xref: /petsc/src/sys/classes/viewer/impls/ascii/filev.c (revision c410d8cc8908fa7552d5d2cadc5c41ff54401973)

#include <../src/sys/classes/viewer/impls/ascii/asciiimpl.h> /*I "petscviewer.h" I*/

#define QUEUESTRINGSIZE 8192

static PetscErrorCode PetscViewerFileClose_ASCII(PetscViewer viewer)
{
  PetscMPIInt        rank;
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  int                err;

  PetscFunctionBegin;
  PetscCheck(!vascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)viewer), &rank));
  if (rank == 0 && vascii->fd != stderr && vascii->fd != PETSC_STDOUT) {
    if (vascii->fd && vascii->closefile) {
      err = fclose(vascii->fd);
      PetscCheck(!err, PETSC_COMM_SELF, PETSC_ERR_SYS, "fclose() failed on file");
    }
    if (vascii->storecompressed) {
      char  par[PETSC_MAX_PATH_LEN], buf[PETSC_MAX_PATH_LEN];
      FILE *fp;
      PetscCall(PetscStrncpy(par, "gzip ", sizeof(par)));
      PetscCall(PetscStrlcat(par, vascii->filename, sizeof(par)));
#if defined(PETSC_HAVE_POPEN)
      PetscCall(PetscPOpen(PETSC_COMM_SELF, NULL, par, "r", &fp));
      PetscCheck(!fgets(buf, 1024, fp), PETSC_COMM_SELF, PETSC_ERR_LIB, "Error from compression command %s\n%s", par, buf);
      PetscCall(PetscPClose(PETSC_COMM_SELF, fp));
#else
      SETERRQ(PETSC_COMM_SELF, PETSC_ERR_SUP_SYS, "Cannot run external programs on this machine");
#endif
    }
  }
  PetscCall(PetscFree(vascii->filename));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/* ----------------------------------------------------------------------*/
PetscErrorCode PetscViewerDestroy_ASCII(PetscViewer viewer)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  PetscViewerLink   *vlink;
  PetscBool          flg;

  PetscFunctionBegin;
  PetscCheck(!vascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscCall(PetscViewerFileClose_ASCII(viewer));
  PetscCall(PetscFree(vascii));

  /* remove the viewer from the list in the MPI Communicator */
  if (Petsc_Viewer_keyval == MPI_KEYVAL_INVALID) PetscCallMPI(MPI_Comm_create_keyval(MPI_COMM_NULL_COPY_FN, Petsc_DelViewer, &Petsc_Viewer_keyval, (void *)0));

  PetscCallMPI(MPI_Comm_get_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_keyval, (void **)&vlink, (PetscMPIInt *)&flg));
  if (flg) {
    if (vlink && vlink->viewer == viewer) {
      if (vlink->next) {
        PetscCallMPI(MPI_Comm_set_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_keyval, vlink->next));
      } else {
        PetscCallMPI(MPI_Comm_delete_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_keyval));
      }
      PetscCall(PetscFree(vlink));
    } else {
      while (vlink && vlink->next) {
        if (vlink->next->viewer == viewer) {
          PetscViewerLink *nv = vlink->next;
          vlink->next         = vlink->next->next;
          PetscCall(PetscFree(nv));
        }
        vlink = vlink->next;
      }
    }
  }

  if (Petsc_Viewer_Stdout_keyval != MPI_KEYVAL_INVALID) {
    PetscViewer aviewer;
    PetscCallMPI(MPI_Comm_get_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_Stdout_keyval, (void **)&aviewer, (PetscMPIInt *)&flg));
    if (flg && aviewer == viewer) PetscCallMPI(MPI_Comm_delete_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_Stdout_keyval));
  }
  if (Petsc_Viewer_Stderr_keyval != MPI_KEYVAL_INVALID) {
    PetscViewer aviewer;
    PetscCallMPI(MPI_Comm_get_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_Stderr_keyval, (void **)&aviewer, (PetscMPIInt *)&flg));
    if (flg && aviewer == viewer) PetscCallMPI(MPI_Comm_delete_attr(PetscObjectComm((PetscObject)viewer), Petsc_Viewer_Stderr_keyval));
  }
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileSetName_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileGetName_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileGetMode_C", NULL));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileSetMode_C", NULL));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerDestroy_ASCII_SubViewer(PetscViewer viewer)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  PetscCall(PetscViewerRestoreSubViewer(vascii->bviewer, 0, &viewer));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerFlush_ASCII(PetscViewer viewer)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  MPI_Comm           comm;
  PetscMPIInt        rank, size;
  FILE              *fd = vascii->fd;

