[PATCH v1 1/4] cli: run_commandf(): small fixups

[Evgeny Bachinin]

* vsnprintf() can truncate cmd, hence it makes no sense to launch such
command (it's broken). Moreover, it's better to signalize to the caller
about such case (for facilitating debugging or bug hunting).

* Fix kernel-doc warnings:
  include/command.h:264: info: Scanning doc for run_commandf
  include/command.h:268: warning: contents before sections
  include/command.h:271: warning: No description found for return value
                                  of 'run_commandf'

* Add printf-like format attribute to validate at compile-time the format
string against parameters's type.

* Fix compilation error in case of -Wall, -Werror, -Wextra:
error: variable ‘i’ set but not used [-Werror=unused-but-set-variable]

* Drop extra ret variable.

Signed-off-by: Evgeny Bachinin <EABachinin at sberdevices.ru>
---
 common/cli.c      | 19 ++++++++++++++-----
 include/command.h | 13 ++++++++++---
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/common/cli.c b/common/cli.c
index 9451e6a142..3db4e0f0b7 100644
--- a/common/cli.c
+++ b/common/cli.c
@@ -8,6 +8,8 @@
  * JinHua Luo, GuangDong Linux Center, <luo.jinhua at gd-linux.com>
  */
 
+#define pr_fmt(fmt) "cli: %s: " fmt, __func__
+
 #include <common.h>
 #include <bootstage.h>
 #include <cli.h>
@@ -20,6 +22,7 @@
 #include <malloc.h>
 #include <asm/global_data.h>
 #include <dm/ofnode.h>
+#include <linux/errno.h>
 
 #ifdef CONFIG_CMDLINE
 /*
@@ -130,15 +133,21 @@ int run_commandf(const char *fmt, ...)
 {
 	va_list args;
 	char cmd[128];
-	int i, ret;
+	int nbytes;
 
 	va_start(args, fmt);
-	i = vsnprintf(cmd, sizeof(cmd), fmt, args);
+	nbytes = vsnprintf(cmd, sizeof(cmd), fmt, args);
 	va_end(args);
 
-	ret = run_command(cmd, 0);
-
-	return ret;
+	if (nbytes < 0) {
+		pr_err("I/O internal error occurred.\n");
+		return -EIO;
+	} else if ((size_t)nbytes >= sizeof(cmd)) {
+		pr_err("'fmt' size:%d exceeds the limit(%zu)\n",
+		       nbytes, sizeof(cmd));
+		return -EINVAL;
+	}
+	return run_command(cmd, 0);
 }
 
 /****************************************************************************/
diff --git a/include/command.h b/include/command.h
index 0db4898062..6c0c97054c 100644
--- a/include/command.h
+++ b/include/command.h
@@ -13,6 +13,8 @@
 #include <env.h>
 #include <linker_lists.h>
 
+#include <linux/compiler_attributes.h>
+
 #ifndef NULL
 #define NULL	0
 #endif
@@ -260,12 +262,17 @@ int run_command_repeatable(const char *cmd, int flag);
 /**
  * run_commandf() - Run a command created by a format string
  *
- * The command cannot be larger than 127 characters
- *
  * @fmt: printf() format string
  * @...: Arguments to use (flag is always 0)
+ *
+ * The command cannot be larger than 127 characters
+ *
+ * Return:
+ * Returns 0 on success, -EIO if internal output error occurred, -EINVAL in
+ *	case of 'fmt' string truncation, or != 0 on error, specific for
+ *	run_command().
  */
-int run_commandf(const char *fmt, ...);
+int run_commandf(const char *fmt, ...) __printf(1, 2);
 
 /**
  * Run a list of commands separated by ; or even \0
-- 
2.17.1