/* g/e.c
**
*/
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>

#include "all.h"

#if 0
/* Image check.
*/
struct {
  c3_w nor_w;
  c3_w sou_w;
  c3_w mug_w[u3a_pages];
} u3K;

/* _ce_check_page(): checksum page.
*/
static c3_w
_ce_check_page(c3_w pag_w)
{
  c3_w* mem_w = u3_Loom + (pag_w << u3a_page);
  c3_w  mug_w = u3r_mug_words(mem_w, (1 << u3a_page));

  return mug_w;
}

/* u3e_check(): compute a checksum on all memory within the watermarks.
*/
void
u3e_check(c3_c* cap_c)
{
  c3_w nor_w = 0;
  c3_w sou_w = 0;

  {
    c3_w nwr_w, swu_w;

    u3m_water(&nwr_w, &swu_w);

    nor_w = (nwr_w + ((1 << u3a_page) - 1)) >> u3a_page;
    sou_w = (swu_w + ((1 << u3a_page) - 1)) >> u3a_page;
  }

  /* Count dirty pages.
  */
  {
    c3_w i_w, sum_w, mug_w;

    sum_w = 0;
    for ( i_w = 0; i_w < nor_w; i_w++ ) {
      mug_w = _ce_check_page(i_w);
      if ( strcmp(cap_c, "boot") ) {
        c3_assert(mug_w == u3K.mug_w[i_w]);
      }
      sum_w += mug_w;
    }
    for ( i_w = 0; i_w < sou_w; i_w++ ) {
      mug_w = _ce_check_page((u3a_pages - (i_w + 1)));
      if ( strcmp(cap_c, "boot") ) {
        c3_assert(mug_w == u3K.mug_w[(u3a_pages - (i_w + 1))]);
      }
      sum_w += mug_w;
    }
    printf("%s: sum %x (%x, %x)\r\n", cap_c, sum_w, nor_w, sou_w);
  }
}

/* _ce_maplloc(): crude off-loom allocator.
*/
static void*
_ce_maplloc(c3_w len_w)
{
  void* map_v;

  map_v = mmap(0,
               len_w,
               (PROT_READ | PROT_WRITE),
               (MAP_ANON | MAP_PRIVATE),
               -1, 0);
  
  if ( -1 == (c3_ps)map_v ) {
    c3_assert(0);
  }
  else {
    c3_w* map_w = map_v;

    map_w[0] = len_w;

    return map_w + 1;
  }
}

/* _ce_mapfree(): crude off-loom allocator.
*/
static void
_ce_mapfree(void* map_v)
{ 
  c3_w* map_w = map_v;
  c3_i res_i;
  
  map_w -= 1;
  res_i = munmap(map_w, map_w[0]);

  c3_assert(0 == res_i);
}
#endif

/* u3e_fault(): handle a memory event with libsigsegv protocol.
*/
c3_i
u3e_fault(void* adr_v, c3_i ser_i)
{
  //  Let the stack overflow handler run.
  if ( 0 == ser_i ) {
    return 0;
  }

  c3_w* adr_w = (c3_w*) adr_v;

  if ( (adr_w < u3_Loom) || (adr_w >= (u3_Loom + u3a_words)) ) {
    fprintf(stderr, "address %p out of loom!\r\n", adr_v);
    fprintf(stderr, "loom: [%p : %p)\r\n", u3_Loom, u3_Loom + u3a_words);
    c3_assert(0);
    return 0;
  }
  else { 
    c3_w off_w = (adr_w - u3_Loom);
    c3_w pag_w = off_w >> u3a_page;
    c3_w blk_w = (pag_w >> 5);
    c3_w bit_w = (pag_w & 31);

