X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/708989f9970b6f37f3ca7c7b568bcbfeaa53867f..b487d5a9259b88670b8cd97e9c16e4b000c11008:/src/mc/mc_checkpoint.c

diff --git a/src/mc/mc_checkpoint.c b/src/mc/mc_checkpoint.c
index 2fbb5bef62..d20592646a 100644
--- a/src/mc/mc_checkpoint.c
+++ b/src/mc/mc_checkpoint.c
@@ -1,184 +1,761 @@
-/* Copyright (c) 2008-2012 Da SimGrid Team. All rights reserved.            */
+/* Copyright (c) 2008-2014. The SimGrid Team.
+ * All rights reserved.                                                     */
 
 /* This program is free software; you can redistribute it and/or modify it
  * under the terms of the license (GNU LGPL) which comes with this package. */
 
-#include <libgen.h>
+#define _GNU_SOURCE
+#define UNW_LOCAL_ONLY
+
+#include <unistd.h>
+
+#include <string.h>
+#include <link.h>
+#include <dirent.h>
+
+#include "internal_config.h"
+#include "mc_private.h"
+#include "xbt/module.h"
+#include <xbt/mmalloc.h>
+#include "../smpi/private.h"
+#include <alloca.h>
+
+#include "xbt/mmalloc/mmprivate.h"
+
+#include "../simix/smx_private.h"
+
+#define UNW_LOCAL_ONLY
+#include <libunwind.h>
+#include <libelf.h>
+
 #include "mc_private.h"
+#include <mc/mc.h>
 
+#include "mc_mmu.h"
 
 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(mc_checkpoint, mc,
                                 "Logging specific to mc_checkpoint");
 
-static mc_mem_region_t MC_region_new(int type, void *start_addr, size_t size);
-static void MC_region_restore(mc_mem_region_t reg);
-static void MC_region_destroy(mc_mem_region_t reg);
+char *libsimgrid_path;
 
-static void MC_snapshot_add_region(mc_snapshot_t snapshot, int type, void *start_addr, size_t size);
+/************************************  Free functions **************************************/
+/*****************************************************************************************/
 
-static mc_mem_region_t MC_region_new(int type, void *start_addr, size_t size)
+static void MC_snapshot_stack_free(mc_snapshot_stack_t s)
 {
-  mc_mem_region_t new_reg = xbt_new0(s_mc_mem_region_t, 1);
-  new_reg->type = type;
+  if (s) {
+    xbt_dynar_free(&(s->local_variables));
+    xbt_dynar_free(&(s->stack_frames));
+    xbt_free(s);
+  }
+}
+
+static void MC_snapshot_stack_free_voidp(void *s)
+{
+  MC_snapshot_stack_free((mc_snapshot_stack_t) * (void **) s);
+}
+
+static void local_variable_free(local_variable_t v)
+{
+  xbt_free(v->name);
+  xbt_free(v);
+}
+
+static void local_variable_free_voidp(void *v)
+{
+  local_variable_free((local_variable_t) * (void **) v);
+}
+
+void MC_region_destroy(mc_mem_region_t reg)
+{
+  if (!reg)
+    return;
+
+  //munmap(reg->data, reg->size);
+  xbt_free(reg->data);
+  if (reg->page_numbers) {
+    mc_free_page_snapshot_region(reg->page_numbers, mc_page_count(reg->size));
+  }
+  xbt_free(reg);
+}
+
+void MC_free_snapshot(mc_snapshot_t snapshot)
+{
+  unsigned int i;
+  for (i = 0; i < NB_REGIONS; i++) {
+    MC_region_destroy(snapshot->regions[i]);
+  }
+
+  xbt_free(snapshot->stack_sizes);
+  xbt_dynar_free(&(snapshot->stacks));
+  xbt_dynar_free(&(snapshot->to_ignore));
+  xbt_dynar_free(&snapshot->ignored_data);
+
+  if (snapshot->privatization_regions) {
+    size_t n = xbt_dynar_length(snapshot->enabled_processes);
+    for (i = 0; i != n; ++i) {
+      MC_region_destroy(snapshot->privatization_regions[i]);
+    }
+    xbt_free(snapshot->privatization_regions);
+  }
+
+  xbt_free(snapshot);
+}
+
+/*******************************  Snapshot regions ********************************/
+/*********************************************************************************/
+
+static mc_mem_region_t mc_region_new_dense(int type, void *start_addr, void* permanent_addr, size_t size, mc_mem_region_t ref_reg)
+{
+  mc_mem_region_t new_reg = xbt_new(s_mc_mem_region_t, 1);
   new_reg->start_addr = start_addr;
+  new_reg->permanent_addr = permanent_addr;
+  new_reg->data = NULL;
   new_reg->size = size;
-  new_reg->data = xbt_malloc0(size);
-  XBT_DEBUG("New reg data %p, start_addr %p, size %zu", new_reg->data, start_addr, size);
-  memcpy(new_reg->data, start_addr, size);
-  
+  new_reg->page_numbers = NULL;
+  new_reg->data = xbt_malloc(size);
+  memcpy(new_reg->data, permanent_addr, size);
+  XBT_DEBUG("New region : type : %d, data : %p (real addr %p), size : %zu",
+            type, new_reg->data, permanent_addr, size);
   return new_reg;
+
+}
+
+/** @brief Take a snapshot of a given region
+ *
+ * @param type
+ * @param start_addr   Address of the region in the simulated process
+ * @param permanent_addr Permanent address of this data (for privatized variables, this is the virtual address of the privatized mapping)
+ * @param size         Size of the data*
+ * @param ref_reg      Reference corresponding region
+ */
+static mc_mem_region_t MC_region_new(int type, void *start_addr, void* permanent_addr, size_t size, mc_mem_region_t ref_reg)
+{
+  if (_sg_mc_sparse_checkpoint) {
+    return mc_region_new_sparse(type, start_addr, permanent_addr, size, ref_reg);
+  } else  {
+    return mc_region_new_dense(type, start_addr, permanent_addr, size, ref_reg);
+  }
 }
 
