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di_init, di_fini - create and destroy a snapshot of kernel device tree

cc [ flag... ] file... -ldevinfo [ library... ]
#include <libdevinfo.h>

di_node_t di_init(const char *phys_path, uint_t flags);

void di_fini(di_node_t root);

flags phys_path root

The di_init() function creates a snapshot of the kernel device tree and returns a handle of the root device node. The caller specifies the contents of the snapshot by providing flag and phys_path.

The di_fini() function destroys the snapshot of the kernel device tree and frees the associated memory. All handles associated with this snapshot become invalid after the call to di_fini().

Upon success, di_init() returns a handle. Otherwise, DI_NODE_NIL is returned and errno is set to indicate the error.

The di_init() function can set errno to any error code that can also be set by open(2), ioctl(2) or mmap(2). The most common error codes include: EACCES

ENXIO EINVAL

Example 1 Using the libdevinfo Interfaces To Print All Device Tree Node Names

The following is an example using the libdevinfo interfaces to print all device tree device node names:

/*
 * Code to print all device tree device node names
 */

#include <stdio.h>
#include <libdevinfo.h>

int
prt_nodename(di_node_t node, void *arg)
{
 printf("%s\en", di_node_name(node));
 return (DI_WALK_CONTINUE);
}

main()
{
 di_node_t root_node;
 if((root_node = di_init("/", DINFOSUBTREE)) == DI_NODE_NIL) {
 fprintf(stderr, "di_init() failed\en");
 exit(1);
 }
 di_walk_node(root_node, DI_WALK_CLDFIRST, NULL, prt_nodename);
 di_fini(root_node);
}

Example 2 Using the libdevinfo Interfaces To Print The Physical Path Of SCSI Disks

The following example uses the libdevinfo interfaces to print the physical path of SCSI disks:

/*
 * Code to print physical path of scsi disks
 */

#include <stdio.h>
#include <libdevinfo.h>
#define DISK_DRIVER "sd" /* driver name */

void
prt_diskinfo(di_node_t node)
{
 int instance;
 char *phys_path;

 /*
 * If the device node exports no minor nodes,
 * there is no physical disk.
 */
 if (di_minor_next(node, DI_MINOR_NIL) == DI_MINOR_NIL) {
 return;
 }

 instance = di_instance(node);
 phys_path = di_devfs_path(node);
 printf("%s%d: %s\en", DISK_DRIVER, instance, phys_path);
 di_devfs_path_free(phys_path);
}

void
walk_disknodes(di_node_t node)
{
 node = di_drv_first_node(DISK_DRIVER, node);
 while (node != DI_NODE_NIL) {
 prt_diskinfo(node);
 node = di_drv_next_node(node);
 }
}

main()
{
 di_node_t root_node;
 if ((root_node = di_init("/", DINFOCPYALL)) == DI_NODE_NIL) {
 fprintf(stderr, "di_init() failed\en");
 exit(1);
 }
 walk_disknodes(root_node);
 di_fini(root_node);
}

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE

Interface Stability Committed

MT-Level Safe

ioctl (2), mmap (2), open (2), libdevinfo (3LIB), attributes (7)

Writing Device Drivers