MFC r307873,r314397,r314399,r314419,r314420,r314533,r316553:

r307873 (by marcel):

Include <stdarg.h> instead of <machine/stdarg.h> when compiled as
part of libsbuf. The former is the standard header, and allows us
to compile libsbuf on macOS/linux.

r314397 (by scottl):

Implement sbuf_prf(), which takes an sbuf and outputs it
to stdout in the non-kernel case and to the console+log
in the kernel case. For the kernel case it hooks the
putbuf() machinery underneath printf(9) so that the buffer
is written completely atomically and without a copy into
another temporary buffer. This is useful for fixing
compound console/log messages that become broken and
interleaved when multiple threads are competing for the
console.

r314399 (by scottl):

Add prototype for sbuf_putbuf()

r314419 (by jkim):

Include stdio.h to fix libsbuf build.

r314420 (by scottl):

Provide a comment on why stdio.h needs to be included.

r314533 (by scottl):

Expose the sbuf_putbuf() symbol to libsbuf. There are a few other symbols
that are present but not exposed, like get/set/clear flags, not sure if they
need to be exposed at this point.

r316553:

sbuf(3): expose sbuf_{clear,get,set}_flags(3) via libsbuf

These functions were added to sbuf(9) in r279992, but never
exposed to userspace. Expose them now so they can be used/tested.

MFC r319916:
Remove stray return.

MFC r303151:
Provide counter_warning(9) KPI.

MFC r303155:
Hide counted_warning(9) under #ifdef _KERNEL braces.

MFC r281785

Always send log(9) messages to the message buffer.

It is truer to the semantics of logging for messages to *always*
go to the message buffer, where they can eventually be collected
and, in fact, be put into a log file.

This restores the behavior prior to r70239, which seems to have
changed it inadvertently.

Submitted by: Eric Badger <eric@badgerio.us>
Obtained from: Dell Inc.

MFC, r284192:

------------------------------------------------------------------------
r284192 | ken | 2015-06-09 15:39:38 -0600 (Tue, 09 Jun 2015) | 102 lines

Add support for reading MAM attributes to camcontrol(8) and libcam(3).

MAM is Medium Auxiliary Memory and is most commonly found as flash
chips on tapes.

This includes support for reading attributes and decoding most
known attributes, but does not yet include support for writing
attributes or reporting attributes in XML format.

libsbuf/Makefile:
Add subr_prf.c for the new sbuf_hexdump() function. This
function is essentially the same function.

libsbuf/Symbol.map:
Add a new shared library minor version, and include the
sbuf_hexdump() function.

libsbuf/Version.def:
Add version 1.4 of the libsbuf library.

libutil/hexdump.3:
Document sbuf_hexdump() alongside hexdump(3), since it is
essentially the same function.

camcontrol/Makefile:
Add attrib.c.

camcontrol/attrib.c:
Implementation of READ ATTRIBUTE support for camcontrol(8).

camcontrol/camcontrol.8:
Document the new 'camcontrol attrib' subcommand.

camcontrol/camcontrol.c:
Add the new 'camcontrol attrib' subcommand.

camcontrol/camcontrol.h:
Add a function prototype for scsiattrib().

share/man/man9/sbuf.9:
Document the existence of sbuf_hexdump() and point users to
the hexdump(3) man page for more details.

sys/cam/scsi/scsi_all.c:
Add a table of known attributes, text descriptions and
handler functions.

Add a new scsi_attrib_sbuf() function along with a number
of other related functions that help decode attributes.

scsi_attrib_ascii_sbuf() decodes ASCII format attributes.

scsi_attrib_int_sbuf() decodes binary format attributes, and
will pass them off to scsi_attrib_hexdump_sbuf() if they're
bigger than 8 bytes.

scsi_attrib_vendser_sbuf() decodes the vendor and drive
serial number attribute.

scsi_attrib_volcoh_sbuf() decodes the Volume Coherency
Information attribute that LTFS writes out.

sys/cam/scsi/scsi_all.h:
Add a number of attribute-related structure definitions and
other defines.

Add function prototypes for all of the functions added in
scsi_all.c.

sys/kern/subr_prf.c:
Add a new function, sbuf_hexdump(). This is the same as
the existing hexdump(9) function, except that it puts the
result in an sbuf.

This also changes subr_prf.c so that it can be compiled in
userland for includsion in libsbuf.

We should work to change this so that the kernel hexdump
implementation is a wrapper around sbuf_hexdump() with a
statically allocated sbuf with a drain. That will require
a drain function that goes to the kernel printf() buffer
that can take a non-NUL terminated string as input.
That is because an sbuf isn't NUL-terminated until it is
finished, and we don't want to finish it while we're still
using it.

We should also work to consolidate the userland hexdump and
kernel hexdump implemenatations, which are currently
separate. This would also mean making applications that
currently link in libutil link in libsbuf.

sys/sys/sbuf.h:
Add the prototype for sbuf_hexdump(), and add another copy
of the hexdump flag values if they aren't already defined.

