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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
83 .Bl -tag -width ".Dv PD_DAEMON"
85 Set close-on-exec on process descriptor.
89 queries the process ID (PID) in the process descriptor
93 is functionally identical to
95 except that it accepts a process descriptor,
100 behaves identically to
102 but operates with respect to a process descriptor argument rather than a PID.
104 The following system calls also have effects specific to process descriptors:
107 queries status of a process descriptor; currently only the
115 If the owner read, write, and execute bits are set then the
116 process represented by the process descriptor is still alive.
121 allow waiting for process state transitions; currently only
123 is defined, and will be raised when the process dies.
124 Process state transitions can also be monitored using
127 .Dv EVFILT_PROCDESC ;
133 will close the process descriptor unless
135 is set; if the process is still alive and this is
136 the last reference to the process descriptor, the process will be terminated
141 returns a PID, 0 or -1, as
148 return 0 on success and -1 on failure.
151 returns a PID on success and -1 on failure.
153 These functions may return the same error numbers as their PID-based equivalents
156 may return the same error numbers as
158 with the following additions:
161 The signal number given to
164 .It Bq Er ENOTCAPABLE
165 The process descriptor being operated on has insufficient rights (e.g.
186 system calls first appeared in
189 Support for process descriptors mode was developed as part of the
194 These functions and the capability facility were created by
195 .An Robert N. M. Watson Aq Mt rwatson@FreeBSD.org
197 .An Jonathan Anderson Aq Mt jonathan@FreeBSD.org
198 at the University of Cambridge Computer Laboratory with support from a grant
202 has not yet been implemented.