[PATCH 04/16] vsprintf: introduce %m shorthand for "%s", strerror(errno)

[Ahmad Fatoum]

We have many places across the code base that use either do
printf("%s..", errno_str()) or printf("%s..", strerror(errno).
We already have %pe support for printing arbitrary errors and it's not
much work to add %m to print errno as well. Do so.

Signed-off-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
---
 lib/vsprintf.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 1d82adc73368..237aab0c02a1 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -373,12 +373,21 @@ static char *pointer(const char *fmt, char *buf, const char *end, const void *pt
 	return raw_pointer(buf, end, ptr, field_width, precision, flags);
 }
 
+static char *errno_string(char *buf, const char *end, int field_width, int precision, int flags)
+{
+	return string(buf, end, strerror(errno), field_width, precision, flags);
+}
 #else
 static char *pointer(const char *fmt, char *buf, const char *end, const void *ptr,
 		     int field_width, int precision, int flags)
 {
 	return raw_pointer(buf, end, ptr, field_width, precision, flags);
 }
+
+static char *errno_string(char *buf, const char *end, int field_width, int precision, int flags)
+{
+	return buf;
+}
 #endif
 
 /**
@@ -569,6 +578,10 @@ int vsnprintf(char *buf, size_t size, const char *fmt, va_list args)
 			case 'u':
 				break;
 
+			case 'm':
+				str = errno_string(str, end, field_width, precision, flags);
+				continue;
+
 			default:
 				if (str < end)
 					*str = '%';
-- 
2.29.2