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docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
.\" (C) Copyright 2020 Jim Warner <warnerjc@comcast.net>
.\"
.\" %%%LICENSE_START(LGPL_2.1+)
.\" This manual is free software; you can redistribute it and/or
.\" modify it under the terms of the GNU Lesser General Public
.\" License as published by the Free Software Foundation; either
.\" version 2.1 of the License, or (at your option) any later version.
.\"
.\" This manual is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
.\" Lesser General Public License for more details.
.\"
.\" You should have received a copy of the GNU Lesser General Public
.\" License along with this library; if not, write to the Free Software
.\" Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
.\" %%%LICENSE_END
.\"
.TH PROCPS_LINUX_VERSION 3 "June 2020" "libproc-2"
.\" Please adjust this date whenever revising the manpage.
.\"
.nh
.SH NAME
docs: just a few changes to that new pids man document A patch to address the following man doc deficiencies: . shorten NAME so there's no wrap in an 80x24 terminal . typo wherein the 'item' parm should have been 'info' . expand RETURN text for a potential NULL upon success [ maybe, this might be my last tweak to this man doc ] Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-25 10:30:00 +05:30
procps_pids \- API to access process information in the /proc filesystem
docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
.SH SYNOPSIS
.nf
#include <procps/pids.h>
.BI "int procps_pids_new (struct pids_info **" info ", enum pids_item *" items ", int " numitems );
.BI "int procps_pids_ref (struct pids_info *" info );
.BI "int procps_pids_unref (struct pids_info **" info );
.BI "struct pids_stack *procps_pids_get ("
.BI " struct pids_info *" info ,
.BI " enum pids_fetch_type " which );
.BI "struct pids_fetch *procps_pids_reap ("
.BI " struct pids_info *" info ,
.BI " enum pids_fetch_type " which );
.BI "struct pids_fetch *procps_pids_select ("
.BI " struct pids_info *" info ,
.BI " unsigned *" these ,
.BI " int " numthese ,
.BI " enum pids_select_type " which );
.BI "struct pids_stack **procps_pids_sort ("
.BI " struct pids_info *" info ,
.BI " struct pids_stack *" stacks[] ,
.BI " int " numstacked ,
.BI " enum pids_item " sortitem ,
.BI " enum pids_sort_order " order );
.BI "int procps_pids_reset ("
.BI " struct pids_info *" info ,
.BI " enum pids_item *" newitems ,
.BI " int " newnumitems );
.BI "struct pids_stack *fatal_proc_unmounted ("
.BI " struct pids_info *" info ,
.BI " int " return_self );
.fi
Link with \fI\-lprocps\fP.
.SH DESCRIPTION
.SS Overview
Central to this interface is a simple `result'
structure reflecting an `item' plus its value (in a union
with standard C language types as members).
All `result' structures are automatically allocated and
provided by the library.
By specifying an array of `items', these structures can be
organized as a `stack', potentially yielding many results
with a single function call.
Thus, a `stack' can be viewed as a variable length record
whose content and order is determined solely by the user.
As part of each interface there are two unique items.
The `noop' and `extra' items exist to hold user values.
They are never set by the library, but the `extra'
result will be zeroed with each library interaction.
The pids.h file will be an essential document during
user program development.
There you will find available items, their return type
(the `result' struct member name) and the source for such values.
Additional enumerators and structures are also documented there.
.SS Usage
The following would be a typical sequence of calls to
this interface.
.nf
docs: tweak both of those newly created man docs a tad An important fact was omitted in the DEBUGGING section for the two newest man documents. Users must utilize a macro in the header files before verification happens. So, this commit will sneak in such mention and in that way reduce future liability if the feature won't work. Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-24 03:59:14 +05:30
.RB "1. " fatal_proc_unmounted()
.RB "2. " procps_pids_new()
.RB "3. " procps_pids_get() ", " procps_pids_reap() " or " procps_pids_select()
.RB "4. " procps_pids_unref()
docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
.fi
Optionally, a user may choose to sort results returned from
\fBreap\fR or \fBselect\fR.
The \fBsort\fR function parameters \fIstacks\fR and \fInumstacked\fR
would normally be those returned in the `pids_fetch' structure.
.SS Caveats
The <pids> API differs from others in that those items
of interest must be provided at \fBnew\fR or \fBreset\fR time,
the latter being unique to this API.
If either the \fIitems\fR or \fInumitems\fR parameter is zero at
\fBnew\fR time, then \fBreset\fR becomes mandatory before
issuing any other call.
For the \fBnew\fR and \fBunref\fR functions, the address of an \fIinfo\fR
struct pointer must be supplied.
With \fBnew\fR it must have been initialized to NULL.
