1 files changed, 61 insertions, 0 deletions
diff --git a/libgamma_strerror_r.c b/libgamma_strerror_r.c
new file mode 100644
index 0000000..42f396e
--- /dev/null
+++ b/libgamma_strerror_r.c
@@ -0,0 +1,61 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Get a description of an error
+ * 
+ * @param   error_code  The error code, may be an `errno` value, if
+ *                      `LIBGAMMA_ERRNO_SET`, the current value of `errno`
+ *                      will be used
+ * @param   buf         Buffer that shall be used if a description must be generated
+ * @param   bufsize     The size of `buf`, 1024 is recommended
+ * @return              The description associated with the error code;
+ *                      can only be `NULL` if `buf` is `NULL`. If the buffer
+ *                      is insufficient, a truncated but NUL-terminated
+ *                      description is returned and `errno` is set to `ERANGE`;
+ *                      `errno` is otherwise unmodified
+ */
+const char *
+libgamma_strerror_r(int error_code, char buf[], size_t bufsize)
+{
+	const char *desc;
+	int saved_errno;
+	if (error_code == LIBGAMMA_ERRNO_SET)
+		error_code = errno;
+	switch (error_code) {
+#define X(NAME, DESC)\
+	case NAME:\
+		desc = #NAME;\
+		break;
+	LIST_ERRORS(X)
+#undef X
+	default:
+		desc = NULL;
+		break;
+	}
+	if (desc)
+		return desc;
+	if (error_code >= 0) {
+		saved_errno = errno;
+		desc = _Generic(strerror_r(error_code, buf, bufsize),
+		                /* XSI strerror_r */
+		                int: (errno = (int)(intptr_t)strerror_r(error_code, buf, bufsize)) ? NULL : buf,
+		                /* GNU strerror_r */
+		                char *: (desc = (char *)(uintptr_t)strerror_r(error_code, buf, bufsize)));
+		if (desc) {
+			errno = saved_errno;
+			if (!buf || strcmp(buf, "No error information"))
+				return buf;
+		} else if (errno == ERANGE) {
+			return buf;
+		} else {
+			errno = saved_errno;
+		}
+	}
+	if (!buf)
+		return buf;
+	*buf = '\0'; /* TODO what happended here? */
+	snprintf(buf, bufsize, "Unknown error #%i\n", error_code);
+	return buf;
+}