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Diffstat (limited to 'static/unix-v10/man4/proc.4')
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diff --git a/static/unix-v10/man4/proc.4 b/static/unix-v10/man4/proc.4 new file mode 100644 index 00000000..1d0de279 --- /dev/null +++ b/static/unix-v10/man4/proc.4 @@ -0,0 +1,243 @@ +.TH PROC 4 +.CT 2 proc_man +.SH NAME +proc \- process file system +.SH SYNOPSIS +.B #include <sys/proc.h> +.br +.B #include <sys/pioctl.h> +.SH DESCRIPTION +.I Proc +is a file-system mount point that provides access to the image of each +running process in the system. +The name of each entry in the +.F /proc +directory is a five-digit decimal number corresponding to the process +id. +The owner of each file is the userid of the process; +the group is \-1. +If the process's text file is readable, the owner is granted +read-write permission and the group is granted read permission. +The size of a file is +the total virtual memory size of the process. +The security label is shared with the process, unless the +process has had capability +.B T_NOCHK +(see +.IR getplab (2)) +since last +.IR exec (2), +in which case the lattice value of the label is lattice +top and the privilege fields contain some past value of the +process' privilege fields. +.PP +The standard system-call interface is used to access +.I proc. +.I Open +and +.IR close (2) +behave as usual. +The object process is unaffected, except that setuid bits +will be ignored if it does an +.IR exec (2). +(Setuid bits are also ignored if the +.IR exec "ing" +process has traced signals, or stops on +.IR exec ; +see the description of +.B PIOCSMASK +and +.B PIOCSEXEC +below.) +Data may be transferred +from or to any locations in the object's address space through +.I lseek, +.I read, +and +.IR write (2). +The +.I text segment +begins at virtual address 0; the +.I data segment +starts above the text. +The +.I user area +extends downward below virtual address 0x80000000, and is +.B UPAGES*NBPG +bytes long; the +.I stack segment +grows downward below the user area. +Between the end of the data and +the beginning of the stack lies no-man's land. +The text, data, and stack sizes +may be determined from the process's +.L proc +structure (see below). +There are two differences from reading and writing ordinary files: +(1) no I/O transfer may span a segment boundary; +(2) the user area is writable only in the locations of saved user registers. +.PP +Several process control actions are available through an +.IR ioctl (2) +of the form +.IP +.L +union { struct proc p; long i; } buffer; +.br +.L retval = ioctl(fildes, code, &buffer); +.LP +The possible +.I codes +are as follows: +.TF PIOCSMASK +.TP +.B PIOCGETPR +copies the object's proc structure from the kernel process table +into +.BR buffer.p . +Since this information resides in system space, it is not accessible +via a normal read. +.PD +.TP +.B PIOCSTOP +sends the signal +.B SIGSTOP +to the object, and waits for it to +enter the stopped state. +.TP +.B PIOCWSTOP +simply waits for the object to stop. +.TP +.B PIOCRUN +makes the object runnable again after a stop. +.TP +.B PIOCSMASK +defines (via the bit mask +.BR buffer.i ) +a set of signals to be traced; +i.e., the arrival of such a signal will cause the object to stop. +(The signal numbered +.I n +is specified by the bit +.BI "1<<(" n "-1)\fR.)" +A mask of zeroes turns off the trace. +The traced state and mask bits are inherited by the child of a +.IR fork (2). +When the object is closed, the mask bits are lost, but +the traced state is retained for side effects. +.TP +.B PIOCSEXEC +causes the object to stop after +.IR exec "ing." +This condition is inherited by children and is retained when the +object is closed. +.TP +.B PIOCREXEC +reverses the effect of +.BR PIOCSEXEC . +.TP +.B PIOCCSIG +clears the object's currently pending signal (if any). +.TP +.B PIOCKILL +sends a signal to the process. +.TP +.B PIOCOPENT +provides, in +.BR retval , +a read-only file descriptor +for the object process's text file. +This allows a debugger to find the +symbol table without having to know any path names. +.TP +.B PIOCNICE +increments the object's +.IR nice (2) +priority by the amount +.BR buffer.i . +Only the super user may better a process's priority in this way, but any +user may make the priority worse. +.PP +All system calls are interruptible by signals, so that, for example, +an +.IR alarm (2) +may be set to avoid waiting forever for a process that may never stop. +Any system call is guaranteed to be atomic with respect to the object, +but, as with ordinary files, there is nothing to prevent more than one +process from trying to control the same object. +.PP +The following header files are useful in analyzing +.I proc +files: +.PP +.TF <sys/param.h> +.TP +.B <signal.h> +list of signal numbers +.TP +.B <sys/param.h> +size parameters +.TP +.B <sys/types.h> +special system types +.TP +.B <sys/user.h> +user structure +.TP +.B <sys/proc.h> +proc structure +.TP +.B <sys/reg.h> +locations of saved user registers +.TP +.B <sys/pioctl.h> +ioctl codes +.PD +.SH FILES +.F /proc/* +.SH SEE ALSO +.IR ps (1), +.IR hang (1), +.IR fmount (2), +.IR signal (2), +.IR mount (8), +.IR pi (9.1) +.SH DIAGNOSTICS +This is a list of errors which can occur in addition to the +errors normally associated with the file system; see +.IR intro (2): +.TF ENOENT +.TP +.B ENOENT +is returned if the object process has exited after being opened. +.TP +.B EIO +is returned if I/O is attempted at an illegal address in the object. +.TP +.B EBUSY +is returned if the object is in the midst of changing virtual memory +attributes, or has pages locked for physical I/O. +.TP +.B ENOSPC +is returned if a write is attempted on a shared text segment, but there +is no room on the swap space to make a copy. +.TP +.B EPERM +is returned if someone other than the super user attempts to better +a process's priority by issuing a +.BR PIOCNICE . +.SH BUGS +A process must be swapped in for reading and writing (but not +.IR ioctl ); +this consumes minimal system resources, but may involve a noticeable +delay. +.br +The spectrum of states which result in the +.B EBUSY +error is too conservative. +.br +A process loaded from a text file with magic number 0407 does not have as +a read-only text segment; in this (presumably rare) case +.B PIOCOPENT +does not work, and the process is accessible even if the +text file is read-only. |