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https://github.com/wolfcw/libfaketime.git
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b687b165b2
POSIX named semaphores (sem_t) have architecture-dependent internal layout in glibc: 32 bytes on 64-bit, 16 bytes on 32-bit. When a 64-bit faketime wrapper creates a semaphore and spawns a 32-bit child, the child misinterprets the counter and hangs on sem_wait forever. Extract ft_sem_* abstraction into shared ft_sem.h/ft_sem.c with three backends: FT_POSIX (existing), FT_SYSV (existing), FT_FLOCK (new default). The flock backend uses kernel-mediated file locking on /dev/shm/faketime_lock_<pid>, which is architecture-independent and auto-releases on process death. Both libfaketime.so and the faketime wrapper now use the same shared abstraction, ensuring protocol agreement regardless of backend.
63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
/*
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* This file is part of libfaketime, version 0.9.12
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*
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* libfaketime is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License v2 as published by the
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* Free Software Foundation.
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*
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* libfaketime is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License v2 along
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* with the libfaketime; if not, write to the Free Software Foundation,
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* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef FT_SEM_H
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#define FT_SEM_H
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/* semaphore backend options */
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#define FT_POSIX 1
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#define FT_SYSV 2
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#define FT_FLOCK 3
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/* set default backend */
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#ifndef FT_SEMAPHORE_BACKEND
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#define FT_SEMAPHORE_BACKEND FT_FLOCK
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#endif
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/* validate selected backend */
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#if FT_SEMAPHORE_BACKEND == FT_POSIX
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#elif FT_SEMAPHORE_BACKEND == FT_SYSV
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#elif FT_SEMAPHORE_BACKEND == FT_FLOCK
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#else
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#error "Unknown FT_SEMAPHORE_BACKEND; select between FT_POSIX, FT_SYSV, and FT_FLOCK"
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#endif
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#if FT_SEMAPHORE_BACKEND == FT_POSIX
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#include <semaphore.h>
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#endif
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typedef struct
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{
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char name[256];
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#if FT_SEMAPHORE_BACKEND == FT_POSIX
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sem_t *sem;
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#elif FT_SEMAPHORE_BACKEND == FT_SYSV
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int semid;
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#elif FT_SEMAPHORE_BACKEND == FT_FLOCK
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int fd;
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#endif
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} ft_sem_t;
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int ft_sem_create(char *name, ft_sem_t *ft_sem);
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int ft_sem_open(char *name, ft_sem_t *ft_sem);
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int ft_sem_lock(ft_sem_t *ft_sem);
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int ft_sem_unlock(ft_sem_t *ft_sem);
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int ft_sem_close(ft_sem_t *ft_sem);
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int ft_sem_unlink(ft_sem_t *ft_sem);
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#endif /* FT_SEM_H */
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