commit 4cc6a5a5fa3d5a5351d59385e614a0a78d167987
from: Stefan Sperling <stsp@stsp.name>
date: Tue Dec 15 22:42:20 2020 UTC

add got_error_from_errno_fmt() for more flexibility in error messages

suggested by and ok millert

commit - 748d5cab9a3d0d5d0edc28c8fd38430c684b1e55
commit + 4cc6a5a5fa3d5a5351d59385e614a0a78d167987
blob - 5fa8ffa0d2de4c2d61942eb2eed66a240149f6d0
blob + d3127f6f9acf465b17b825b7deb3d42b7a42fe7d
--- include/got_error.h
+++ include/got_error.h
@@ -334,6 +334,14 @@ const struct got_error *got_error_from_errno2(const ch
  */
 const struct got_error *got_error_from_errno3(const char *, const char *,
     const char *);
+
+/*
+ * Get a statically allocated error object with code GOT_ERR_ERRNO
+ * and an error message obtained from strerror(3), prefixed with a
+ * string built with vsnprintf(3) from the provided format string
+ * and the variable-length list of additional arguments.
+ */
+const struct got_error *got_error_from_errno_fmt(const char *, ...);
 
 /*
  * Set errno to the specified error code and return a statically
blob - 6cbb7ca6b8a72218dbc5725fed24856910329b8f
blob + f8cf59b20a799b2b360c647f8eb7f1c331257431
--- lib/error.c
+++ lib/error.c
@@ -18,6 +18,7 @@
 
 #include <errno.h>
 #include <limits.h>
+#include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -111,6 +112,25 @@ got_error_from_errno3(const char *prefix, const char *
 }
 
 const struct got_error *
+got_error_from_errno_fmt(const char *fmt, ...)
+{
+	static struct got_error err;
+	static char err_msg[PATH_MAX * 4 + 64];
+	char buf[PATH_MAX * 4];
+	va_list ap;
+
+	va_start(ap, fmt);
+	vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	snprintf(err_msg, sizeof(err_msg), "%s: %s", buf, strerror(errno));
+
+	err.code = GOT_ERR_ERRNO;
+	err.msg = err_msg;
+	return &err;
+}
+
+const struct got_error *
 got_error_set_errno(int code, const char *prefix)
 {
 	errno = code;