bootm: Split out bootargs environment reading / writing

At present bootm_process_cmdline_env() reads the 'bootargs' variable and
then writes it back afterwards. This is painful for tests, which would
rather use a simple buffer.

It is also useful for zimage to use a buffer, since it does not actually
put the Linux command line in the bootargs variable.

Refactor the existing code into two pieces. One handles reading and
writing the environment variable, as well as allocating a buffer for use
by the rest of the code, which now operates on a buffer.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 73 insertions, 22 deletions

diff --git a/common/bootm.c b/common/bootm.c
index 9295cf5..4fa909f 100644
--- a/common/bootm.c
+++ b/common/bootm.c
@@ -19,6 +19,7 @@
 #include <net.h>
 #include <asm/cache.h>
 #include <asm/io.h>
+#include <linux/sizes.h>
 #if defined(CONFIG_CMD_USB)
 #include <usb.h>
 #endif
@@ -35,6 +36,8 @@
 #define CONFIG_SYS_BOOTM_LEN	0x800000
 #endif
 
+#define MAX_CMDLINE_SIZE	SZ_4K
+
 #define IH_INITRD_ARCH IH_ARCH_DEFAULT
 
 #ifndef USE_HOSTCC
@@ -468,20 +471,31 @@ ulong bootm_disable_interrupts(void)
 #define CONSOLE_ARG		"console="
 #define CONSOLE_ARG_SIZE	sizeof(CONSOLE_ARG)
 
-int bootm_process_cmdline_env(bool do_silent)
+/**
+ * fixup_silent_linux() - Handle silencing the linux boot if required
+ *
+ * This uses the silent_linux envvar to control whether to add/set a "console="
+ * parameter to the command line
+ *
+ * @buf: Buffer containing the string to process
+ * @maxlen: Maximum length of buffer
+ * @return 0 if OK, -ENOSPC if @maxlen is too small
+ */
+static int fixup_silent_linux(char *buf, int maxlen)
 {
-	char *buf;
-	const char *env_val;
-	char *cmdline;
 	int want_silent;
+	char *cmdline;
+	int size;
 
-	/* First check if any action is needed */
-	do_silent = IS_ENABLED(CONFIG_SILENT_CONSOLE) &&
-	    !IS_ENABLED(CONFIG_SILENT_U_BOOT_ONLY) && do_silent;
-	if (!do_silent)
-		return 0;
-	cmdline = env_get("bootargs");
-
+	/*
+	 * Move the input string to the end of buffer. The output string will be
+	 * built up at the start.
+	 */
+	size = strlen(buf) + 1;
+	if (size * 2 > maxlen)
+		return -ENOSPC;
+	cmdline = buf + maxlen - size;
+	memmove(cmdline, buf, size);
 	/*
 	 * Only fix cmdline when requested. The environment variable can be:
 	 *
@@ -496,15 +510,12 @@ int bootm_process_cmdline_env(bool do_silent)
 		return 0;
 
 	debug("before silent fix-up: %s\n", cmdline);
-	if (cmdline && (cmdline[0] != '\0')) {
+	if (*cmdline) {
 		char *start = strstr(cmdline, CONSOLE_ARG);
 
-		/* Allocate space for maximum possible new command line */
-		buf = malloc(strlen(cmdline) + 1 + CONSOLE_ARG_SIZE);
-		if (!buf) {
-			debug("%s: out of memory\n", __func__);
+		/* Check space for maximum possible new command line */
+		if (size + CONSOLE_ARG_SIZE > maxlen)
 			return -ENOSPC;
-		}
 
 		if (start) {
 			char *end = strchr(start, ' ');
@@ -519,15 +530,55 @@ int bootm_process_cmdline_env(bool do_silent)
 		} else {
 			sprintf(buf, "%s %s", cmdline, CONSOLE_ARG);
 		}
-		env_val = buf;
+		if (buf + strlen(buf) >= cmdline)
+			return -ENOSPC;
 	} else {
-		buf = NULL;
-		env_val = CONSOLE_ARG;
+		if (maxlen < sizeof(CONSOLE_ARG))
+			return -ENOSPC;
+		strcpy(buf, CONSOLE_ARG);
 	}
+	debug("after silent fix-up: %s\n", buf);
 
-	env_set("bootargs", env_val);
-	debug("after silent fix-up: %s\n", env_val);
+	return 0;
+}
+
+int bootm_process_cmdline_env(bool do_silent)
+{
+	const int maxlen = MAX_CMDLINE_SIZE;
+	const char *env;
+	char *buf;
+	int ret;
+
+	/* First check if any action is needed */
+	do_silent = IS_ENABLED(CONFIG_SILENT_CONSOLE) &&
+	    !IS_ENABLED(CONFIG_SILENT_U_BOOT_ONLY) && do_silent;
+	if (!do_silent)
+		return 0;
+
+	env = env_get("bootargs");
+	if (env && strlen(env) >= maxlen)
+		return -E2BIG;
+	buf = malloc(maxlen);
+	if (!buf)
+		return -ENOMEM;
+	if (env)
+		strcpy(buf, env);
+	else
+		*buf = '\0';
+	ret = fixup_silent_linux(buf, maxlen);
+	if (!ret) {
+		ret = env_set("bootargs", buf);
+
+		/*
+		 * If buf is "" and bootargs does not exist, this will produce
+		 * an error trying to delete bootargs. Ignore it
+		 */
+		if (ret == -ENOENT)
+			ret = 0;
+	}
 	free(buf);
+	if (ret)
+		return log_msg_ret("env", ret);
 
 	return 0;
 }