From: Christian Brauner <christian.brauner@ubuntu.com>
Date: Sat, 25 Aug 2018 09:56:10 +0000 (+0200)
Subject: macro: add INTTYPE_TO_STRLEN()
X-Git-Tag: lxc-3.1.0~127^2~20
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f246d9b89f4e5c6d1ec18f704b95ddd40584b108;p=thirdparty%2Flxc.git

macro: add INTTYPE_TO_STRLEN()

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---

diff --git a/src/lxc/macro.h b/src/lxc/macro.h
index 17cf0eb19..8e7ef12c6 100644
--- a/src/lxc/macro.h
+++ b/src/lxc/macro.h
@@ -104,9 +104,24 @@
 #define OVERLAY_SUPER_MAGIC 0x794c7630
 #endif
 
+/* Calculate the number of chars needed to represent a given integer as a C
+ * string. Include room for '-' to indicate negative numbers and the \0 byte.
+ * This is based on systemd.
+ */
+#define INTTYPE_TO_STRLEN(type)                   \
+	(2 + (sizeof(type) <= 1                   \
+		  ? 3                             \
+		  : sizeof(type) <= 2             \
+			? 5                       \
+			: sizeof(type) <= 4       \
+			      ? 10                \
+			      : sizeof(type) <= 8 \
+				    ? 20          \
+				    : sizeof(int[-2 * (sizeof(type) > 8)])))
+
 /* Useful macros */
 /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
-#define LXC_NUMSTRLEN64 21
+#define LXC_NUMSTRLEN64 INTTYPE_TO_STRLEN(int64_t)
 #define LXC_LINELEN 4096
 #define LXC_IDMAPLEN 4096
 #define LXC_MAX_BUFFER 4096