Adding upstream version 2.38.1.upstream/2.38.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1172 insertions, 0 deletions

diff --git a/lib/sysfs.c b/lib/sysfs.c
new file mode 100644
index 0000000..84af4fe
--- /dev/null
+++ b/lib/sysfs.c
@@ -0,0 +1,1172 @@
+/*
+ * No copyright is claimed.  This code is in the public domain; do with
+ * it what you wish.
+ *
+ * Written by Karel Zak <kzak@redhat.com>
+ */
+#include <ctype.h>
+#include <libgen.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "c.h"
+#include "pathnames.h"
+#include "sysfs.h"
+#include "fileutils.h"
+#include "all-io.h"
+#include "debug.h"
+#include "strutils.h"
+
+static void sysfs_blkdev_deinit_path(struct path_cxt *pc);
+static int  sysfs_blkdev_enoent_redirect(struct path_cxt *pc, const char *path, int *dirfd);
+
+/*
+ * Debug stuff (based on include/debug.h)
+ */
+static UL_DEBUG_DEFINE_MASK(ulsysfs);
+UL_DEBUG_DEFINE_MASKNAMES(ulsysfs) = UL_DEBUG_EMPTY_MASKNAMES;
+
+#define ULSYSFS_DEBUG_INIT	(1 << 1)
+#define ULSYSFS_DEBUG_CXT	(1 << 2)
+
+#define DBG(m, x)       __UL_DBG(ulsysfs, ULSYSFS_DEBUG_, m, x)
+#define ON_DBG(m, x)    __UL_DBG_CALL(ulsysfs, ULSYSFS_DEBUG_, m, x)
+
+#define UL_DEBUG_CURRENT_MASK	UL_DEBUG_MASK(ulsysfs)
+#include "debugobj.h"
+
+void ul_sysfs_init_debug(void)
+{
+	if (ulsysfs_debug_mask)
+		return;
+	__UL_INIT_DEBUG_FROM_ENV(ulsysfs, ULSYSFS_DEBUG_, 0, ULSYSFS_DEBUG);
+}
+
+struct path_cxt *ul_new_sysfs_path(dev_t devno, struct path_cxt *parent, const char *prefix)
+{
+	struct path_cxt *pc = ul_new_path(NULL);
+
+	if (!pc)
+		return NULL;
+	if (prefix)
+		ul_path_set_prefix(pc, prefix);
+
+	if (sysfs_blkdev_init_path(pc, devno, parent) != 0) {
+		ul_unref_path(pc);
+		return NULL;
+	}
+
+	DBG(CXT, ul_debugobj(pc, "alloc"));
+	return pc;
+}
+
+/*
+ * sysfs_blkdev_* is sysfs extension to ul_path_* API for block devices.
+ *
+ * The function is possible to call in loop and without sysfs_blkdev_deinit_path().
+ * The sysfs_blkdev_deinit_path() is automatically called by ul_unref_path().
+ *
+ */
+int sysfs_blkdev_init_path(struct path_cxt *pc, dev_t devno, struct path_cxt *parent)
+{
+	struct sysfs_blkdev *blk;
+	int rc;
+	char buf[sizeof(_PATH_SYS_DEVBLOCK)
+		 + sizeof(stringify_value(UINT32_MAX)) * 2
+		 + 3];
+
+	/* define path to devno stuff */
+	snprintf(buf, sizeof(buf), _PATH_SYS_DEVBLOCK "/%d:%d", major(devno), minor(devno));
+	rc = ul_path_set_dir(pc, buf);
+	if (rc)
+		return rc;
+
+	/* make sure path exists */
+	rc = ul_path_get_dirfd(pc);
+	if (rc < 0)
+		return rc;
+
+	/* initialize sysfs blkdev specific stuff */
+	blk = ul_path_get_dialect(pc);
+	if (!blk) {
+		DBG(CXT, ul_debugobj(pc, "alloc new sysfs handler"));
+		blk = calloc(1, sizeof(struct sysfs_blkdev));
+		if (!blk)
+			return -ENOMEM;
+
+		ul_path_set_dialect(pc, blk, sysfs_blkdev_deinit_path);
+		ul_path_set_enoent_redirect(pc, sysfs_blkdev_enoent_redirect);
+	}
+
+	DBG(CXT, ul_debugobj(pc, "init sysfs stuff"));
+
+	blk->devno = devno;
+	sysfs_blkdev_set_parent(pc, parent);
+
+	return 0;
+}
+
+static void sysfs_blkdev_deinit_path(struct path_cxt *pc)
+{
+	struct sysfs_blkdev *blk;
+
+	if (!pc)
+		return;
+
+	DBG(CXT, ul_debugobj(pc, "deinit"));
+
+	blk = ul_path_get_dialect(pc);
+	if (!blk)
+		return;
+
+	ul_unref_path(blk->parent);
+	free(blk);
