From 73040e3a8ee02a92e5af53aff3a751533c96c99e Mon Sep 17 00:00:00 2001
From: Tim Duesterhus <tim@bastelstu.be>
Date: Mon, 13 Apr 2026 19:37:27 +0200
Subject: [PATCH] MINOR: Add `generate_unique_id()` helper

This new function will handle the actual generation of the unique ID according
to a format. The caller is responsible to check that no unique ID is stored
yet.
---
 include/haproxy/log.h |  2 ++
 src/log.c             | 24 ++++++++++++++++++++++++
 src/stream.c          | 11 +----------
 3 files changed, 27 insertions(+), 10 deletions(-)

diff --git a/include/haproxy/log.h b/include/haproxy/log.h
index 966bc94f1..98483eee0 100644
--- a/include/haproxy/log.h
+++ b/include/haproxy/log.h
@@ -196,6 +196,8 @@ char *update_log_hdr(const time_t time);
 char * get_format_pid_sep1(int format, size_t *len);
 char * get_format_pid_sep2(int format, size_t *len);
 
+void generate_unique_id(struct ist *dst, struct session *sess, struct stream *strm, struct lf_expr *format);
+
 /*
  * Builds a log line for the stream (must be valid).
  */
diff --git a/src/log.c b/src/log.c
index ba2d9d183..8d51f0c93 100644
--- a/src/log.c
+++ b/src/log.c
@@ -3879,6 +3879,30 @@ int lf_expr_dup(const struct lf_expr *orig, struct lf_expr *dest)
 	return 0;
 }
 
+/* Generates a unique ID based on the given <format> and stores it
+ * in <dst>. <dst> must be IST_NULL when this function is called.
+ *
+ * If this function fails to allocate memory IST_NULL is stored.
+ */
+void generate_unique_id(struct ist *dst, struct session *sess, struct stream *strm, struct lf_expr *format)
+{
+	char *unique_id;
+
+	BUG_ON(isttest(*dst));
+
+	unique_id = pool_alloc(pool_head_uniqueid);
+	if (unique_id == NULL) {
+		*dst = IST_NULL;
+		return;
+	}
+
+	/* Initialize <dst> to an empty string to prevent infinite
+	 * recursion when the <format> references %[unique-id] or %ID.
+	 */
+	*dst = ist2(unique_id, 0);
+	dst->len = sess_build_logline(sess, strm, unique_id, UNIQUEID_LEN, format);
+}
+
 /* Builds a log line in <dst> based on <lf_expr>, and stops before reaching
  * <maxsize> characters. Returns the size of the output string in characters,
  * not counting the trailing zero which is always added if the resulting size
diff --git a/src/stream.c b/src/stream.c
index eb13cf277..9e026c23d 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -3094,16 +3094,7 @@ INITCALL0(STG_INIT, init_stream);
 struct ist stream_generate_unique_id(struct stream *strm, struct lf_expr *format)
 {
 	if (!isttest(strm->unique_id)) {
-		char *unique_id;
-
-		if ((unique_id = pool_alloc(pool_head_uniqueid)) == NULL)
-			return IST_NULL;
-
-		/* Initialize ->unique_id to an empty string to prevent infinite
-		 * recursion when the <format> references %[unique-id] or %ID.
-		 */
-		strm->unique_id = ist2(unique_id, 0);
-		strm->unique_id.len = build_logline(strm, unique_id, UNIQUEID_LEN, format);
+		generate_unique_id(&strm->unique_id, strm_sess(strm), strm, format);
 	}
 
 	return strm->unique_id;