-static void MC_region_restore(mc_mem_region_t reg)
+/** @brief Restore a region from a snapshot
+ *
+ *  If we are using per page snapshots, it is possible to use the reference
+ *  region in order to do an incremental restoration of the region: the
+ *  softclean pages which are shared between the two snapshots do not need
+ *  to be restored.
+ *
+ *  @param reg     Target region
+ *  @param reg_reg Current region (if not NULL), used for lazy per page restoration
+ */
+static void MC_region_restore(mc_mem_region_t reg, mc_mem_region_t ref_reg)
 {
   /*FIXME: check if start_addr is still mapped, if it is not, then map it
     before copying the data */
-  if(reg->type == 3){
-    memory_map_t maps = get_memory_map();
-    MC_UNSET_RAW_MEM;
-    unsigned int i=0;
-    s_map_region_t r;
-    while(i < maps->mapsize){
-      r = maps->regions[i];
-      if (maps->regions[i].pathname != NULL){
-	if (!memcmp(maps->regions[i].pathname, "[stack]", 7)){
-	  size_t diff = (char*)reg->start_addr - (char*)r.start_addr;
-	  void *segment = malloc(reg->size + diff);
-	  XBT_DEBUG("Size of segment : %zu", sizeof(segment));
-	  memcpy((char *)segment + diff, reg->data, reg->size);
-	  memcpy(r.start_addr, segment, sizeof(segment));
-	  XBT_DEBUG("Memcpy region ok");
-	  break;
-	}
-      }
-      i++;
-    }
-  }else{
-    XBT_DEBUG("Memcpy : dest %p, src %p, size %zu", reg->start_addr, reg->data, reg->size);
-    memcpy(reg->start_addr, reg->data, reg->size);
+  if (!reg->page_numbers) {
+    memcpy(reg->permanent_addr, reg->data, reg->size);
+  } else {
+    mc_region_restore_sparse(reg, ref_reg);
   }
-  
   return;
 }
 
-static void MC_region_destroy(mc_mem_region_t reg)
+static void MC_snapshot_add_region(mc_snapshot_t snapshot, int type,
+                                   void *start_addr, void* permanent_addr, size_t size)
+
 {
-  xbt_free(reg->data);
-  xbt_free(reg);
+  mc_mem_region_t ref_reg =
+    mc_model_checker->parent_snapshot ? mc_model_checker->parent_snapshot->regions[type] : NULL;
+  mc_mem_region_t new_reg = MC_region_new(type, start_addr, permanent_addr, size, ref_reg);
+  snapshot->regions[type] = new_reg;
+  return;
 }
 
