x SuSE Linux 13.1-RELEASE x
x SuSE Linux 13.1-RELEASEx
SD_JOURNAL_GET_CURSOR(3) sd_journal_get_cursor SD_JOURNAL_GET_CURSOR(3)
NAME
sd_journal_get_cursor, sd_journal_test_cursor - Get cursor string for
or test cursor string against the current journal entry
SYNOPSIS
#include <systemd/sd-journal.h>
int sd_journal_get_cursor(sd_journal *j, char **cursor);
int sd_journal_test_cursor(sd_journal *j, const char *cursor);
DESCRIPTION
sd_journal_get_cursor() returns a cursor string for the current journal
entry. A cursor is a serialization of the current journal position
formatted as text. The string only contains printable characters and
can be passed around in text form. The cursor identifies a journal
entry globally and in a stable way and may be used to later seek to it
via sd_journal_seek_cursor(3). The cursor string should be considered
opaque and not be parsed by clients. Seeking to a cursor position
without the specific entry being available locally will seek to the
next closest (in terms of time) available entry. The call takes two
arguments: a journal context object and a pointer to a string pointer
where the cursor string will be placed. The string is allocated via
libc malloc(3) and should be freed after use with free(3).
sd_journal_test_cursor() may be used to check whether the current
position in the journal matches the specified cursor. This is useful
since cursor strings do not uniquely identify an entry: the same entry
might be referred to by multiple different cursor strings, and hence
string comparing cursors is not possible. Use this call to verify after
an invocation of sd_journal_seek_cursor(3), whether the entry being
sought to was actually found in the journal or the next closest entry
was used instead.
Note that sd_journal_get_cursor() and sd_journal_test_cursor() will not
work before sd_journal_next(3) (or one of the other functions which
move to an entry) has been called at least once to position the read
pointer at a valid entry.
RETURN VALUE
sd_journal_get_cursor() returns 0 on success or a negative errno-style
error code. sd_journal_test_cursor() returns positive if the current
entry matches the specified cursor, 0 if it does not match the
specified cursor or a negative errno-style error code on failure.
NOTES
All functions listed here are thread-agnostic and only a single
specific thread may operate on a given object during its entire
lifetime. It's safe to allocate multiple independent objects and use
each from a specific thread in parallel. However, it's not safe to
allocate such an object in one thread, and operate or free it from any
other, even if locking is used to ensure these threads don't operate on
it at the very same time.
Functions described here are available as a shared library, which can
be compiled against and linked to with the libsystemd pkg-config(1)
file.
SEE ALSO
systemd(1), sd-journal(3), sd_journal_open(3),
sd_journal_seek_cursor(3)
systemd 254 SD_JOURNAL_GET_CURSOR(3)
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