libpayload: Add strerror

Change-Id: I33d45ad7d09473b8c6f5b7ee5fbadc0d184f9dcd
Signed-off-by: Stefan Tauner <stefan.tauner@gmx.at>
Reviewed-on: http://review.coreboot.org/3537
Tested-by: build bot (Jenkins)
Reviewed-by: Nico Huber <nico.huber@secunet.com>

2 files changed, 17 insertions, 2 deletions

diff --git a/payloads/libpayload/include/string.h b/payloads/libpayload/include/string.h
index 9e4f791a7d..952261fa15 100644
--- a/payloads/libpayload/include/string.h
+++ b/payloads/libpayload/include/string.h
@@ -63,8 +63,9 @@ char *strstr(const char *h, const char *n);
 char *strsep(char **stringp, const char *delim);
 size_t strspn(const char *s, const char *a);
 size_t strcspn(const char *s, const char *a);
-char* strtok(char *str, const char *delim);
-char* strtok_r(char *str, const char *delim, char **ptr);
+char *strtok(char *str, const char *delim);
+char *strtok_r(char *str, const char *delim, char **ptr);
+char *strerror(int errnum);
 /** @} */
 
 /**
diff --git a/payloads/libpayload/libc/string.c b/payloads/libpayload/libc/string.c
index 6151164d68..71dd1a6d1b 100644
--- a/payloads/libpayload/libc/string.c
+++ b/payloads/libpayload/libc/string.c
@@ -639,3 +639,17 @@ void perror(const char *s)
 {
 	printf("%s: %d\n", s?s:"(none)", errno);
 }
+
+/**
+ * Get a message string describing the given error number.
+ *
+ * @param errnum The error number to be interpreted
+ * @return A pointer to a string describing the given error number
+ */
+char *strerror(int errnum)
+{
+	/* Reserve enough space for the string below + INT64_MIN in decimal + \0 */
+	static char errstr[35];
+	snprintf(errstr, sizeof(errstr), "Unknown error %d", errnum);
+	return errstr;
+}