-static void MC_snapshot_add_region(mc_snapshot_t snapshot, int type, void *start_addr, size_t size)
+static void MC_get_memory_regions(mc_snapshot_t snapshot)
 {
-  switch(type){
-  case 0 : 
-    XBT_DEBUG("New region heap (%zu)", size);
-    break;
-  case 1 : 
-    XBT_DEBUG("New region libsimgrid (%zu)", size);
-    break;
-  case 2 : 
-    XBT_DEBUG("New region program data (%zu)", size);
-    break;
+
+  void *start_heap = std_heap->base;
+  void *end_heap = std_heap->breakval;
+  MC_snapshot_add_region(snapshot, 0, start_heap, start_heap,
+                         (char *) end_heap - (char *) start_heap);
+  snapshot->heap_bytes_used = mmalloc_get_bytes_used(std_heap);
+  snapshot->privatization_regions = NULL;
+
+  MC_snapshot_add_region(snapshot, 1,
+      mc_libsimgrid_info->start_rw, mc_libsimgrid_info->start_rw,
+      mc_libsimgrid_info->end_rw - mc_libsimgrid_info->start_rw);
+
+#ifdef HAVE_SMPI
+  size_t i;
+  if (smpi_privatize_global_variables && smpi_process_count()) {
+    // Snapshot the global variable of the application separately for each
+    // simulated process:
+    snapshot->privatization_regions =
+      xbt_new(mc_mem_region_t, smpi_process_count());
+    for (i = 0; i < smpi_process_count(); i++) {
+      mc_mem_region_t ref_reg =
+        mc_model_checker->parent_snapshot ? mc_model_checker->parent_snapshot->privatization_regions[i] : NULL;
+      snapshot->privatization_regions[i] =
+        MC_region_new(-1, mc_binary_info->start_rw, smpi_privatisation_regions[i].address, size_data_exe, ref_reg);
+    }
+    snapshot->privatization_index = smpi_loaded_page;
+    snapshot->regions[2] = NULL;
+  } else
+#endif
+  {
+    MC_snapshot_add_region(snapshot, 2,
+                           mc_binary_info->start_rw, mc_binary_info->start_rw,
+                           mc_binary_info->end_rw - mc_binary_info->start_rw);
+    snapshot->privatization_regions = NULL;
+    snapshot->privatization_index = -1;
   }
-  mc_mem_region_t new_reg = MC_region_new(type, start_addr, size);
-  snapshot->regions = xbt_realloc(snapshot->regions, (snapshot->num_reg + 1) * sizeof(mc_mem_region_t));
-  snapshot->regions[snapshot->num_reg] = new_reg;
-  snapshot->num_reg++;
-  return;
-} 
+}
 
-void MC_take_snapshot(mc_snapshot_t snapshot)
+/** @brief Finds the range of the different memory segments and binary paths */
+void MC_init_memory_map_info()
 {
+
   unsigned int i = 0;
   s_map_region_t reg;
-  memory_map_t maps = get_memory_map();
+  memory_map_t maps = MC_get_memory_map();
+
+  maestro_stack_start = NULL;
+  maestro_stack_end = NULL;
+  libsimgrid_path = NULL;
 
-  /* Save the std heap and the writable mapped pages of libsimgrid */
   while (i < maps->mapsize) {
     reg = maps->regions[i];
-    if ((reg.prot & PROT_WRITE)){
-      if (maps->regions[i].pathname == NULL){
-        if (reg.start_addr == std_heap){ // only save the std heap (and not the raw one)
-          MC_snapshot_add_region(snapshot, 0, reg.start_addr, (char*)reg.end_addr - (char*)reg.start_addr);
-        }
-      } else {
-        if (!memcmp(basename(maps->regions[i].pathname), "libsimgrid", 10)){
-          MC_snapshot_add_region(snapshot, 1, reg.start_addr, (char*)reg.end_addr - (char*)reg.start_addr);
-        } 
-      }
+    if (maps->regions[i].pathname == NULL) {
+      // Nothing to do
+    } else if ((reg.prot & PROT_WRITE)
+               && !memcmp(maps->regions[i].pathname, "[stack]", 7)) {
+      maestro_stack_start = reg.start_addr;
+      maestro_stack_end = reg.end_addr;
+    } else if ((reg.prot & PROT_READ) && (reg.prot & PROT_EXEC)
+               && !memcmp(basename(maps->regions[i].pathname), "libsimgrid",
+                          10)) {
+      if (libsimgrid_path == NULL)
+        libsimgrid_path = strdup(maps->regions[i].pathname);
     }
     i++;
   }
 