  PetscFunctionBegin;
  PetscCheck(!vascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscCall(PetscObjectGetComm((PetscObject)viewer, &comm));
  PetscCallMPI(MPI_Comm_rank(comm, &rank));
  PetscCallMPI(MPI_Comm_size(comm, &size));

  if (!vascii->bviewer && rank == 0 && (vascii->mode != FILE_MODE_READ)) PetscCall(PetscFFlush(vascii->fd));

  if (vascii->allowsynchronized) {
    PetscMPIInt tag, i, j, n = 0, dummy = 0;
    char       *message;
    MPI_Status  status;

    PetscCall(PetscCommDuplicate(comm, &comm, &tag));

    /* First processor waits for messages from all other processors */
    if (rank == 0) {
      /* flush my own messages that I may have queued up */
      PrintfQueue next = vascii->petsc_printfqueuebase, previous;
      for (i = 0; i < vascii->petsc_printfqueuelength; i++) {
        if (!vascii->bviewer) {
          PetscCall(PetscFPrintf(comm, fd, "%s", next->string));
        } else {
          PetscCall(PetscViewerASCIISynchronizedPrintf(vascii->bviewer, "%s", next->string));
        }
        previous = next;
        next     = next->next;
        PetscCall(PetscFree(previous->string));
        PetscCall(PetscFree(previous));
      }
      vascii->petsc_printfqueue       = NULL;
      vascii->petsc_printfqueuelength = 0;
      for (i = 1; i < size; i++) {
        /* to prevent a flood of messages to process zero, request each message separately */
        PetscCallMPI(MPI_Send(&dummy, 1, MPI_INT, i, tag, comm));
        PetscCallMPI(MPI_Recv(&n, 1, MPI_INT, i, tag, comm, &status));
        for (j = 0; j < n; j++) {
          PetscMPIInt size = 0;

          PetscCallMPI(MPI_Recv(&size, 1, MPI_INT, i, tag, comm, &status));
          PetscCall(PetscMalloc1(size, &message));
          PetscCallMPI(MPI_Recv(message, size, MPI_CHAR, i, tag, comm, &status));
          if (!vascii->bviewer) {
            PetscCall(PetscFPrintf(comm, fd, "%s", message));
          } else {
            PetscCall(PetscViewerASCIISynchronizedPrintf(vascii->bviewer, "%s", message));
          }
          PetscCall(PetscFree(message));
        }
      }
    } else { /* other processors send queue to processor 0 */
      PrintfQueue next = vascii->petsc_printfqueuebase, previous;

      PetscCallMPI(MPI_Recv(&dummy, 1, MPI_INT, 0, tag, comm, &status));
      PetscCallMPI(MPI_Send(&vascii->petsc_printfqueuelength, 1, MPI_INT, 0, tag, comm));
      for (i = 0; i < vascii->petsc_printfqueuelength; i++) {
        PetscCallMPI(MPI_Send(&next->size, 1, MPI_INT, 0, tag, comm));
        PetscCallMPI(MPI_Send(next->string, next->size, MPI_CHAR, 0, tag, comm));
        previous = next;
        next     = next->next;
        PetscCall(PetscFree(previous->string));
        PetscCall(PetscFree(previous));
      }
      vascii->petsc_printfqueue       = NULL;
      vascii->petsc_printfqueuelength = 0;
    }
    PetscCall(PetscCommDestroy(&comm));
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIGetPointer - Extracts the file pointer from an ASCII `PetscViewer`.

    Not Collective, depending on the viewer the value may be meaningless except for process 0 of the viewer; No Fortran Support

    Input Parameter:
.    viewer - `PetscViewer` context, obtained from `PetscViewerASCIIOpen()`

    Output Parameter:
.    fd - file pointer

    Level: intermediate

    Note:
    For the standard `PETSCVIEWERASCII` the value is valid only on MPI rank 0 of the viewer