With \fBunref\fR it will be reset to NULL if the reference count reaches zero.
The \fBget\fR function is an iterator, for successive
PIDs/TIDs, returning those items previously identified
via \fBnew\fR or \fBreset\fR.
The \fBselect\fR function requires an array of PIDs or UIDs as
\fIthese\fR along with \fInumthese\fR to identify which processes
are to be fetched.
This function then operates as a subset of \fBreap\fR
while returning those items previously identified via \fBnew\fR
or \fBreset\fR.
Lastly, a \fBfatal_proc_unmounted\fR function may be called before
any other function to ensure that the /proc/ directory is mounted.
docs: just a few changes to that new pids man document A patch to address the following man doc deficiencies: . shorten NAME so there's no wrap in an 80x24 terminal . typo wherein the 'item' parm should have been 'info' . expand RETURN text for a potential NULL upon success [ maybe, this might be my last tweak to this man doc ] Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-25 10:30:00 +05:30
As such, the \fIinfo\fR parameter would be NULL and the
docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
\fIreturn_self\fR parameter zero.
If, however, some items are desired for the issuing program (a
\fIreturn_self\fR other than zero) then the \fBnew\fR call must precede
it to obtain the required \fIinfo\fR pointer.
.SH RETURN VALUE
.SS Functions Returning an `int'
An error will be indicated by a negative number that
is always the inverse of some well known errno.h value.
Success is indicated by a zero return value.
However, the \fBref\fR and \fBunref\fR functions return
the current \fIinfo\fR structure reference count.
.SS Functions Returning an `address'
An error will be indicated by a NULL return pointer
with the reason found in the formal errno value.
Success is indicated by a pointer to the named structure.
docs: just a few changes to that new pids man document A patch to address the following man doc deficiencies: . shorten NAME so there's no wrap in an 80x24 terminal . typo wherein the 'item' parm should have been 'info' . expand RETURN text for a potential NULL upon success [ maybe, this might be my last tweak to this man doc ] Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-25 10:30:00 +05:30
However, if one survives the \fBfatal_proc_unmounted\fR call,
NULL is always returned when \fIreturn_self\fR is zero.
docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
.SH DEBUGGING
To aid in program development, there is a provision that can
help ensure `result' member references agree with library
expectations.
docs: tweak both of those newly created man docs a tad An important fact was omitted in the DEBUGGING section for the two newest man documents. Users must utilize a macro in the header files before verification happens. So, this commit will sneak in such mention and in that way reduce future liability if the feature won't work. Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-24 03:59:14 +05:30
It assumes that a supplied macro in the header file is
used to access the `result' value.
docs: replace 'procps_pids' stuff with revised version The original approach contained a fatal flaw. In order to use those man pages, users would have been required to already know how to use the library. Or alternately one could randomly search each of them while trying to ascertain which function call satisfies their need and what exactly was the proper compliment/order required. So, this revised approach tries to simplify things and document only what is not apparent in the header file. Along the way, the following assumptions were germane. 1) It is the kernel folks' job to document /proc files not to mention fields within those files. And since we don't yet know what some of those fields represent, we shouldn't attempt to document any of those we do know. 2) Our header file serves as an essential reference in successful exploitation of this new library interface. 3) The description represents functions as they appear in the header itself making them immediately familiar. 4) Armed with our header file users can easily see the self-documenting enumerators & structures. There isn't a need to explain them yet again in this man document. 5) Contrary to man guidelines, we shouldn't list error codes. Simple generic guidance serves everyone better. The following references represent a history for those man documents this new version is intended to replace. Reference(s): . 04/18/16, create libproc.3 + procps_pids_new.3 commit 4217eddf474debe55a7651757ccce1e86aeb04a5 . 04/19/16, create procps_pids_read_open.3 commit d48c54f6793d5faf44e420df43a75e04372d5945 . 01/05/17, create many procps_pids_... docs commit 2598e9f2ce39c93ebf55f664454d3bea919ed4e0 Signed-off-by: Jim Warner <james.warner@comcast.net>
2020-06-21 10:30:00 +05:30
This feature can be activated through either of the following
methods and any discrepancies will be wrtten to \fBstderr\fR.
.IP 1) 3
Add CFLAGS='-DXTRA_PROCPS_DEBUG' to any other ./configure
options employed.
.IP 2) 3
Add #include <procps/xtra-procps-debug.h> to any program
\fIafter\fR the #include <procps/pids.h>.
.PP
This verification feature incurs substantial overhead.
Therefore, it is important that it \fInot\fR be activated
for a production/release build.
.SH SEE ALSO
.BR procps (3)
.BR procps_misc (3)
.BR proc (5).
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