From: Tobias Stoeckmann <tobias@stoeckmann.org>
Date: Wed, 4 Feb 2026 18:01:13 +0000 (+0100)
Subject: dmesg: Split preparing and printing of buffer
X-Git-Tag: v2.43-devel~92^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=962c9105aea34c9b62f2f7b447d2c93e800f94f4;p=thirdparty%2Futil-linux.git

dmesg: Split preparing and printing of buffer

Have a strict separation between preparing the buffer and printing
content of buffer. This will help in further changes to more efficiently
prepare output, i.e. pager setup.

Signed-off-by: Tobias Stoeckmann <tobias@stoeckmann.org>
---

diff --git a/sys-utils/dmesg.c b/sys-utils/dmesg.c
index 8af67476c..8bfd712e8 100644
--- a/sys-utils/dmesg.c
+++ b/sys-utils/dmesg.c
@@ -273,8 +273,8 @@ struct dmesg_record {
 		(_r)->caller_id[0] = 0; \
 	} while (0)
 
-static int process_kmsg(struct dmesg_control *ctl);
-static int process_kmsg_file(struct dmesg_control *ctl, char **buf);
+static int print_kmsg(struct dmesg_control *ctl);
+static int print_kmsg_file(struct dmesg_control *ctl, size_t sz);
 
 static int set_level_color(int log_level, const char *mesg, size_t mesgsz)
 {
@@ -713,7 +713,7 @@ static ssize_t read_syslog_buffer(struct dmesg_control *ctl, char **buf)
 /*
  * Top level function to read (and print in case of kmesg) messages
  */
-static ssize_t process_buffer(struct dmesg_control *ctl, char **buf)
+static ssize_t prepare_buffer(struct dmesg_control *ctl, char **buf)
 {
 	ssize_t n = -1;
 
@@ -731,12 +731,9 @@ static ssize_t process_buffer(struct dmesg_control *ctl, char **buf)
 		break;
 	case DMESG_METHOD_KMSG:
 		if (ctl->filename)
-			n = process_kmsg_file(ctl, buf);
+			n = mmap_file_buffer(ctl, buf);
 		else
-			/*
-			 * Since kernel 3.5.0
-			 */
-			n = process_kmsg(ctl);
+			n = ctl->kmsg_first_read;
 		break;
 	default:
 		abort();	/* impossible method -> drop core */
@@ -1355,6 +1352,17 @@ static void print_buffer(struct dmesg_control *ctl,
 {
 	struct dmesg_record rec = { .next = buf, .next_size = size };
 
+	if (ctl->method == DMESG_METHOD_KMSG) {
+		if (ctl->filename)
+			print_kmsg_file(ctl, size);
+		else
+			/*
+			 * Since kernel 3.5.0
+			 */
+			print_kmsg(ctl);
+		return;
+	}
+
 	if (ctl->raw) {
 		raw_print(ctl, buf, size);
 		return;
@@ -1511,7 +1519,7 @@ mesg:
  *
  * Returns 0 on success, -1 on error.
  */
-static int process_kmsg(struct dmesg_control *ctl)
+static int print_kmsg(struct dmesg_control *ctl)
 {
 	struct dmesg_record rec;
 	ssize_t sz;
@@ -1542,20 +1550,15 @@ static int process_kmsg(struct dmesg_control *ctl)
 	return 0;
 }
 
-static int process_kmsg_file(struct dmesg_control *ctl, char **buf)
+static int print_kmsg_file(struct dmesg_control *ctl, size_t sz)
 {
 	char str[sizeof(ctl->kmsg_buf)];
 	struct dmesg_record rec;
-	ssize_t sz;
 	size_t len;
 
 	if (ctl->method != DMESG_METHOD_KMSG || !ctl->filename)
 		return -1;
 
-	sz = mmap_file_buffer(ctl, buf);
-	if (sz == -1)
-		return -1;
-
 	while (sz > 0) {
 		len = strnlen(ctl->mmap_buff, sz);
 		if (len > sizeof(str))
@@ -1566,7 +1569,7 @@ static int process_kmsg_file(struct dmesg_control *ctl, char **buf)
 		if (parse_kmsg_record(ctl, &rec, str, len) == 0)
 			print_record(ctl, &rec);
 
-		if (len < (size_t)sz)
+		if (len < sz)
 			len++;
 
 		sz -= len;
@@ -1911,7 +1914,7 @@ int main(int argc, char *argv[])
 			errx(EXIT_FAILURE, _("only kmsg supports multi-line messages"));
 		if (ctl.pager)
 			pager_redirect();
-		n = process_buffer(&ctl, &buf);
+		n = prepare_buffer(&ctl, &buf);
 		if (n > 0)
 			print_buffer(&ctl, buf, n);
 		if (!ctl.mmap_buff)