-  /* FIXME: free the memory map */
+  xbt_assert(maestro_stack_start, "maestro_stack_start");
+  xbt_assert(maestro_stack_end, "maestro_stack_end");
+  xbt_assert(libsimgrid_path, "libsimgrid_path&");
+
+  MC_free_memory_map(maps);
+
 }
 
-void MC_take_snapshot_liveness(mc_snapshot_t snapshot)
+/** \brief Fills the position of the segments (executable, read-only, read/write).
+ *
+ * TODO, use dl_iterate_phdr to be more robust
+ * */
+void MC_find_object_address(memory_map_t maps, mc_object_info_t result)
 {
+
   unsigned int i = 0;
   s_map_region_t reg;
-  memory_map_t maps = get_memory_map();
+  const char *name = basename(result->file_name);
+  while (i < maps->mapsize) {
+    reg = maps->regions[i];
+    if (maps->regions[i].pathname == NULL
+        || strcmp(basename(maps->regions[i].pathname), name)) {
+      // Nothing to do
+    } else if ((reg.prot & PROT_WRITE)) {
+      xbt_assert(!result->start_rw,
+                 "Multiple read-write segments for %s, not supported",
+                 maps->regions[i].pathname);
+      result->start_rw = reg.start_addr;
+      result->end_rw = reg.end_addr;
+      // .bss is usually after the .data:
+      s_map_region_t *next = &(maps->regions[i + 1]);
+      if (next->pathname == NULL && (next->prot & PROT_WRITE)
+          && next->start_addr == reg.end_addr) {
+        result->end_rw = maps->regions[i + 1].end_addr;
+      }
+    } else if ((reg.prot & PROT_READ) && (reg.prot & PROT_EXEC)) {
+      xbt_assert(!result->start_exec,
+                 "Multiple executable segments for %s, not supported",
+                 maps->regions[i].pathname);
+      result->start_exec = reg.start_addr;
+      result->end_exec = reg.end_addr;
+    } else if ((reg.prot & PROT_READ) && !(reg.prot & PROT_EXEC)) {
+      xbt_assert(!result->start_ro,
+                 "Multiple read only segments for %s, not supported",
+                 maps->regions[i].pathname);
+      result->start_ro = reg.start_addr;
+      result->end_ro = reg.end_addr;
+    }
+    i++;
+  }
 
-  for(i=0; i< snapshot->num_reg; i++){
-    MC_region_destroy(snapshot->regions[i]);
+  xbt_assert(result->file_name);
+  xbt_assert(result->start_rw);
+  xbt_assert(result->start_exec);
+}
+
+/************************************* Take Snapshot ************************************/
+/****************************************************************************************/
+
+/** \brief Checks whether the variable is in scope for a given IP.
+ *
+ *  A variable may be defined only from a given value of IP.
+ *
+ *  \param var   Variable description
+ *  \param frame Scope description
+ *  \param ip    Instruction pointer
+ *  \return      true if the variable is valid
+ * */
+static bool mc_valid_variable(dw_variable_t var, dw_frame_t scope,
+                              const void *ip)
+{
+  // The variable is not yet valid:
+  if ((const void *) ((const char *) scope->low_pc + var->start_scope) > ip)
+    return false;
+  else
+    return true;
+}
+
+static void mc_fill_local_variables_values(mc_stack_frame_t stack_frame,
+                                           dw_frame_t scope, int process_index, xbt_dynar_t result)
+{
+  void *ip = (void *) stack_frame->ip;
+  if (ip < scope->low_pc || ip >= scope->high_pc)
+    return;
+
+  unsigned cursor = 0;
+  dw_variable_t current_variable;
+  xbt_dynar_foreach(scope->variables, cursor, current_variable) {
+
+    if (!mc_valid_variable(current_variable, scope, (void *) stack_frame->ip))
+      continue;
+
+    int region_type;
+    if ((long) stack_frame->ip > (long) mc_libsimgrid_info->start_exec)
+      region_type = 1;
+    else
+      region_type = 2;
+
+    local_variable_t new_var = xbt_new0(s_local_variable_t, 1);
+    new_var->subprogram = stack_frame->frame;
+    new_var->ip = stack_frame->ip;
+    new_var->name = xbt_strdup(current_variable->name);
+    new_var->type = current_variable->type;
+    new_var->region = region_type;
+
+    if (current_variable->address != NULL) {
+      new_var->address = current_variable->address;
+    } else if (current_variable->locations.size != 0) {
+      s_mc_location_t location;
+      mc_dwarf_resolve_locations(&location, &current_variable->locations,
+                                              current_variable->object_info,
+                                              &(stack_frame->unw_cursor),
+                                              (void *) stack_frame->frame_base,
+                                              NULL, process_index);
+
+      switch(mc_get_location_type(&location)) {
+      case MC_LOCATION_TYPE_ADDRESS:
+        new_var->address = location.memory_location;
+        break;
+      case MC_LOCATION_TYPE_REGISTER:
+      default:
+        xbt_die("Cannot handle non-address variable");
+      }
+
+    } else {
+      xbt_die("No address");
+    }
+
+    xbt_dynar_push(result, &new_var);
+  }
+
+  // Recursive processing of nested scopes:
+  dw_frame_t nested_scope = NULL;
+  xbt_dynar_foreach(scope->scopes, cursor, nested_scope) {
+    mc_fill_local_variables_values(stack_frame, nested_scope, process_index, result);
+  }
+}
+
+static xbt_dynar_t MC_get_local_variables_values(xbt_dynar_t stack_frames, int process_index)
+{
+
+  unsigned cursor1 = 0;
+  mc_stack_frame_t stack_frame;
+  xbt_dynar_t variables =
+      xbt_dynar_new(sizeof(local_variable_t), local_variable_free_voidp);
+
+  xbt_dynar_foreach(stack_frames, cursor1, stack_frame) {
+    mc_fill_local_variables_values(stack_frame, stack_frame->frame, process_index, variables);
   }
 
