eCos contains support for the POSIX Specification (ISO/IEC - 9945-1)[POSIX]. -
POSIX support is divided between the POSIX and the FILEIO - packages. The POSIX package provides support for threads, - signals, synchronization, timers and message queues. The FILEIO - package provides support for file and device I/O. The two - packages may be used together or separately, depending on - configuration. -
This document takes a functional approach to the POSIX - library. Support for a function implies that the data types and - definitions necessary to support that function, and the objects - it manipulates, are also defined. Any exceptions to this are - noted, and unless otherwise noted, implemented functions behave - as specified in the POSIX standard. -
This document only covers the differences between the eCos - implementation and the standard; it does not provide complete - documentation. For full information, see the POSIX standard - [POSIX]. Online, the Open Group Single Unix - Specification [SUS2] provides complete documentation - of a superset of POSIX. If you have access to a Unix system with - POSIX compatibility, then the manual pages for this will be of - use. There are also a number of books available. - [Lewine] covers the process, signal, file and I/O - functions, while [Lewis1], [Lewis2], - [Nichols] and [Norton] cover Pthreads and - related topics (see Bibliography, xref). However, many of these - books are oriented toward using POSIX in non-embedded systems, - so care should be taken in applying them to programming under - eCos. -
The remainder of this chapter broadly follows the structure - of the POSIX Specification. References to the appropriate - section of the Standard are included. -
Omitted functions marked with “// TBA” - are potential candidates for later implementation. -
int kill(pid_t pid, int sig); -int pthread_kill(pthread_t thread, int sig); -int sigaction(int sig, const struct sigaction *act, - struct sigaction *oact); -int sigqueue(pid_t pid, int sig, const union sigval value); -int sigprocmask(int how, const sigset_t *set, - sigset_t *oset); -int pthread_sigmask(int how, const sigset_t *set, - sigset_t *oset); -int sigpending(sigset_t *set); -int sigsuspend(const sigset_t *set); -int sigwait(const sigset_t *set, int *sig); -int sigwaitinfo(const sigset_t *set, siginfo_t *info); -int sigtimedwait(const sigset_t *set, siginfo_t *info, - const struct timespec *timeout); -int sigemptyset(sigset_t *set); -int sigfillset(sigset_t *set); -int sigaddset(sigset_t *set, int signo); -int sigdelset(sigset_t *set, int signo); -int sigismember(const sigset_t *set, int signo); -unsigned int alarm( unsigned int seconds ); -int pause( void ); -unsigned int sleep( unsigned int seconds ); |
pid_t fork(void); -int execl( const char *path, const char *arg, ... ); -int execv( const char *path, char *const argv[] ); -int execle( const char *path, const char *arg, ... ); -int execve( const char *path, char *const argv[], - char *const envp[] ); -int execlp( const char *path, const char *arg, ... ); -int execvp( const char *path, char *const argv[] ); -int pthread_atfork( void(*prepare)(void), - void (*parent)(void), - void (*child)() ); -pid_t wait( int *stat_loc ); -pid_t waitpid( pid_t pid, int *stat_loc, - int options ); -void _exit( int status ); |
Signal handling may be enabled or disabled with the - CYGPKG_POSIX_SIGNALS option. Since signals are used - by other POSIX components, such as timers, disabling signals will - disable those components too. -
kill() and - sigqueue() may only take a - pid argument of zero, - which maps to the current process. -
The SIGEV_THREAD notification type is - not currently implemented. -
Job Control and Memory Protection signals are - not supported. -
An extra implementation defined - si_code value, - SI_EXCEPT, is defined to - distinguish hardware generated exceptions from - others. -
Extra signals are defined: - _SIGTRAP_,_SIGIOT_, - _SIGEMT_, and _SIGSYS_. These are - largely to maintain compatibility with the signal numbers used by - GDB. -
Signal delivery may currently occur at unexpected places in some - API functions. Using longjmp() to transfer - control out of a signal handler may result in the interrupted - function not being able to complete properly. This may result in - later function calls failing or deadlocking. -