+
+	ul_path_set_dialect(pc, NULL, NULL);
+}
+
+int sysfs_blkdev_set_parent(struct path_cxt *pc, struct path_cxt *parent)
+{
+	struct sysfs_blkdev *blk = ul_path_get_dialect(pc);
+
+	if (!pc || !blk)
+		return -EINVAL;
+
+	if (blk->parent) {
+		ul_unref_path(blk->parent);
+		blk->parent = NULL;
+	}
+
+	if (parent) {
+		ul_ref_path(parent);
+		blk->parent = parent;
+	} else
+		blk->parent = NULL;
+
+	DBG(CXT, ul_debugobj(pc, "new parent"));
+	return 0;
+}
+
+struct path_cxt *sysfs_blkdev_get_parent(struct path_cxt *pc)
+{
+	struct sysfs_blkdev *blk = ul_path_get_dialect(pc);
+	return blk ? blk->parent : NULL;
+}
+
+/*
+ * Redirects ENOENT errors to the parent, if the path is to the queue/
+ * sysfs directory. For example
+ *
+ *	/sys/dev/block/8:1/queue/logical_block_size redirects to
+ *	/sys/dev/block/8:0/queue/logical_block_size
+ */
+static int sysfs_blkdev_enoent_redirect(struct path_cxt *pc, const char *path, int *dirfd)
+{
+	struct sysfs_blkdev *blk = ul_path_get_dialect(pc);
+
+	if (blk && blk->parent && path && strncmp(path, "queue/", 6) == 0) {
+		*dirfd = ul_path_get_dirfd(blk->parent);
+		if (*dirfd >= 0) {
+			DBG(CXT, ul_debugobj(pc, "%s redirected to parent", path));
+			return 0;
+		}
+	}
+	return 1;	/* no redirect */
+}
+
+char *sysfs_blkdev_get_name(struct path_cxt *pc, char *buf, size_t bufsiz)
+{
+	char link[PATH_MAX];
+	char *name;
+	ssize_t	sz;
+
+        /* read /sys/dev/block/<maj:min> link */
+	sz = ul_path_readlink(pc, link, sizeof(link), NULL);
+	if (sz < 0)
+		return NULL;
+
+	name = strrchr(link, '/');
+	if (!name)
+		return NULL;
+
+	name++;
+	sz = strlen(name);
+	if ((size_t) sz + 1 > bufsiz)
+		return NULL;
+
+	memcpy(buf, name, sz + 1);
+	sysfs_devname_sys_to_dev(buf);
+	return buf;
+}
+
+int sysfs_blkdev_is_partition_dirent(DIR *dir, struct dirent *d, const char *parent_name)
+{
+	char path[NAME_MAX + 6 + 1];
+
+#ifdef _DIRENT_HAVE_D_TYPE
+	if (d->d_type != DT_DIR &&
+	    d->d_type != DT_LNK &&
+	    d->d_type != DT_UNKNOWN)
+		return 0;
+#endif
+	size_t len = 0;
+
+	if (parent_name) {
+		const char *p = parent_name;
+
+		/* /dev/sda --> "sda" */
+		if (*parent_name == '/') {
+			p = strrchr(parent_name, '/');
+			if (!p)
+				return 0;
+			p++;
+		}
+
+		len = strlen(p);
+		if ((strlen(d->d_name) <= len) || (strncmp(p, d->d_name, len) != 0))
+			len = 0;
+	}
+
+	if (len > 0) {
+		/* partitions subdir name is
+		 *	"<parent>[:digit:]" or "<parent>p[:digit:]"
+		 */
+		return ((*(d->d_name + len) == 'p' && isdigit(*(d->d_name + len + 1)))
+			|| isdigit(*(d->d_name + len)));
+	}
+
+	/* Cannot use /partition file, not supported on old sysfs */
+	snprintf(path, sizeof(path), "%s/start", d->d_name);
+
+	return faccessat(dirfd(dir), path, R_OK, 0) == 0;
+}
+
+int sysfs_blkdev_count_partitions(struct path_cxt *pc, const char *devname)
+{
+	DIR *dir;
+	struct dirent *d;
+	int r = 0;
+
+	dir = ul_path_opendir(pc, NULL);
+	if (!dir)
+		return 0;
+
+	while ((d = xreaddir(dir))) {
+		if (sysfs_blkdev_is_partition_dirent(dir, d, devname))
+			r++;
+	}
+
+	closedir(dir);
+	return r;
+}
+
+/*
+ * Converts @partno (partition number) to devno of the partition.
+ * The @pc handles wholedisk device.
+ *
+ * Note that this code does not expect any special format of the
+ * partitions devnames.