-  snapshot->num_reg = 0;
+  return variables;
+}
 
-  i = 0;
+static void MC_stack_frame_free_voipd(void *s)
+{
+  mc_stack_frame_t stack_frame = *(mc_stack_frame_t *) s;
+  if (stack_frame) {
+    xbt_free(stack_frame->frame_name);
+    xbt_free(stack_frame);
+  }
+}
 
-  /* Save the std heap and the writable mapped pages of libsimgrid */
-  while (i < maps->mapsize) {
-    reg = maps->regions[i];
-    if ((reg.prot & PROT_WRITE)){
-      if (maps->regions[i].pathname == NULL){
-        if (reg.start_addr == std_heap){ // only save the std heap (and not the raw one)
-	  MC_snapshot_add_region(snapshot, 0, reg.start_addr, (char*)reg.end_addr - (char*)reg.start_addr);
-        }
+static xbt_dynar_t MC_unwind_stack_frames(void *stack_context)
+{
+  xbt_dynar_t result =
+      xbt_dynar_new(sizeof(mc_stack_frame_t), MC_stack_frame_free_voipd);
+
+  unw_cursor_t c;
+
+  // TODO, check condition check (unw_init_local==0 means end of frame)
+  if (unw_init_local(&c, (unw_context_t *) stack_context) != 0) {
+
+    xbt_die("Could not initialize stack unwinding");
+
+  } else
+    while (1) {
+
+      mc_stack_frame_t stack_frame = xbt_new(s_mc_stack_frame_t, 1);
+      xbt_dynar_push(result, &stack_frame);
+
+      stack_frame->unw_cursor = c;
+
+      unw_word_t ip, sp;
+
+      unw_get_reg(&c, UNW_REG_IP, &ip);
+      unw_get_reg(&c, UNW_REG_SP, &sp);
+
+      stack_frame->ip = ip;
+      stack_frame->sp = sp;
+
+      // TODO, use real addresses in frame_t instead of fixing it here
+
+      dw_frame_t frame = MC_find_function_by_ip((void *) ip);
+      stack_frame->frame = frame;
+
+      if (frame) {
+        stack_frame->frame_name = xbt_strdup(frame->name);
+        stack_frame->frame_base =
+            (unw_word_t) mc_find_frame_base(frame, frame->object_info, &c);
       } else {
-        if (!memcmp(basename(maps->regions[i].pathname), "libsimgrid", 10)){
-          MC_snapshot_add_region(snapshot, 1, reg.start_addr, (char*)reg.end_addr - (char*)reg.start_addr);
-        } else {
-	  if (!memcmp(basename(maps->regions[i].pathname), basename(prog_name), strlen(basename(prog_name)))){
-	    MC_snapshot_add_region(snapshot, 2, reg.start_addr, (char*)reg.end_addr - (char*)reg.start_addr);
-	  } 
-	}
+        stack_frame->frame_base = 0;
+        stack_frame->frame_name = NULL;
+      }
+
+      /* Stop before context switch with maestro */
+      if (frame != NULL && frame->name != NULL
+          && !strcmp(frame->name, "smx_ctx_sysv_wrapper"))
+        break;
+
+      int ret = ret = unw_step(&c);
+      if (ret == 0) {
+        xbt_die("Unexpected end of stack.");
+      } else if (ret < 0) {
+        xbt_die("Error while unwinding stack.");
       }
     }
-    i++;
+
+  if (xbt_dynar_length(result) == 0) {
+    XBT_INFO("unw_init_local failed");
+    xbt_abort();
   }
 
