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Re: [PATCH v3 5/7] Add __vsyslog_internal, with same flags as __v*printf_internal.
On 15/11/2018 19:44, Gabriel F. T. Gomes wrote:
> From: Zack Weinberg <zackw@panix.com>
>
> Changes since v2
>
> - None, but dependent on previous patch in the set, thus resending.
LGTM.
>
> Changed since v1:
>
> - Fixed white-space errors.
> - Removed internal declaration of __vsyslog_chk, because it's no
> longer called from within libc. There's a call to it in the inline
> definition of vsyslog in bits/syslog.h, but that definition is only
> inlined in user code with:
> #if __USE_FORTIFY_LEVEL > 0 && defined __fortify_function
> - Removed libc_hidden_def and libc_hidden_proto for vsyslog, as it is
> never called internally (it never was).
> - Added attribute_hidden to the internal declaration of
> __vsyslog_internal. Here are the objdumps of one internal call,
> before and after this change, on a 32-bits powerpc machine:
> Without attribute_hidden:
> $ objdump -d --reloc SYSLOG-PRISTINE-glibc/libc.so | grep "<vsyslog@@GLIBC_2.4>:" -A 17
> 000fc790 <vsyslog@@GLIBC_2.4>:
> fc790: 94 21 ff f0 stwu r1,-16(r1)
> fc794: 38 c0 00 00 li r6,0
> fc798: 7c 08 02 a6 mflr r0
> fc79c: 42 9f 00 05 bcl 20,4*cr7+so,fc7a0 <vsyslog@@GLIBC_2.4+0x10>
> fc7a0: 93 c1 00 08 stw r30,8(r1)
> fc7a4: 90 01 00 14 stw r0,20(r1)
> fc7a8: 7f c8 02 a6 mflr r30
> fc7ac: 3f de 00 0a addis r30,r30,10
> fc7b0: 3b de 38 54 addi r30,r30,14420
> fc7b4: 4b ff f9 9d bl fc150 <__vsyslog_internal>
> fc7b8: 80 01 00 14 lwz r0,20(r1)
> fc7bc: 83 c1 00 08 lwz r30,8(r1)
> fc7c0: 38 21 00 10 addi r1,r1,16
> fc7c4: 7c 08 03 a6 mtlr r0
> fc7c8: 4e 80 00 20 blr
> fc7cc: 60 00 00 00 nop
> With attribute_hidden:
> $ objdump -d --reloc SYSLOG-PATCHED-glibc/libc.so | grep "<vsyslog@@GLIBC_2.4>:" -A 5
> 000fc780 <vsyslog@@GLIBC_2.4>:
> fc780: 38 c0 00 00 li r6,0
> fc784: 4b ff f9 cc b fc150 <__vsyslog_internal>
> fc788: 60 00 00 00 nop
> fc78c: 60 00 00 00 nop
>
> -- 8< --
> __nldbl___vsyslog_chk will ultimately want to pass PRINTF_LDBL_IS_DBL
> down to __vfprintf_internal *as well as* possibly setting PRINTF_FORTIFY.
> To make that possible, we need a __vsyslog_internal that takes the
> same flags as printf. The code in misc/syslog.c does also get a
> little simpler.
>
> Tested for powerpc and powerpc64le.
>
> 2018-10-16 Zack Weinberg <zackw@panix.com>
> Gabriel F. T. Gomes <gabriel@inconstante.eti.br>
>
> * misc/syslog.c: Include libioP.h, not iolibio.h.
> (__vsyslog_internal): New function with the former body of
> __vsyslog_chk; takes mode_flags argument same as
> __v*printf_internal. Call __vfprintf_internal directly.
>
> (__vsyslog_chk): Now a wrapper around __vsyslog_internal.
> Remove libc_hidden_def.
> (__syslog, __syslog_chk): Use __vsyslog_internal.
> (__vsyslog): Move to just below __syslog. Use __vsyslog_internal.
>
> * include/sys/syslog.h: Add multiple inclusion guard.
> Add prototype for __vsyslog_internal.
> Remove declaration and libc_hidden_proto for __vsyslog_chk.
>
> * sysdeps/ieee754/ldbl-opt/nldbl-compat.c (__nldbl___vsyslog_chk):
> Use __vsyslog_internal.
