From: Alejandro Colomar <alx@kernel.org>
Date: Sat, 8 Feb 2025 15:13:39 +0000 (+0100)
Subject: lib/string/: vsnprintf_(), strtcpy(): Set errno = E2BIG on truncation
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=470cfa23c74694918396e603c78381f27c2be99e;p=thirdparty%2Fshadow.git

lib/string/: vsnprintf_(), strtcpy(): Set errno = E2BIG on truncation

Signed-off-by: Alejandro Colomar <alx@kernel.org>
---

diff --git a/lib/string/sprintf/snprintf.h b/lib/string/sprintf/snprintf.h
index f6dee1245..dc6009457 100644
--- a/lib/string/sprintf/snprintf.h
+++ b/lib/string/sprintf/snprintf.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-FileCopyrightText: 2023-2025, Alejandro Colomar <alx@kernel.org>
 // SPDX-License-Identifier: BSD-3-Clause
 
 
@@ -8,6 +8,7 @@
 
 #include "config.h"
 
+#include <errno.h>
 #include <stdarg.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -53,8 +54,10 @@ vsnprintf_(char *restrict s, size_t size, const char *restrict fmt, va_list ap)
 	len = vsnprintf(s, size, fmt, ap);
 	if (len == -1)
 		return -1;
-	if ((size_t) len >= size)
+	if ((size_t) len >= size) {
+		errno = E2BIG;
 		return -1;
+	}
 
 	return len;
 }
diff --git a/lib/string/strcpy/strtcpy.h b/lib/string/strcpy/strtcpy.h
index a440bcdfb..4b9d34b72 100644
--- a/lib/string/strcpy/strtcpy.h
+++ b/lib/string/strcpy/strtcpy.h
@@ -8,6 +8,7 @@
 
 #include "config.h"
 
+#include <errno.h>
 #include <stdbool.h>
 #include <stddef.h>
 #include <string.h>
@@ -42,8 +43,10 @@ strtcpy(char *restrict dst, const char *restrict src, size_t dsize)
 
 	stpcpy(mempcpy(dst, src, dlen), "");
 
-	if (trunc)
+	if (trunc) {
+		errno = E2BIG;
 		return -1;
+	}
 
 	return slen;
 }