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Refactor attach loop device in pure Go
This commit is contained in:
Guillaume J. Charmes
@@ -2,124 +2,14 @@ package devmapper
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/*
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#cgo LDFLAGS: -L. -ldevmapper
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <libdevmapper.h>
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#include <linux/loop.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <linux/fs.h>
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#include <errno.h>
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#ifndef LOOP_CTL_GET_FREE
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#define LOOP_CTL_GET_FREE 0x4C82
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#endif
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// FIXME: this could easily be rewritten in go
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char* attach_loop_device(const char *filename, int *loop_fd_out)
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{
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struct loop_info64 loopinfo = {0};
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struct stat st;
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char buf[64];
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int i, loop_fd, fd, start_index;
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char* loopname;
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*loop_fd_out = -1;
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start_index = 0;
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fd = open("/dev/loop-control", O_RDONLY);
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if (fd >= 0) {
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start_index = ioctl(fd, LOOP_CTL_GET_FREE);
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close(fd);
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if (start_index < 0)
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start_index = 0;
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}
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fd = open(filename, O_RDWR);
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if (fd < 0) {
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perror("open");
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return NULL;
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}
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loop_fd = -1;
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for (i = start_index ; loop_fd < 0 ; i++ ) {
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if (sprintf(buf, "/dev/loop%d", i) < 0) {
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close(fd);
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return NULL;
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}
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if (stat(buf, &st)) {
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if (!S_ISBLK(st.st_mode)) {
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fprintf(stderr, "[error] Loopback device %s is not a block device.\n", buf);
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} else if (errno == ENOENT) {
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fprintf(stderr, "[error] There are no more loopback device available.\n");
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} else {
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fprintf(stderr, "[error] Unkown error trying to stat the loopback device %s (errno: %d).\n", buf, errno);
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}
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close(fd);
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return NULL;
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}
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loop_fd = open(buf, O_RDWR);
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if (loop_fd < 0 && errno == ENOENT) {
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fprintf(stderr, "[error] The loopback device %s does not exists.\n", buf);
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close(fd);
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return NULL;
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} else if (loop_fd < 0) {
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fprintf(stderr, "[error] Unkown error openning the loopback device %s. (errno: %d)\n", buf, errno);
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continue;
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}
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if (ioctl(loop_fd, LOOP_SET_FD, (void *)(size_t)fd) < 0) {
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int errsv = errno;
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close(loop_fd);
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loop_fd = -1;
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if (errsv != EBUSY) {
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close(fd);
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fprintf(stderr, "cannot set up loopback device %s: %s", buf, strerror(errsv));
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return NULL;
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}
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continue;
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}
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close(fd);
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strncpy((char*)loopinfo.lo_file_name, buf, LO_NAME_SIZE);
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loopinfo.lo_offset = 0;
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loopinfo.lo_flags = LO_FLAGS_AUTOCLEAR;
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if (ioctl(loop_fd, LOOP_SET_STATUS64, &loopinfo) < 0) {
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perror("ioctl LOOP_SET_STATUS64");
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if (ioctl(loop_fd, LOOP_CLR_FD, 0) < 0) {
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perror("ioctl LOOP_CLR_FD");
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}
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close(loop_fd);
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fprintf (stderr, "cannot set up loopback device info");
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return (NULL);
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}
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loopname = strdup(buf);
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if (loopname == NULL) {
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close(loop_fd);
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return (NULL);
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}
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*loop_fd_out = loop_fd;
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return (loopname);
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}
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return (NULL);
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}
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#include <linux/loop.h> // FIXME: present only for defines, maybe we can remove it?
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#include <linux/fs.h> // FIXME: present only for BLKGETSIZE64, maybe we can remove it?
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// FIXME: Can't we find a way to do the logging in pure Go?
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extern void DevmapperLogCallback(int level, char *file, int line, int dm_errno_or_class, char *str);
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static void log_cb(int level, const char *file, int line,
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int dm_errno_or_class, const char *f, ...)
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static void log_cb(int level, const char *file, int line, int dm_errno_or_class, const char *f, ...)
