| libtraceevent(3) |
| ================ |
| |
| NAME |
| ---- |
| tep_get_any_field_val, tep_get_common_field_val, tep_get_field_val, |
| tep_get_field_raw - Get value of a field. |
| |
| SYNOPSIS |
| -------- |
| [verse] |
| -- |
| *#include <event-parse.h>* |
| *#include <trace-seq.h>* |
| |
| int *tep_get_any_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_); |
| int *tep_get_common_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_); |
| int *tep_get_field_val*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, unsigned long long pass:[*]_val_, int _err_); |
| void pass:[*]*tep_get_field_raw*(struct trace_seq pass:[*]_s_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int pass:[*]_len_, int _err_); |
| -- |
| |
| DESCRIPTION |
| ----------- |
| These functions can be used to find a field and retrieve its value. |
| |
| The _tep_get_any_field_val()_ function searches in the _record_ for a field |
| with _name_, part of the _event_. If the field is found, its value is stored in |
| _val_. If there is an error and _err_ is not zero, then an error string is |
| written into _s_. |
| |
| The _tep_get_common_field_val()_ function does the same as |
| _tep_get_any_field_val()_, but searches only in the common fields. This works |
| for any event as all events include the common fields. |
| |
| The _tep_get_field_val()_ function does the same as _tep_get_any_field_val()_, |
| but searches only in the event specific fields. |
| |
| The _tep_get_field_raw()_ function searches in the _record_ for a field with |
| _name_, part of the _event_. If the field is found, a pointer to where the field |
| exists in the record's raw data is returned. The size of the data is stored in |
| _len_. If there is an error and _err_ is not zero, then an error string is |
| written into _s_. |
| |
| RETURN VALUE |
| ------------ |
| The _tep_get_any_field_val()_, _tep_get_common_field_val()_ and |
| _tep_get_field_val()_ functions return 0 on success, or -1 in case of an error. |
| |
| The _tep_get_field_raw()_ function returns a pointer to field's raw data, and |
| places the length of this data in _len_. In case of an error NULL is returned. |
| |
| EXAMPLE |
| ------- |
| [source,c] |
| -- |
| #include <event-parse.h> |
| #include <trace-seq.h> |
| ... |
| 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_format *event; |
| unsigned long long val; |
| |
| event = tep_find_event_by_record(pevent, 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 */ |
| } |
| } |
| } |
| -- |
| |
| FILES |
| ----- |
| [verse] |
| -- |
| *event-parse.h* |
| Header file to include in order to have access to the library APIs. |
| *trace-seq.h* |
| 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. |
| *-ltraceevent* |
| Linker switch to add when building a program that uses the library. |
| -- |
| |
| SEE ALSO |
| -------- |
| _libtraceevent(3)_, _trace-cmd(1)_ |
| |
| AUTHOR |
| ------ |
| [verse] |
| -- |
| *Steven Rostedt* <rostedt@goodmis.org>, author of *libtraceevent*. |
| *Tzvetomir Stoyanov* <tz.stoyanov@gmail.com>, author of this man page. |
| -- |
| REPORTING BUGS |
| -------------- |
| Report bugs to <linux-trace-devel@vger.kernel.org> |
| |
| LICENSE |
| ------- |
| libtraceevent is Free Software licensed under the GNU LGPL 2.1 |
| |
| RESOURCES |
| --------- |
| https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git |