Ideally the flags should be defined in one place but the
implemenation makes it difficult to do properly. (See
above.)

Sponsored by: Spectra Logic Corporation

------------------------------------------------------------------------

MFC r261786, r261789

Rework the EARLY_PRINTF mechanism. Instead of defining a special eprintf()
routine, now a platform can provide a pointer to an early_putc() routine
which is used instead of cn_putc(). Control can be handed off from early
printf support to standard console support by NULLing out the pointer
during standard console init.

Convert two while(1); statements into proper panics.

MFC r261038, r261039, r261040, r261041

Implement generic support for early printf.

MFC r264795:

Fix grammar error and trailing newline.

MFC r263129:

Combine similar code from vprintf(9) and log(9).

MFC r281785

Always send log(9) messages to the message buffer.

It is truer to the semantics of logging for messages to *always*
go to the message buffer, where they can eventually be collected
and, in fact, be put into a log file.

This restores the behavior prior to r70239, which seems to have
changed it inadvertently.

Submitted by: Eric Badger <eric@badgerio.us>
Obtained from: Dell Inc.

MFC, r284192:

------------------------------------------------------------------------
r284192 | ken | 2015-06-09 15:39:38 -0600 (Tue, 09 Jun 2015) | 102 lines

Add support for reading MAM attributes to camcontrol(8) and libcam(3).

MAM is Medium Auxiliary Memory and is most commonly found as flash
chips on tapes.

This includes support for reading attributes and decoding most
known attributes, but does not yet include support for writing
attributes or reporting attributes in XML format.

libsbuf/Makefile:
Add subr_prf.c for the new sbuf_hexdump() function. This
function is essentially the same function.

libsbuf/Symbol.map:
Add a new shared library minor version, and include the
sbuf_hexdump() function.

libsbuf/Version.def:
Add version 1.4 of the libsbuf library.

libutil/hexdump.3:
Document sbuf_hexdump() alongside hexdump(3), since it is
essentially the same function.

camcontrol/Makefile:
Add attrib.c.

camcontrol/attrib.c:
Implementation of READ ATTRIBUTE support for camcontrol(8).

camcontrol/camcontrol.8:
Document the new 'camcontrol attrib' subcommand.

camcontrol/camcontrol.c:
Add the new 'camcontrol attrib' subcommand.

camcontrol/camcontrol.h:
Add a function prototype for scsiattrib().

share/man/man9/sbuf.9:
Document the existence of sbuf_hexdump() and point users to
the hexdump(3) man page for more details.

sys/cam/scsi/scsi_all.c:
Add a table of known attributes, text descriptions and
handler functions.

Add a new scsi_attrib_sbuf() function along with a number
of other related functions that help decode attributes.

scsi_attrib_ascii_sbuf() decodes ASCII format attributes.

scsi_attrib_int_sbuf() decodes binary format attributes, and
will pass them off to scsi_attrib_hexdump_sbuf() if they're
bigger than 8 bytes.

scsi_attrib_vendser_sbuf() decodes the vendor and drive
serial number attribute.

scsi_attrib_volcoh_sbuf() decodes the Volume Coherency
Information attribute that LTFS writes out.

sys/cam/scsi/scsi_all.h:
Add a number of attribute-related structure definitions and
other defines.

Add function prototypes for all of the functions added in
scsi_all.c.

sys/kern/subr_prf.c:
Add a new function, sbuf_hexdump(). This is the same as
the existing hexdump(9) function, except that it puts the
result in an sbuf.

This also changes subr_prf.c so that it can be compiled in
userland for includsion in libsbuf.

We should work to change this so that the kernel hexdump
implementation is a wrapper around sbuf_hexdump() with a
statically allocated sbuf with a drain. That will require
a drain function that goes to the kernel printf() buffer
that can take a non-NUL terminated string as input.
That is because an sbuf isn't NUL-terminated until it is
finished, and we don't want to finish it while we're still
using it.

We should also work to consolidate the userland hexdump and
kernel hexdump implemenatations, which are currently
separate. This would also mean making applications that
currently link in libutil link in libsbuf.

sys/sys/sbuf.h:
Add the prototype for sbuf_hexdump(), and add another copy
of the hexdump flag values if they aren't already defined.

Ideally the flags should be defined in one place but the
implemenation makes it difficult to do properly. (See
above.)

Sponsored by: Spectra Logic Corporation

------------------------------------------------------------------------

MFC r261786, r261789

Rework the EARLY_PRINTF mechanism. Instead of defining a special eprintf()
routine, now a platform can provide a pointer to an early_putc() routine
which is used instead of cn_putc(). Control can be handed off from early
printf support to standard console support by NULLing out the pointer
during standard console init.

Convert two while(1); statements into proper panics.

MFC r261038, r261039, r261040, r261041

Implement generic support for early printf.

MFC r264795:

Fix grammar error and trailing newline.

MFC r263129:

Combine similar code from vprintf(9) and log(9).