'\" t .\" Title: libtraceevent .\" Author: [see the "AUTHOR" section] .\" Generator: DocBook XSL Stylesheets vsnapshot .\" Date: 01/14/2024 .\" Manual: libtraceevent Manual .\" Source: libtraceevent 1.8.2 .\" Language: English .\" .TH "LIBTRACEEVENT" "3" "01/14/2024" "libtraceevent 1\&.8\&.2" "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_get_any_field_val, tep_get_common_field_val, tep_get_field_val, tep_get_field_raw \- Get value of a field\&. .SH "SYNOPSIS" .sp .nf \fB#include \fR \fB#include \fR int \fBtep_get_any_field_val\fR(struct trace_seq *\fIs\fR, struct tep_event *\fIevent\fR, const char *\fIname\fR, struct tep_record *\fIrecord\fR, unsigned long long *\fIval\fR, int \fIerr\fR); int \fBtep_get_common_field_val\fR(struct trace_seq *\fIs\fR, struct tep_event *\fIevent\fR, const char *\fIname\fR, struct tep_record *\fIrecord\fR, unsigned long long *\fIval\fR, int \fIerr\fR); int \fBtep_get_field_val\fR(struct trace_seq *\fIs\fR, struct tep_event *\fIevent\fR, const char *\fIname\fR, struct tep_record *\fIrecord\fR, unsigned long long *\fIval\fR, int \fIerr\fR); void *\fBtep_get_field_raw\fR(struct trace_seq *\fIs\fR, struct tep_event *\fIevent\fR, const char *\fIname\fR, struct tep_record *\fIrecord\fR, int *\fIlen\fR, int \fIerr\fR); .fi .SH "DESCRIPTION" .sp These functions can be used to find a field and retrieve its value\&. .sp The \fBtep_get_any_field_val()\fR function searches in the \fIrecord\fR for a field with \fIname\fR, part of the \fIevent\fR\&. If the field is found, its value is stored in \fIval\fR\&. If there is an error and \fIerr\fR is not zero, then an error string is written into \fIs\fR\&. .sp The \fBtep_get_common_field_val()\fR function does the same as \fBtep_get_any_field_val()\fR, but searches only in the common fields\&. This works for any event as all events include the common fields\&. .sp The \fBtep_get_field_val()\fR function does the same as \fBtep_get_any_field_val()\fR, but searches only in the event specific fields\&. .sp The \fBtep_get_field_raw()\fR function searches in the \fIrecord\fR for a field with \fIname\fR, part of the \fIevent\fR\&. If the field is found, a pointer to where the field exists in the record\(cqs raw data is returned\&. The size of the data is stored in \fIlen\fR\&. If there is an error and \fIerr\fR is not zero, then an error string is written into \fIs\fR\&. .SH "RETURN VALUE" .sp The \fBtep_get_any_field_val()\fR, \fBtep_get_common_field_val()\fR and \fBtep_get_field_val()\fR functions return 0 on success, or \-1 in case of an error\&. .sp The \fBtep_get_field_raw()\fR function returns a pointer to field\(cqs raw data, and places the length of this data in \fIlen\fR\&. In case of an error NULL is returned\&. .SH "EXAMPLE" .sp .if n \{\ .RS 4 .\} .nf #include #include \&.\&.\&. struct tep_handle *tep = tep_alloc(); \&.\&.\&. struct tep_event *event = tep_find_event_by_name(tep, "kvm", "kvm_exit"); \&.\&.\&. void process_record(struct tep_record *record) { int len; char *comm; struct tep_event *event; unsigned long long val; event = tep_find_event_by_record(tep, record); if (event != NULL) { if (tep_get_common_field_val(NULL, event, "common_type", record, &val, 0) == 0) { /* Got the value of common type field */ } if (tep_get_field_val(NULL, event, "pid", record, &val, 0) == 0) { /* Got the value of pid specific field */ } comm = tep_get_field_raw(NULL, event, "comm", record, &len, 0); if (comm != NULL) { /* Got a pointer to the comm event specific field */ } } } .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\&. \fBtrace\-seq\&.h\fR Header file to include in order to have access to trace sequences related APIs\&. Trace sequences are used to allow a function to call several other functions to create a string of data to use\&. \fB\-ltraceevent\fR Linker switch to add when building a program that uses the library\&. .fi .if n \{\ .RE .\} .SH "SEE ALSO" .sp \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\&. \fBTzvetomir Stoyanov\fR <\m[blue]\fBtz\&.stoyanov@gmail\&.com\fR\m[]\&\s-2\u[2]\d\s+2>, author of this man page\&. .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 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 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