From 7828e7fcfbd89f71d097841d2ea6ddd2cfe2473b Mon Sep 17 00:00:00 2001
From: Marius Vlad <marius.vlad@collabora.com>
Date: Thu, 18 Dec 2025 16:37:20 +0200
Subject: [PATCH] libweston: Add a bits_to_str_stream() equivalent variant

This is useful for cases where we already have an open stream which we
can pass straight in and use it when printing node information.

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
---
 libweston/compositor.c  |  9 ++++---
 shared/string-helpers.h | 52 ++++++++++++++++++++++++++++-------------
 2 files changed, 40 insertions(+), 21 deletions(-)

diff --git a/libweston/compositor.c b/libweston/compositor.c
index dac228463..2adc2bf9d 100644
--- a/libweston/compositor.c
+++ b/libweston/compositor.c
@@ -9672,11 +9672,10 @@ debug_scene_view_print_paint_node(FILE *fp,
 	}
 
 	if (pnode->try_view_on_plane_failure_reasons) {
-		char *fr_str = bits_to_str(pnode->try_view_on_plane_failure_reasons,
-					   weston_plane_failure_reasons_to_str);
-		fprintf(fp, "\t\t\t\tPlane failure reasons: %s\n", fr_str);
-
-		free(fr_str);
+		fprintf(fp, "\t\t\t\tPlane failure reasons: ");
+		bits_to_str_stream(pnode->try_view_on_plane_failure_reasons,
+				   weston_plane_failure_reasons_to_str, fp);
+		fprintf(fp, "\n");
 	}
 }
 
diff --git a/shared/string-helpers.h b/shared/string-helpers.h
index d566f8c2f..e17348ca4 100644
--- a/shared/string-helpers.h
+++ b/shared/string-helpers.h
@@ -130,12 +130,42 @@ str_printf(char **str_out, const char *fmt, ...)
 }
 
 /**
- * Utility to print combination of enum values as string
+ * Utility to print combination of enum values as string. Use an opened FILE
+ * stream to write data.
  *
- * Only works for enum whose values are defined as power of two. Given a bitmask
- * in which each bit represents an enum value and a function that maps each enum
- * value to a string, this function returns a string (comma separated) with all
- * the enum values that are present in the bitmask.
+ * \param bits The bitmask of enum values.
+ * \param map Function that maps enum values to string.
+ * \param fp an opened FILE stream
+ */
+static inline void
+bits_to_str_stream(uint32_t bits, const char *(*map)(uint32_t), FILE *fp)
+{
+	unsigned i;
+	const char *sep = "";
+
+	if (!fp)
+		return;
+
+	for (i = 0; bits; i++) {
+		uint32_t bitmask = 1u << i;
+
+		if (bits & bitmask) {
+			fprintf(fp, "%s%s", sep, map(bitmask));
+			sep = ", ";
+		}
+
+		bits &= ~bitmask;
+	}
+}
+
+/**
+ * Utility to print combination of enum values as string.
+ * Uses bits_to_str_stream() helper.
+ *
+ * Only works for enum whose values are defined as power of two. Given a
+ * bitmask in which each bit represents an enum value and a function that maps
+ * each enum value to a string, this function returns a string (comma
+ * separated) with all the enum values that are present in the bitmask.
  *
  * \param bits The bitmask of enum values.
  * \param map Function that maps enum values to string.
@@ -148,23 +178,13 @@ bits_to_str(uint32_t bits, const char *(*map)(uint32_t))
 	FILE *fp;
 	char *str = NULL;
 	size_t size = 0;
-	unsigned i;
-	const char *sep = "";
 
 	fp = open_memstream(&str, &size);
 	if (!fp)
 		return NULL;
 
-	for (i = 0; bits; i++) {
-		uint32_t bitmask = 1u << i;
+	bits_to_str_stream(bits, map, fp);
 
-		if (bits & bitmask) {
-			fprintf(fp, "%s%s", sep, map(bitmask));
-			sep = ", ";
-		}
-
-		bits &= ~bitmask;
-	}
 	fclose(fp);
 
 	return str;