+ */
+dev_t sysfs_blkdev_partno_to_devno(struct path_cxt *pc, int partno)
+{
+	DIR *dir;
+	struct dirent *d;
+	dev_t devno = 0;
+
+	dir = ul_path_opendir(pc, NULL);
+	if (!dir)
+		return 0;
+
+	while ((d = xreaddir(dir))) {
+		int n;
+
+		if (!sysfs_blkdev_is_partition_dirent(dir, d, NULL))
+			continue;
+
+		if (ul_path_readf_s32(pc, &n, "%s/partition", d->d_name))
+			continue;
+
+		if (n == partno) {
+			if (ul_path_readf_majmin(pc, &devno, "%s/dev", d->d_name) == 0)
+				break;
+		}
+	}
+
+	closedir(dir);
+	DBG(CXT, ul_debugobj(pc, "partno (%d) -> devno (%d)", (int) partno, (int) devno));
+	return devno;
+}
+
+
+/*
+ * Returns slave name if there is only one slave, otherwise returns NULL.
+ * The result should be deallocated by free().
+ */
+char *sysfs_blkdev_get_slave(struct path_cxt *pc)
+{
+	DIR *dir;
+	struct dirent *d;
+	char *name = NULL;
+
+	dir = ul_path_opendir(pc, "slaves");
+	if (!dir)
+		return NULL;
+
+	while ((d = xreaddir(dir))) {
+		if (name)
+			goto err;	/* more slaves */
+		name = strdup(d->d_name);
+	}
+
+	closedir(dir);
+	return name;
+err:
+	free(name);
+	closedir(dir);
+	return NULL;
+}
+
+
+#define SUBSYSTEM_LINKNAME	"/subsystem"
+
+/*
+ * For example:
+ *
+ * chain: /sys/dev/block/../../devices/pci0000:00/0000:00:1a.0/usb1/1-1/1-1.2/ \
+ *                           1-1.2:1.0/host65/target65:0:0/65:0:0:0/block/sdb
+ *
+ * The function check if <chain>/subsystem symlink exists, if yes then returns
+ * basename of the readlink result, and remove the last subdirectory from the
+ * <chain> path.
+ */
+static char *get_subsystem(char *chain, char *buf, size_t bufsz)
+{
+	size_t len;
+	char *p;
+
+	if (!chain || !*chain)
+		return NULL;
+
+	len = strlen(chain);
+	if (len + sizeof(SUBSYSTEM_LINKNAME) > PATH_MAX)
+		return NULL;
+
+	do {
+		ssize_t sz;
+
+		/* append "/subsystem" to the path */
+		memcpy(chain + len, SUBSYSTEM_LINKNAME, sizeof(SUBSYSTEM_LINKNAME));
+
+		/* try if subsystem symlink exists */
+		sz = readlink(chain, buf, bufsz - 1);
+
+		/* remove last subsystem from chain */
+		chain[len] = '\0';
+		p = strrchr(chain, '/');
+		if (p) {
+			*p = '\0';
+			len = p - chain;
+		}
+
+		if (sz > 0) {
+			/* we found symlink to subsystem, return basename */
+			buf[sz] = '\0';
+			return basename(buf);
+		}
+
+	} while (p);
+
+	return NULL;
+}
+
+/*
+ * Returns complete path to the device, the patch contains all subsystems
+ * used for the device.
+ */
+char *sysfs_blkdev_get_devchain(struct path_cxt *pc, char *buf, size_t bufsz)
+{
+	/* read /sys/dev/block/<maj>:<min> symlink */
+	ssize_t sz = ul_path_readlink(pc, buf, bufsz, NULL);
+	const char *prefix;
+	size_t psz = 0;
+
+	if (sz <= 0 || sz + sizeof(_PATH_SYS_DEVBLOCK "/") > bufsz)
+		return NULL;
+
+	sz++;
+	prefix = ul_path_get_prefix(pc);
+	if (prefix)
+		psz = strlen(prefix);
+
+	/* create absolute patch from the link */
+	memmove(buf + psz + sizeof(_PATH_SYS_DEVBLOCK "/") - 1, buf, sz);
+	if (prefix)
+		memcpy(buf, prefix, psz);
+
+	memcpy(buf + psz, _PATH_SYS_DEVBLOCK "/", sizeof(_PATH_SYS_DEVBLOCK "/") - 1);
+	return buf;
+}
+
+/*
+ * The @subsys returns the next subsystem in the chain. Function modifies
+ * @devchain string.
