Return with an explicit error code/message if sysfs isn't mounted.

git-svn-id: http://lm-sensors.org/svn/lm-sensors/branches/lm-sensors-3.0.0@4464 7894878c-1315-0410-8ee3-d5d059ff63e0

lib/error.c

@@ -34,7 +34,7 @@ static const char *errorlist[] =
    /* SENSORS_ERR_WILDCARDS */ "Wildcard found in chip name",
    /* SENSORS_ERR_NO_ENTRY  */ "No such feature known",
    /* SENSORS_ERR_ACCESS    */ "Can't read or write",
-   /* SENSORS_ERR_PROC      */ "Can't access procfs/sysfs file",
+   /* SENSORS_ERR_PROC      */ "Can't access sysfs file",
    /* SENSORS_ERR_DIV_ZERO  */ "Divide by zero",
    /* SENSORS_ERR_CHIP_NAME */ "Can't parse chip name",
    /* SENSORS_ERR_BUS_NAME  */ "Can't parse bus name",

lib/sysfs.c

@@ -20,6 +20,9 @@
 /* this define needed for strndup() */
 #define _GNU_SOURCE
 
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
 #include <string.h>
 #include <stdlib.h>
 #include <limits.h>
@@ -197,10 +200,16 @@ sensors_chip_features sensors_read_dynamic_chip(struct sysfs_device *sysdir)
 /* returns !0 if sysfs filesystem was found, 0 otherwise */
 int sensors_init_sysfs(void)
 {
-	if (sysfs_get_mnt_path(sensors_sysfs_mount, NAME_MAX) == 0)
-		return 1;
+	struct stat statbuf;
 
-	return 0;
+	/* libsysfs will return success even if sysfs is not mounted,
+	   so we have to double-check */
+	if (sysfs_get_mnt_path(sensors_sysfs_mount, NAME_MAX)
+	 || stat(sensors_sysfs_mount, &statbuf) < 0
+	 || statbuf.st_nlink <= 2)	/* Empty directory */
+		return 0;
+
+	return 1;
 }
 
 /* returns: 0 if successful, !0 otherwise */

prog/sensors/main.c

@@ -237,12 +237,7 @@ int main (int argc, char *argv[])
 
   open_config_file(config_file_name);
   if ((res = sensors_init(config_file))) {
-    fprintf(stderr,"%s\n",sensors_strerror(res));
-    if (res == -SENSORS_ERR_PROC)
-      fprintf(stderr,
-              "Kernel interface access error\n"
-              "For 2.6 kernels, make sure you have mounted sysfs and libsensors\n"
-              "was compiled with sysfs support!\n");
+    fprintf(stderr, "sensors_init: %s\n", sensors_strerror(res));
     exit(1);
   }
   close_config_file(config_file_name);