> ---
> include/sys/syslog.h | 19 ++++++++++-------
> misc/syslog.c | 36 +++++++++++++++++----------------
> sysdeps/ieee754/ldbl-opt/nldbl-compat.c | 2 +-
> 3 files changed, 32 insertions(+), 25 deletions(-)
>
> diff --git a/include/sys/syslog.h b/include/sys/syslog.h
> index 3be3189ed1..89d3479ebc 100644
> --- a/include/sys/syslog.h
> +++ b/include/sys/syslog.h
> @@ -1,11 +1,16 @@
> +#ifndef _LIBC_SYS_SYSLOG_H
> +#define _LIBC_SYS_SYSLOG_H 1
> #include <misc/sys/syslog.h>
> -
> #ifndef _ISOMAC
> +
> libc_hidden_proto (syslog)
> -libc_hidden_proto (vsyslog)
>
> -extern void __vsyslog_chk (int __pri, int __flag, const char *__fmt,
> - __gnuc_va_list __ap)
> - __attribute__ ((__format__ (__printf__, 3, 0)));
> -libc_hidden_proto (__vsyslog_chk)
> -#endif
> +/* __vsyslog_internal uses the same mode_flags bits as
> + __v*printf_internal; see libio/libioP.h. */
> +extern void __vsyslog_internal (int pri, const char *fmt, __gnuc_va_list ap,
> + unsigned int mode_flags)
> + attribute_hidden
> + __attribute__ ((__format__ (__printf__, 2, 0)));
> +
> +#endif /* _ISOMAC */
> +#endif /* syslog.h */
Ok.
> diff --git a/misc/syslog.c b/misc/syslog.c
> index 644dbe80ec..3a15da41ce 100644
> --- a/misc/syslog.c
> +++ b/misc/syslog.c
> @@ -53,7 +53,7 @@ static char sccsid[] = "@(#)syslog.c 8.4 (Berkeley) 3/18/94";
>
> #include <stdarg.h>
>
> -#include <libio/iolibio.h>
> +#include <libio/libioP.h>
> #include <math_ldbl_opt.h>
>
> #include <kernel-features.h>
> @@ -114,24 +114,38 @@ __syslog(int pri, const char *fmt, ...)
> va_list ap;
>
> va_start(ap, fmt);
> - __vsyslog_chk(pri, -1, fmt, ap);
> + __vsyslog_internal(pri, fmt, ap, 0);
> va_end(ap);
> }
> ldbl_hidden_def (__syslog, syslog)
> ldbl_strong_alias (__syslog, syslog)
>
> +void
> +__vsyslog(int pri, const char *fmt, va_list ap)
> +{
> + __vsyslog_internal(pri, fmt, ap, 0);
> +}
> +ldbl_weak_alias (__vsyslog, vsyslog)
> +
> void
> __syslog_chk(int pri, int flag, const char *fmt, ...)
> {
> va_list ap;
>
> va_start(ap, fmt);
> - __vsyslog_chk(pri, flag, fmt, ap);
> + __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
> va_end(ap);
> }
>
> void
> __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
> +{
> + __vsyslog_internal(pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
> +}
> +
> +void
> +__vsyslog_internal(int pri, const char *fmt, va_list ap,
> + unsigned int mode_flags)
> {
> struct tm now_tm;
> time_t now;
> @@ -215,11 +229,8 @@ __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
> __set_errno (saved_errno);
>
> /* We have the header. Print the user's format into the
> - buffer. */
> - if (flag == -1)
> - vfprintf (f, fmt, ap);
> - else
> - __vfprintf_chk (f, flag, fmt, ap);
> + buffer. */
> + __vfprintf_internal (f, fmt, ap, mode_flags);
>
> /* Close the memory stream; this will finalize the data
> into a malloc'd buffer in BUF. */
> @@ -316,15 +327,6 @@ __vsyslog_chk(int pri, int flag, const char *fmt, va_list ap)
> if (buf != failbuf)
> free (buf);
> }
> -libc_hidden_def (__vsyslog_chk)
> -
> -void
> -__vsyslog(int pri, const char *fmt, va_list ap)
> -{
> - __vsyslog_chk (pri, -1, fmt, ap);
> -}
> -ldbl_hidden_def (__vsyslog, vsyslog)
> -ldbl_weak_alias (__vsyslog, vsyslog)
>
> static struct sockaddr_un SyslogAddr; /* AF_UNIX address of local logger */
>
Ok.
> diff --git a/sysdeps/ieee754/ldbl-opt/nldbl-compat.c b/sysdeps/ieee754/ldbl-opt/nldbl-compat.c
> index bda84af0bb..958bbc1834 100644
> --- a/sysdeps/ieee754/ldbl-opt/nldbl-compat.c
> +++ b/sysdeps/ieee754/ldbl-opt/nldbl-compat.c
> @@ -843,7 +843,7 @@ attribute_compat_text_section
> __nldbl___vsyslog_chk (int pri, int flag, const char *fmt, va_list ap)
> {
> set_no_long_double ();
> - __vsyslog_chk (pri, flag, fmt, ap);
> + __vsyslog_internal (pri, fmt, ap, (flag > 0) ? PRINTF_FORTIFY : 0);
> clear_no_long_double ();
> }
> libc_hidden_def (__nldbl___vsyslog_chk)
>
Ok.