE_IO]: Include <bits/stdio-lock.h>. * stdio-common/scanf15.c (_IO_MTSAFE_IO): Undefine. * stdio-common/scanf17.c (_IO_MTSAFE_IO): Likewise.	2015-09-03 20:24:54 +00:00
Ulrich Drepper	b48a267b8f	Preserve SSE registers in runtime relocations on x86-64. ... SSE registers are used for passing parameters and must be preserved in runtime relocations. This is inside ld.so enforced through the tests in tst-xmmymm.sh. But the malloc routines used after startup come from libc.so and can be arbitrarily complex. It's overkill to save the SSE registers all the time because of that. These calls are rare. Instead we save them on demand. The new infrastructure put in place in this patch makes this possible and efficient.	2009-07-29 08:33:03 -07:00
Jakub Jelinek	ad8a551196	* libio/stdio.h (vscanf): Fix -std=c99 redirect. ... * stdio-common/Makefile (tests): Add scanf16 and scanf17. (CFLAGS-scanf17.c): New. * stdio-common/scanf14.c (main): Add fscanf and scanf tests. * stdio-common/scanf15.c (main): Likewise. * stdio-common/scanf16.c: New test. * stdio-common/scanf17.c: New test. 2008-05-24 Jakub Jelinek <jakub@redhat.com> * libio/stdio.h (vscanf): Fix -std=c99 redirect. * stdio-common/Makefile (tests): Add scanf16 and scanf17. (CFLAGS-scanf17.c): New. * stdio-common/scanf14.c (main): Add fscanf and scanf tests. * stdio-common/scanf15.c (main): Likewise. * stdio-common/scanf16.c: New test. * stdio-common/scanf17.c: New test.	2008-05-24 18:14:36 +00:00