migration/global_state.c

   1 /*
   2  * Global State configuration
   3  *
   4  * Copyright (c) 2014-2017 Red Hat Inc
   5  *
   6  * Authors:
   7  *  Juan Quintela <quintela@redhat.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10  * See the COPYING file in the top-level directory.
  11  */
  12
  13 #include "qemu/osdep.h"
  14 #include "qemu/cutils.h"
  15 #include "qemu/error-report.h"
  16 #include "qapi/error.h"
  17 #include "migration.h"
  18 #include "migration/global_state.h"
  19 #include "migration/vmstate.h"
  20 #include "trace.h"
  21
  22 typedef struct {
  23     uint32_t size;
  24     uint8_t runstate[100];
  25     RunState state;
  26     bool received;
  27 } GlobalState;
  28
  29 static GlobalState global_state;
  30
  31 int global_state_store(void)
  32 {
  33     if (!runstate_store((char *)global_state.runstate,
  34                         sizeof(global_state.runstate))) {
  35         error_report("runstate name too big: %s", global_state.runstate);
  36         trace_migrate_state_too_big();
  37         return -EINVAL;
  38     }
  39     return 0;
  40 }
  41
  42 void global_state_store_running(void)
  43 {
  44     const char *state = RunState_str(RUN_STATE_RUNNING);
  45     assert(strlen(state) < sizeof(global_state.runstate));
  46     strncpy((char *)global_state.runstate,
  47            state, sizeof(global_state.runstate));
  48 }
  49
  50 bool global_state_received(void)
  51 {
  52     return global_state.received;
  53 }
  54
  55 RunState global_state_get_runstate(void)
  56 {
  57     return global_state.state;
  58 }
  59
  60 static bool global_state_needed(void *opaque)
  61 {
  62     GlobalState *s = opaque;
  63     char *runstate = (char *)s->runstate;
  64
  65     /* If it is not optional, it is mandatory */
  66
  67     if (migrate_get_current()->store_global_state) {
  68         return true;
  69     }
  70
  71     /* If state is running or paused, it is not needed */
  72
  73     if (strcmp(runstate, "running") == 0 ||
  74         strcmp(runstate, "paused") == 0) {
  75         return false;
  76     }
  77
  78     /* for any other state it is needed */
  79     return true;
  80 }
  81
  82 static int global_state_post_load(void *opaque, int version_id)
  83 {
  84     GlobalState *s = opaque;
  85     Error *local_err = NULL;
  86     int r;
  87     char *runstate = (char *)s->runstate;
  88
  89     s->received = true;
  90     trace_migrate_global_state_post_load(runstate);
  91
  92     if (strnlen((char *)s->runstate,
  93                 sizeof(s->runstate)) == sizeof(s->runstate)) {
  94         /*
  95          * This condition should never happen during migration, because
  96          * all runstate names are shorter than 100 bytes (the size of
  97          * s->runstate). However, a malicious stream could overflow
  98          * the qapi_enum_parse() call, so we force the last character
  99          * to a NUL byte.
 100          */
 101         s->runstate[sizeof(s->runstate) - 1] = '\0';
 102     }
 103     r = qapi_enum_parse(&RunState_lookup, runstate, -1, &local_err);
 104
 105     if (r == -1) {
 106         if (local_err) {
 107             error_report_err(local_err);
 108         }
 109         return -EINVAL;
 110     }
 111     s->state = r;
 112
 113     return 0;
 114 }
 115
 116 static int global_state_pre_save(void *opaque)
 117 {
 118     GlobalState *s = opaque;
 119
 120     trace_migrate_global_state_pre_save((char *)s->runstate);
 121     s->size = strnlen((char *)s->runstate, sizeof(s->runstate)) + 1;
 122     assert(s->size <= sizeof(s->runstate));
 123
 124     return 0;
 125 }
 126
 127 static const VMStateDescription vmstate_globalstate = {
 128     .name = "globalstate",
 129     .version_id = 1,
 130     .minimum_version_id = 1,
 131     .post_load = global_state_post_load,
 132     .pre_save = global_state_pre_save,
 133     .needed = global_state_needed,
 134     .fields = (VMStateField[]) {
 135         VMSTATE_UINT32(size, GlobalState),
 136         VMSTATE_BUFFER(runstate, GlobalState),
 137         VMSTATE_END_OF_LIST()
 138     },
 139 };
 140
 141 void register_global_state(void)
 142 {
 143     /* We would use it independently that we receive it */
 144     strcpy((char *)&global_state.runstate, "");
 145     global_state.received = false;
 146     vmstate_register(NULL, 0, &vmstate_globalstate, &global_state);
 147 }