-  /* FIXME: free the memory map */
+  return result;
+};
+
+static xbt_dynar_t MC_take_snapshot_stacks(mc_snapshot_t * snapshot)
+{
+
+  xbt_dynar_t res =
+      xbt_dynar_new(sizeof(s_mc_snapshot_stack_t),
+                    MC_snapshot_stack_free_voidp);
+
+  unsigned int cursor = 0;
+  stack_region_t current_stack;
+
+  xbt_dynar_foreach(stacks_areas, cursor, current_stack) {
+    mc_snapshot_stack_t st = xbt_new(s_mc_snapshot_stack_t, 1);
+    st->stack_frames = MC_unwind_stack_frames(current_stack->context);
+    st->local_variables = MC_get_local_variables_values(st->stack_frames, current_stack->process_index);
+    st->process_index = current_stack->process_index;
+
+    unw_word_t sp = xbt_dynar_get_as(st->stack_frames, 0, mc_stack_frame_t)->sp;
+
+    xbt_dynar_push(res, &st);
+    (*snapshot)->stack_sizes =
+        xbt_realloc((*snapshot)->stack_sizes, (cursor + 1) * sizeof(size_t));
+    (*snapshot)->stack_sizes[cursor] =
+      (char*) current_stack->address + current_stack->size - (char*) sp;
+  }
+
+  return res;
+
 }
 
