osmith has uploaded this change for review.

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logging: ensure ANSI color escape is sent in same line/before newline

This fixes multi-line color clobbering in logging daemons like
systemd-journald, which work with single-lines only.

Change-Id: Ia7de9d88aa5ac48ec0d5c1a931a89d21c02c5433
Closes: OS#6249
(cherry picked from commit 11a416827dd9f2da6b7c1db0e1e83adb1e6e5cc8)
---
M src/core/logging.c
M tests/loggingrb/logging_test.err
2 files changed, 25 insertions(+), 4 deletions(-)

git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/42/35142/1

diff --git a/src/core/logging.c b/src/core/logging.c
index c6774f5..dc19cf3 100644
--- a/src/core/logging.c
+++ b/src/core/logging.c
@@ -616,7 +616,15 @@
 	}
 
 	if (target->use_color && c_subsys) {
-		ret = snprintf(buf + offset, rem, OSMO_LOGCOLOR_END);
+		/* Ensure the last color escape is sent before the newline
+		* (to not clobber journald, which works on single-lines only) */
+		if (offset > 0 && buf[offset - 1] == '\n') {
+			offset--; rem++;
+			ret = snprintf(buf + offset, rem, OSMO_LOGCOLOR_END "\n");
+		} else {
+			ret = snprintf(buf + offset, rem, OSMO_LOGCOLOR_END);
+		}
+
 		if (ret < 0)
 			goto err;
 		OSMO_SNPRINTF_RET(ret, rem, offset, len);
diff --git a/tests/loggingrb/logging_test.err b/tests/loggingrb/logging_test.err
index b59d2e8..e070561 100644
--- a/tests/loggingrb/logging_test.err
+++ b/tests/loggingrb/logging_test.err
@@ -1,3 +1,2 @@
-You should see this
-You should see this
-
\ No newline at end of file
+You should see this
+You should see this

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