.seealso: [](sec_viewers), `PETSCVIEWERASCII`, `PetscViewerASCIIOpen()`, `PetscViewerDestroy()`, `PetscViewerSetType()`,
          `PetscViewerCreate()`, `PetscViewerASCIIPrintf()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerFlush()`
@*/
PetscErrorCode PetscViewerASCIIGetPointer(PetscViewer viewer, FILE **fd)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  *fd = vascii->fd;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerFileGetMode_ASCII(PetscViewer viewer, PetscFileMode *mode)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  *mode = vascii->mode;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerFileSetMode_ASCII(PetscViewer viewer, PetscFileMode mode)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  vascii->mode = mode;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*
   If petsc_history is on, then all Petsc*Printf() results are saved
   if the appropriate (usually .petschistory) file.
*/
PETSC_INTERN FILE *petsc_history;

/*@
    PetscViewerASCIISetTab - Causes `PetscViewer` to tab in a number of times before printing

    Not Collective, but only first processor in set has any effect; No Fortran Support

    Input Parameters:
+    viewer - obtained with `PetscViewerASCIIOpen()`
-    tabs - number of tabs

    Level: developer

    Note:
     `PetscViewerASCIIPushTab()` and `PetscViewerASCIIPopTab()` are the preferred usage

.seealso: [](sec_viewers), `PETSCVIEWERASCII`, `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIGetTab()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`,
          `PetscViewerASCIIPushTab()`
@*/
PetscErrorCode PetscViewerASCIISetTab(PetscViewer viewer, PetscInt tabs)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) ascii->tab = tabs;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
    PetscViewerASCIIGetTab - Return the number of tabs used by `PetscViewer`.

    Not Collective, meaningful on first processor only; No Fortran Support

    Input Parameter:
.    viewer - obtained with `PetscViewerASCIIOpen()`

    Output Parameter:
.    tabs - number of tabs

    Level: developer

.seealso: [](sec_viewers), `PETSCVIEWERASCII`, `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIISetTab()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`, `PetscViewerASCIIPushTab()`
@*/
PetscErrorCode PetscViewerASCIIGetTab(PetscViewer viewer, PetscInt *tabs)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii && tabs) *tabs = ascii->tab;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
    PetscViewerASCIIAddTab - Add to the number of times a `PETSCVIEWERASCII` viewer tabs before printing

    Not Collective, but only first processor in set has any effect; No Fortran Support

    Input Parameters:
+    viewer - obtained with `PetscViewerASCIIOpen()`
-    tabs - number of tabs

    Level: developer

    Note:
     `PetscViewerASCIIPushTab()` and `PetscViewerASCIIPopTab()` are the preferred usage

.seealso: [](sec_viewers), `PETSCVIEWERASCII`, `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`, `PetscViewerASCIIPushTab()`
@*/
PetscErrorCode PetscViewerASCIIAddTab(PetscViewer viewer, PetscInt tabs)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) ascii->tab += tabs;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
    PetscViewerASCIISubtractTab - Subtracts from the number of times a `PETSCVIEWERASCII` viewer tabs before printing

    Not Collective, but only first processor in set has any effect; No Fortran Support

    Input Parameters:
+    viewer - obtained with `PetscViewerASCIIOpen()`
-    tabs - number of tabs

    Level: developer

    Note:
     `PetscViewerASCIIPushTab()` and `PetscViewerASCIIPopTab()` are the preferred usage

.seealso: [](sec_viewers), `PETSCVIEWERASCII`, `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`,
          `PetscViewerASCIIPushTab()`
@*/
PetscErrorCode PetscViewerASCIISubtractTab(PetscViewer viewer, PetscInt tabs)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) ascii->tab -= tabs;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIPushSynchronized - Allows calls to `PetscViewerASCIISynchronizedPrintf()` for this viewer

    Collective

    Input Parameter:
.    viewer - obtained with `PetscViewerASCIIOpen()`

    Level: intermediate

    Note:
    See documentation of `PetscViewerASCIISynchronizedPrintf()` for more details how the synchronized output should be done properly.

.seealso: [](sec_viewers), `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerFlush()`, `PetscViewerASCIIPopSynchronized()`,
          `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`
@*/
PetscErrorCode PetscViewerASCIIPushSynchronized(PetscViewer viewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCheck(!ascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) ascii->allowsynchronized++;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIPopSynchronized - Undoes most recent `PetscViewerASCIIPushSynchronized()` for this viewer

    Collective

    Input Parameter:
.    viewer - obtained with `PetscViewerASCIIOpen()`

    Level: intermediate

    Note:
    See documentation of `PetscViewerASCIISynchronizedPrintf()` for more details how the synchronized output should be done properly.