#if 0
    if ( pag_w == 131041 ) { 
      printf("dirty page %d (at %p); unprotecting %p to %p\r\n", 
              pag_w, 
              adr_v, 
              (u3_Loom + (pag_w << u3a_page)),
              (u3_Loom + (pag_w << u3a_page) + (1 << u3a_page)));
    }
#endif
    if ( 0 != (u3P.dit_w[blk_w] & (1 << bit_w)) ) {
      fprintf(stderr, "strange page: %d, at %p, off %x\r\n",
                      pag_w, adr_w, off_w);
      abort();
    }

    c3_assert(0 == (u3P.dit_w[blk_w] & (1 << bit_w)));
    u3P.dit_w[blk_w] |= (1 << bit_w);
  
    if ( -1 == mprotect((void *)(u3_Loom + (pag_w << u3a_page)),
                        (1 << (u3a_page + 2)),
                        (PROT_READ | PROT_WRITE)) )
    {
      perror("mprotect");
      c3_assert(0);
      return 0;
    }
  }
  return 1;
}

/* _ce_image_open(): open or create image.
*/
static c3_o
_ce_image_open(u3e_image* img_u, c3_o nuu_o)
{
  c3_i mod_i = _(nuu_o) ? (O_RDWR | O_CREAT) : O_RDWR;
  c3_c ful_c[8193];

  snprintf(ful_c, 8192, "%s", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb/chk", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb/chk/%s.bin", u3P.dir_c, img_u->nam_c);
  if ( -1 == (img_u->fid_i = open(ful_c, mod_i, 0666)) ) {
    perror(ful_c);
    return c3n;
  }
  else {
    struct stat buf_u;

    if ( -1 == fstat(img_u->fid_i, &buf_u) ) {
      perror(ful_c);
      c3_assert(0);
      return c3n;
    }
    else { 
      c3_d siz_d = buf_u.st_size;
      c3_d pgs_d = (siz_d + (c3_d)((1 << (u3a_page + 2)) - 1)) >> 
                   (c3_d)(u3a_page + 2);

      if ( c3y == nuu_o ) {
        if ( siz_d ) { 
          c3_assert(0);
          return c3n;
        }
        return c3y;
      }
      else { 
        if ( siz_d != (pgs_d << (c3_d)(u3a_page + 2)) ) {
          fprintf(stderr, "%s: corrupt size %" PRIx64 "\r\n", ful_c, siz_d);
          return c3n;
        }
        img_u->pgs_w = (c3_w) pgs_d;
        c3_assert(pgs_d == (c3_d)img_u->pgs_w);

        return c3y;
      }
    }
  }
}

/* _ce_patch_write_control(): write control block file.
*/
static void
_ce_patch_write_control(u3_ce_patch* pat_u)
{
  c3_w len_w = sizeof(u3e_control) + 
               (pat_u->con_u->pgs_w * sizeof(u3e_line));

  if ( len_w != write(pat_u->ctl_i, pat_u->con_u, len_w) ) {
    c3_assert(0);
  }
}

/* _ce_patch_read_control(): read control block file.
*/
static c3_o
_ce_patch_read_control(u3_ce_patch* pat_u)
{
  c3_w len_w;

  c3_assert(0 == pat_u->con_u);
  {
    struct stat buf_u;

    if ( -1 == fstat(pat_u->ctl_i, &buf_u) ) {
      c3_assert(0);
      return c3n;
    }
    len_w = (c3_w) buf_u.st_size;
  }

  pat_u->con_u = malloc(len_w);
  if ( (len_w != read(pat_u->ctl_i, pat_u->con_u, len_w)) ||
        (len_w != sizeof(u3e_control) +
                  (pat_u->con_u->pgs_w * sizeof(u3e_line))) )
  {
    free(pat_u->con_u);
    pat_u->con_u = 0;
    return c3n;
  }
  return c3y;
}

/* _ce_patch_create(): create patch files.
*/
static void
_ce_patch_create(u3_ce_patch* pat_u)
{
  c3_c ful_c[8193];

  snprintf(ful_c, 8192, "%s", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb/chk/control.bin", u3P.dir_c);
  if ( -1 == (pat_u->ctl_i = open(ful_c, O_RDWR | O_CREAT | O_EXCL, 0666)) ) {
    perror(ful_c);
    c3_assert(0);
  }

  snprintf(ful_c, 8192, "%s/.urb/chk/memory.bin", u3P.dir_c);
  if ( -1 == (pat_u->mem_i = open(ful_c, O_RDWR | O_CREAT | O_EXCL, 0666)) ) {
    perror(ful_c);
    c3_assert(0);
  }
}

