tep_parse_saved_cmdlines(3) — Linux manual page
LIBTRACEEVENT(3) libtraceevent Manual LIBTRACEEVENT(3)
NAME
tep_parse_saved_cmdlines, tep_parse_printk_formats,
tep_parse_kallsyms - Parsing functions to load mappings
SYNOPSIS
#include <event-parse.h>
int tep_parse_saved_cmdlines(struct tep_handle *tep, const char *buf);
int tep_parse_printk_formats(struct tep_handle *tep, const char *buf);
int tep_parse_kallsyms(struct tep_handle *tep, const char *buf);
DESCRIPTION
tep_parse_saved_cmdlines() is a helper function to parse content
in the tracefs file system of the "saved_cmdlines" file (stored
in a string buffer passed in by buf) and loads the mapping of the
process IDs (pid) to the comm names in the tep handler. The
events store the pid and this is used to be able to show the
process names associated to those process ids. It parses the
string buf that holds the content of saved_cmdlines and ends with
a nul character (\0).
tep_parse_printk_formats() is a helper function to parse content
in the tracefs file system of the "printk_formats" file (stored
in a string buffer passed in by buf) and loads the mapping of
addresses of strings that may be referenced by events. Events
only store the address of constant strings in the kernel, and the
mapping of their address to the string is exported to user space
in the printk_formats file. It parses the string buf that holds
the content of printk_formats and ends with a nul character (\0).
tep_parse_kallsyms() is a helper function to parse the Linux
kernel /proc/kallsyms format (stored in a string buffer passed in
by buf) and load the functions into the tep handler such that
function IP addresses can be mapped to their name when parsing
events with %pS in the print format field. It parses the string
buf that holds the content of /proc/kallsyms and ends with a nul
character (\0).
RETURN VALUE
The tep_parse_saved_cmdlines() function returns 0 in case of
success, or -1 in case of an error.
The tep_parse_printk_formats() function returns 0 in case of
success, or -1 in case of an error.
The tep_parse_kallsyms() function returns 0 in case of success,
or -1 in case of an error.
EXAMPLE
...
#include <event-parse.h>
#include <tracefs.h>
#include <stdlib.h>
int load_cmdlines(struct tep_handle *tep)
{
char *buf = NULL;
int r;
buf = tracefs_instance_file_read(NULL, "saved_cmdlines", NULL);
if (!buf)
return -1;
r = tep_parse_saved_cmdlines(tep, buf);
free(buf);
return r;
}
int load_print_strings(struct tep_handle *tep)
{
char *buf = NULL;
int r;
buf = tracefs_instance_file_read(NULL, "printk_formats", NULL);
if (!buf)
return -1;
r = tep_parse_printk_formats(tep, buf);
free(buf);
return r;
}
int load_kallsyms(struct tep_handle *tep)
{
char *line = NULL;
char *buf = NULL;
size_t sz = 0;
FILE *fp;
int len = 0;
int r;
fp = fopen("/proc/kallsyms", "r");
while ((r = getline(&line, &sz, fp)) >= 0) {
buf = realloc(buf, len + r + 1);
memcpy(buf + len, line, r);
len += r;
}
free(line);
fclose(fp);
if (!buf)
return -1;
buf[len] = 0;
r = tep_parse_kallsyms(tep, buf);
free(buf);
return r;
}
...
FILES
event-parse.h
Header file to include in order to have access to the library APIs.
-ltraceevent
Linker switch to add when building a program that uses the library.
SEE ALSO
libtraceevent(3), trace-cmd(1), tep_register_comm(3),
tep_register_function(3), tep_register_print_string(3)
AUTHOR
Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, coauthor of libtraceevent.
REPORTING BUGS
Report bugs to <linux-trace-devel@vger.kernel.org[3]>
LICENSE
libtraceevent is Free Software licensed under the GNU LGPL 2.1
RESOURCES
https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/
NOTES
1. rostedt@goodmis.org
mailto:rostedt@goodmis.org
2. tz.stoyanov@gmail.com
mailto:tz.stoyanov@gmail.com
3. linux-trace-devel@vger.kernel.org
mailto:linux-trace-devel@vger.kernel.org
COLOPHON
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library) project. Information about the project can be found at
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manual page, see ⟨https://www.trace-cmd.org/⟩. This page was
obtained from the project's upstream Git repository
⟨https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git⟩
on 2024-06-14. (At that time, the date of the most recent commit
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