Browse Source
qcow2-snapshot.c contains the code related to snapshotting. Signed-off-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>stable-0.11
Kevin Wolf
17 years ago
committed by
Anthony Liguori
Anthony Liguori
4 changed files with 422 additions and 392 deletions
@ -0,0 +1,405 @@ |
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/*
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* Block driver for the QCOW version 2 format |
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* |
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* Copyright (c) 2004-2006 Fabrice Bellard |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a copy |
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* of this software and associated documentation files (the "Software"), to deal |
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* in the Software without restriction, including without limitation the rights |
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
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* copies of the Software, and to permit persons to whom the Software is |
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* furnished to do so, subject to the following conditions: |
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* |
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* The above copyright notice and this permission notice shall be included in |
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* all copies or substantial portions of the Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
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* THE SOFTWARE. |
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*/ |
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#include "qemu-common.h" |
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#include "block_int.h" |
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#include "block/qcow2.h" |
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typedef struct __attribute__((packed)) QCowSnapshotHeader { |
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/* header is 8 byte aligned */ |
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uint64_t l1_table_offset; |
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uint32_t l1_size; |
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uint16_t id_str_size; |
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uint16_t name_size; |
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uint32_t date_sec; |
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uint32_t date_nsec; |
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uint64_t vm_clock_nsec; |
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uint32_t vm_state_size; |
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uint32_t extra_data_size; /* for extension */ |
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/* extra data follows */ |
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/* id_str follows */ |
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/* name follows */ |
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} QCowSnapshotHeader; |
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void qcow_free_snapshots(BlockDriverState *bs) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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qemu_free(s->snapshots[i].name); |
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qemu_free(s->snapshots[i].id_str); |
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} |
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qemu_free(s->snapshots); |
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s->snapshots = NULL; |
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s->nb_snapshots = 0; |
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} |
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int qcow_read_snapshots(BlockDriverState *bs) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshotHeader h; |
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QCowSnapshot *sn; |
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int i, id_str_size, name_size; |
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int64_t offset; |
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uint32_t extra_data_size; |
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if (!s->nb_snapshots) { |
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s->snapshots = NULL; |
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s->snapshots_size = 0; |
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return 0; |
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} |
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offset = s->snapshots_offset; |
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s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot)); |
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for(i = 0; i < s->nb_snapshots; i++) { |
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offset = align_offset(offset, 8); |
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if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h)) |
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goto fail; |
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offset += sizeof(h); |
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sn = s->snapshots + i; |
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sn->l1_table_offset = be64_to_cpu(h.l1_table_offset); |
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sn->l1_size = be32_to_cpu(h.l1_size); |
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sn->vm_state_size = be32_to_cpu(h.vm_state_size); |
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sn->date_sec = be32_to_cpu(h.date_sec); |
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sn->date_nsec = be32_to_cpu(h.date_nsec); |
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sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec); |
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extra_data_size = be32_to_cpu(h.extra_data_size); |
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id_str_size = be16_to_cpu(h.id_str_size); |
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name_size = be16_to_cpu(h.name_size); |
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offset += extra_data_size; |
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sn->id_str = qemu_malloc(id_str_size + 1); |
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if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size) |
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goto fail; |
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offset += id_str_size; |
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sn->id_str[id_str_size] = '\0'; |
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sn->name = qemu_malloc(name_size + 1); |
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if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size) |
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goto fail; |
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offset += name_size; |
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sn->name[name_size] = '\0'; |
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} |
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s->snapshots_size = offset - s->snapshots_offset; |
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return 0; |
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fail: |
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qcow_free_snapshots(bs); |
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return -1; |
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} |
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/* add at the end of the file a new list of snapshots */ |
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static int qcow_write_snapshots(BlockDriverState *bs) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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QCowSnapshotHeader h; |
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int i, name_size, id_str_size, snapshots_size; |
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uint64_t data64; |
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uint32_t data32; |
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int64_t offset, snapshots_offset; |
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/* compute the size of the snapshots */ |
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offset = 0; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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offset = align_offset(offset, 8); |
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offset += sizeof(h); |
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offset += strlen(sn->id_str); |
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offset += strlen(sn->name); |
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} |