-void MC_restore_snapshot(mc_snapshot_t snapshot)
+static xbt_dynar_t MC_take_snapshot_ignore()
 {
-  unsigned int i;
-  for(i=0; i < snapshot->num_reg; i++){
-    MC_region_restore(snapshot->regions[i]);
-    switch(snapshot->regions[i]->type){
-    case 0 : 
-      XBT_DEBUG("heap restored");
-      break;
-    case 1:
-      XBT_DEBUG("libsimgrid (data) restored");
-      break;
-    case 2:
-      XBT_DEBUG("data program restored");
-      break;
+
+  if (mc_heap_comparison_ignore == NULL)
+    return NULL;
+
+  xbt_dynar_t cpy =
+      xbt_dynar_new(sizeof(mc_heap_ignore_region_t),
+                    heap_ignore_region_free_voidp);
+
+  unsigned int cursor = 0;
+  mc_heap_ignore_region_t current_region;
+
+  xbt_dynar_foreach(mc_heap_comparison_ignore, cursor, current_region) {
+    mc_heap_ignore_region_t new_region = NULL;
+    new_region = xbt_new0(s_mc_heap_ignore_region_t, 1);
+    new_region->address = current_region->address;
+    new_region->size = current_region->size;
+    new_region->block = current_region->block;
+    new_region->fragment = current_region->fragment;
+    xbt_dynar_push(cpy, &new_region);
+  }
+
+  return cpy;
+
+}
+
+static void mc_free_snapshot_ignored_data_pvoid(void* data) {
+  mc_snapshot_ignored_data_t ignored_data = (mc_snapshot_ignored_data_t) data;
+  free(ignored_data->data);
+}
+
+static void MC_snapshot_handle_ignore(mc_snapshot_t snapshot)
+{
+  snapshot->ignored_data = xbt_dynar_new(sizeof(s_mc_snapshot_ignored_data_t), mc_free_snapshot_ignored_data_pvoid);
+
+  // Copy the memory:
+  unsigned int cursor = 0;
+  mc_checkpoint_ignore_region_t region;
+  xbt_dynar_foreach (mc_checkpoint_ignore, cursor, region) {
+    s_mc_snapshot_ignored_data_t ignored_data;
+    ignored_data.start = region->addr;
+    ignored_data.size = region->size;
+    ignored_data.data = malloc(region->size);
+    memcpy(ignored_data.data, region->addr, region->size);
+    xbt_dynar_push(snapshot->ignored_data, &ignored_data);
+  }
+
+  // Zero the memory:
+  xbt_dynar_foreach (mc_checkpoint_ignore, cursor, region) {
+    memset(region->addr, 0, region->size);
+  }
+
+}
+
+static void MC_snapshot_ignore_restore(mc_snapshot_t snapshot)
+{
+  unsigned int cursor = 0;
+  s_mc_snapshot_ignored_data_t ignored_data;
+  xbt_dynar_foreach (snapshot->ignored_data, cursor, ignored_data) {
+    memcpy(ignored_data.start, ignored_data.data, ignored_data.size);
+  }
+}
+
+/** @brief Can we remove this snapshot?
+ *
+ * Some snapshots cannot be removed (yet) because we need them
+ * at this point.
+ *
+ * @param snapshot
+ */
+int mc_important_snapshot(mc_snapshot_t snapshot)
+{
+  // We need this snapshot in order to know which
+  // pages needs to be stored in the next snapshot.
+  // This field is only non-NULL when using soft-dirty
+  // page tracking.
+  if (snapshot == mc_model_checker->parent_snapshot)
+    return true;
+
+  return false;
+}
+
+static void MC_get_current_fd(mc_snapshot_t snapshot){
+
+  snapshot->total_fd = 0;
+
+  const size_t fd_dir_path_size = 20;
+  char fd_dir_path[fd_dir_path_size];
+  if (snprintf(fd_dir_path, fd_dir_path_size,
+    "/proc/%lli/fd", (long long int) getpid()) > fd_dir_path_size)
+    xbt_die("Unexpected buffer is too small for fd_dir_path");
+
+  DIR* fd_dir = opendir (fd_dir_path);
+  if (fd_dir == NULL)
+    xbt_die("Cannot open directory '/proc/self/fd'\n");
+
+  size_t total_fd = 0;
+  struct dirent* fd_number;
+  while ((fd_number = readdir(fd_dir))) {
+
+    int fd_value = atoi(fd_number->d_name);
+
+    if(fd_value < 3)
+      continue;
+
+    const size_t source_size = 25;
+    char source[25];
+    if (snprintf(source, source_size, "/proc/self/fd/%s", fd_number->d_name) > source_size)
+      xbt_die("Unexpected buffer is too small for fd %s", fd_number->d_name);
+
+    const size_t link_size = 200;
+    char link[200];
+    int res = readlink(source, link, link_size);
+    if (res<0) {
+      xbt_die("Could not read link for %s", source);
     }
+    if (res==200) {
+      xbt_die("Buffer to small for link of %s", source);
+    }
+    link[res] = '\0';
+
+    if(smpi_is_privatisation_file(link))
+      continue;
+
+    // This is (probably) the DIR* we are reading:
+    // TODO, read all the file entries at once and close the DIR.*
+    if(strcmp(fd_dir_path, link) == 0)
+      continue;
 
+    // We don't handle them.
+    // It does not mean we should silently ignore them however.
+    if (strncmp(link, "pipe:", 5) == 0 || strncmp(link, "socket:", 7) == 0)
+      continue;
+
+    // This is probably a shared memory used by lttng-ust:
+    if(strncmp("/dev/shm/ust-shm-tmp-", link, 21)==0)
+      continue;
+
+    // Add an entry for this FD in the snapshot:
+    fd_infos_t fd = xbt_new0(s_fd_infos_t, 1);
+    fd->filename = strdup(link);
+    fd->number = fd_value;
+    fd->flags = fcntl(fd_value, F_GETFL) | fcntl(fd_value, F_GETFD) ;
+    fd->current_position = lseek(fd_value, 0, SEEK_CUR);
+    snapshot->current_fd = xbt_realloc(snapshot->current_fd, (total_fd + 1) * sizeof(fd_infos_t));
+    snapshot->current_fd[total_fd] = fd;
+    total_fd++;
   }
 