+ *
+ * Returns: 0 in success, <0 on error, 1 on end of chain
+ */
+int sysfs_blkdev_next_subsystem(struct path_cxt *pc __attribute__((unused)),
+			 char *devchain, char **subsys)
+{
+	char subbuf[PATH_MAX];
+	char *sub;
+
+	if (!subsys || !devchain)
+		return -EINVAL;
+
+	*subsys = NULL;
+
+	while ((sub = get_subsystem(devchain, subbuf, sizeof(subbuf)))) {
+		*subsys = strdup(sub);
+		if (!*subsys)
+			return -ENOMEM;
+		return 0;
+	}
+
+	return 1;
+}
+
+
+static int is_hotpluggable_subsystem(const char *name)
+{
+	static const char * const hotplug_subsystems[] = {
+		"usb",
+		"ieee1394",
+		"pcmcia",
+		"mmc",
+		"ccw"
+	};
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(hotplug_subsystems); i++)
+		if (strcmp(name, hotplug_subsystems[i]) == 0)
+			return 1;
+
+	return 0;
+}
+
+int sysfs_blkdev_is_hotpluggable(struct path_cxt *pc)
+{
+	char buf[PATH_MAX], *chain, *sub;
+	int rc = 0;
+
+
+	/* check /sys/dev/block/<maj>:<min>/removable attribute */
+	if (ul_path_read_s32(pc, &rc, "removable") == 0 && rc == 1)
+		return 1;
+
+	chain = sysfs_blkdev_get_devchain(pc, buf, sizeof(buf));
+
+	while (chain && sysfs_blkdev_next_subsystem(pc, chain, &sub) == 0) {
+		rc = is_hotpluggable_subsystem(sub);
+		if (rc) {
+			free(sub);
+			break;
+		}
+		free(sub);
+	}
+
+	return rc;
+}
+
+static int get_dm_wholedisk(struct path_cxt *pc, char *diskname,
+                size_t len, dev_t *diskdevno)
+{
+    int rc = 0;
+    char *name;
+
+    /* Note, sysfs_blkdev_get_slave() returns the first slave only,
+     * if there is more slaves, then return NULL
+     */
+    name = sysfs_blkdev_get_slave(pc);
+    if (!name)
+        return -1;
+
+    if (diskname && len)
+        xstrncpy(diskname, name, len);
+
+    if (diskdevno) {
+        *diskdevno = __sysfs_devname_to_devno(ul_path_get_prefix(pc), name, NULL);
+        if (!*diskdevno)
+            rc = -1;
+    }
+
+    free(name);
+    return rc;
+}
+
+/*
+ * Returns by @diskdevno whole disk device devno and (optionally) by
+ * @diskname the whole disk device name.
+ */
+int sysfs_blkdev_get_wholedisk(	struct path_cxt *pc,
+				char *diskname,
+				size_t len,
+				dev_t *diskdevno)
+{
+    int is_part = 0;
+
+    if (!pc)
+        return -1;
+
+    is_part = ul_path_access(pc, F_OK, "partition") == 0;
+    if (!is_part) {
+        /*
+         * Extra case for partitions mapped by device-mapper.
+         *
+         * All regular partitions (added by BLKPG ioctl or kernel PT
+         * parser) have the /sys/.../partition file. The partitions
+         * mapped by DM don't have such file, but they have "part"
+         * prefix in DM UUID.
+         */
+        char *uuid = NULL, *tmp, *prefix;
+
+	ul_path_read_string(pc, &uuid, "dm/uuid");
+	tmp = uuid;
+	prefix = uuid ? strsep(&tmp, "-") : NULL;
+
+        if (prefix && strncasecmp(prefix, "part", 4) == 0)
+            is_part = 1;
+        free(uuid);
+
+        if (is_part &&
+            get_dm_wholedisk(pc, diskname, len, diskdevno) == 0)
+            /*
+             * partitioned device, mapped by DM
+             */
+            goto done;
+
+        is_part = 0;
+    }
+
+    if (!is_part) {
+        /*
+         * unpartitioned device
+         */
+        if (diskname && !sysfs_blkdev_get_name(pc, diskname, len))
+            goto err;
+        if (diskdevno)
+            *diskdevno = sysfs_blkdev_get_devno(pc);
+
+    } else {
+        /*
+         * partitioned device
+         *  - readlink /sys/dev/block/8:1   = ../../block/sda/sda1
+         *  - dirname  ../../block/sda/sda1 = ../../block/sda
+         *  - basename ../../block/sda      = sda
+         */
+        char linkpath[PATH_MAX];
+        char *name;
+	ssize_t	linklen;
+
+	linklen = ul_path_readlink(pc, linkpath, sizeof(linkpath), NULL);
+        if (linklen < 0)
+            goto err;
+
+        stripoff_last_component(linkpath);      /* dirname */
+        name = stripoff_last_component(linkpath);   /* basename */
+        if (!name)
+            goto err;
+
+	sysfs_devname_sys_to_dev(name);
+        if (diskname && len)
+            xstrncpy(diskname, name, len);
+
+        if (diskdevno) {
+            *diskdevno = __sysfs_devname_to_devno(ul_path_get_prefix(pc), name, NULL);
+            if (!*diskdevno)
+                goto err;
+        }
+    }
+
+done:
+    return 0;
+err:
+    return -1;
+}
+
+int sysfs_devno_to_wholedisk(dev_t devno, char *diskname,
+		             size_t len, dev_t *diskdevno)
+{
+	struct path_cxt *pc;
+	int rc = 0;
+
+	if (!devno)
+		return -EINVAL;
+	pc = ul_new_sysfs_path(devno, NULL, NULL);
+	if (!pc)
+		return -ENOMEM;
+
+	rc = sysfs_blkdev_get_wholedisk(pc, diskname, len, diskdevno);
+	ul_unref_path(pc);
+	return rc;
+}
+
+/*
+ * Returns 1 if the device is private device mapper device. The @uuid
+ * (if not NULL) returns DM device UUID, use free() to deallocate.
