// find a field in the uevent buffer, using vdev_read_file and vdev_sysfs_uevent_get_key
// return 0 on success, and set *value and *value_len
// return negative on error
int vdev_sysfs_uevent_read_key( char const* sysfs_device_path, char const* uevent_key, char** uevent_value, size_t* uevent_value_len ) {
int rc = 0;
char* uevent_buf = NULL;
size_t uevent_len = 0;
char* uevent_path = (char*)calloc( strlen(sysfs_device_path) + strlen("/uevent") + 1, 1 );
if( uevent_path == NULL ) {
return -ENOMEM;
}
sprintf( uevent_path, "%s/uevent", sysfs_device_path );
// get uevent
rc = vdev_read_file( uevent_path, &uevent_buf, &uevent_len );
if( rc < 0 ) {
if( DEBUG ) {
fprintf(stderr, "[WARN]: vdev_read_file('%s') rc = %d\n", uevent_path, rc );
}
return rc;
}
// get devtype
rc = vdev_sysfs_uevent_get_key( uevent_buf, uevent_len, uevent_key, uevent_value, uevent_value_len );
free( uevent_buf );
free( uevent_path );
return rc;
}
// walk up a sysfs device path to find the ancestor device with the given subsystem and devtype
// if devtype_name is NULL, match any devtype (only match the subsystem)
// return 0 on success
// return -ENOMEM on OOM
// return -ENOENT if a subsystem or uevent was not found, when one was expected
int vdev_sysfs_get_parent_with_subsystem_devtype( char const* sysfs_device_path, char const* subsystem_name, char const* devtype_name, char** devpath, size_t* devpath_len ) {
char cur_dir[4097];
char subsystem_path[4097];
char subsystem_link[4097];
char uevent_path[4097];
memset( subsystem_path, 0, 4097 );
memset( subsystem_link, 0, 4097 );
char* tmp = NULL;
int rc = 0;
char* uevent_buf = NULL;
size_t uevent_len = 0;
char* devtype = NULL;
size_t devtype_len = 0;
char* parent_device = NULL;
size_t parent_device_len = 0;
strcpy( cur_dir, sysfs_device_path );
while( 1 ) {
// get parent device
rc = vdev_sysfs_get_parent_device( cur_dir, &parent_device, &parent_device_len );
if( rc != 0 ) {
break;
}
// subsystem?
sprintf( subsystem_path, "%s/subsystem", parent_device );
memset( subsystem_link, 0, 4096 );
rc = readlink( subsystem_path, subsystem_link, 4096 );
if( rc < 0 ) {
rc = -errno;
if( rc != -ENOENT ) {
fprintf(stderr, "[WARN]: readlink('%s') errno = %d\n", subsystem_path, rc );
}
free( parent_device );
parent_device = NULL;
return rc;
}
// get subsystem name...
tmp = rindex( subsystem_link, '/' );
if( tmp != NULL && strcmp( tmp + 1, subsystem_name ) != 0 ) {
// subsystem does not match
// crawl up to the parent
strcpy( cur_dir, parent_device );
free( parent_device );
parent_device = NULL;
continue;
}
// subsystem matches...
*tmp = 0;
if( devtype_name != NULL ) {
// get uevent
// get DEVTYPE from uevent
// make uevent path
sprintf( uevent_path, "%s/uevent", parent_device );
// get uevent
rc = vdev_read_file( uevent_path, &uevent_buf, &uevent_len );
if( rc < 0 ) {
fprintf(stderr, "[WARN]: vdev_read_file('%s') rc = %d\n", uevent_path, rc );
free( parent_device );
parent_device = NULL;
return rc;
}
// get devtype
rc = vdev_sysfs_uevent_get_key( uevent_buf, uevent_len, "DEVTYPE", &devtype, &devtype_len );
free( uevent_buf );
if( rc != 0 ) {
if( rc == -ENOENT ) {
// not found
// next parent
strcpy( cur_dir, parent_device );
free( parent_device );
parent_device = NULL;
continue;
}
else {
free( parent_device );
parent_device = NULL;
return rc;
}
}
// matches?
if( strcmp( devtype, devtype_name ) == 0 ) {
free( devtype );
// this is the path to the device
*devpath = parent_device;
*devpath_len = strlen( parent_device );
// found!
rc = 0;
break;
}
else {
// no match.
// next device
free( devtype );
strcpy( cur_dir, parent_device );
free( parent_device );
parent_device = NULL;
continue;
}
}
else {
// match only on subsystem
*devpath = parent_device;
*devpath_len = strlen(parent_device);
rc = 0;
break;
}
}
return rc;
}
// get a uevent from a uevent file
// replace newlines with '\0', making the uevent look like it came from the netlink socket
// (i.e. so it can be parsed by vdev_linux_parse_request)
// return 0 on success
// return -ENOMEM on OOM
// return -errno on failure to stat or read
static int vdev_linux_sysfs_read_uevent( char const* fp_uevent, char** ret_uevent_buf, size_t* ret_uevent_len ) {
int rc = 0;
struct stat sb;
char* uevent_buf = NULL;
size_t uevent_buf_len = 0;
size_t uevent_len = 0;
// get uevent size
rc = stat( fp_uevent, &sb );
if( rc != 0 ) {
rc = -errno;
vdev_error("stat('%s') rc = %d\n", fp_uevent, rc );
return rc;
}
else {
uevent_buf_len = sb.st_size;
}
// read the uevent
if( fp_uevent != NULL ) {
uevent_buf = VDEV_CALLOC( char, uevent_buf_len );
if( uevent_buf == NULL ) {
return -ENOMEM;
}
rc = vdev_read_file( fp_uevent, uevent_buf, uevent_buf_len );
if( rc != 0 ) {
// failed in this
vdev_error("vdev_read_file('%s') rc = %d\n", fp_uevent, rc );
free( uevent_buf );
}
else {
for( unsigned int i = 0; i < uevent_buf_len; i++ ) {
if( uevent_buf[i] == '\n' ) {
uevent_buf[i] = '\0';
}
}
// NOTE: the stat size is an upper-bound. Find the exact number of bytes.
for( uevent_len = 0; uevent_len < uevent_buf_len; ) {
if( *(uevent_buf + uevent_len) == '\0' ) {
break;
}
uevent_len += strlen( uevent_buf + uevent_len ) + 1;
}
*ret_uevent_buf = uevent_buf;
*ret_uevent_len = uevent_len;
}
}
