From: Thomas Weißschuh <thomas@t-8ch.de>
Date: Sun, 30 Oct 2022 18:12:21 +0000 (+0100)
Subject: sysfs: read runtime byteorder
X-Git-Tag: v2.39-rc1~367^2~7
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3672d2beeedd4d55cb310c47c1adb91adc759cf3;p=thirdparty%2Futil-linux.git

sysfs: read runtime byteorder
---

diff --git a/include/pathnames.h b/include/pathnames.h
index 0887bd76eb..afb6af56e8 100644
--- a/include/pathnames.h
+++ b/include/pathnames.h
@@ -119,6 +119,7 @@
 #define _PATH_SYS_DEVCHAR	"/sys/dev/char"
 #define _PATH_SYS_CLASS		"/sys/class"
 #define _PATH_SYS_SCSI		"/sys/bus/scsi"
+#define _PATH_SYS_CPU_BYTEORDER	"/sys/kernel/cpu_byteorder"
 
 #define _PATH_SYS_SELINUX	"/sys/fs/selinux"
 #define _PATH_SYS_APPARMOR	"/sys/kernel/security/apparmor"
diff --git a/include/sysfs.h b/include/sysfs.h
index a10e948996..a5200141bf 100644
--- a/include/sysfs.h
+++ b/include/sysfs.h
@@ -111,5 +111,11 @@ int sysfs_blkdev_scsi_path_contains(struct path_cxt *pc, const char *pattern);
 
 char *sysfs_chrdev_devno_to_devname(dev_t devno, char *buf, size_t bufsiz);
 
+enum sysfs_byteorder {
+	SYSFS_BYTEORDER_LITTLE,
+	SYSFS_BYTEORDER_BIG,
+};
+
+extern enum sysfs_byteorder sysfs_get_byteorder(void);
 
 #endif /* UTIL_LINUX_SYSFS_H */
diff --git a/lib/sysfs.c b/lib/sysfs.c
index 219f871d63..ad6b31fb81 100644
--- a/lib/sysfs.c
+++ b/lib/sysfs.c
@@ -1072,6 +1072,36 @@ char *sysfs_chrdev_devno_to_devname(dev_t devno, char *buf, size_t bufsiz)
 
 }
 
+enum sysfs_byteorder sysfs_get_byteorder(void)
+{
+	int rc;
+	char buf[BUFSIZ];
+	enum sysfs_byteorder ret;
+
+	rc = ul_path_read_buffer(NULL, buf, sizeof(buf), _PATH_SYS_CPU_BYTEORDER);
+	if (rc < 0)
+		goto unknown;
+
+	if (strncmp(buf, "little", sizeof(buf)) == 0) {
+		ret = SYSFS_BYTEORDER_LITTLE;
+		goto out;
+	} else if (strncmp(buf, "big", sizeof(buf)) == 0) {
+		ret = SYSFS_BYTEORDER_BIG;
+		goto out;
+	}
+
+unknown:
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+	ret = SYSFS_BYTEORDER_LITTLE;
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+	ret = SYSFS_BYTEORDER_BIG;
+#else
+#error Unknown byte order
+#endif
+
+out:
+	return ret;
+}
 
 
 #ifdef TEST_PROGRAM_SYSFS