'\" t
.\"     Title: libtraceevent
.\"    Author: [see the "AUTHOR" section]
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: 03/09/2026
.\"    Manual: libtraceevent Manual
.\"    Source: libtraceevent
.\"  Language: English
.\"
.TH "LIBTRACEEVENT" "3" "03/09/2026" "libtraceevent" "libtraceevent Manual"
.\" -----------------------------------------------------------------
.\" * Define some portability stuff
.\" -----------------------------------------------------------------
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.\" http://bugs.debian.org/507673
.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
.ie \n(.g .ds Aq \(aq
.el       .ds Aq '
.\" -----------------------------------------------------------------
.\" * set default formatting
.\" -----------------------------------------------------------------
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.\" -----------------------------------------------------------------
.\" * MAIN CONTENT STARTS HERE *
.\" -----------------------------------------------------------------
.SH "NAME"
tep_btf_list_args \- Show the arguments of a function from BTF
.SH "SYNOPSIS"
.sp
.nf
\fB#include <event\-parse\&.h>\fR

int \fBtep_btf_list_args\fR(struct tep_handle *\fItep\fR, struct trace_seq *\fIs\fR, const char *\fIfunc\fR);
.fi
.SH "DESCRIPTION"
.sp
If the Linux kernel has BTF configured, then a binary file will exist in the path of \fB/sys/kernel/btf/vmlinux\fR\&. If this file is read into memory and passed to \fBtep_load_btf()\fR function, then it can be used to read the arguments of a given function, if that function data is found within the BTF file\&.
.sp
The \fBtep_btf_print_args()\fR takes a \fItep\fR handle, a trace_seq \fIs\fR pointer (that was initialized by \fBtrace_seq_init(3)\fR), and a \fIfunc\fR string that is the name of the function to find the BTF information to use to print the function\(cqs prototype\&. If BTF is not loaded or the \fIfunc\fR name is not found it will return a negative\&.
.SH "RETURN VALUE"
.sp
\fBtep_btf_list_args()\fR returns the number of arguments read on success and \-1 on failure (for example, if the function is not found)\&.
.SH "EXAMPLE"
.sp
.if n \{\
.RS 4
.\}
.nf
#include <stdlib\&.h>
#include <stdio\&.h>
#include <fcntl\&.h>
#include <event\-parse\&.h>
#include <sys/stat\&.h>
#include <unistd\&.h>

#define BTF_FILE "/sys/kernel/btf/vmlinux"

int main(int argc, char **argv)
{
        struct tep_handle *tep;
        struct trace_seq s;
        struct stat st;
        char *buf;
        int fd, r, z;

        if (argc < 2)
                exit(\-1);

        if (stat(BTF_FILE, &st) < 0) {
                perror(BTF_FILE);
                exit(\-1);
        }

        buf = malloc(st\&.st_size);
        if (!buf)
                exit(\-1);
        fd = open(BTF_FILE, O_RDONLY);
        if (fd < 0) {
                perror(BTF_FILE);
                exit(\-1);
        }
        for (z = 0; z < st\&.st_size; ) {
                r = read(fd, buf + z, st\&.st_size \- z);
                if (r <= 0)
                        break;
                z += r;
        }
        close(fd);
        tep = tep_alloc();
        if (!tep)
                exit(\-1);

        tep_load_btf(tep, buf, z);
        free(buf);

        trace_seq_init(&s);
        tep_btf_list_args(tep, &s, argv[1]);
        printf("%s(", argv[1]);
        trace_seq_do_printf(&s);
        printf(")\en");
        exit(0);
}
.fi
.if n \{\
.RE
.\}
.SH "FILES"
.sp
.if n \{\
.RS 4
.\}
.nf
\fBevent\-parse\&.h\fR
        Header file to include in order to have access to the library APIs\&.
\fB\-ltraceevent\fR
        Linker switch to add when building a program that uses the library\&.
.fi
.if n \{\
.RE
.\}
.SH "SEE ALSO"
.sp
\fBtep_btf_load\fR(3), \fBtep_btf_print_args\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>, author of \fBlibtraceevent\fR\&.
.fi
.if n \{\
.RE
.\}
.SH "REPORTING BUGS"
.sp
Report bugs to <\m[blue]\fBlinux\-trace\-devel@vger\&.kernel\&.org\fR\m[]\&\s-2\u[2]\d\s+2>
.SH "LICENSE"
.sp
libtraceevent is Free Software licensed under the GNU LGPL 2\&.1
.SH "RESOURCES"
.sp
\m[blue]\fBhttps://git\&.kernel\&.org/pub/scm/libs/libtrace/libtraceevent\&.git/\fR\m[]
.SH "NOTES"
.IP " 1." 4
rostedt@goodmis.org
.RS 4
\%mailto:rostedt@goodmis.org
.RE
.IP " 2." 4
linux-trace-devel@vger.kernel.org
.RS 4
\%mailto:linux-trace-devel@vger.kernel.org
.RE