Re: [PATCH 2/9] Add __vfscanf_internal and __vfwscanf_internal with flags arguments.

["Gabriel F. T. Gomes" <gabriel at inconstante dot eti dot br>]

On Wed, 07 Mar 2018, Zack Weinberg wrote:

>(It was necessary to introduce ldbl_compat_symbol for _IO_vfscanf.
>Please check that part of the patch very carefully, I am still not
>confident I understand all of the details of ldbl-opt.)

It looks good on powerpc64...  Oldest symbol (where long double had the
same format as double) is still there as a compat symbol with version
GLIBC_2.3...  The newer symbol, is a bit different, in the sense that it
is now a compat symbol (it was a default symbol previously).

Here's what readelf has to tell us:

Before the patch set:
  1355: 00000000001eea70   124 FUNC    GLOBAL DEFAULT   27 _IO_vfscanf@GLIBC_2.3
  1356: 00000000001f0a98 23552 FUNC    GLOBAL DEFAULT   27 _IO_vfscanf@@GLIBC_2.4

After the patch set:
  1355: 00000000001f0bd0   136 FUNC    GLOBAL DEFAULT   27 _IO_vfscanf@GLIBC_2.4
  1356: 00000000001ee968   136 FUNC    GLOBAL DEFAULT   27 _IO_vfscanf@GLIBC_2.3

For the static library, I think that Adhemerval is right (see comment below).

>	* libio/libioP.h (SCANF_LDBL_IS_DBL, SCANF_ISOC99_A): New constants.
>	(__vfscanf_internal, __vfwscanf_internal): New function prototypes.
>        * libio/libio.h: Remove libc_hidden_proto for _IO_vfscanf.
 ~~~~~~~~
Spaces instead of tabs.

>	* libio/strfile.h: Add multiple inclusion guard.

Perhaps mention the removal of stdio.h inclusion?

>        * stdio-common/Versions: Mention GLIBC_2.28, so that
>        it can be used in SHLIB_COMPAT expressions.
 ~~~~~~~~
Spaces instead of tabs.

>+extern int __vfscanf_internal (FILE *fp, const char *format, va_list argp,
>+                               unsigned int flags);
  ~~~~~~~~~~~~~~~~~~~~~~~~
>+extern int __vfwscanf_internal (FILE *fp, const wchar_t *format, va_list argp,
>+                                unsigned int flags);
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Spaces instead of tabs.

>+/* Initialize an _IO_strfile SF and _IO_wide_data WD to read from wide
>+   string STRING, and return the corresponding FILE object.  It is not
>+   necessary to fclose the FILE when it is no longer needed.  */
>+static inline FILE *
>+_IO_strfile_readw (_IO_strfile *sf, struct _IO_wide_data *wd,
>+                   const wchar_t *string)
  ~~~~~~~~~~~~~~~~
Spaces instead of tabs.

>--- /dev/null
>+++ b/stdio-common/iovfscanf.c
>@@ -0,0 +1,34 @@
>+/* Copyright (C) 1991-2018 Free Software Foundation, Inc.

Should this (and other new files) be copyright 2018, since they're new?

>--- a/stdio-common/vfscanf.c
>+++ b/stdio-common/vfscanf-internal.c
>-_IO_vfwscanf (FILE *s, const wchar_t *format, va_list argptr,
>-	      int *errp)
>+__vfwscanf_internal (FILE *s, const wchar_t *format, va_list argptr,
>+                     unsigned int mode_flags)
  ~~~~~~~~~~~~~~~~
Spaces instead of tabs.

>-_IO_vfscanf_internal (FILE *s, const char *format, va_list argptr,
>-		      int *errp)
>+__vfscanf_internal (FILE *s, const char *format, va_list argptr,
>+                    unsigned int mode_flags)
  ~~~~~~~~~~~~~~~~
Spaces instead of tabs.

>--- a/sysdeps/ieee754/ldbl-opt/math_ldbl_opt.h
>+++ b/sysdeps/ieee754/ldbl-opt/math_ldbl_opt.h
>@@ -20,10 +20,14 @@
>   long_double_symbol (libc, __GL_##name##_##aliasname, aliasname);
> # define long_double_symbol_1(lib, local, symbol, version) \
>   versioned_symbol (lib, local, symbol, version)
>+# define ldbl_compat_symbol(lib, local, symbol, version) \
>+  compat_symbol (lib, local, symbol, LONG_DOUBLE_COMPAT_VERSION)
> #else
> # define ldbl_hidden_def(local, name) libc_hidden_def (name)
> # define ldbl_strong_alias(name, aliasname) strong_alias (name, aliasname)
> # define ldbl_weak_alias(name, aliasname) weak_alias (name, aliasname)
>+# define ldbl_compat_symbol(lib, local, symbol, version) \
>+  compat_symbol (lib, local, symbol, version)

I believe that Adhemerval's comment is correct and ldbl_compat_symbol
should translate to nothing when building static libraries.