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{
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char buffer[256];
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va_list ap;
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@@ -135,7 +25,6 @@ static void log_with_errno_init()
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{
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dm_log_with_errno_init(log_cb);
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}
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*/
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import "C"
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@@ -147,6 +36,19 @@ type (
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CDmTask C.struct_dm_task
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)
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// FIXME: Make sure the values are defined in C
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const (
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LoopSetFd = C.LOOP_SET_FD
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LoopCtlGetFree = C.LOOP_CTL_GET_FREE
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LoopSetStatus64 = C.LOOP_SET_STATUS64
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LoopClrFd = C.LOOP_CLR_FD
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LoFlagsAutoClear = C.LO_FLAGS_AUTOCLEAR
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LoFlagsReadOnly = C.LO_FLAGS_READ_ONLY
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LoFlagsPartScan = C.LO_FLAGS_PARTSCAN
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LoKeySize = C.LO_KEY_SIZE
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LoNameSize = C.LO_NAME_SIZE
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)
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var (
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DmAttachLoopDevice = dmAttachLoopDeviceFct
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DmGetBlockSize = dmGetBlockSizeFct
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@@ -185,28 +87,26 @@ func dmTaskCreateFct(taskType int) *CDmTask {
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}
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func dmTaskRunFct(task *CDmTask) int {
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return int(C.dm_task_run((*C.struct_dm_task)(task)))
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ret, _ := C.dm_task_run((*C.struct_dm_task)(task))
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return int(ret)
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}
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func dmTaskSetNameFct(task *CDmTask, name string) int {
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Cname := C.CString(name)
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defer free(Cname)
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return int(C.dm_task_set_name((*C.struct_dm_task)(task),
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Cname))
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return int(C.dm_task_set_name((*C.struct_dm_task)(task), Cname))
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}
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func dmTaskSetMessageFct(task *CDmTask, message string) int {
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Cmessage := C.CString(message)
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defer free(Cmessage)
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return int(C.dm_task_set_message((*C.struct_dm_task)(task),
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Cmessage))
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return int(C.dm_task_set_message((*C.struct_dm_task)(task), Cmessage))
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}
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func dmTaskSetSectorFct(task *CDmTask, sector uint64) int {
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return int(C.dm_task_set_sector((*C.struct_dm_task)(task),
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C.uint64_t(sector)))
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return int(C.dm_task_set_sector((*C.struct_dm_task)(task), C.uint64_t(sector)))
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}
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func dmTaskSetCookieFct(task *CDmTask, cookie *uint, flags uint16) int {
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@@ -214,13 +114,11 @@ func dmTaskSetCookieFct(task *CDmTask, cookie *uint, flags uint16) int {
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defer func() {
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*cookie = uint(cCookie)
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}()
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return int(C.dm_task_set_cookie((*C.struct_dm_task)(task), &cCookie,
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C.uint16_t(flags)))
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return int(C.dm_task_set_cookie((*C.struct_dm_task)(task), &cCookie, C.uint16_t(flags)))
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}
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func dmTaskSetAddNodeFct(task *CDmTask, addNode AddNodeType) int {
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return int(C.dm_task_set_add_node((*C.struct_dm_task)(task),
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C.dm_add_node_t(addNode)))
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return int(C.dm_task_set_add_node((*C.struct_dm_task)(task), C.dm_add_node_t(addNode)))
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}
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func dmTaskSetRoFct(task *CDmTask) int {
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@@ -236,14 +134,12 @@ func dmTaskAddTargetFct(task *CDmTask,
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Cparams := C.CString(params)
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defer free(Cparams)
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return int(C.dm_task_add_target((*C.struct_dm_task)(task),
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C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
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return int(C.dm_task_add_target((*C.struct_dm_task)(task), C.uint64_t(start), C.uint64_t(size), Cttype, Cparams))
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}
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func dmGetLoopbackBackingFileFct(fd uintptr) (uint64, uint64, sysErrno) {
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var lo64 C.struct_loop_info64
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_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_GET_STATUS64,
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uintptr(unsafe.Pointer(&lo64)))
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_, _, err := sysSyscall(sysSysIoctl, fd, C.LOOP_GET_STATUS64, uintptr(unsafe.Pointer(&lo64)))
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return uint64(lo64.lo_device), uint64(lo64.lo_inode), sysErrno(err)
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}
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@@ -287,23 +183,23 @@ func dmGetNextTargetFct(task *CDmTask, next uintptr, start, length *uint64, targ
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*params = C.GoString(Cparams)
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}()
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nextp := C.dm_get_next_target((*C.struct_dm_task)(task),
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unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
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nextp := C.dm_get_next_target((*C.struct_dm_task)(task), unsafe.Pointer(next), &Cstart, &Clength, &CtargetType, &Cparams)
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return uintptr(nextp)
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}
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func dmAttachLoopDeviceFct(filename string, fd *int) string {
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cFilename := C.CString(filename)
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defer free(cFilename)
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return ""
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// cFilename := C.CString(filename)
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// defer free(cFilename)
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var cFd C.int
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defer func() {
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*fd = int(cFd)
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}()
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// var cFd C.int
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// defer func() {
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// *fd = int(cFd)
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// }()
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ret := C.attach_loop_device(cFilename, &cFd)
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defer free(ret)
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return C.GoString(ret)
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// ret := C.attach_loop_device(cFilename, &cFd)
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// defer free(ret)
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// return C.GoString(ret)
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}
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func getBlockSizeFct(fd uintptr, size *uint64) sysErrno {
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