/* _ce_patch_delete(): delete a patch.
*/
static void
_ce_patch_delete(void)
{
  c3_c ful_c[8193];

  snprintf(ful_c, 8192, "%s/.urb/chk/control.bin", u3P.dir_c);
  unlink(ful_c);

  snprintf(ful_c, 8192, "%s/.urb/chk/memory.bin", u3P.dir_c);
  unlink(ful_c);
}

/* _ce_patch_verify(): check patch data mug.
*/
static c3_o
_ce_patch_verify(u3_ce_patch* pat_u)
{
  c3_w i_w;

  for ( i_w = 0; i_w < pat_u->con_u->pgs_w; i_w++ ) {
    c3_w pag_w = pat_u->con_u->mem_u[i_w].pag_w;
    c3_w mug_w = pat_u->con_u->mem_u[i_w].mug_w;
    c3_w mem_w[1 << u3a_page];

    if ( -1 == lseek(pat_u->mem_i, (i_w << (u3a_page + 2)), SEEK_SET) ) {
      perror("seek");
      c3_assert(0);
      return c3n;
    }
    if ( -1 == read(pat_u->mem_i, mem_w, (1 << (u3a_page + 2))) ) {
      perror("read");
      c3_assert(0);
      return c3n;
    }
    {
      c3_w nug_w = u3r_mug_words(mem_w, (1 << u3a_page));

      if ( mug_w != nug_w ) {
        printf("_ce_patch_verify: mug mismatch %d/%d; (%x, %x)\r\n", 
            pag_w, i_w, mug_w, nug_w);
        c3_assert(0);
        return c3n;
      }
#if 0
      else {
        printf("verify: patch %d/%d, %x\r\n", pag_w, i_w, mug_w);
      }
#endif
    }
  }
  return c3y;
}

/* _ce_patch_free(): free a patch.
*/
static void
_ce_patch_free(u3_ce_patch* pat_u)
{
  free(pat_u->con_u);
  close(pat_u->ctl_i);
  close(pat_u->mem_i);
  free(pat_u);
}

/* _ce_patch_open(): open patch, if any.
*/
static u3_ce_patch*
_ce_patch_open(void)
{
  u3_ce_patch* pat_u;
  c3_c ful_c[8193];
  c3_i ctl_i, mem_i;

  snprintf(ful_c, 8192, "%s", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb", u3P.dir_c);
  mkdir(ful_c, 0700);

  snprintf(ful_c, 8192, "%s/.urb/chk/control.bin", u3P.dir_c);
  if ( -1 == (ctl_i = open(ful_c, O_RDWR)) ) {
    return 0;
  }

  snprintf(ful_c, 8192, "%s/.urb/chk/memory.bin", u3P.dir_c);
  if ( -1 == (mem_i = open(ful_c, O_RDWR)) ) {
    close(ctl_i);

    _ce_patch_delete();
    return 0;
  }
  pat_u = malloc(sizeof(u3_ce_patch));
  pat_u->ctl_i = ctl_i;
  pat_u->mem_i = mem_i;
  pat_u->con_u = 0;

  if ( c3n == _ce_patch_read_control(pat_u) ) {
    close(pat_u->ctl_i);
    close(pat_u->mem_i);
    free(pat_u);

    _ce_patch_delete();
    return 0;
  }
  if ( c3n == _ce_patch_verify(pat_u) ) {
    _ce_patch_free(pat_u);
    _ce_patch_delete();
    return 0;
  }
  return pat_u;
}