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snapshots_size = offset; |
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snapshots_offset = alloc_clusters(bs, snapshots_size); |
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offset = snapshots_offset; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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memset(&h, 0, sizeof(h)); |
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h.l1_table_offset = cpu_to_be64(sn->l1_table_offset); |
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h.l1_size = cpu_to_be32(sn->l1_size); |
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h.vm_state_size = cpu_to_be32(sn->vm_state_size); |
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h.date_sec = cpu_to_be32(sn->date_sec); |
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h.date_nsec = cpu_to_be32(sn->date_nsec); |
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h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec); |
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id_str_size = strlen(sn->id_str); |
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name_size = strlen(sn->name); |
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h.id_str_size = cpu_to_be16(id_str_size); |
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h.name_size = cpu_to_be16(name_size); |
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offset = align_offset(offset, 8); |
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if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h)) |
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goto fail; |
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offset += sizeof(h); |
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if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size) |
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goto fail; |
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offset += id_str_size; |
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if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size) |
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goto fail; |
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offset += name_size; |
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} |
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/* update the various header fields */ |
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data64 = cpu_to_be64(snapshots_offset); |
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if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset), |
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&data64, sizeof(data64)) != sizeof(data64)) |
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goto fail; |
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data32 = cpu_to_be32(s->nb_snapshots); |
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if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots), |
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&data32, sizeof(data32)) != sizeof(data32)) |
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goto fail; |
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/* free the old snapshot table */ |
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free_clusters(bs, s->snapshots_offset, s->snapshots_size); |
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s->snapshots_offset = snapshots_offset; |
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s->snapshots_size = snapshots_size; |
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return 0; |
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fail: |
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return -1; |
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} |
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static void find_new_snapshot_id(BlockDriverState *bs, |
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char *id_str, int id_str_size) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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int i, id, id_max = 0; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn = s->snapshots + i; |
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id = strtoul(sn->id_str, NULL, 10); |
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if (id > id_max) |
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id_max = id; |
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} |
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snprintf(id_str, id_str_size, "%d", id_max + 1); |
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} |
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static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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if (!strcmp(s->snapshots[i].id_str, id_str)) |
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return i; |
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} |
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return -1; |
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} |
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static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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int i, ret; |
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ret = find_snapshot_by_id(bs, name); |
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if (ret >= 0) |
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return ret; |
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for(i = 0; i < s->nb_snapshots; i++) { |
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if (!strcmp(s->snapshots[i].name, name)) |
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return i; |
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} |
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return -1; |
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} |
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/* if no id is provided, a new one is constructed */ |
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int qcow_snapshot_create(BlockDriverState *bs, QEMUSnapshotInfo *sn_info) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *snapshots1, sn1, *sn = &sn1; |
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int i, ret; |
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uint64_t *l1_table = NULL; |
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memset(sn, 0, sizeof(*sn)); |
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if (sn_info->id_str[0] == '\0') { |
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/* compute a new id */ |
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find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str)); |
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} |
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/* check that the ID is unique */ |
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if (find_snapshot_by_id(bs, sn_info->id_str) >= 0) |
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return -ENOENT; |
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sn->id_str = qemu_strdup(sn_info->id_str); |
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if (!sn->id_str) |
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goto fail; |
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sn->name = qemu_strdup(sn_info->name); |
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if (!sn->name) |
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goto fail; |
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sn->vm_state_size = sn_info->vm_state_size; |
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sn->date_sec = sn_info->date_sec; |
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sn->date_nsec = sn_info->date_nsec; |
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sn->vm_clock_nsec = sn_info->vm_clock_nsec; |
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ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1); |
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if (ret < 0) |
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goto fail; |
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/* create the L1 table of the snapshot */ |
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sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t)); |
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sn->l1_size = s->l1_size; |
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l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t)); |
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for(i = 0; i < s->l1_size; i++) { |
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l1_table[i] = cpu_to_be64(s->l1_table[i]); |
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} |
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if (bdrv_pwrite(s->hd, sn->l1_table_offset, |
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l1_table, s->l1_size * sizeof(uint64_t)) != |
