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43 .Nd System calls to manage process descriptors
49 .Fn pdfork "int *fdp" "int flags"
51 .Fn pdgetpid "int fd" "pid_t *pidp"
53 .Fn pdkill "int fd" "int signum"
55 .Fn pdwait4 "int fd" "int *status" "int options" "struct rusage *rusage"
57 Process descriptors are special file descriptors that represent processes,
62 which, if successful, returns a process descriptor in the integer pointed to
72 .Bl -tag -width ".Dv PD_DAEMON"
74 Instead of the default terminate-on-close behaviour, allow the process to
75 live until it is explicitly killed with
78 This option is not permitted in
85 queries the process ID (PID) in the process descriptor
89 is functionally identical to
91 except that it accepts a process descriptor,
96 behaves identically to
98 but operates with respect to a process descriptor argument rather than a PID.
100 The following system calls also have effects specific to process descriptors:
103 queries status of a process descriptor; currently only the
111 If the owner read, write, and execute bits are set then the
112 process represented by the process descriptor is still alive.
117 allow waiting for process state transitions; currently only
119 is defined, and will be raised when the process dies.
120 Process state transitions can also be monitored using
123 .Dv EVFILT_PROCDESC ;
129 will close the process descriptor unless
131 is set; if the process is still alive and this is
132 the last reference to the process descriptor, the process will be terminated
137 returns a PID, 0 or -1, as
144 return 0 on success and -1 on failure.
147 returns a PID on success and -1 on failure.
149 These functions may return the same error numbers as their PID-based equivalents
152 may return the same error numbers as
154 with the following additions:
157 The signal number given to
160 .It Bq Er ENOTCAPABLE
161 The process descriptor being operated on has insufficient rights (e.g.
182 system calls first appeared in
185 Support for process descriptors mode was developed as part of the
190 These functions and the capability facility were created by
191 .An Robert N. M. Watson Aq Mt rwatson@FreeBSD.org
193 .An Jonathan Anderson Aq Mt jonathan@FreeBSD.org
194 at the University of Cambridge Computer Laboratory with support from a grant
198 has not yet been implemented.