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BUG/MINOR: log: prevent double spaces emission in sess_build_logline()

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Christian reported in GH #2556 that since 3.0-dev double spaces may be
found in log messages on some cases where it was not the case before.

As we were able to easily reproduce, a quick bisect led us to c6a7138
("MINOR: log: simplify last_isspace in sess_build_logline()"). While
it is true that all switch cases set the last_isspace variable to 0,
there was a subtelty for some fields such as '%hr', '%hrl', '%hs' or
'%hsl' and I overlooked it. Indeed, for '%hr', last_isspace was only set
to 0 if data was emitted, else the assignment didn't occur.

But with c6a7138, last_isspace is always set to 0 as long as the current
node type is not a separator. Because of that, if no data is emitted for
the current node value, and a space was already emitted prior to the
current node, then an extra space could be emitted after the node,
resulting in two spaces being emitted.

Note that while c6a7138 introduces a slight behavior regression regarding
last_isspace logic with the specific fields mentionned above, this
behavior could already be triggered with a failing or empty logformat
node sample expression. Consider this logformat expression:

  log-format "%{-M}o | %[str()] |"

str() will not print anything, and since we disabled mandatory option with
'-M', nothing gets printed for the node sample expression. As a result, we
have the following output:

  "|  |"

Instead of (when mandatory option is enabled):

  "| - |"

Thus in order to stick to the historical behavior, systematically set
last_isspace to 0 for EXPR nodes, and only set last_isspace to 0 when
data was written for TAG nodes. This way, '%hr', '%hrl', '%hs' or
'%hsl' should behave as before.

No backport needed.
This commit is contained in:
Aurelien DARRAGON 2024-05-02 09:30:28 +02:00
parent 48e0efb00b
commit cc2e94a948
1 changed files with 8 additions and 2 deletions
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10
src/log.c
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@ -3797,6 +3797,7 @@ int sess_build_logline(struct session *sess, struct stream *s, char *dst, size_t
if (ret == NULL)
goto out;
tmplog = ret;
last_isspace = 0; /* consider that data was written */
goto next_fmt;
}
@ -4756,8 +4757,6 @@ int sess_build_logline(struct session *sess, struct stream *s, char *dst, size_t
}
next_fmt:
last_isspace = 0;
if (value_beg == tmplog) {
/* handle the case where no data was generated for the value after
* the key was already announced
@ -4782,6 +4781,13 @@ int sess_build_logline(struct session *sess, struct stream *s, char *dst, size_t
* to end it
*/
LOG_VARTEXT_END();
if (tmplog != value_beg) {
/* data was actually generated for the current dynamic
* node, reset the space hint so that a new space may
* now be emitted when relevant.
*/
last_isspace = 0;
}
}
/* back to global ctx (some encoding types may need to output