[PATCH] patch for libsysfs sysfs directory handling

Here's a quick patch to:

1) Add an environment variable "SYSFS_PATH" that libsysfs will check
for when getting mount point before searching system's sysfs mount
point.

2) A quick fix to sysfs_get_link where the bug was.

I have tested this out with libsysfs and with udev. I couldn't test
with klibc because I haven't got the tree to build with klibc without
my changes either. I made the link but get an error finding
linux/linits.h. I will figure that out.

Please have a look at the patch. If it's agreeable, please test it. I
really want to add some generic path manipulation functions for the
sysfs_get_link error, rather than my patch's hack. But, I haven't had
time yet to do that. You really sounded like you needed this for
testing, so I'm sending it out to you. I should probably add a
function to set the env variable(?).

diff --git a/libsysfs/libsysfs.h b/libsysfs/libsysfs.h
index ccb9898cb534e27484a4aecce4a85cef04a8105e..b3ffc467d065699346f76d2282133d1cb70775a1 100644 (file)
--- a/libsysfs/libsysfs.h
+++ b/libsysfs/libsysfs.h
@@ -40,6 +40,7 @@
 #define SYSFS_DRIVERS_NAME     "drivers"
 #define SYSFS_NAME_ATTRIBUTE   "name"
 #define SYSFS_UNKNOWN          "unknown"
+#define SYSFS_PATH_ENV         "SYSFS_PATH"
 
 /* Some "block" subsystem specific #defines */
 #define SYSFS_QUEUE_NAME       "queue"

diff --git a/libsysfs/sysfs_utils.c b/libsysfs/sysfs_utils.c
index f1303cacb302e2a011cdd45cf6f18f1139e4ec44..3e50bc61206622b57b384efaa343f95772d7a1c4 100644 (file)
--- a/libsysfs/sysfs_utils.c
+++ b/libsysfs/sysfs_utils.c
@@ -84,12 +84,18 @@ static int sysfs_get_fs_mnt_path(const unsigned char *fs_type,
  */
 int sysfs_get_mnt_path(unsigned char *mnt_path, size_t len)
 {
-       int ret = -1;
+       char *sysfs_path = NULL;
+       int ret = 0;
 
-       if (mnt_path != NULL)
-               ret = sysfs_get_fs_mnt_path(SYSFS_FSTYPE_NAME, mnt_path, len);
-       else
+       if (mnt_path == NULL) {
                errno = EINVAL;
+               return -1;
+       }
+       sysfs_path = getenv(SYSFS_PATH_ENV);
+       if (sysfs_path != NULL)
+               strncpy(mnt_path, sysfs_path, len);
+       else
+               ret = sysfs_get_fs_mnt_path(SYSFS_FSTYPE_NAME, mnt_path, len);
 
        return ret;
 }
@@ -130,7 +136,8 @@ int sysfs_get_link(const unsigned char *path, unsigned char *target, size_t len)
 {
        unsigned char devdir[SYSFS_PATH_MAX];
        unsigned char linkpath[SYSFS_PATH_MAX];
-       unsigned char *d = NULL;
+       unsigned char *d = NULL, *s = NULL;
+       int slashes = 0, count = 0;
 
        if (path == NULL || target == NULL) {
                errno = EINVAL;
@@ -139,12 +146,8 @@ int sysfs_get_link(const unsigned char *path, unsigned char *target, size_t len)
 
        memset(devdir, 0, SYSFS_PATH_MAX);
        memset(linkpath, 0, SYSFS_PATH_MAX);
+       strncpy(devdir, path, SYSFS_PATH_MAX);
 
-       if ((sysfs_get_mnt_path(devdir, SYSFS_PATH_MAX)) != 0) {
-               dprintf("Sysfs not supported on this system\n");
-               return -1;
-       }
-                                                                       
        if ((readlink(path, linkpath, SYSFS_PATH_MAX)) < 0) {
                return -1;
        }
@@ -152,12 +155,25 @@ int sysfs_get_link(const unsigned char *path, unsigned char *target, size_t len)
        d = linkpath;
 
        /* getting rid of leading "../.." */    
-       while (*d == '/' || *d == '.')
+       while (*d == '/' || *d == '.') {
+               if (*d == '/')
+                       slashes++;
                d++;
+       }
 
        d--;
-       
-       strcat(devdir, d);
+
+       s = &devdir[strlen(devdir)-1];
+       while (s != NULL && count != (slashes+1)) {
+               s--;
+               if (*s == '/')
+                       count++;
+       }
+
+       if (s == NULL)
+               return -1;
+
+       strncpy(s, d, (SYSFS_PATH_MAX-strlen(devdir)));
        strncpy(target, devdir, len);
 
        return 0;