.seealso: [](sec_viewers), `PetscViewerASCIIPushSynchronized()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerFlush()`,
          `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`
@*/
PetscErrorCode PetscViewerASCIIPopSynchronized(PetscViewer viewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCheck(!ascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) {
    ascii->allowsynchronized--;
    PetscCheck(ascii->allowsynchronized >= 0, PETSC_COMM_SELF, PETSC_ERR_PLIB, "Called more times than PetscViewerASCIIPushSynchronized()");
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIPushTab - Adds one more tab to the amount that `PetscViewerASCIIPrintf()`
     lines are tabbed.

    Not Collective, but only first MPI rank in the viewer has any effect; No Fortran Support

    Input Parameter:
.    viewer - obtained with `PetscViewerASCIIOpen()`

    Level: developer

.seealso: [](sec_viewers), `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`
@*/
PetscErrorCode PetscViewerASCIIPushTab(PetscViewer viewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) ascii->tab++;
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIPopTab - Removes one tab from the amount that `PetscViewerASCIIPrintf()` lines are tabbed that was provided by
    `PetscViewerASCIIPushTab()`

    Not Collective, but only first MPI rank in the viewer has any effect; No Fortran Support

    Input Parameter:
.    viewer - obtained with `PetscViewerASCIIOpen()`

    Level: developer

.seealso: [](sec_viewers), `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIPushTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`
@*/
PetscErrorCode PetscViewerASCIIPopTab(PetscViewer viewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) {
    PetscCheck(ascii->tab > 0, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "More tabs popped than pushed");
    ascii->tab--;
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@
    PetscViewerASCIIUseTabs - Turns on or off the use of tabs with the `PETSCVIEWERASCII` `PetscViewer`

    Not Collective, but only first MPI rank in the viewer has any effect; No Fortran Support

    Input Parameters:
+    viewer - obtained with `PetscViewerASCIIOpen()`
-    flg - `PETSC_TRUE` or `PETSC_FALSE`

    Level: developer

.seealso: [](sec_viewers), `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`,
          `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`, `PetscViewerASCIIPushTab()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`
@*/
PetscErrorCode PetscViewerASCIIUseTabs(PetscViewer viewer, PetscBool flg)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  if (iascii) {
    if (flg) ascii->tab = ascii->tab_store;
    else {
      ascii->tab_store = ascii->tab;
      ascii->tab       = 0;
    }
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIIPrintf - Prints to a file, only from the first
    processor in the `PetscViewer` of type `PETSCVIEWERASCII`

    Not Collective, but only the first MPI rank in the viewer has any effect

    Input Parameters:
+    viewer - obtained with `PetscViewerASCIIOpen()`
-    format - the usual printf() format string

    Level: developer

    Fortran Note:
    The call sequence is `PetscViewerASCIIPrintf`(`PetscViewer`, character(*), int ierr) from Fortran.
    That is, you can only pass a single character string from Fortran.

.seealso: [](sec_viewers), `PetscPrintf()`, `PetscSynchronizedPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerASCIIPushTab()`, `PetscViewerASCIIPopTab()`, `PetscViewerASCIISynchronizedPrintf()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`, `PetscViewerASCIIGetPointer()`, `PetscViewerASCIIPushSynchronized()`
@*/
PetscErrorCode PetscViewerASCIIPrintf(PetscViewer viewer, const char format[], ...)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;
  PetscMPIInt        rank;
  PetscInt           tab, intab = ascii->tab;
  FILE              *fd = ascii->fd;
  PetscBool          iascii;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCheck(!ascii->sviewer, PetscObjectComm((PetscObject)viewer), PETSC_ERR_ARG_WRONGSTATE, "Cannot call with outstanding call to PetscViewerRestoreSubViewer()");
  PetscValidCharPointer(format, 2);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  PetscCheck(iascii, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Not ASCII PetscViewer");
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)viewer), &rank));
  if (rank) PetscFunctionReturn(PETSC_SUCCESS);

  if (ascii->bviewer) { /* pass string up to parent viewer */
    char   *string;
    va_list Argp;
    size_t  fullLength;

