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.

5 files changed, 68 insertions, 13 deletions

diff --git a/lib/libsbuf/Symbol.map b/lib/libsbuf/Symbol.map
index 164b8f3..7bbc4bf 100644
--- a/lib/libsbuf/Symbol.map
+++ b/lib/libsbuf/Symbol.map
@@ -21,6 +21,9 @@ FBSD_1.2 {
 	sbuf_len;
 	sbuf_done;
 	sbuf_delete;
+	sbuf_clear_flags;
+	sbuf_get_flags;
+	sbuf_set_flags;
 };
 
 FBSD_1.3 {
@@ -31,3 +34,8 @@ FBSD_1.3 {
 FBSD_1.4 {
 	sbuf_hexdump;
 };
+
+FBSD_1.5 {
+	sbuf_putbuf;
+};
+
diff --git a/lib/libsbuf/Version.def b/lib/libsbuf/Version.def
index fd5c6be..2894712 100644
--- a/lib/libsbuf/Version.def
+++ b/lib/libsbuf/Version.def
@@ -8,3 +8,6 @@ FBSD_1.3 {
 
 FBSD_1.4 {
 } FBSD_1.3;
+
+FBSD_1.5 {
+} FBSD_1.4;
diff --git a/share/man/man9/sbuf.9 b/share/man/man9/sbuf.9
index 0014884..fda9191 100644
--- a/share/man/man9/sbuf.9
+++ b/share/man/man9/sbuf.9
@@ -57,7 +57,8 @@
 .Nm sbuf_delete ,
 .Nm sbuf_start_section ,
 .Nm sbuf_end_section ,
-.Nm sbuf_hexdump
+.Nm sbuf_hexdump ,
+.Nm sbuf_putbuf
 .Nd safe string composition
 .Sh SYNOPSIS
 .In sys/types.h
@@ -124,6 +125,8 @@
 .Fa "const char *hdr"
 .Fa "int flags"
 .Fc
+.Ft void
+.Fn sbuf_putbuf "struct sbuf *s"
 .In sys/sysctl.h
 .Ft struct sbuf *
 .Fn sbuf_new_for_sysctl "struct sbuf *s" "char *buf" "int length" "struct sysctl_req *req"
@@ -472,6 +475,12 @@ representation of the bytes if possible.
 See the
 .Xr hexdump 3
 man page for more details on the interface.
+.Pp
+The
+.Fn sbuf_putbuf
+function printfs the sbuf to stdout if in userland, and to the console
+and log if in the kernel.
+It does not drain the buffer or update any pointers.
 .Sh NOTES
 If an operation caused an
 .Fa sbuf
diff --git a/sys/kern/subr_prf.c b/sys/kern/subr_prf.c
index 264e694..576c419 100644
--- a/sys/kern/subr_prf.c
+++ b/sys/kern/subr_prf.c
@@ -72,7 +72,19 @@ __FBSDID("$FreeBSD$");
  * Note that stdarg.h and the ANSI style va_start macro is used for both
  * ANSI and traditional C compilers.
  */
+#ifdef _KERNEL
 #include <machine/stdarg.h>
+#else
+#include <stdarg.h>
+#endif
+
+/*
+ * This is needed for sbuf_putbuf() when compiled into userland.  Due to the
+ * shared nature of this file, it's the only place to put it.
+ */
+#ifndef _KERNEL
+#include <stdio.h>
+#endif
 
 #ifdef _KERNEL
 
@@ -406,6 +418,23 @@ vprintf(const char *fmt, va_list ap)
 }
 
 static void
+prf_putbuf(char *bufr, int flags, int pri)
+{
+
+	if (flags & TOLOG)
+		msglogstr(bufr, pri, /*filter_cr*/1);
+
+	if (flags & TOCONS) {
+		if ((panicstr == NULL) && (constty != NULL))
+			msgbuf_addstr(&consmsgbuf, -1,
+			    bufr, /*filter_cr*/ 0);
+
+		if ((constty == NULL) ||(always_console_output))
+			cnputs(bufr);
+	}
+}
+
+static void
 putbuf(int c, struct putchar_arg *ap)
 {
 	/* Check if no console output buffer was provided. */
@@ -426,18 +455,7 @@ putbuf(int c, struct putchar_arg *ap)
 
 		/* Check if the buffer needs to be flushed. */
 		if (ap->remain == 2 || c == '\n') {
-
-			if (ap->flags & TOLOG)
-				msglogstr(ap->p_bufr, ap->pri, /*filter_cr*/1);
-
-			if (ap->flags & TOCONS) {
-				if ((panicstr == NULL) && (constty != NULL))
-					msgbuf_addstr(&consmsgbuf, -1,
-					    ap->p_bufr, /*filter_cr*/ 0);
-
-				if ((constty == NULL) ||(always_console_output))
-					cnputs(ap->p_bufr);
-			}
+			prf_putbuf(ap->p_bufr, ap->flags, ap->pri);
 
 			ap->p_next = ap->p_bufr;
 			ap->remain = ap->n_bufr;
@@ -1216,3 +1234,19 @@ counted_warning(unsigned *counter, const char *msg)
 	}
 }
 #endif
+
+#ifdef _KERNEL
+void
+sbuf_putbuf(struct sbuf *sb)
+{
+
+	prf_putbuf(sbuf_data(sb), TOLOG | TOCONS, -1);
+}
+#else
+void
+sbuf_putbuf(struct sbuf *sb)
+{
+
+	printf("%s", sbuf_data(sb));
+}
+#endif
diff --git a/sys/sys/sbuf.h b/sys/sys/sbuf.h
index 580cbd2..c05bafd 100644
--- a/sys/sys/sbuf.h
+++ b/sys/sys/sbuf.h
@@ -99,6 +99,7 @@ void		 sbuf_start_section(struct sbuf *, ssize_t *);
 ssize_t		 sbuf_end_section(struct sbuf *, ssize_t, size_t, int);
 void		 sbuf_hexdump(struct sbuf *, const void *, int, const char *,
 		     int);
+void		 sbuf_putbuf(struct sbuf *);
 
 #ifdef _KERNEL
 struct uio;