shithub: 9ferno

ref: 6966e8d72ae8fb72ebf98909acbd464aff84a3cc

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.TH PROG 3 
.SH NAME
prog \- running programs
.SH SYNOPSIS
.nf
.B bind #p /prog

.BI /prog/ n /ctl
.BI /prog/ n /dbgctl
.BI /prog/ n /exception
.BI /prog/ n /fd
.BI /prog/ n /heap
.BI /prog/ n /ns
.BI /prog/ n /nsgrp
.BI /prog/ n /pgrp
.BI /prog/ n /stack
.BI /prog/ n /status
.BI /prog/ n /text
.BI /prog/ n /wait
\&...
.fi
.SH DESCRIPTION
The
.B prog
device serves a two-level directory structure.
The first level contains numbered directories
corresponding to pids of live Limbo processes;
each such directory contains a set of files
representing the corresponding process.
All files operate on
.I UTF
(see
.IR utf (6))
strings.
.PP
The read-only
.B status
file contains seven space-separated fields.
The fields are: the process and process group identifiers, each 8 characters right justified;
the user name, at least 10 characters left justified;
cpu time in minutes, seconds and tenths of seconds;
the process state, 10 characters left justified;
the amount of memory used by the process in units of 1024 bytes,
at least 5 characters, right justified, followed by a
.BR K ;
and the name of the current program module,
up to 28 characters, left justified.
.PP
The read-only
.B pgrp
file contains the process group identifier, in decimal.
.PP
The read-only
.B nsgrp
file contains the namespace group identifier, in decimal.
.PP
The read-only
.B ns
file contains a set of mount and bind commands
which describe the
.IR sys-bind (2)
and
.B mount
operations used to construct the name space, in
the format of
.IR namespace (6).
The last
line of the file is a
.B cd
command indicating the working directory.
.PP
The read-only
.B wait
file may be read to recover
information about the exiting children of the process.
A read of
.B wait
will block until a child of the process, created after
.B wait
was opened, exits.
When such a child exits, it produces a string with three fields:
the pid of the exiting process, a space,
module name enclosed in
\ \f5"\fP's,
a colon,
and a possibly empty error message.
The error message will contain at most 64 characters.
.PP
The read-only
.B fd
file
describes the open file descriptors in the
file descriptor group of the process.
Each line describes an open file.
The fields are: the file descriptor index, the open mode
.RB ( r ,
.BR w ,
.BR rw );
the type and number of the device;
the path, version and type of the file's
.I qid
(see
.IR intro (5));
the file's atomic I/O unit, as defined in
.IR sys-iounit (2));
the file I/O offset in bytes;
and the name with which it was opened.
.PP
The read-only
.B exception
file gives details of the last exception to occur in the process, if any. The fields
are the program counter value when the exception occurred, the module it
occurred in and the exception itself, each separated by a space. If none, the
result is the empty string.
.PP
Messages written to the
.B ctl
file control the execution of the process.
.TF killgrp
.PD
.TP
.B kill
Kill the process.
.TP
.B killgrp
Kill all processes in the same group as the process.
A process writing to its own ctl file does not kill itself.
.TP
.B exceptions propagate
Applies to process group leaders only (ie any process that executes a system
call
.I sys->pctl(Sys->NEWPGRP, ...
).
If any process in the same group as the leader incurs an exception which it
does not handle, atomically raise the exception in all processes in the group.
In this case exceptions are generated for killed processes as well. This mechanism allows
all processes in a process group to perfom error recovery when one of them
faults.
.TP
.B exceptions notifyleader
Applies to process group leaders only.
If any process in the same group as the leader incurs an exception which it
does not handle, atomically destroy all processes in the group except for the
leader and raise the exception in the leader. This error recovery mechanism might
be appropriate when a fault occurs amongst a group of processes and the group
leader takes sole responsibilty for recovery.
.TP
.B restricted
Mark all processes that the process spawns in future as restricted. A restricted
process is one which can run out of memory when a configured limit has been
reached and before total memory is exhausted. An unrestricted process can
allocate memory until memory is truly exhausted. Typically a window manager
or server might be unrestricted as they are processes fundamental to the
running of a system.
.PP
The
.B dbgctl
file provides facilities for debugging a process.
Messages written to the file control the execution of the process.
.TP 10n
.BI step " n"
Step the interpreter for at most
.I n
instructions, or until a breakpoint is reached.
.TP 10n
.B toret
Step the interpreter until a return from the current activation frame
or a breakpoint is reached.
.TP 10n
.B cont
Step the interpreter until a breakpoint is reached.
.TP 10n
.B stop
Stop the process as soon as possible.
Do not allow the process to execute again until an
.B unstop
message is received.
.TP 10n
.B unstop
Cancel the effect of any previous
.BR stop .
.TP 10n
.BI "bpt set " "path pc"
Set a breakpoint at
.I pc
for the module given by
.IR path .
.TP 10n
.BI "bpt del " "path pc"
Clear a breakpoint if one exists.
.PP
Reading 
.B
dbgctl
gives updates for some state transitions while the process is being debugged.
Each update is terminated by a newline.
.TP 10n
.B exited
The process exited without error.
.TP 10n
.BI broken: " error"
The process died due to
.IR error ,
a string with up to 64 characters.
.TP 10n
.B send
The process is blocked sending on a channel.
.TP 10n
.B recv
The process is blocked receiving on a channel.
.TP 10n
.B alt
The process is blocked in an
.B alt
statement.
.TP 10n
.B run
The process is unblocked and now ready to run.
.TP 10n
.BI new " pid"
The process has spawned a new process identified by
.IR pid .
.PP
The read-only
.B stack
file contains the dynamic call stack trace.
Each activation frame is described by one line with six fields, separated by a space:
the frame pointer, program counter,
module data pointer, and module code pointer,
each 8 hexadecimal digits;
the execution method for the module (0 means interpreted, 1 compiled);
and the path name of the module.
The top activation frame starts at offset 0.
.PP
The
.B heap
file may be queried to examine the state of the process.
A data query contains an address, a period, a format character,
and a count.
An instruction query contains a pc, a plus, a mode address, a period,
the format
.BR I ,
and a count.
The addresses in the query may be decimal,
hexadecimal preceded by
.B 0x
or
.BR 0X ,
or octal preceded by
.BR 0 .
Count gives the number of consecutive
data items retrieved by reading
.B heap
starting at offset 0;
the format varies according to the format character.
All data items other than strings are terminated by a newline.
.TP 10n
.B W
32-bit decimal ints.
.TP 10n
.B B
8-bit unsigned decimal bytes.
.TP 10n
.B V
64-bit decimal bytes.
.TP 10n
.B R
64-bit reals.
.TP 10n
.B I
Disassembled Dis instructions.
.TP 10n
.B P
32-bit hexadecimal address, or
.BR nil .
.PP
The following formats examine properties of specific 32-bit pointers.
.TP 10n
.B L
Examine a list, yielding
a pair of hexadecimal addresses separated by a period,
giving the address of the head and tail of a list.
It is an error to use
.B L
on
.BR nil .
.TP 10n
.B A
Examine an array, yielding
a decimal length, a period, and the address of the 0th element of an array,
or
.BR nil .
.TP 10n
.B C
Examine a string, yielding
the decimal length in characters, a period, and the
.IR utf (6)
representation of the string.
.TP 10n
.B M
Examine a module reference, yielding the address of its global data or
.BR nil .
.PP
The
.B text
file is currently unimplemented.
.SH SOURCE
.B /emu/port/devprog.c
.br
.B /os/port/devprog.c