+ */
+int sysfs_devno_is_dm_private(dev_t devno, char **uuid)
+{
+	struct path_cxt *pc = NULL;
+	char *id = NULL;
+	int rc = 0;
+
+	pc = ul_new_sysfs_path(devno, NULL, NULL);
+	if (!pc)
+		goto done;
+	if (ul_path_read_string(pc, &id, "dm/uuid") <= 0 || !id)
+		goto done;
+
+	/* Private LVM devices use "LVM-<uuid>-<name>" uuid format (important
+	 * is the "LVM" prefix and "-<name>" postfix).
+	 */
+	if (strncmp(id, "LVM-", 4) == 0) {
+		char *p = strrchr(id + 4, '-');
+
+		if (p && *(p + 1))
+			rc = 1;
+
+	/* Private Stratis devices prefix the UUID with "stratis-1-private"
+	 */
+	} else if (strncmp(id, "stratis-1-private", 17) == 0) {
+		rc = 1;
+	}
+done:
+	ul_unref_path(pc);
+	if (uuid)
+		*uuid = id;
+	else
+		free(id);
+	return rc;
+}
+
+/*
+ * Return 0 or 1, or < 0 in case of error
+ */
+int sysfs_devno_is_wholedisk(dev_t devno)
+{
+	dev_t disk;
+
+	if (sysfs_devno_to_wholedisk(devno, NULL, 0, &disk) != 0)
+		return -1;
+
+	return devno == disk;
+}
+
+
+int sysfs_blkdev_scsi_get_hctl(struct path_cxt *pc, int *h, int *c, int *t, int *l)
+{
+	char buf[PATH_MAX], *hctl;
+	struct sysfs_blkdev *blk;
+	ssize_t len;
+
+	blk = ul_path_get_dialect(pc);
+
+	if (!blk || blk->hctl_error)
+		return -EINVAL;
+	if (blk->has_hctl)
+		goto done;
+
+	blk->hctl_error = 1;
+	len = ul_path_readlink(pc, buf, sizeof(buf), "device");
+	if (len < 0)
+		return len;
+
+	hctl = strrchr(buf, '/');
+	if (!hctl)
+		return -1;
+	hctl++;
+
+	if (sscanf(hctl, "%u:%u:%u:%u",	&blk->scsi_host, &blk->scsi_channel,
+				&blk->scsi_target, &blk->scsi_lun) != 4)
+		return -1;
+
+	blk->has_hctl = 1;
+done:
+	if (h)
+		*h = blk->scsi_host;
+	if (c)
+		*c = blk->scsi_channel;
+	if (t)
+		*t = blk->scsi_target;
+	if (l)
+		*l = blk->scsi_lun;
+
+	blk->hctl_error = 0;
+	return 0;
+}
+
+
+static char *scsi_host_attribute_path(
+			struct path_cxt *pc,
+			const char *type,
+			char *buf,
+			size_t bufsz,
+			const char *attr)
+{
+	int len;
+	int host;
+	const char *prefix;
+
+	if (sysfs_blkdev_scsi_get_hctl(pc, &host, NULL, NULL, NULL))
+		return NULL;
+
+	prefix = ul_path_get_prefix(pc);
+	if (!prefix)
+		prefix = "";
+
+	if (attr)
+		len = snprintf(buf, bufsz, "%s%s/%s_host/host%d/%s",
+				prefix, _PATH_SYS_CLASS, type, host, attr);
+	else
+		len = snprintf(buf, bufsz, "%s%s/%s_host/host%d",
+				prefix, _PATH_SYS_CLASS, type, host);
+
+	return (len < 0 || (size_t) len >= bufsz) ? NULL : buf;
+}
+
+char *sysfs_blkdev_scsi_host_strdup_attribute(struct path_cxt *pc,
+			const char *type, const char *attr)
+{
+	char buf[1024];
+	int rc;
+	FILE *f;
+
+	if (!attr || !type ||
+	    !scsi_host_attribute_path(pc, type, buf, sizeof(buf), attr))
+		return NULL;
+
+	if (!(f = fopen(buf, "r" UL_CLOEXECSTR)))
+                return NULL;
+
+	rc = fscanf(f, "%1023[^\n]", buf);
+	fclose(f);
+
+	return rc == 1 ? strdup(buf) : NULL;
+}
+
+int sysfs_blkdev_scsi_host_is(struct path_cxt *pc, const char *type)
+{
+	char buf[PATH_MAX];
+	struct stat st;
+
+	if (!type || !scsi_host_attribute_path(pc, type,
+				buf, sizeof(buf), NULL))
+		return 0;
+
+	return stat(buf, &st) == 0 && S_ISDIR(st.st_mode);
