GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libc/gen/errno.c Lines: 1 1 100.0 %
Date: 2017-11-13 Branches: 0 0 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: errno.c,v 1.6 2016/05/07 19:05:22 guenther Exp $ */
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/* PUBLIC DOMAIN: No Rights Reserved.   Marco S Hyman <marc@snafu.org> */
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#include <tib.h>
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#include <errno.h>
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#include <unistd.h>
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#include "thread_private.h"
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#ifdef TCB_HAVE_MD_GET
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/*
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 * If there's an MD TCB_GET() macro, then getting the TCB address is
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 * cheap enough that we can do it even in single-threaded programs,
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 * so the tc_errnoptr and tc_tcb callbacks will be unused, and __errno()
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 * can just use TIB_GET().
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 */
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int *
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__errno(void)
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{
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	return (&TIB_GET()->tib_errno);
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}
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DEF_STRONG(__errno);
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#else /* ! TCB_HAVE_MD_GET */
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/*
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 * Otherwise, getting the TCB address requires the __get_tcb()
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 * syscall.  Rather than pay that cost for single-threaded programs,
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 * the syscall stubs will invoke the tc_errnoptr callback to set errno
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 * and other code will invoke the tc_tcb callback to get the TCB
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 * for cancelation checks, etc.  The default callbacks will just
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 * work from the cached location of the initial thread's TCB;
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 * libpthread can override them to the necessary more expensive
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 * versions that use __get_tcb().
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 */
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/* cached pointer to the TCB of the only thread in single-threaded programs */
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void	*_libc_single_tcb = NULL;
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static inline void *
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single_threaded_tcb(void)
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{
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	if (__predict_false(_libc_single_tcb == NULL))
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		_libc_single_tcb = TCB_GET();
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	return (_libc_single_tcb);
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}
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static int *
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single_threaded_errnoptr(void)
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{
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	return &TCB_TO_TIB(single_threaded_tcb())->tib_errno;
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}
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/*
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 * __errno(): just use the callback to get the applicable current method
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 */
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int *
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__errno(void)
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{
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	return (_thread_cb.tc_errnoptr());
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}
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DEF_STRONG(__errno);
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#endif /* !TCB_HAVE_MD_GET */
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struct thread_callbacks _thread_cb =
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{
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#ifndef	TCB_HAVE_MD_GET
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	.tc_errnoptr	= &single_threaded_errnoptr,
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	.tc_tcb		= &single_threaded_tcb,
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#endif
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};