Add manpages for the gctl API.
Submitted by: le Tweaks by: phk
This commit is contained in:
Poul-Henning Kamp
parent
2cd7fe4dc1
commit
5e5bfe7757
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=126721
@ -25,6 +25,12 @@ MLINKS+= \
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libgeom.3 geom_stats_snapshot_free.3 \
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libgeom.3 geom_stats_snapshot_timestamp.3 \
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libgeom.3 geom_stats_snapshot_reset.3 \
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libgeom.3 geom_stats_snapshot_next.3
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libgeom.3 geom_stats_snapshot_next.3 \
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libgeom.3 gctl_get_handle.3 \
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libgeom.3 gctl_ro_param.3 \
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libgeom.3 gctl_rw_param.3 \
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libgeom.3 gctl_issue.3 \
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libgeom.3 gctl_free.3 \
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libgeom.3 gctl_dump.3
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.include <bsd.lib.mk>
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@ -38,7 +38,13 @@
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.Nm geom_stats_snapshot_free ,
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.Nm geom_stats_snapshot_timestamp ,
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.Nm geom_stats_snapshot_reset ,
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.Nm geom_stats_snapshot_next
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.Nm geom_stats_snapshot_next ,
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.Nm gctl_get_handle ,
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.Nm gctl_ro_param ,
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.Nm gctl_rw_param ,
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.Nm gctl_issue ,
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.Nm gctl_free ,
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.Nm gctl_dump
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.Nd userland API library for kernel GEOM subsystem
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.Sh LIBRARY
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.Lb libgeom
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@ -61,6 +67,19 @@
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.Fn geom_stats_snapshot_reset "void *arg"
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.Ft "struct g_stat *"
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.Fn geom_stats_snapshot_next "void *arg"
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.Ss "Control Functions"
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.Ft "struct gctl_req *"
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.Fn gctl_get_handle "void"
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.Ft void
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.Fn gctl_ro_param "struct gctl_req *req" "const char *name" "int len" "const void *value"
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.Ft void
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.Fn gctl_rw_param "struct gctl_req *req" "const char *name" "int len" "void *value"
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.Ft "const char *"
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.Fn gctl_issue "struct gctl_req *req"
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.Ft void
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.Fn gctl_free "struct gctl_req *req"
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.Ft void
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.Fn gctl_dump "struct gctl_req *req" "FILE *f"
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.Sh DESCRIPTION
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The
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.Nm geom
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@ -129,10 +148,99 @@ function
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returns the next item, and
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.Dv NULL
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if there are no more items in the snapshot.
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.Sh AUTHORS
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.An Poul-Henning Kamp Aq phk@FreeBSD.org
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.Ss "Control Functions"
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The
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.Fn gctl_*
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functions are used to send requests to GEOM classes. In order for a GEOM
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class to actually be able to receive these requests, it must have defined a
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"ctlreq" method.
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.Pp
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A
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.Ar struct gctl_req * ,
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obtained with
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.Fn gctl_get_handle ,
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can hold any number of parameters, which must be added to it with
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.Fn gctl_ro_param
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(for read-only parameters) or
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.Fn gctl_rw_param
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(for read/write parameters).
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.Pp
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Both
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.Fn gctl_ro_param
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and
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.Fn gctl_rw_param
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take a string
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.Ar name ,
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which is used to identify the parameter, and a
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.Ar value ,
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which contains - in the read-only case - the data to be passed to the
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GEOM class, or - in the read/write case - a pointer to preallocated memory
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that the GEOM class should fill with the desired data. If
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.Ar len
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is negative, it is assumed that
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.Ar value
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is an ASCII string and the actual length is taken from the string length of
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.Ar value ;
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otherwise it must hold the size of
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.Ar value .
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.Pp
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A parameter with a
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.Ar name
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containing the string "class" is mandatory for each request, and the
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corresponding
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.Ar value
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must hold the name of the GEOM class where the request should be sent to.
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.Pp
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Also mandatory for each request is a parameter with a
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.Ar name
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called "verb", and the corresponding
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.Ar value
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needs to hold the command string that the GEOM class should react upon.
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.Pp
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Once all desired parameters are filled in, the request must be sent to
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the GEOM subsystem with
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.Fn gctl_issue ,
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which returns NULL on success, or a string containing the error message
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on failure.
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.Pp
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After the request is finished, the allocated memory should be released with
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.Fn gctl_free .
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.Pp
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.Fn gctl_dump
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can be used to format the contents of
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.Ar req
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to the open file handle pointed to by
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.Ar f
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for debugging purposes.
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.Pp
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Error handling for the control functions is postponed until the call
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to
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.Fn gctl_issue
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which returns NULL on success or an error message corresponding to the
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first error which happened.
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.Sh EXAMPLES
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Create a request that is to be sent to the CCD class and tell
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it to destroy a specific geom:
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.Bd -literal -offset indent
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H = gctl_get_handle();
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gctl_ro_param(H, "verb", -1, "destroy geom");
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gctl_ro_param(H, "class", -1, "CCD");
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sprintf(buf, "ccd%d", ccd);
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gctl_ro_param(H, "geom", -1, buf);
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errstr = gctl_issue(H);
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if (errstr != NULL)
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err(1, "Could not destroy ccd: %s", errstr);
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gctl_free(H);
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.Ed
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.Sh SEE ALSO
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.Rs
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http://ezine.daemonnews.org/200308/blueprints.html
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.Re
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.Sh HISTORY
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The
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.Nm geom
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library appeared in
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.Fx 5.1 .
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.Sh AUTHORS
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.An Poul-Henning Kamp Aq phk@FreeBSD.org
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.An Lukas Ertl Aq le@FreeBSD.org
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