logger: concatenate multiple lines of MESSAGE into a single field.

this is deemed a useful special case since journalctl will only show
either the first or last element of the message array if the field
appears multiple times.

Based on patch from: Kjetil Torgrim Homme <kjetil.homme@redpill-linpro.com>
https://github.com/karelzak/util-linux/pull/743

Addresses: https://github.com/karelzak/util-linux/issues/742
Signed-off-by: Karel Zak <kzak@redhat.com>

2 files changed, 26 insertions, 2 deletions

diff --git a/misc-utils/logger.1 b/misc-utils/logger.1
index bf11c411b..37a87e5c9 100644
--- a/misc-utils/logger.1
+++ b/misc-utils/logger.1
@@ -108,6 +108,10 @@ execution of
 will display MESSAGE field.  Use
 .B journalctl \-\-output json-pretty
 to see rest of the fields.
+.sp
+To include newlines in MESSAGE, specify MESSAGE several times.  This is
+handled as a special case, other fields will be stored as an array in
+the journal if they appear multiple times.
 .TP
 .BR \-\-msgid " \fImsgid
 Sets the RFC5424 MSGID field.  Note that the space character is not permitted
diff --git a/misc-utils/logger.c b/misc-utils/logger.c
index ebdc56ec2..10b307ef9 100644
--- a/misc-utils/logger.c
+++ b/misc-utils/logger.c
@@ -336,11 +336,11 @@ static int journald_entry(struct logger_ctl *ctl, FILE *fp)
 	struct iovec *iovec;
 	char *buf = NULL;
 	ssize_t sz;
-	int n, lines, vectors = 8, ret = 0;
+	int n, lines = 0, vectors = 8, ret = 0, msgline = -1;
 	size_t dummy = 0;
 
 	iovec = xmalloc(vectors * sizeof(struct iovec));
-	for (lines = 0; /* nothing */ ; lines++) {
+	while (1) {
 		buf = NULL;
 		sz = getline(&buf, &dummy, fp);
 		if (sz == -1 ||
@@ -348,6 +348,25 @@ static int journald_entry(struct logger_ctl *ctl, FILE *fp)
 			free(buf);
 			break;
 		}
+
+		if (strncmp(buf, "MESSAGE=", 8) == 0) {
+			if (msgline == -1)
+				msgline = lines;	/* remember the first message */
+			else {
+				char *p = xrealloc(iovec[msgline].iov_base,
+						   iovec[msgline].iov_len + sz - 8 + 2);
+
+				iovec[msgline].iov_base = p;
+				p += iovec[msgline].iov_len;
+				*p++ = '\n';
+				memcpy(p, buf + 8, sz - 8);
+				free(buf);
+
+				iovec[msgline].iov_len += sz - 8 + 1;
+				continue;
+			}
+		}
+
 		if (lines == vectors) {
 			vectors *= 2;
 			if (IOV_MAX < vectors)
@@ -356,6 +375,7 @@ static int journald_entry(struct logger_ctl *ctl, FILE *fp)
 		}
 		iovec[lines].iov_base = buf;
 		iovec[lines].iov_len = sz;
+		++lines;
 	}
 
 	if (!ctl->noact)