/* _ce_patch_write_page(): write a page of patch memory.
*/
static void
_ce_patch_write_page(u3_ce_patch* pat_u, 
                     c3_w         pgc_w,
                     c3_w*        mem_w)
{
  if ( -1 == lseek(pat_u->mem_i, (pgc_w << (u3a_page + 2)), SEEK_SET) ) {
    c3_assert(0);
  }
  if ( (1 << (u3a_page + 2)) != 
       write(pat_u->mem_i, mem_w, (1 << (u3a_page + 2))) )
  {
    c3_assert(0);
  }
}

/* _ce_patch_count_page(): count a page, producing new counter.
*/
static c3_w
_ce_patch_count_page(c3_w pag_w,
                     c3_w pgc_w)
{
  c3_w blk_w = (pag_w >> 5);
  c3_w bit_w = (pag_w & 31);

  if ( u3P.dit_w[blk_w] & (1 << bit_w) ) {
    pgc_w += 1;
  }
  return pgc_w;
}

/* _ce_patch_save_page(): save a page, producing new page counter.
*/
static c3_w
_ce_patch_save_page(u3_ce_patch* pat_u,
                    c3_w         pag_w,
                    c3_w         pgc_w)
{
  c3_w blk_w = (pag_w >> 5);
  c3_w bit_w = (pag_w & 31);

  if ( u3P.dit_w[blk_w] & (1 << bit_w) ) {
    c3_w* mem_w = u3_Loom + (pag_w << u3a_page);

    pat_u->con_u->mem_u[pgc_w].pag_w = pag_w;
    pat_u->con_u->mem_u[pgc_w].mug_w = u3r_mug_words(mem_w, 
                                                       (1 << u3a_page));

#if 0
    printf("protect a: page %d\r\n", pag_w);
#endif
    _ce_patch_write_page(pat_u, pgc_w, mem_w);

    if ( -1 == mprotect(u3_Loom + (pag_w << u3a_page),
                        (1 << (u3a_page + 2)),
                        PROT_READ) ) 
    {
      c3_assert(0);
    }
            
    u3P.dit_w[blk_w] &= ~(1 << bit_w); 
    pgc_w += 1;
  }
  return pgc_w;
}

/* _ce_patch_junk_page(): mark a page as junk.
*/
static void
_ce_patch_junk_page(u3_ce_patch* pat_u,
                    c3_w         pag_w)
{
  c3_w blk_w = (pag_w >> 5);
  c3_w bit_w = (pag_w & 31);

  // printf("protect b: page %d\r\n", pag_w);
  if ( -1 == mprotect(u3_Loom + (pag_w << u3a_page),
                      (1 << (u3a_page + 2)),
                      PROT_READ) ) 
  {
    c3_assert(0);
  }
  u3P.dit_w[blk_w] &= ~(1 << bit_w); 
}

/* u3e_dirty(): count dirty pages.
*/
c3_w
u3e_dirty(void)
{
  c3_w pgs_w = 0;
  c3_w nor_w = 0;
  c3_w sou_w = 0;

  /* Calculate number of saved pages, north and south.
  */
  {
    c3_w nwr_w, swu_w;

    u3m_water(&nwr_w, &swu_w);

    nor_w = (nwr_w + ((1 << u3a_page) - 1)) >> u3a_page;
    sou_w = (swu_w + ((1 << u3a_page) - 1)) >> u3a_page;
  }
  //  u3K.nor_w = nor_w;
  //  u3K.sou_w = sou_w;

  /* Count dirty pages.
  */
  {
    c3_w i_w;

    for ( i_w = 0; i_w < nor_w; i_w++ ) {
      pgs_w = _ce_patch_count_page(i_w, pgs_w);
    }
    for ( i_w = 0; i_w < sou_w; i_w++ ) {
      pgs_w = _ce_patch_count_page((u3a_pages - (i_w + 1)), pgs_w);
    }
  }
  return pgs_w;
}

/* _ce_patch_compose(): make and write current patch.
*/
static u3_ce_patch*
_ce_patch_compose(void)
{
  c3_w pgs_w = 0;
  c3_w nor_w = 0;
  c3_w sou_w = 0;

