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libio: Properly link in libio functions in static binaries

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commit 3020f72618
Author: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
Date:   Tue Dec 27 18:11:43 2022 -0300

    libio: Remove the usage of __libc_IO_vtables

added

 #define libio_static_fn_required(name) __asm (".globl " #name);

to link in libio functions in static binaries.  But there is no relocation
in
	.globl	_IO_file_open

and "strip --strip-unneeded" will remove such unreferenced symbols which
breaks static binaries.  Redefine libio_static_fn_required to create a
reference to the required function with

static __typeof (name) *const name##_p __attribute__((used)) = name;

This fixes BZ #33300.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Tested-by: Xi Ruoyao <xry111@xry111.site>
This commit is contained in:
H.J. Lu
2025-08-21 16:57:22 -07:00
parent 3997c50f0b
commit b4ab549ae5
3 changed files with 39 additions and 1 deletions
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9
libio/Makefile
View File

@@ -130,6 +130,7 @@ tests = \
tst-sprintf-chk-ub \ tst-sprintf-chk-ub \
tst-sprintf-ub \ tst-sprintf-ub \
tst-sscanf \ tst-sscanf \
tst-stdio-static \
tst-swscanf \ tst-swscanf \
tst-ungetwc1 \ tst-ungetwc1 \
tst-ungetwc2 \ tst-ungetwc2 \
@@ -149,6 +150,8 @@ tests = \
tst_wscanf \ tst_wscanf \
# tests # tests
tests-static += tst-stdio-static
$(objpfx)tst-popen-fork: $(shared-thread-library) $(objpfx)tst-popen-fork: $(shared-thread-library)
tests-internal = tst-vtables tst-vtables-interposed tests-internal = tst-vtables tst-vtables-interposed
@@ -445,3 +448,9 @@ $(objpfx)tst-bz22415-mem.out: $(objpfx)tst-bz22415.out
$(objpfx)tst-bz24228-mem.out: $(objpfx)tst-bz24228.out $(objpfx)tst-bz24228-mem.out: $(objpfx)tst-bz24228.out
$(common-objpfx)malloc/mtrace $(objpfx)tst-bz24228.mtrace > $@; \ $(common-objpfx)malloc/mtrace $(objpfx)tst-bz24228.mtrace > $@; \
$(evaluate-test) $(evaluate-test)
# Test stdio.o with "strip --strip-unneeded".
$(objpfx)tst-stdio-static: $(objpfx)stdio-stripped.o
$(objpfx)stdio-stripped.o: $(objpfx)stdio.o
$(STRIP) --strip-unneeded -o $@ $<

3
libio/libioP.h
View File

@@ -535,7 +535,8 @@ extern const struct _IO_jump_t __io_vtables[] attribute_hidden;
#ifdef SHARED #ifdef SHARED
# define libio_static_fn_required(name) # define libio_static_fn_required(name)
#else #else
# define libio_static_fn_required(name) __asm (".globl " #name); # define libio_static_fn_required(name) \
static __typeof (name) *const name##_p __attribute__((used)) = name;
#endif #endif
extern int _IO_do_write (FILE *, const char *, size_t); extern int _IO_do_write (FILE *, const char *, size_t);

28
libio/tst-stdio-static.c Normal file
View File

@@ -0,0 +1,28 @@
/* Test static stdio.o with "strip --strip-unneeded".
Copyright (C) 2025 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <stdio.h>
/* NB: Call main directly to trigger BZ #33300. */
int
main (void)
{
printf ("OK\n");
return 0;
}