+}
+
+static char *scsi_attribute_path(struct path_cxt *pc,
+		char *buf, size_t bufsz, const char *attr)
+{
+	int len, h, c, t, l;
+	const char *prefix;
+
+	if (sysfs_blkdev_scsi_get_hctl(pc, &h, &c, &t, &l) != 0)
+		return NULL;
+
+	prefix = ul_path_get_prefix(pc);
+	if (!prefix)
+		prefix = "";
+
+	if (attr)
+		len = snprintf(buf, bufsz, "%s%s/devices/%d:%d:%d:%d/%s",
+				prefix, _PATH_SYS_SCSI,
+				h,c,t,l, attr);
+	else
+		len = snprintf(buf, bufsz, "%s%s/devices/%d:%d:%d:%d",
+				prefix, _PATH_SYS_SCSI,
+				h,c,t,l);
+	return (len < 0 || (size_t) len >= bufsz) ? NULL : buf;
+}
+
+int sysfs_blkdev_scsi_has_attribute(struct path_cxt *pc, const char *attr)
+{
+	char path[PATH_MAX];
+	struct stat st;
+
+	if (!scsi_attribute_path(pc, path, sizeof(path), attr))
+		return 0;
+
+	return stat(path, &st) == 0;
+}
+
+int sysfs_blkdev_scsi_path_contains(struct path_cxt *pc, const char *pattern)
+{
+	char path[PATH_MAX], linkc[PATH_MAX];
+	struct stat st;
+	ssize_t len;
+
+	if (!scsi_attribute_path(pc, path, sizeof(path), NULL))
+		return 0;
+
+	if (stat(path, &st) != 0)
+		return 0;
+
+	len = readlink(path, linkc, sizeof(linkc) - 1);
+	if (len < 0)
+		return 0;
+
+	linkc[len] = '\0';
+	return strstr(linkc, pattern) != NULL;
+}
+
+static dev_t read_devno(const char *path)
+{
+	FILE *f;
+	int maj = 0, min = 0;
+	dev_t dev = 0;
+
+	f = fopen(path, "r" UL_CLOEXECSTR);
+	if (!f)
+		return 0;
+
+	if (fscanf(f, "%d:%d", &maj, &min) == 2)
+		dev = makedev(maj, min);
+	fclose(f);
+	return dev;
+}
+
+int sysfs_devname_is_hidden(const char *prefix, const char *name)
+{
+	char buf[PATH_MAX];
+	int rc = 0, hidden = 0, len;
+	FILE *f;
+
+	if (strncmp("/dev/", name, 5) == 0)
+		return 0;
+
+	if (!prefix)
+		prefix = "";
+	/*
+	 * Create path to /sys/block/<name>/hidden
+	 */
+	len = snprintf(buf, sizeof(buf),
+			"%s" _PATH_SYS_BLOCK "/%s/hidden",
+			prefix, name);
+
+	if (len < 0 || (size_t) len + 1 > sizeof(buf))
+		return 0;
+
+	f = fopen(buf, "r" UL_CLOEXECSTR);
+	if (!f)
+		return 0;
+
+	rc = fscanf(f, "%d", &hidden);
+	fclose(f);
+
+	return rc == 1 ? hidden : 0;
+}
+
+
+dev_t __sysfs_devname_to_devno(const char *prefix, const char *name, const char *parent)
+{
+	char buf[PATH_MAX];
+	char *_name = NULL, *_parent = NULL;	/* name as encoded in sysfs */
+	dev_t dev = 0;
+	int len;
+
+	if (!prefix)
+		prefix = "";
+
+	assert(name);
+
+	if (strncmp("/dev/", name, 5) == 0) {
+		/*
+		 * Read from /dev
+		 */
+		struct stat st;
+
+		if (stat(name, &st) == 0) {
+			dev = st.st_rdev;
+			goto done;
+		}
+		name += 5;	/* unaccessible, or not node in /dev */
+	}
+
+	_name = strdup(name);
+	if (!_name)
+		goto done;
+	sysfs_devname_dev_to_sys(_name);
+
+	if (parent) {
+		_parent = strdup(parent);
+		if (!_parent)
+			goto done;
+	}
+
+	if (parent && strncmp("dm-", name, 3) != 0) {
+		/*
+		 * Create path to /sys/block/<parent>/<name>/dev
+		 */
+		sysfs_devname_dev_to_sys(_parent);
+		len = snprintf(buf, sizeof(buf),
+				"%s" _PATH_SYS_BLOCK "/%s/%s/dev",
+				prefix,	_parent, _name);
+		if (len < 0 || (size_t) len >= sizeof(buf))
+			goto done;
+
+		/* don't try anything else for dm-* */
