| libtraceevent(3) |
| ================ |
| |
| NAME |
| ---- |
| tep_print_field, tep_print_fields, tep_print_num_field, tep_print_func_field - |
| Print the field content. |
| |
| SYNOPSIS |
| -------- |
| [verse] |
| -- |
| *#include <event-parse.h>* |
| *#include <trace-seq.h>* |
| |
| void *tep_print_field*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, struct tep_format_field pass:[*]_field_); |
| void *tep_print_fields*(struct trace_seq pass:[*]_s_, void pass:[*]_data_, int _size_, struct tep_event pass:[*]_event_); |
| int *tep_print_num_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_); |
| int *tep_print_func_field*(struct trace_seq pass:[*]_s_, const char pass:[*]_fmt_, struct tep_event pass:[*]_event_, const char pass:[*]_name_, struct tep_record pass:[*]_record_, int _err_); |
| -- |
| |
| DESCRIPTION |
| ----------- |
| These functions print recorded field's data, according to the field's type. |
| |
| The _tep_print_field()_ function extracts from the recorded raw _data_ value of |
| the _field_ and prints it into _s_, according to the field type. |
| |
| The _tep_print_fields()_ prints each field name followed by the record's field |
| value according to the field's type: |
| [verse] |
| -- |
| "field1_name=field1_value field2_name=field2_value ..." |
| -- |
| It iterates all fields of the _event_, and calls _tep_print_field()_ for each of |
| them. |
| |
| The _tep_print_num_field()_ function prints a numeric field with given format |
| string. A search is performed in the _event_ for a field with _name_. If such |
| field is found, its value is extracted from the _record_ and is printed in the |
| _s_, according to the given format string _fmt_. If the argument _err_ is |
| non-zero, and an error occures - it is printed in the _s_. |
| |
| The _tep_print_func_field()_ function prints a function field with given format |
| string. A search is performed in the _event_ for a field with _name_. If such |
| field is found, its value is extracted from the _record_. The value is assumed |
| to be a function address, and a search is perform to find the name of this |
| function. The function name (if found) and its address are printed in the _s_, |
| according to the given format string _fmt_. If the argument _err_ is non-zero, |
| and an error occures - it is printed in _s_. |
| |
| RETURN VALUE |
| ------------ |
| The _tep_print_num_field()_ and _tep_print_func_field()_ functions return 1 |
| on success, -1 in case of an error or 0 if the print buffer _s_ is full. |
| |
| EXAMPLE |
| ------- |
| [source,c] |
| -- |
| #include <event-parse.h> |
| #include <trace-seq.h> |
| ... |
| struct tep_handle *tep = tep_alloc(); |
| ... |
| struct trace_seq seq; |
| trace_seq_init(&seq); |
| struct tep_event *event = tep_find_event_by_name(tep, "timer", "hrtimer_start"); |
| ... |
| void process_record(struct tep_record *record) |
| { |
| struct tep_format_field *field_pid = tep_find_common_field(event, "common_pid"); |
| |
| trace_seq_reset(&seq); |
| |
| /* Print the value of "common_pid" */ |
| tep_print_field(&seq, record->data, field_pid); |
| |
| /* Print all fields of the "hrtimer_start" event */ |
| tep_print_fields(&seq, record->data, record->size, event); |
| |
| /* Print the value of "expires" field with custom format string */ |
| tep_print_num_field(&seq, " timer expires in %llu ", event, "expires", record, 0); |
| |
| /* Print the address and the name of "function" field with custom format string */ |
| tep_print_func_field(&seq, " timer function is %s ", event, "function", record, 0); |
| } |
| ... |
| -- |
| |
| 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 |