  /* Calculate number of saved pages, north and south.
  */
  {
    c3_w nwr_w, swu_w;

    u3m_water(&nwr_w, &swu_w);

    nor_w = (nwr_w + ((1 << u3a_page) - 1)) >> u3a_page;
    sou_w = (swu_w + ((1 << u3a_page) - 1)) >> u3a_page;
  }
  //  u3K.nor_w = nor_w;
  //  u3K.sou_w = sou_w;

  /* Count dirty pages.
  */
  {
    c3_w i_w;

    for ( i_w = 0; i_w < nor_w; i_w++ ) {
      pgs_w = _ce_patch_count_page(i_w, pgs_w);
    }
    for ( i_w = 0; i_w < sou_w; i_w++ ) {
      pgs_w = _ce_patch_count_page((u3a_pages - (i_w + 1)), pgs_w);
    }
  }

  if ( !pgs_w ) {
    return 0;
  }
  else {
    u3_ce_patch* pat_u = malloc(sizeof(u3_ce_patch));
    c3_w i_w, pgc_w;

    _ce_patch_create(pat_u);
    pat_u->con_u = malloc(sizeof(u3e_control) + (pgs_w * sizeof(u3e_line)));
    pgc_w = 0;

    for ( i_w = 0; i_w < nor_w; i_w++ ) {
      pgc_w = _ce_patch_save_page(pat_u, i_w, pgc_w);
    } 
    for ( i_w = 0; i_w < sou_w; i_w++ ) {
      pgc_w = _ce_patch_save_page(pat_u, (u3a_pages - (i_w + 1)), pgc_w);
    }
    for ( i_w = nor_w; i_w < (u3a_pages - sou_w); i_w++ ) {
      _ce_patch_junk_page(pat_u, i_w);
    }

    pat_u->con_u->nor_w = nor_w;
    pat_u->con_u->sou_w = sou_w;
    pat_u->con_u->pgs_w = pgc_w;
  
    _ce_patch_write_control(pat_u);
    return pat_u;
  }
}

/* _ce_sync(): sync a file descriptor.
*/
static void
_ce_sync(c3_i fid_i)
{
#if defined(U3_OS_linux)
  fdatasync(fid_i);
#elif defined(U3_OS_osx)
  fcntl(fid_i, F_FULLFSYNC);
#elif defined(U3_OS_bsd)
  fsync(fid_i);
#else
# error "port: datasync"
#endif
}

/* _ce_patch_sync(): make sure patch is synced to disk.
*/
static void
_ce_patch_sync(u3_ce_patch* pat_u)
{
  _ce_sync(pat_u->ctl_i);
  _ce_sync(pat_u->mem_i);
}

/* _ce_image_sync(): make sure image is synced to disk.
*/
static void
_ce_image_sync(u3e_image* img_u)
{
  _ce_sync(img_u->fid_i);
}

/* _ce_patch_apply(): apply patch to image.
*/
static void
_ce_patch_apply(u3_ce_patch* pat_u)
{
  c3_w i_w;

  //printf("image: nor_w %d, new %d\r\n", u3P.nor_u.pgs_w, pat_u->con_u->nor_w);
  //printf("image: sou_w %d, new %d\r\n", u3P.sou_u.pgs_w, pat_u->con_u->sou_w);

  if ( u3P.nor_u.pgs_w > pat_u->con_u->nor_w ) {
    ftruncate(u3P.nor_u.fid_i, u3P.nor_u.pgs_w << (u3a_page + 2));
  }
  u3P.nor_u.pgs_w = pat_u->con_u->nor_w;

  if ( u3P.sou_u.pgs_w > pat_u->con_u->sou_w ) {
    ftruncate(u3P.sou_u.fid_i, u3P.sou_u.pgs_w << (u3a_page + 2));
  }
  u3P.sou_u.pgs_w = pat_u->con_u->sou_w;
 
  if ( (-1 == lseek(pat_u->mem_i, 0, SEEK_SET)) ||
       (-1 == lseek(u3P.nor_u.fid_i, 0, SEEK_SET)) ||
       (-1 == lseek(u3P.sou_u.fid_i, 0, SEEK_SET)) )
  {
    perror("apply: seek");
    c3_assert(0);
  }