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(s->l1_size * sizeof(uint64_t))) |
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goto fail; |
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qemu_free(l1_table); |
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l1_table = NULL; |
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snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot)); |
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if (s->snapshots) { |
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memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot)); |
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qemu_free(s->snapshots); |
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} |
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s->snapshots = snapshots1; |
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s->snapshots[s->nb_snapshots++] = *sn; |
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if (qcow_write_snapshots(bs) < 0) |
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goto fail; |
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#ifdef DEBUG_ALLOC |
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check_refcounts(bs); |
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#endif |
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return 0; |
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fail: |
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qemu_free(sn->name); |
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qemu_free(l1_table); |
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return -1; |
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} |
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/* copy the snapshot 'snapshot_name' into the current disk image */ |
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int qcow_snapshot_goto(BlockDriverState *bs, const char *snapshot_id) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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int i, snapshot_index, l1_size2; |
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snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
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if (snapshot_index < 0) |
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return -ENOENT; |
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sn = &s->snapshots[snapshot_index]; |
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if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0) |
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goto fail; |
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if (grow_l1_table(bs, sn->l1_size) < 0) |
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goto fail; |
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s->l1_size = sn->l1_size; |
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l1_size2 = s->l1_size * sizeof(uint64_t); |
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/* copy the snapshot l1 table to the current l1 table */ |
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if (bdrv_pread(s->hd, sn->l1_table_offset, |
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s->l1_table, l1_size2) != l1_size2) |
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goto fail; |
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if (bdrv_pwrite(s->hd, s->l1_table_offset, |
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s->l1_table, l1_size2) != l1_size2) |
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goto fail; |
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for(i = 0;i < s->l1_size; i++) { |
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be64_to_cpus(&s->l1_table[i]); |
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} |
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if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0) |
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goto fail; |
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#ifdef DEBUG_ALLOC |
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check_refcounts(bs); |
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#endif |
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return 0; |
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fail: |
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return -EIO; |
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} |
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int qcow_snapshot_delete(BlockDriverState *bs, const char *snapshot_id) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QCowSnapshot *sn; |
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int snapshot_index, ret; |
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snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id); |
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if (snapshot_index < 0) |
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return -ENOENT; |
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sn = &s->snapshots[snapshot_index]; |
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ret = update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1); |
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if (ret < 0) |
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return ret; |
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/* must update the copied flag on the current cluster offsets */ |
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ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0); |
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if (ret < 0) |
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return ret; |
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free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t)); |
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qemu_free(sn->id_str); |
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qemu_free(sn->name); |
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memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn)); |
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s->nb_snapshots--; |
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ret = qcow_write_snapshots(bs); |
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if (ret < 0) { |
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/* XXX: restore snapshot if error ? */ |
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return ret; |
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} |
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#ifdef DEBUG_ALLOC |
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check_refcounts(bs); |
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#endif |
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return 0; |
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} |
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int qcow_snapshot_list(BlockDriverState *bs, QEMUSnapshotInfo **psn_tab) |
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{ |
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BDRVQcowState *s = bs->opaque; |
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QEMUSnapshotInfo *sn_tab, *sn_info; |
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QCowSnapshot *sn; |
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int i; |
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if (!s->nb_snapshots) { |
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*psn_tab = NULL; |
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return s->nb_snapshots; |
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} |
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sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo)); |
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for(i = 0; i < s->nb_snapshots; i++) { |
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sn_info = sn_tab + i; |
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sn = s->snapshots + i; |
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pstrcpy(sn_info->id_str, sizeof(sn_info->id_str), |
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sn->id_str); |
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pstrcpy(sn_info->name, sizeof(sn_info->name), |
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sn->name); |
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sn_info->vm_state_size = sn->vm_state_size; |
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sn_info->date_sec = sn->date_sec; |
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sn_info->date_nsec = sn->date_nsec; |
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sn_info->vm_clock_nsec = sn->vm_clock_nsec; |
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} |
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*psn_tab = sn_tab; |
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return s->nb_snapshots; |
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} |
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