1LIBTRACECMD(3) libtracefs Manual LIBTRACECMD(3)
2
6 tracecmd_buffer_instances, tracecmd_buffer_instance_name,
7 tracecmd_buffer_instance_handle - Read tracing instances from a trace
8 file.
9
11 #include <trace-cmd.h>
12 int tracecmd_buffer_instances(struct tracecmd_input *handle);
14 const char *tracecmd_buffer_instance_name(struct tracecmd_input *handle, int indx);
15 struct tracecmd_input *tracecmd_buffer_instance_handle(struct tracecmd_input *handle, int indx);
16
18 This set of APIs can be used to get information and read tracing data
19 from tracing instances stored in a trace file.
20 The tracecmd_buffer_instances() function gets the number of tracing
22 instances recorded in a trace file. The top instance is not counted.
23 The handle is a tracecmd_input handler returned by
24 tracecmd_open_head().
25 The tracecmd_buffer_instance_name() function gets the name of the
27 tracing instance with given index indx, recorded in a trace file. The
28 indx is a number in the interval [0 .. count-1], where count is the
29 number returned by tracecmd_buffer_instances(). The handle is a
30 tracecmd_input handler returned by tracecmd_open_head().
31 The tracecmd_buffer_instance_handle() allocates and initializes a
33 tracecmd_input handle, associated with trace instance with index indx
34 from a trace file. The handle is a tracecmd_input handler returned by
35 tracecmd_open_head(). The indx is a number in the interval [0 ..
36 count-1], where count is the number returned by
37 tracecmd_buffer_instances().
38
40 The tracecmd_buffer_instances() function returns the number of tracing
41 instances recorded in a trace file.
42 The tracecmd_buffer_instance_name() function returns a string, the name
44 of a tracing instance, or NULL in case of an error The string must not
45 be freed.
46 The tracecmd_buffer_instance_handle() function returns a pointer to
48 newly allocated tracecmd_input handler or NULL in case if an error. The
49 returned handler must be closed by tracecmd_close()(3)
50
52 #include <trace-cmd.h>
53 ...
54 struct tracecmd_input *handle = tracecmd_open_head("trace.dat");
55 if (!handle) {
56 /* Failed to open trace.dat file */
57 }
58 ...
59 int num = tracecmd_buffer_instances(handle);
60 while(num) {
62 struct tracecmd_input *h;
63 char *name;
64 name = tracecmd_buffer_instance_name(handle, num);
66 if (!name) {
67 /* Failed to get name of instance num */
68 }
69 h = tracecmd_buffer_instance_handle(handle, num);
70 if (!h) {
71 /* Failed to initialize handler for instance num */
72 }
73 ...
75 tracecmd_close(h);
76 num--;
77 }
78 ...
79 tracecmd_close(handle);
80
82 trace-cmd.h
83 Header file to include in order to have access to the library APIs.
84 -ltracecmd
85 Linker switch to add when building a program that uses the library.
86
88 libtracefs(3), libtraceevent(3), trace-cmd(1) trace-cmd.dat(5)
89
91 Steven Rostedt <rostedt@goodmis.org[1]>
92 Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>
93
95 Report bugs to <linux-trace-devel@vger.kernel.org[3]>
96
98 libtracecmd is Free Software licensed under the GNU LGPL 2.1
99
101 https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git/
102
104 Copyright (C) 2020 VMware, Inc. Free use of this software is granted
105 under the terms of the GNU Public License (GPL).
106
108 1. rostedt@goodmis.org
109 mailto:rostedt@goodmis.org
110 2. tz.stoyanov@gmail.com
112 mailto:tz.stoyanov@gmail.com
113 3. linux-trace-devel@vger.kernel.org
115 mailto:linux-trace-devel@vger.kernel.org
116libtracefs 03/29/2021 LIBTRACECMD(3)