  for ( i_w = 0; i_w < pat_u->con_u->pgs_w; i_w++ ) {
    c3_w pag_w = pat_u->con_u->mem_u[i_w].pag_w;
    c3_w mem_w[1 << u3a_page];
    c3_i fid_i;
    c3_w off_w;

    if ( pag_w < pat_u->con_u->nor_w ) {
      fid_i = u3P.nor_u.fid_i;
      off_w = pag_w;
    } 
    else {
      fid_i = u3P.sou_u.fid_i;
      off_w = (u3a_pages - (pag_w + 1));
    }
 
    if ( -1 == read(pat_u->mem_i, mem_w, (1 << (u3a_page + 2))) ) {
      perror("apply: read");
      c3_assert(0);
    }
    else {
      if ( -1 == lseek(fid_i, (off_w << (u3a_page + 2)), SEEK_SET) ) {
        perror("apply: lseek");
        c3_assert(0);
      }
      if ( -1 == write(fid_i, mem_w, (1 << (u3a_page + 2))) ) {
        perror("apply: write");
        c3_assert(0);
      }
    }
#if 0
    printf("apply: %d, %x\n", pag_w, u3r_mug_words(mem_w, (1 << u3a_page)));
#endif
  }
}

/* _ce_image_blit(): apply image to memory.
*/
static void
_ce_image_blit(u3e_image* img_u,
               c3_w*        ptr_w,
               c3_ws        stp_ws)
{
  c3_w i_w;

  lseek(img_u->fid_i, 0, SEEK_SET);
  for ( i_w=0; i_w < img_u->pgs_w; i_w++ ) {
    if ( -1 == read(img_u->fid_i, ptr_w, (1 << (u3a_page + 2))) ) {
      perror("read");
      c3_assert(0);
    }
#if 0
    {
      c3_w off_w = (ptr_w - u3_Loom);
      c3_w pag_w = (off_w >> u3a_page);

      printf("blit: page %d, mug %x\r\n", pag_w, 
          u3r_mug_words(ptr_w, (1 << u3a_page)));
    }
#endif
    ptr_w += stp_ws;
  }
}

#if 0
/* _ce_image_fine(): compare image to memory.
*/
static void
_ce_image_fine(u3e_image* img_u,
               c3_w*        ptr_w,
               c3_ws        stp_ws)
{
  c3_w i_w;
  c3_w buf_w[1 << u3a_page];

  lseek(img_u->fid_i, 0, SEEK_SET);
  for ( i_w=0; i_w < img_u->pgs_w; i_w++ ) {
    c3_w mem_w, fil_w;

    if ( -1 == read(img_u->fid_i, buf_w, (1 << (u3a_page + 2))) ) {
      perror("read");
      c3_assert(0);
    }
    mem_w = u3r_mug_words(ptr_w, (1 << u3a_page));
    fil_w = u3r_mug_words(buf_w, (1 << u3a_page));

    if ( mem_w != fil_w ) {
      c3_w pag_w = (ptr_w - u3_Loom) >> u3a_page;

      fprintf(stderr, "mismatch: page %d, mem_w %x, fil_w %x, K %x\r\n", 
                       pag_w, 
                       mem_w, 
                       fil_w,
                       u3K.mug_w[pag_w]);
      abort();
    }
    ptr_w += stp_ws;
  }
}
#endif

/* u3e_save(): save current changes.
*/
void
u3e_save(void)
{
  u3_ce_patch* pat_u;

  //  In dry-run mode, we never touch this stuff.
  //
  if ( u3C.wag_w & u3o_dryrun ) {
    return;
  }

  //  Write all dirty pages to disk; clear protection and dirty bits.
  //
  //  This has to block the main thread.  All further processing can happen
  //  in a separate thread, though we can't save again till this completes.
  //

  if ( !(pat_u = _ce_patch_compose()) ) {
    return;
  }
 
  //  Sync the patch files.
  //
  // u3a_print_memory("sync: save", 4096 * pat_u->con_u->pgs_w);
  _ce_patch_sync(pat_u);