+  snapshot->total_fd = total_fd;
+  closedir (fd_dir);
 }
 
-void MC_free_snapshot(mc_snapshot_t snapshot)
+mc_snapshot_t MC_take_snapshot(int num_state)
+{
+
+  mc_snapshot_t snapshot = xbt_new0(s_mc_snapshot_t, 1);
+  snapshot->enabled_processes = xbt_dynar_new(sizeof(int), NULL);
+  smx_process_t process;
+  xbt_swag_foreach(process, simix_global->process_list) {
+    xbt_dynar_push_as(snapshot->enabled_processes, int, (int)process->pid);
+  }
+
+  MC_snapshot_handle_ignore(snapshot);
+
+  MC_get_current_fd(snapshot);
+
+  /* Save the std heap and the writable mapped pages of libsimgrid and binary */
+  MC_get_memory_regions(snapshot);
+  if (_sg_mc_sparse_checkpoint && _sg_mc_soft_dirty) {
+    mc_softdirty_reset();
+  }
+
+  snapshot->to_ignore = MC_take_snapshot_ignore();
+
+  if (_sg_mc_visited > 0 || strcmp(_sg_mc_property_file, "")) {
+    snapshot->stacks =
+        MC_take_snapshot_stacks(&snapshot);
+    if (_sg_mc_hash && snapshot->stacks != NULL) {
+      snapshot->hash = mc_hash_processes_state(num_state, snapshot->stacks);
+    } else {
+      snapshot->hash = 0;
+    }
+  } else {
+    snapshot->hash = 0;
+  }
+
+  MC_snapshot_ignore_restore(snapshot);
+  if (_sg_mc_sparse_checkpoint && _sg_mc_soft_dirty) {
+    mc_model_checker->parent_snapshot = snapshot;
+  }
+  return snapshot;
+}
+
+void MC_restore_snapshot(mc_snapshot_t snapshot)
 {
+  mc_snapshot_t parent_snapshot = mc_model_checker->parent_snapshot;
+
+  int new_fd;
   unsigned int i;
-  for(i=0; i < snapshot->num_reg; i++)
-    MC_region_destroy(snapshot->regions[i]);
+  for (i = 0; i < NB_REGIONS; i++) {
+    // For privatized, variables we decided it was not necessary to take the snapshot:
+    if (snapshot->regions[i])
+      MC_region_restore(snapshot->regions[i],
+        parent_snapshot ? parent_snapshot->regions[i] : NULL);
+  }
+
+#ifdef HAVE_SMPI
+  if (snapshot->privatization_regions) {
+    // Restore the global variables of the application separately for each
+    // simulated process:
+    for (i = 0; i < smpi_process_count(); i++) {
+      if (snapshot->privatization_regions[i]) {
+        MC_region_restore(snapshot->privatization_regions[i],
+          parent_snapshot ? parent_snapshot->privatization_regions[i] : NULL);
+      }
+    }
+  }
+  if(snapshot->privatization_index >= 0) {
+    // We just rewrote the global variables.
+    // The privatisation segment SMPI thinks
+    // is mapped might be inconsistent with the segment which
+    // is really mapped in memory (kernel state).
+    // We ask politely SMPI to map the segment anyway,
+    // even if it thinks it is the current one:
+    smpi_really_switch_data_segment(snapshot->privatization_index);
+  }
+#endif
+
+  for(i=0; i < snapshot->total_fd; i++){
+    
+    new_fd = open(snapshot->current_fd[i]->filename, snapshot->current_fd[i]->flags);
+    if (new_fd <0) {
+      xbt_die("Could not reopen the file %s fo restoring the file descriptor",
+        snapshot->current_fd[i]->filename);
+    }
+    if(new_fd != -1 && new_fd != snapshot->current_fd[i]->number){
+      dup2(new_fd, snapshot->current_fd[i]->number);
+      //fprintf(stderr, "%p\n", fdopen(snapshot->current_fd[i]->number, "rw"));
+      close(new_fd);
+    };
+    lseek(snapshot->current_fd[i]->number, snapshot->current_fd[i]->current_position, SEEK_SET);
+  }
+
+  if (_sg_mc_sparse_checkpoint && _sg_mc_soft_dirty) {
+    mc_softdirty_reset();
+  }
+
+  MC_snapshot_ignore_restore(snapshot);
+  if (_sg_mc_sparse_checkpoint && _sg_mc_soft_dirty) {
+    mc_model_checker->parent_snapshot = snapshot;
+  }
 
-  xbt_free(snapshot);
 }
 
+mc_snapshot_t simcall_HANDLER_mc_snapshot(smx_simcall_t simcall)
+{
+  return MC_take_snapshot(1);
+}
 
+void *MC_snapshot(void)
+{
+  return simcall_mc_snapshot();
+}