+		dev = read_devno(buf);
+		goto done;
+	}
+
+	/*
+	 * Read from /sys/block/<sysname>/dev
+	 */
+	len = snprintf(buf, sizeof(buf),
+			"%s" _PATH_SYS_BLOCK "/%s/dev",
+			prefix, _name);
+	if (len < 0 || (size_t) len >= sizeof(buf))
+		goto done;
+	dev = read_devno(buf);
+
+	/*
+	 * Read from /sys/block/<parent>/<partition>/dev
+	 */
+	if (!dev && parent && startswith(name, parent)) {
+		len = snprintf(buf, sizeof(buf),
+				"%s" _PATH_SYS_BLOCK "/%s/%s/dev",
+				prefix, _parent, _name);
+		if (len < 0 || (size_t) len >= sizeof(buf))
+			goto done;
+		dev = read_devno(buf);
+	}
+
+	/*
+	 * Read from /sys/block/<sysname>/device/dev
+	 */
+	if (!dev) {
+		len = snprintf(buf, sizeof(buf),
+				"%s" _PATH_SYS_BLOCK "/%s/device/dev",
+				prefix, _name);
+		if (len < 0 || (size_t) len >= sizeof(buf))
+			goto done;
+		dev = read_devno(buf);
+	}
+done:
+	free(_name);
+	free(_parent);
+	return dev;
+}
+
+dev_t sysfs_devname_to_devno(const char *name)
+{
+	return __sysfs_devname_to_devno(NULL, name, NULL);
+}
+
+char *sysfs_blkdev_get_path(struct path_cxt *pc, char *buf, size_t bufsiz)
+{
+	const char *name = sysfs_blkdev_get_name(pc, buf, bufsiz);
+	char *res = NULL;
+	size_t sz;
+	struct stat st;
+
+	if (!name)
+		goto done;
+
+	sz = strlen(name);
+	if (sz + sizeof("/dev/") > bufsiz)
+		goto done;
+
+	/* create the final "/dev/<name>" string */
+	memmove(buf + 5, name, sz + 1);
+	memcpy(buf, "/dev/", 5);
+
+	if (!stat(buf, &st) && S_ISBLK(st.st_mode) && st.st_rdev == sysfs_blkdev_get_devno(pc))
+		res = buf;
+done:
+	return res;
+}
+
+dev_t sysfs_blkdev_get_devno(struct path_cxt *pc)
+{
+	return ((struct sysfs_blkdev *) ul_path_get_dialect(pc))->devno;
+}
+
+/*
+ * Returns devname (e.g. "/dev/sda1") for the given devno.
+ *
+ * Please, use more robust blkid_devno_to_devname() in your applications.
+ */
+char *sysfs_devno_to_devpath(dev_t devno, char *buf, size_t bufsiz)
+{
+	struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
+	char *res = NULL;
+
+	if (pc) {
+		res = sysfs_blkdev_get_path(pc, buf, bufsiz);
+		ul_unref_path(pc);
+	}
+	return res;
+}
+
+char *sysfs_devno_to_devname(dev_t devno, char *buf, size_t bufsiz)
+{
+	struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
+	char *res = NULL;
+
+	if (pc) {
+		res = sysfs_blkdev_get_name(pc, buf, bufsiz);
+		ul_unref_path(pc);
+	}
+	return res;
+}
+
+int sysfs_devno_count_partitions(dev_t devno)
+{
+	struct path_cxt *pc = ul_new_sysfs_path(devno, NULL, NULL);
+	int n = 0;
+
+	if (pc) {
+		char buf[PATH_MAX + 1];
+		char *name = sysfs_blkdev_get_name(pc, buf, sizeof(buf));
+
+		n = sysfs_blkdev_count_partitions(pc, name);
+		ul_unref_path(pc);
+	}
+	return n;
+}
+
+char *sysfs_chrdev_devno_to_devname(dev_t devno, char *buf, size_t bufsiz)
+{
+	char link[PATH_MAX];
+	struct path_cxt *pc;
+	char *name;
+	ssize_t	sz;
+
+	pc = ul_new_path(_PATH_SYS_DEVCHAR "/%u:%u", major(devno), minor(devno));
+	if (!pc)
+		return NULL;
+
+        /* read /sys/dev/char/<maj:min> link */
+	sz = ul_path_readlink(pc, link, sizeof(link), NULL);
+	ul_unref_path(pc);
+
+	if (sz < 0)
+		return NULL;
