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6b7067460f
Clang issues a warning for double alias redirection, indicating that thei
original symbol is used even if a weak definition attempts to override it.
For instance, in the construction:
int __internal_impl (...) {}
weak_alias (__internal_impl, external_impl);
#if SOMETHING
weak_alias (external_impl, another_external_impl)
#endif
Clang warns that another_external_impl always resolves to __internal_impl,
even if external_impl is a weak reference. Using the internal symbol for
both aliases resolves this warning.
This issue also occurs with certain libc_hidden_def usage:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_weak (__internal_alias)
In this case, using a strong_alias is sufficient to avoid the warning
(since the alias is internal, there is no need to use a weak alias).
However, for the constructions like:
int __internal_impl (...) {}
weak_alias (__internal_impl, __internal_alias)
libc_hidden_def (__internal_alias)
weak_alias (__internal_impl, external_alias)
libc_hidden_def (external_alias)
Clang warns that the internal external_alias will always resolve to
__GI___internal_impl, even if a weak definition of __GI_internal_impl is
overridden. For this case, a new macro named static_weak_alias is used
to create a strong alias for SHARED, or a weak_alias otherwise.
With these changes, there is no need to check and enable the
-Wno-ignored-attributes suppression when using clang.
Checked with a build on affected ABIs, and a full check on aarch64,
armhf, i686, and x86_64.
Reviewed-by: Sam James <sam@gentoo.org>
68 lines
2.4 KiB
C
68 lines
2.4 KiB
C
/* Copyright (C) 1993-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>.
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As a special exception, if you link the code in this file with
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files compiled with a GNU compiler to produce an executable,
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that does not cause the resulting executable to be covered by
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the GNU Lesser General Public License. This exception does not
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however invalidate any other reasons why the executable file
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might be covered by the GNU Lesser General Public License.
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This exception applies to code released by its copyright holders
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in files containing the exception. */
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#include "libioP.h"
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#include <stdio.h>
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char *
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__fgets_unlocked (char *buf, int n, FILE *fp)
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{
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size_t count;
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char *result;
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int old_error;
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CHECK_FILE (fp, NULL);
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if (n <= 0)
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return NULL;
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if (__glibc_unlikely (n == 1))
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{
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/* Another irregular case: since we have to store a NUL byte and
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there is only room for exactly one byte, we don't have to
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read anything. */
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buf[0] = '\0';
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return buf;
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}
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/* This is very tricky since a file descriptor may be in the
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non-blocking mode. The error flag doesn't mean much in this
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case. We return an error only when there is a new error. */
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old_error = fp->_flags & _IO_ERR_SEEN;
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fp->_flags &= ~_IO_ERR_SEEN;
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count = _IO_getline (fp, buf, n - 1, '\n', 1);
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/* If we read in some bytes and errno is EAGAIN, that error will
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be reported for next read. */
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if (count == 0 || ((fp->_flags & _IO_ERR_SEEN) && errno != EAGAIN))
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result = NULL;
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else
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{
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buf[count] = '\0';
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result = buf;
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}
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fp->_flags |= old_error;
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return result;
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}
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libc_hidden_def (__fgets_unlocked)
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static_weak_alias (__fgets_unlocked, fgets_unlocked)
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libc_hidden_weak (fgets_unlocked)
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