  //  Verify the patch - because why not?
  //
  // printf("_ce_patch_verify\r\n");
  _ce_patch_verify(pat_u);

  //  Write the patch data into the image file.  Idempotent.
  //
  // printf("_ce_patch_apply\r\n");
  _ce_patch_apply(pat_u);

#if 0
  {
    _ce_image_fine(&u3P.nor_u, 
                   u3_Loom, 
                   (1 << u3a_page));

    _ce_image_fine(&u3P.sou_u, 
                   (u3_Loom + (1 << u3a_bits) - (1 << u3a_page)),
                   -(1 << u3a_page));

    c3_assert(u3P.nor_u.pgs_w == u3K.nor_w);
    c3_assert(u3P.sou_u.pgs_w == u3K.sou_w);
  }
#endif

  //  Sync the image file.
  //
  // printf("_ce_image_sync\r\n");
  _ce_image_sync(&u3P.nor_u);
  _ce_image_sync(&u3P.sou_u);

  //  Delete the patchfile and free it.
  //
  // printf("_ce_patch_delete\r\n");
  _ce_patch_delete();
  // printf("_ce_patch_free\r\n");
  _ce_patch_free(pat_u);
}

/* u3e_live(): start the persistence system.
*/
c3_o
u3e_live(c3_o nuu_o, c3_c* dir_c)
{
  u3P.dir_c = dir_c;
  u3P.nor_u.nam_c = "north";
  u3P.sou_u.nam_c = "south";

#if 0
  if ( u3C.wag_w & u3o_dryrun ) {
    return c3y;
  } else
#endif
  {
    /* Open and apply any patches.
    */
    if ( _(nuu_o) ) {
      if ( (c3n == _ce_image_open(&u3P.nor_u, c3y)) ||
           (c3n == _ce_image_open(&u3P.sou_u, c3y)) )
      {
        printf("boot: image failed\r\n");
        exit(1);
      }
    }
    else {
      u3_ce_patch* pat_u;

      /* Open image files.
      */
      {
        if ( (c3n == _ce_image_open(&u3P.nor_u, c3n)) ||
             (c3n == _ce_image_open(&u3P.sou_u, c3n)) ) 
        {
          fprintf(stderr, "boot: no image\r\n");
          return u3e_live(c3y, dir_c);
        }
      }
      /* Load any patch files; apply them to images.
      */
      if ( 0 != (pat_u = _ce_patch_open()) ) {
        printf("_ce_patch_apply\r\n");
        _ce_patch_apply(pat_u);

        printf("_ce_image_sync\r\n");
        _ce_image_sync(&u3P.nor_u);
        _ce_image_sync(&u3P.sou_u);

        printf("_ce_patch_delete\r\n");
        _ce_patch_delete();
        printf("_ce_patch_free\r\n");
        _ce_patch_free(pat_u);
      }

      /* Write image files to memory; reinstate protection.
      */
      {
        _ce_image_blit(&u3P.nor_u, 
                       u3_Loom, 
                       (1 << u3a_page));

        _ce_image_blit(&u3P.sou_u, 
                       (u3_Loom + (1 << u3a_bits) - (1 << u3a_page)),
                       -(1 << u3a_page));

        if ( 0 != mprotect((void *)u3_Loom, u3a_bytes, PROT_READ) ) {
          perror("protect");
          c3_assert(0);
        }
        printf("protected loom\r\n");
      }

      /* If the images were empty, we are logically booting.
      */
      if ( (0 == u3P.nor_u.pgs_w) && (0 == u3P.sou_u.pgs_w) ) {
        printf("live: logical boot\r\n");
        nuu_o = c3y;
      }
      else {
        u3a_print_memory("live: loaded",
                         (u3P.nor_u.pgs_w + u3P.sou_u.pgs_w) << u3a_page);
      }
    }
  }
  return nuu_o;
}