The buffer resizing algorithm is slightly different.  The initial
buffer is on the stack, and small buffers are directly allocated
on the heap using the exact required size.  The overhead of the
additional copy is compensated by the lowered setup cost for buffers
compared to libio streams.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.

I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah.  I don't
know why I run into these diagnostics whereas others evidently do not.

remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines

I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 6694 files FOO.
I then removed trailing white space from benchtests/bench-pthread-locks.c
and iconvdata/tst-iconv-big5-hkscs-to-2ucs4.c, to work around this
diagnostic from Savannah:
remote: *** pre-commit check failed ...
remote: *** error: lines with trailing whitespace found
remote: error: hook declined to update refs/heads/master

Also, change sources.redhat.com to sourceware.org.
This patch was automatically generated by running the following shell
script, which uses GNU sed, and which avoids modifying files imported
from upstream:

sed -ri '
  s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g
  s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g
' \
  $(find $(git ls-files) -prune -type f \
      ! -name '*.po' \
      ! -name 'ChangeLog*' \
      ! -path COPYING ! -path COPYING.LIB \
      ! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \
      ! -path manual/texinfo.tex ! -path scripts/config.guess \
      ! -path scripts/config.sub ! -path scripts/install-sh \
      ! -path scripts/mkinstalldirs ! -path scripts/move-if-change \
      ! -path INSTALL ! -path  locale/programs/charmap-kw.h \
      ! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \
      ! '(' -name configure \
            -execdir test -f configure.ac -o -f configure.in ';' ')' \
      ! '(' -name preconfigure \
            -execdir test -f preconfigure.ac ';' ')' \
      -print)

and then by running 'make dist-prepare' to regenerate files built
from the altered files, and then executing the following to cleanup:

  chmod a+x sysdeps/unix/sysv/linux/riscv/configure
  # Omit irrelevant whitespace and comment-only changes,
  # perhaps from a slightly-different Autoconf version.
  git checkout -f \
    sysdeps/csky/configure \
    sysdeps/hppa/configure \
    sysdeps/riscv/configure \
    sysdeps/unix/sysv/linux/csky/configure
  # Omit changes that caused a pre-commit check to fail like this:
  # remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines
  git checkout -f \
    sysdeps/powerpc/powerpc64/ppc-mcount.S \
    sysdeps/unix/sysv/linux/s390/s390-64/syscall.S
  # Omit change that caused a pre-commit check to fail like this:
  # remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline
  git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S

	* 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.

There are a lot more printf variants than there are scanf variants,
and the code for setting up and tearing down their custom FILE
variants around the call to __vf(w)printf is more complicated and
variable.  Therefore, I have added _internal versions of all the
v*printf variants, rather than introducing helper routines so that
they can all directly call __vf(w)printf_internal, as was done with
scanf.

As with the scanf changes, in this patch the _internal functions still
look at the environmental mode bits and all callers pass 0 for the
flags parameter.

Several of the affected public functions had _IO_ name aliases that
were not exported (but, in one case, appeared in libio.h anyway);
I was originally planning to leave them as aliases to avoid having
to touch internal callers, but it turns out ldbl_*_alias only work
for exported symbols, so they've all been removed instead.  It also
turns out there were hardly any internal callers.  _IO_vsprintf and
_IO_vfprintf *are* exported, so those two stick around.

Summary for the changes to each of the affected symbols:

  _IO_vfprintf, _IO_vsprintf:
    All internal calls removed, thus the internal declarations, as well
    as uses of libc_hidden_proto and libc_hidden_def, were also removed.
    The external symbol is now exposed via uses of ldbl_strong_alias
    to __vfprintf_internal and __vsprintf_internal, respectively.

  _IO_vasprintf, _IO_vdprintf, _IO_vsnprintf,
  _IO_vfwprintf, _IO_vswprintf,
  _IO_obstack_vprintf, _IO_obstack_printf:
    All internal calls removed, thus declaration in internal headers
    were also removed.  They were never exported, so there are no
    aliases tying them to the internal functions.  I.e.: entirely gone.

  __vsnprintf:
    Internal calls were always preceded by macros such as
      #define __vsnprintf _IO_vsnprintf, and
      #define __vsnprintf vsnprintf
    The macros were removed and their uses replaced with calls to the
    new internal function __vsnprintf_internal.  Since there were no
    internal calls, the internal declaration was also removed.  The
    external symbol is preserved with ldbl_weak_alias to ___vsnprintf.

  __vfwprintf:
    All internal calls converted into calls to __vfwprintf_internal,
    thus the internal declaration was removed.  The function is now a
    wrapper that calls __vfwprintf_internal.  The external symbol is
    preserved.

  __vswprintf:
    Similarly, but no external symbol.

  __vasprintf, __vdprintf, __vfprintf, __vsprintf:
    New internal wrappers.  Not exported.

  vasprintf, vdprintf, vfprintf, vsprintf, vsnprintf,
  vfwprintf, vswprintf,
  obstack_vprintf, obstack_printf:
    These functions used to be aliases to the respective _IO_* function,
    they are now aliases to their respective __* functions.

Tested for powerpc and powerpc64le.

These unmangled function pointers reside on the heap and could
be targeted by exploit writers, effectively bypassing libio vtable
validation.  Instead, we ignore these pointers and always call
malloc or free.

In theory, this is a backwards-incompatible change, but using the
global heap instead of the user-supplied callback functions should
have little application impact.  (The old libstdc++ implementation
exposed this functionality via a public, undocumented constructor
in its strstreambuf class.)

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.