Enrico Fraccaroli
77 lines
3.8 KiB
C
77 lines
3.8 KiB
C
/// @file wait.h
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/// @brief Event management functions.
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/// @copyright (c) 2014-2021 This file is distributed under the MIT License.
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/// See LICENSE.md for details.
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#pragma once
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/// @brief Return immediately if no child is there to be waited for.
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#define WNOHANG 0x00000001
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/// @brief Return for children that are stopped, and whose status has not
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/// been reported.
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#define WUNTRACED 0x00000002
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/// @brief returns true if the child process exited because of a signal that
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/// was not caught.
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#define WIFSIGNALED(status) (!WIFSTOPPED(status) && !WIFEXITED(status))
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/// @brief returns true if the child process that caused the return is
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/// currently stopped; this is only possible if the call was done using
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/// WUNTRACED().
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#define WIFSTOPPED(status) (((status)&0xff) == 0x7f)
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/// @brief evaluates to the least significant eight bits of the return code
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/// of the child that terminated, which may have been set as the argument
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/// to a call to exit() or as the argument for a return statement in the
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/// main program. This macro can only be evaluated if WIFEXITED()
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/// returned nonzero.
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#define WEXITSTATUS(status) (((status)&0xff00) >> 8)
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/// @brief returns the number of the signal that caused the child process to
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/// terminate. This macro can only be evaluated if WIFSIGNALED() returned
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/// nonzero.
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#define WTERMSIG(status) ((status)&0x7f)
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/// @brief Is nonzero if the child exited normally.
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#define WIFEXITED(status) (WTERMSIG(status) == 0)
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/// @brief returns the number of the signal that caused the child to stop.
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/// This macro can only be evaluated if WIFSTOPPED() returned nonzero.
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#define WSTOPSIG(status) (WEXITSTATUS(status))
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//==== Task States ============================================================
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#define TASK_RUNNING 0x00 ///< The process is either: 1) running on CPU or 2) waiting in a run queue.
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#define TASK_INTERRUPTIBLE (1 << 0) ///< The process is sleeping, waiting for some event to occur.
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#define TASK_UNINTERRUPTIBLE (1 << 1) ///< Similar to TASK_INTERRUPTIBLE, but it doesn't process signals.
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#define TASK_STOPPED (1 << 2) ///< Stopped, it's not running, and not able to run.
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#define TASK_TRACED (1 << 3) ///< Is being monitored by other processes such as debuggers.
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#define EXIT_ZOMBIE (1 << 4) ///< The process has terminated.
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#define EXIT_DEAD (1 << 5) ///< The final state.
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//==============================================================================
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/// @brief Suspends the execution of the calling thread until ANY child has
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/// changed state.
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/// @param status Variable where the new status of the child is stored.
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/// @return On error, -1 is returned, otherwise it returns the pid of the
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/// child that has unlocked the wait.
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extern pid_t wait(int *status);
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/// @brief Suspends the execution of the calling thread until a child
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/// specified by pid argument has changed state.
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/// @param pid Se details below for more information.
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/// @param status Variable where the new status of the child is stored.
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/// @param options Waitpid options.
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/// @return On error, -1 is returned, otherwise it returns the pid of the
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/// child that has unlocked the wait.
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/// @details
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/// By default, waitpid() waits only for terminated children, but this
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/// behavior is modifiable via the options argument, as described below.
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/// The value of pid can be:
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/// - 1 meaning wait for any child process.
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/// 0 meaning wait for any child process whose process group ID is
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/// equal to that of the calling process.
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/// > 0 meaning wait for the child whose process ID is equal to the
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/// value of pid.
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extern pid_t waitpid(pid_t pid, int *status, int options);
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