driver: ram_console: leave one byte from the defined buffer size

Leave one byte from the CONFIG_RAM_CONSOLE_BUFFER_SIZE to ensure the NULL-termination. Signed-off-by: Hou Zhiqiang <[email protected]>
zephyrproject-rtos · Jun 12, 2024 · 209568e · 209568e
1 parent c1765ff
commit 209568e
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Showing 3 changed files with 8 additions and 6 deletions.
diff --git a/drivers/console/Kconfig b/drivers/console/Kconfig
@@ -108,8 +108,10 @@ config RAM_CONSOLE_BUFFER_SIZE
 	default 1024
 	depends on RAM_CONSOLE
 	help
-	  Size of the RAM console buffer. Messages will wrap around if the
-	  length is exceeded.
+	  Total size of the RAM console buffer, to ensure it's always
+	  NULL-terminated leave one byte unused, the actual length is
+	  one byte less. Messages will wrap around if the actual length
+	  is exceeded.
 
 config RTT_CONSOLE
 	bool "Use RTT console"

diff --git a/drivers/console/ram_console.c b/drivers/console/ram_console.c
@@ -15,14 +15,14 @@
 extern void __printk_hook_install(int (*fn)(int));
 extern void __stdout_hook_install(int (*fn)(int));
 
-/* Extra byte to ensure we're always NULL-terminated */
-char ram_console[CONFIG_RAM_CONSOLE_BUFFER_SIZE + 1];
+char ram_console[CONFIG_RAM_CONSOLE_BUFFER_SIZE];
 static int pos;
 
 static int ram_console_out(int character)
 {
 	ram_console[pos] = (char)character;
-	pos = (pos + 1) % CONFIG_RAM_CONSOLE_BUFFER_SIZE;
+	/* Leave one byte to ensure we're always NULL-terminated */
+	pos = (pos + 1) % (CONFIG_RAM_CONSOLE_BUFFER_SIZE - 1);
 	return character;
 }
 

diff --git a/lib/open-amp/resource_table.c b/lib/open-amp/resource_table.c
@@ -68,7 +68,7 @@ static struct fw_resource_table __resource resource_table = {
 #if defined(CONFIG_RAM_CONSOLE)
 	.cm_trace = {
 		RSC_TRACE,
-		(uint32_t)ram_console, CONFIG_RAM_CONSOLE_BUFFER_SIZE + 1, 0,
+		(uint32_t)ram_console, CONFIG_RAM_CONSOLE_BUFFER_SIZE, 0,
 		"Zephyr_log",
 	},
 #endif