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The manual contained several instances of incorrect formatting
that were correct texinfo but produced incorrectly rendered manuals
or incorrect behaviour from the tooling.
The most important was incorrect quoting of function returns
by failing to use {} to quote the return. The impact of this
mistake means that 'info libc func' does not jump to the function
in question but instead to the introductory page under the assumption
that func doesn't exist. The function returns are now correctly
quoted.
The second issue was the use of a category specifier with
@deftypefun which doesn't accept a category specifier. If a category
specifier is required then @deftypefn needs to be used. This is
corrected by changing the command to @deftypefn for such functions
that used {Deprecated function} as a category.
The last issue is a missing space between the function name and the
arguments which results in odd function names like "epoll_wait(int"
instead of "epoll_wait". This also impacts the use of 'info libc'
and is corrected.
We additionally remove ';' from the end of function arguments and
add an 'int' return type for dprintf.
Lastly we add a new test check-deftype.sh which verifies the expected
formatting of @deftypefun, @deftypefunx, @deftypefn, and
@deftypefnx. The new test is also run as the summary file is
generated to ensure we don't generate incorrect results.
The existing check-safety.sh is also run directly as a test to increase
coverage since the existing tests only ran on manual install.
The new tests now run as part of the standard "make check" that
pre-commit CI runs and developers should run.
No regressions on x86_64.
HTML and PDF rendering reviewed and looks correct for all changes.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
117 lines
4.0 KiB
Plaintext
117 lines
4.0 KiB
Plaintext
@node Inter-Process Communication, Job Control, Processes, Top
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@c %MENU% All about inter-process communication
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@chapter Inter-Process Communication
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@cindex ipc
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This chapter describes the @glibcadj{} inter-process communication primitives.
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@menu
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* Semaphores:: Support for creating and managing semaphores
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@end menu
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@node Semaphores
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@section Semaphores
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@Theglibc{} implements the semaphore APIs as defined in POSIX and
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System V. Semaphores can be used by multiple processes to coordinate shared
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resources. The following is a complete list of the semaphore functions provided
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by @theglibc{}.
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@c Need descriptions for all of these functions.
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@subsection System V Semaphores
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@deftypefun int semctl (int @var{semid}, int @var{semnum}, int @var{cmd})
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@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{/linux}}}
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@c syscall(ipc) ok
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@c
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@c AC-unsafe because we need to translate the new kernel
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@c semid_ds buf into the userspace layout. Cancellation
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@c at that point results in an inconsistent userspace
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@c semid_ds.
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@end deftypefun
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@deftypefun int semget (key_t @var{key}, int @var{nsems}, int @var{semflg})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c syscall(ipc) ok
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@end deftypefun
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@deftypefun int semop (int @var{semid}, struct sembuf *@var{sops}, size_t @var{nsops})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c syscall(ipc) ok
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@end deftypefun
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@deftypefun int semtimedop (int @var{semid}, struct sembuf *@var{sops}, size_t @var{nsops}, const struct timespec *@var{timeout})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c syscall(ipc) ok
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@end deftypefun
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@subsection POSIX Semaphores
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@deftypefun int sem_init (sem_t *@var{sem}, int @var{pshared}, unsigned int @var{value})
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@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{}}}
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@c Does not atomically update sem_t therefore AC-unsafe
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@c because it can leave sem_t partially initialized.
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@end deftypefun
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@deftypefun int sem_destroy (sem_t *@var{sem})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c Function does nothing and is therefore always safe.
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@end deftypefun
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@deftypefun {sem_t *} sem_open (const char *@var{name}, int @var{oflag}, ...)
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@safety{@prelim{}@mtsafe{}@asunsafe{@asuinit{}}@acunsafe{@acuinit{}}}
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@c pthread_once asuinit
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@c
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@c We are AC-Unsafe because we use pthread_once to initialize
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@c a global variable that holds the location of the mounted
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@c shmfs on Linux.
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@end deftypefun
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@deftypefun int sem_close (sem_t *@var{sem})
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@safety{@prelim{}@mtsafe{}@asunsafe{@asulock{}}@acunsafe{@aculock{}}}
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@c lll_lock asulock aculock
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@c twalk mtsrace{:root}
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@c
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@c We are AS-unsafe because we take a non-recursive lock.
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@c We are AC-unsafe because several internal data structures
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@c are not updated atomically.
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@end deftypefun
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@deftypefun int sem_unlink (const char *@var{name})
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@safety{@prelim{}@mtsafe{}@asunsafe{@asuinit{}}@acunsafe{@acucorrupt{}}}
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@c pthread_once asuinit acucorrupt aculock
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@c mempcpy acucorrupt
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@end deftypefun
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@deftypefun int sem_wait (sem_t *@var{sem})
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@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{}}}
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@c atomic_fetch_add_relaxed (nwaiters) acucorrupt
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@c
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@c Given the use atomic operations this function seems
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@c to be AS-safe. It is AC-unsafe because there is still
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@c a window between atomic_fetch_add_relaxed and the pthread_push
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@c of the handler that undoes that operation. A cancellation
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@c at that point would fail to remove the process from the
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@c waiters count.
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@end deftypefun
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@deftypefun int sem_timedwait (sem_t *@var{sem}, const struct timespec *@var{abstime})
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@safety{@prelim{}@mtsafe{}@assafe{}@acunsafe{@acucorrupt{}}}
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@c Same safety issues as sem_wait.
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@end deftypefun
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@deftypefun int sem_trywait (sem_t *@var{sem})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c All atomic operations are safe in all contexts.
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@end deftypefun
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@deftypefun int sem_post (sem_t *@var{sem})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c Same safety as sem_trywait.
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@end deftypefun
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@deftypefun int sem_getvalue (sem_t *@var{sem}, int *@var{sval})
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c Atomic write of a value is safe in all contexts.
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@end deftypefun
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