tep_parse_saved_cmdlines(3) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | EXAMPLE | FILES | SEE ALSO | AUTHOR | REPORTING BUGS | LICENSE | RESOURCES | NOTES | COLOPHON

LIBTRACEEVENT(3)          libtraceevent Manual          LIBTRACEEVENT(3)

NAME         top

       tep_parse_saved_cmdlines, tep_parse_printk_formats,
       tep_parse_kallsyms - Parsing functions to load mappings

SYNOPSIS         top

       #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         top

       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         top

       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         top

           ...
           #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         top

           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         top

       libtraceevent(3), trace-cmd(1), tep_register_comm(3),
       tep_register_function(3), tep_register_print_string(3)

AUTHOR         top

           Steven Rostedt <rostedt@goodmis.org[1]>, author of libtraceevent.
           Tzvetomir Stoyanov <tz.stoyanov@gmail.com[2]>, coauthor of libtraceevent.

REPORTING BUGS         top

       Report bugs to <linux-trace-devel@vger.kernel.org[3]>

LICENSE         top

       libtraceevent is Free Software licensed under the GNU LGPL 2.1

RESOURCES         top

       https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ 

NOTES         top

        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         top

       This page is part of the libtraceevent (Linux kernel trace event
       library) project.  Information about the project can be found at
       ⟨https://www.trace-cmd.org/⟩.  If you have a bug report for this
       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
       that was found in the repository was 2024-05-17.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

libtraceevent 1.7.3            09/24/2023               LIBTRACEEVENT(3)