From: Karel Zak <kzak@redhat.com>
Date: Thu, 18 Feb 2010 10:09:46 +0000 (+0100)
Subject: libblkid: add generic functions for sysfs attributes
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=220c60151dad64bb79fef28552f02003cf735a36;p=util-linux

libblkid: add generic functions for sysfs attributes

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/shlibs/blkid/src/blkidP.h b/shlibs/blkid/src/blkidP.h
index 377cf0e5..7dc39fc3 100644
--- a/shlibs/blkid/src/blkidP.h
+++ b/shlibs/blkid/src/blkidP.h
@@ -21,6 +21,7 @@
 #include <sys/stat.h>
 #include <stdio.h>
 #include <stdarg.h>
+#include <stdint.h>
 
 #include "c.h"
 #include "bitops.h"	/* $(top_srcdir)/include/ */
@@ -331,6 +332,9 @@ struct dir_list {
 };
 extern void blkid__scan_dir(char *, dev_t, struct dir_list **, char **);
 extern int blkid_driver_has_major(const char *drvname, int major);
+extern int blkid_devno_has_attribute(dev_t devno, const char *attribute);
+extern int blkid_devno_get_attribute(dev_t devno, const char *attribute,
+							uint64_t *result);
 
 /* lseek.c */
 extern blkid_loff_t blkid_llseek(int fd, blkid_loff_t offset, int whence);
diff --git a/shlibs/blkid/src/devno.c b/shlibs/blkid/src/devno.c
index 288e82ee..1b64ec1e 100644
--- a/shlibs/blkid/src/devno.c
+++ b/shlibs/blkid/src/devno.c
@@ -30,6 +30,7 @@
 #include <sys/mkdev.h>
 #endif
 #include <fcntl.h>
+#include <inttypes.h>
 
 #include "blkidP.h"
 #include "pathnames.h"
@@ -451,6 +452,50 @@ int blkid_driver_has_major(const char *drvname, int major)
 	return match;
 }
 
+static char *mk_devno_attribute_path(char *buf, size_t buflen,
+				dev_t devno, const char *attr)
+{
+	int len = snprintf(buf, buflen, "/sys/dev/block/%d:%d/%s",
+			major(devno), minor(devno), attr);
+
+	if (len < 0 || len + 1 > buflen)
+		return NULL;
+
+	return buf;
+}
+
+int blkid_devno_has_attribute(dev_t devno, const char *attribute)
+{
+	char path[PATH_MAX];
+	struct stat info;
+
+	if (!mk_devno_attribute_path(path, sizeof(path), devno, attribute))
+		return 0;
+
+	if (stat(path, &info) == 0)
+		return 1;
+
+	return 0;
+}
+
+int blkid_devno_get_attribute(dev_t devno, const char *attribute, uint64_t *result)
+{
+	FILE *f;
+	char path[PATH_MAX];
+	int rc = 0;
+
+	if (!mk_devno_attribute_path(path, sizeof(path), devno, attribute))
+		return -1;
+
+	f = fopen(path, "r");
+	if (f) {
+		rc = fscanf(f, "%" SCNu64, result);
+		fclose(f);
+	}
+
+	return rc == 1 ? 0 : -1;
+}
+
 #ifdef TEST_PROGRAM
 int main(int argc, char** argv)
 {
diff --git a/shlibs/blkid/src/topology/sysfs.c b/shlibs/blkid/src/topology/sysfs.c
index 20c507f1..ce870f22 100644
--- a/shlibs/blkid/src/topology/sysfs.c
+++ b/shlibs/blkid/src/topology/sysfs.c
@@ -11,7 +11,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
-#include <stdint.h>
+#include <inttypes.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
@@ -22,57 +22,30 @@
 static unsigned long dev_topology_attribute(const char *attribute,
 				dev_t dev, dev_t *primary)
 {
-	const char *sysfs_fmt_str = "/sys/dev/block/%d:%d/%s";
-	char path[PATH_MAX];
-	int len;
-	FILE *fp = NULL;
-	struct stat info;
-	unsigned long result = 0UL;
-
-	len = snprintf(path, sizeof(path), sysfs_fmt_str,
-			major(dev), minor(dev), attribute);
-	if (len < 0 || len + 1 > sizeof(path))
-		goto err;
+	uint64_t result;
 
 	/*
 	 * check if the desired sysfs attribute exists
 	 * - if not: either the kernel doesn't have topology support or the
 	 *   device could be a partition
 	 */
-	if (stat(path, &info) < 0) {
+	if (!blkid_devno_has_attribute(dev, attribute)) {
 		if (!*primary &&
 		    blkid_devno_to_wholedisk(dev, NULL, 0, primary))
 			goto err;
 
 		/* get attribute from partition's primary device */
-		len = snprintf(path, sizeof(path), sysfs_fmt_str,
-				major(*primary), minor(*primary), attribute);
-		if (len < 0 || len + 1 > sizeof(path))
-			goto err;
+		dev = *primary;
 	}
 
-	fp = fopen(path, "r");
-	if (!fp) {
-		DBG(DEBUG_LOWPROBE, printf(
-			"topology: %s: fopen failed, errno=%d\n", path, errno));
+	if (blkid_devno_get_attribute(dev, attribute, &result))
 		goto err;
-	}
-
-	if (fscanf(fp, "%lu", &result) != 1) {
-		DBG(DEBUG_LOWPROBE, printf(
-			"topology: %s: unexpected file format\n", path));
-		goto err;
-	}
-
-	fclose(fp);
 
 	DBG(DEBUG_LOWPROBE,
-		printf("topology: attribute %s = %lu\n", attribute, result));
+		printf("topology: attribute %s = %" PRIu64 "\n", attribute, result));
 
 	return result;
 err:
-	if (fp)
-		fclose(fp);
 	DBG(DEBUG_LOWPROBE,
 		printf("topology: failed to read %s attribute\n", attribute));
 	return 0;