kbuffer: Add kbuffer_dup()

Add the function kbuffer_dup() that will duplicate a current kbuffer structure
that can be used separately on the same subbuffer or load a new buffer on it.

Link: https://lore.kernel.org/linux-trace-devel/20231224191813.1076074-5-rostedt@goodmis.org

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

4 files changed, 29 insertions, 1 deletions

diff --git a/Documentation/libtraceevent-kbuffer-create.txt b/Documentation/libtraceevent-kbuffer-create.txt
index 12e5d6c..7279dbe 100644
--- a/Documentation/libtraceevent-kbuffer-create.txt
+++ b/Documentation/libtraceevent-kbuffer-create.txt
@@ -3,7 +3,7 @@ libtraceevent(3)
 
 NAME
 ----
-kbuffer_alloc, kbuffer_free, kbuffer_load_subbuffer, kbuffer_subbuffer_size, kbuffer_start_of_data - Creating of kbuffer element to parse
+kbuffer_alloc, kbuffer_dup, kbuffer_free, kbuffer_load_subbuffer, kbuffer_subbuffer_size, kbuffer_start_of_data - Creating of kbuffer element to parse
 the Linux kernel tracing ring buffer
 
 SYNOPSIS
@@ -28,6 +28,7 @@ struct kbuffer;
 struct tep_handle;
 
 struct kbuffer pass:[*]*kbuffer_alloc*(enum kbuffer_long_size _size_, enum kbuffer_endian _endian_);
+struct kbuffer pass:[*]*kbuffer_dup*(struct kbuffer pass:[*]_kbuf_);
 void *kbuffer_free*(struct kbuffer pass:[*]_kbuf_);
 int *kbuffer_load_subbuffer*(struct kbuffer pass:[*]_kbuf_, void pass:[*]_subbuffer_);
 int *kbuffer_subbuffer_size*(struct kbuffer pass:[*]_kbuf);
@@ -59,6 +60,11 @@ will then perform a *uname(2)* call, and if the _machine_ field has the string "
 in it, it will be set to 8 byte long size and not 4 byte. This is because the
 ring buffer long size is dependent on the kernel and not user space.
 
+The *kbuffer_dup()* function will duplicate an existing kbuffer structure with
+an allocated new one. It will have all the properties of the passed in _kbuf_,
+including pointing to the same subbuffer that was loaded in the _kbuf_.
+It must be freed with *kbuffer_free()*.
+
 The *kbuffer_free()* function will free the resources created by *kbuffer_alloc()*.
 
 The *kbuffer_load_subbuffer()* will take a _subbuffer_ which is a raw data blob
diff --git a/Documentation/libtraceevent.txt b/Documentation/libtraceevent.txt
index 407c068..8b63982 100644
--- a/Documentation/libtraceevent.txt
+++ b/Documentation/libtraceevent.txt
@@ -181,6 +181,7 @@ Trace sequences:
 kbuffer parsing:
 #include <kbuffer.h>
 	struct kbuffer pass:[*]*kbuffer_alloc*(enum kbuffer_long_size _size_, enum kbuffer_endian _endian_);
+	struct kbuffer pass:[*]*kbuffer_dup*(struct kbuffer pass:[*]_kbuf_);
 	void *kbuffer_free*(struct kbuffer pass:[*]_kbuf_);
 	int *kbuffer_load_subbuffer*(struct kbuffer pass:[*]_kbuf_, void pass:[*]_subbuffer_);
 	int *kbuffer_subbuffer_size*(struct kbuffer pass:[*]_kbuf);
diff --git a/include/traceevent/kbuffer.h b/include/traceevent/kbuffer.h
index e5d377b..7086e03 100644
--- a/include/traceevent/kbuffer.h
+++ b/include/traceevent/kbuffer.h
@@ -31,6 +31,7 @@ enum {
 struct kbuffer;
 
 struct kbuffer *kbuffer_alloc(enum kbuffer_long_size size, enum kbuffer_endian endian);
+struct kbuffer *kbuffer_dup(struct kbuffer *kbuf);
 void kbuffer_free(struct kbuffer *kbuf);
 int kbuffer_load_subbuffer(struct kbuffer *kbuf, void *subbuffer);
 void *kbuffer_read_event(struct kbuffer *kbuf, unsigned long long *ts);
diff --git a/src/kbuffer-parse.c b/src/kbuffer-parse.c
index b86c8f0..b117094 100644
--- a/src/kbuffer-parse.c
+++ b/src/kbuffer-parse.c
@@ -269,6 +269,26 @@ kbuffer_alloc(enum kbuffer_long_size size, enum kbuffer_endian endian)
 	return kbuf;
 }
 
+/**
+ * kbuffer_dup - duplicate a given kbuffer
+ * @kbuf_orig; The kbuffer to duplicate
+ *
+ * Allocates a new kbuffer based off of anothe kbuffer.
+ * Returns the duplicate on success or NULL on error.
+ */
+struct kbuffer *kbuffer_dup(struct kbuffer *kbuf_orig)
+{
+	struct kbuffer *kbuf;
+
+	kbuf = malloc(sizeof(*kbuf));
+	if (!kbuf)
+		return NULL;
+
+	*kbuf = *kbuf_orig;
+
+	return kbuf;
+}
+
 /** kbuffer_free - free an allocated kbuffer
  * @kbuf:	The kbuffer to free
  *