This patch adds a new ktrace(2) record type, KTR_STRUCT, whose payload

consists of the null-terminated name and the contents of any structure
you wish to record.  A new ktrstruct() function constructs and emits a
KTR_STRUCT record.  It is accompanied by convenience macros for struct
stat and struct sockaddr.

In kdump(1), KTR_STRUCT records are handled by a dispatcher function
that runs stringent sanity checks on its contents before handing it
over to individual decoding funtions for each type of structure.
Currently supported structures are struct stat and struct sockaddr for
the AF_INET, AF_INET6 and AF_UNIX families; support for AF_APPLETALK
and AF_IPX is present but disabled, as I am unable to test it properly.

Since 's' was already taken, the letter 't' is used by ktrace(1) to
enable KTR_STRUCT trace points, and in kdump(1) to enable their
decoding.

Derived from patches by Andrew Li <andrew2.li@citi.com>.

PR:		kern/117836
MFC after:	3 weeks

1 files changed, 8 insertions, 0 deletions

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 27a5289..7025587 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 
 #include "opt_compat.h"
 #include "opt_ddb.h"
+#include "opt_ktrace.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -72,6 +73,9 @@ __FBSDID("$FreeBSD$");
 #include <sys/unistd.h>
 #include <sys/user.h>
 #include <sys/vnode.h>
+#ifdef KTRACE
+#include <sys/ktrace.h>
+#endif
 
 #include <security/audit/audit.h>
 
@@ -1126,6 +1130,10 @@ kern_fstat(struct thread *td, int fd, struct stat *sbp)
 
 	error = fo_stat(fp, sbp, td->td_ucred, td);
 	fdrop(fp, td);
+#ifdef KTRACE
+	if (error == 0 && KTRPOINT(td, KTR_STRUCT))
+		ktrstat(sbp);
+#endif
 	return (error);
 }