+
+	name = strrchr(link, '/');
+	if (!name)
+		return NULL;
+
+	name++;
+	sz = strlen(name);
+	if ((size_t) sz + 1 > bufsiz)
+		return NULL;
+
+	memcpy(buf, name, sz + 1);
+	sysfs_devname_sys_to_dev(buf);
+	return buf;
+
+}
+
+
+
+#ifdef TEST_PROGRAM_SYSFS
+#include <errno.h>
+#include <err.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+	struct path_cxt *pc;
+	char *devname;
+	dev_t devno, disk_devno;
+	char path[PATH_MAX], *sub, *chain;
+	char diskname[32];
+	int i, is_part, rc = EXIT_SUCCESS;
+	uint64_t u64;
+
+	if (argc != 2)
+		errx(EXIT_FAILURE, "usage: %s <devname>", argv[0]);
+
+	ul_sysfs_init_debug();
+
+	devname = argv[1];
+	devno = sysfs_devname_to_devno(devname);
+
+	if (!devno)
+		err(EXIT_FAILURE, "failed to read devno");
+
+	printf("non-context:\n");
+	printf(" DEVNO:   %u (%d:%d)\n", (unsigned int) devno, major(devno), minor(devno));
+	printf(" DEVNAME: %s\n", sysfs_devno_to_devname(devno, path, sizeof(path)));
+	printf(" DEVPATH: %s\n", sysfs_devno_to_devpath(devno, path, sizeof(path)));
+
+	sysfs_devno_to_wholedisk(devno, diskname, sizeof(diskname), &disk_devno);
+	printf(" WHOLEDISK-DEVNO:   %u (%d:%d)\n", (unsigned int) disk_devno, major(disk_devno), minor(disk_devno));
+	printf(" WHOLEDISK-DEVNAME: %s\n", diskname);
+
+	pc = ul_new_sysfs_path(devno, NULL, NULL);
+	if (!pc)
+		goto done;
+
+	printf("context based:\n");
+	devno = sysfs_blkdev_get_devno(pc);
+	printf(" DEVNO:   %u (%d:%d)\n", (unsigned int) devno, major(devno), minor(devno));
+	printf(" DEVNAME: %s\n", sysfs_blkdev_get_name(pc, path, sizeof(path)));
+	printf(" DEVPATH: %s\n", sysfs_blkdev_get_path(pc, path, sizeof(path)));
+
+	sysfs_devno_to_wholedisk(devno, diskname, sizeof(diskname), &disk_devno);
+	printf(" WHOLEDISK-DEVNO: %u (%d:%d)\n", (unsigned int) disk_devno, major(disk_devno), minor(disk_devno));
+	printf(" WHOLEDISK-DEVNAME: %s\n", diskname);
+
+	is_part = ul_path_access(pc, F_OK, "partition") == 0;
+	printf(" PARTITION: %s\n", is_part ? "YES" : "NOT");
+
+	if (is_part && disk_devno) {
+		struct path_cxt *disk_pc =  ul_new_sysfs_path(disk_devno, NULL, NULL);
+		sysfs_blkdev_set_parent(pc, disk_pc);
+
+		ul_unref_path(disk_pc);
+	}
+
+	printf(" HOTPLUG: %s\n", sysfs_blkdev_is_hotpluggable(pc) ? "yes" : "no");
+	printf(" SLAVES: %d\n", ul_path_count_dirents(pc, "slaves"));
+
+	if (!is_part) {
+		printf("First 5 partitions:\n");
+		for (i = 1; i <= 5; i++) {
+			dev_t dev = sysfs_blkdev_partno_to_devno(pc, i);
+			if (dev)
+				printf("\t#%d %d:%d\n", i, major(dev), minor(dev));
+		}
+	}
+
+	if (ul_path_read_u64(pc, &u64, "size") != 0)
+		printf(" (!) read SIZE failed\n");
+	else
+		printf(" SIZE: %jd\n", u64);
+
+	if (ul_path_read_s32(pc, &i, "queue/hw_sector_size"))
+		printf(" (!) read SECTOR failed\n");
+	else
+		printf(" SECTOR: %d\n", i);
+
+
+	chain = sysfs_blkdev_get_devchain(pc, path, sizeof(path));
+	printf(" SUBSUSTEMS:\n");
+
+	while (chain && sysfs_blkdev_next_subsystem(pc, chain, &sub) == 0) {
+		printf("\t%s\n", sub);
+		free(sub);
+	}
+
+	rc = EXIT_SUCCESS;
+done:
+	ul_unref_path(pc);
+	return rc;
+}
+#endif /* TEST_PROGRAM_SYSFS */