'\" t
.\"     Title: libtracefs
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 07/25/2024
.\"    Manual: libtracefs Manual
.\"    Source: libtracefs 1.8.1
.\"  Language: English
.\"
.TH "LIBTRACEFS" "3" "07/25/2024" "libtracefs 1\&.8\&.1" "libtracefs Manual"
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.SH "NAME"
tracefs_local_events, tracefs_local_events_system, tracefs_fill_local_events, tracefs_load_cmdlines, tracefs_load_headers \- Initialize a tep handler with trace events from the local system\&.
.SH "SYNOPSIS"
.sp
.nf
\fB#include <tracefs\&.h>\fR

struct tep_handle *\fBtracefs_local_events\fR(const char *\fItracing_dir\fR);
struct tep_handle *\fBtracefs_local_events_system\fR(const char *\fItracing_dir\fR, const char * const *\fIsys_names\fR);
int \fBtracefs_fill_local_events\fR(const char *\fItracing_dir\fR, struct tep_handle *\fItep\fR, int *\fIparsing_failures\fR);
int \fBtracefs_load_cmdlines\fR(const char *\fItracing_dir\fR, struct tep_handle *\fItep\fR);
int \fBtracefs_load_headers\fR(const char *\fItracing_dir\fR, struct tep_handle *\fItep\fR);
.fi
.SH "DESCRIPTION"
.sp
Functions for initializing a tep handler with trace events from the local system\&.
.sp
The \fBtracefs_local_events()\fR function allocates a new \fItep\fR handler and initializes it with events from all trace systems, located in the given \fItracing_dir\fR directory\&. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine\&.
.sp
The \fBtracefs_local_events_system()\fR function allocates a new \fItep\fR handler and initializes it with events from specified trace systems \fIsys_names\fR, located in the given \fItracing_dir\fR directory\&. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine\&. The \fIsys_names\fR argument is an array of trace system names, that will be used for \fItep\fR handler initialization\&. The last element in that array must be a NULL pointer\&.
.sp
The \fBtracefs_fill_local_events()\fR function initializes already allocated \fItep\fR handler with events from all trace systems, located in the given \fItracing_dir\fR directory\&. This could be NULL or the location of the tracefs mount point for the trace systems of the local machine, or it may be a path to a copy of the tracefs directory from another machine\&. The \fItep\fR argument must be a pointer to already allocated tep handler, that is going to be initialized\&. The \fIparsing_failures\fR argument could be NULL or a pointer to an integer, where the number of failures while parsing the event files are returned\&.
.sp
The above functions will also load the mappings between pids and the process command line names\&. In some cases the \fItep\fR handle is created with one of the above before tracing begins\&. As the mappings get updated during the trace, there may be a need to read the mappings again after the trace\&. The \fBtracefs_load_cmdlines()\fR does just that\&. The \fItracing_dir\fR is the directory of the mount point to load from, or NULL to use the mount point of the tracefs file system\&.
.sp
The \fBtracefs_load_headers()\fR will reade the "header_page" of the events directory that will update the \fItep\fR handle with information on how to parse the tracing ring buffer sub\-buffer\&.
.SH "RETURN VALUE"
.sp
The \fBtracefs_local_events()\fR and \fBtracefs_local_events_system()\fR functions return pointer to allocated and initialized \fItep\fR handler, or NULL in case of an error\&. The returned \fItep\fR handler must be freed with \fBtep_free\fR(3)\&.
.sp
The \fBtracefs_fill_local_events()\fR function returns \-1 in case of an error or 0 otherwise\&.
.sp
The \fBtracefs_load_cmdlines()\fR function returns \-1 in case of an error, or 0 otherwise\&.
.SH "EXAMPLE"
.sp
.if n \{\
.RS 4
.\}
.nf
#include <tracefs\&.h>

struct tep_handle *tep;
\&.\&.\&.
        tep = tracefs_local_events(NULL);
        if (!tep) {
                /* Failed to initialise tep handler with local events from top instance */
                \&.\&.\&.
        }
\&.\&.\&.
        tep_free(tep);
\&.\&.\&.
        const char *systems[] = {"ftrace", "irq", NULL};
        tep = tracefs_local_events_system(NULL, systems);
        if (!tep) {
                /* Failed to initialise tep handler with local events from
                 * ftrace and irq systems in top instance\&.
                 */
                \&.\&.\&.
        }
\&.\&.\&.
        tep_free(tep);
\&.\&.\&.
        int parsing_failures;
        tep = tep_alloc();
        if (!tep) {
                /* Failed to allocate a tep handler */
                \&.\&.\&.
        }
        if (tracefs_fill_local_events(NULL, tep, &parsing_failures) < 0) {
                /* Failed to initialise tep handler with local events from top instance */
        }
        tracefs_load_cmdlines(NULL, tep);
\&.\&.\&.
        tep_free(tep);
.fi
.if n \{\
.RE
.\}
.SH "FILES"
.sp
.if n \{\
.RS 4
.\}
.nf
\fBtracefs\&.h\fR
        Header file to include in order to have access to the library APIs\&.
\fB\-ltracefs\fR
        Linker switch to add when building a program that uses the library\&.
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.sp
\fBlibtracefs\fR(3), \fBlibtraceevent\fR(3), \fBtrace\-cmd\fR(1)
.SH "AUTHOR"
.sp
.if n \{\
.RS 4
.\}
.nf
\fBSteven Rostedt\fR <\m[blue]\fBrostedt@goodmis\&.org\fR\m[]\&\s-2\u[1]\d\s+2>
\fBTzvetomir Stoyanov\fR <\m[blue]\fBtz\&.stoyanov@gmail\&.com\fR\m[]\&\s-2\u[2]\d\s+2>
.fi
.if n \{\
.RE
.\}
.SH "REPORTING BUGS"
.sp
Report bugs to <\m[blue]\fBlinux\-trace\-devel@vger\&.kernel\&.org\fR\m[]\&\s-2\u[3]\d\s+2>
.SH "LICENSE"
.sp
libtracefs is Free Software licensed under the GNU LGPL 2\&.1
.SH "RESOURCES"
.sp
\m[blue]\fBhttps://git\&.kernel\&.org/pub/scm/libs/libtrace/libtracefs\&.git/\fR\m[]
.SH "COPYING"
.sp
Copyright (C) 2020 VMware, Inc\&. Free use of this software is granted under the terms of the GNU Public License (GPL)\&.
.SH "NOTES"
.IP " 1." 4
rostedt@goodmis.org
.RS 4
\%mailto:rostedt@goodmis.org
.RE
.IP " 2." 4
tz.stoyanov@gmail.com
.RS 4
\%mailto:tz.stoyanov@gmail.com
.RE
.IP " 3." 4
linux-trace-devel@vger.kernel.org
.RS 4
\%mailto:linux-trace-devel@vger.kernel.org
.RE