    PetscCall(PetscCalloc1(QUEUESTRINGSIZE, &string));
    va_start(Argp, format);
    PetscCall(PetscVSNPrintf(string, QUEUESTRINGSIZE, format, &fullLength, Argp));
    va_end(Argp);
    PetscCall(PetscViewerASCIISynchronizedPrintf(viewer, "%s", string));
    PetscCall(PetscFree(string));
  } else { /* write directly to file */
    va_list Argp;
    /* flush my own messages that I may have queued up */
    PrintfQueue next = ascii->petsc_printfqueuebase, previous;
    PetscInt    i;
    for (i = 0; i < ascii->petsc_printfqueuelength; i++) {
      PetscCall(PetscFPrintf(PETSC_COMM_SELF, fd, "%s", next->string));
      previous = next;
      next     = next->next;
      PetscCall(PetscFree(previous->string));
      PetscCall(PetscFree(previous));
    }
    ascii->petsc_printfqueue       = NULL;
    ascii->petsc_printfqueuelength = 0;
    tab                            = intab;
    while (tab--) PetscCall(PetscFPrintf(PETSC_COMM_SELF, fd, "  "));

    va_start(Argp, format);
    PetscCall((*PetscVFPrintf)(fd, format, Argp));
    va_end(Argp);
    PetscCall(PetscFFlush(fd));
    if (petsc_history) {
      tab = intab;
      while (tab--) PetscCall(PetscFPrintf(PETSC_COMM_SELF, petsc_history, "  "));
      va_start(Argp, format);
      PetscCall((*PetscVFPrintf)(petsc_history, format, Argp));
      va_end(Argp);
      PetscCall(PetscFFlush(petsc_history));
    }
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
     PetscViewerFileSetName - Sets the name of the file the `PetscViewer` should use.

    Collective

  Input Parameters:
+  viewer - the `PetscViewer`; for example, of type `PETSCVIEWERASCII` or `PETSCVIEWERBINARY`
-  name - the name of the file it should use

    Level: advanced

  Note:
  This will have no effect on viewers that are not related to files

.seealso: [](sec_viewers), `PetscViewerCreate()`, `PetscViewerSetType()`, `PetscViewerASCIIOpen()`, `PetscViewerBinaryOpen()`, `PetscViewerDestroy()`,
          `PetscViewerASCIIGetPointer()`, `PetscViewerASCIIPrintf()`, `PetscViewerASCIISynchronizedPrintf()`
@*/
PetscErrorCode PetscViewerFileSetName(PetscViewer viewer, const char name[])
{
  char filename[PETSC_MAX_PATH_LEN];

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscValidCharPointer(name, 2);
  PetscCall(PetscStrreplace(PetscObjectComm((PetscObject)viewer), name, filename, sizeof(filename)));
  PetscTryMethod(viewer, "PetscViewerFileSetName_C", (PetscViewer, const char[]), (viewer, filename));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
     PetscViewerFileGetName - Gets the name of the file the `PetscViewer` is using

    Not Collective

  Input Parameter:
.  viewer - the `PetscViewer`

  Output Parameter:
.  name - the name of the file it is using

    Level: advanced

  Note:
  This will have no effect on viewers that are not related to files

.seealso: [](sec_viewers), `PetscViewerCreate()`, `PetscViewerSetType()`, `PetscViewerASCIIOpen()`, `PetscViewerBinaryOpen()`, `PetscViewerFileSetName()`
@*/
PetscErrorCode PetscViewerFileGetName(PetscViewer viewer, const char **name)
{
  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscValidPointer(name, 2);
  PetscUseMethod(viewer, "PetscViewerFileGetName_C", (PetscViewer, const char **), (viewer, name));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerFileGetName_ASCII(PetscViewer viewer, const char **name)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  *name = vascii->filename;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerFileSetName_ASCII(PetscViewer viewer, const char name[])
{
  size_t             len;
  char               fname[PETSC_MAX_PATH_LEN], *gz = NULL;
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  PetscBool          isstderr, isstdout;
  PetscMPIInt        rank;

  PetscFunctionBegin;
  PetscCall(PetscViewerFileClose_ASCII(viewer));
  if (!name) PetscFunctionReturn(PETSC_SUCCESS);
  PetscCall(PetscStrallocpy(name, &vascii->filename));

  /* Is this file to be compressed */
  vascii->storecompressed = PETSC_FALSE;

  PetscCall(PetscStrstr(vascii->filename, ".gz", &gz));
  if (gz) {
    PetscCall(PetscStrlen(gz, &len));
    if (len == 3) {
      PetscCheck(vascii->mode == FILE_MODE_WRITE, PetscObjectComm((PetscObject)viewer), PETSC_ERR_SUP, "Cannot open ASCII PetscViewer file that is compressed; uncompress it manually first");
      *gz                     = 0;
      vascii->storecompressed = PETSC_TRUE;
    }
  }
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)viewer), &rank));
  if (rank == 0) {
    PetscCall(PetscStrcmp(name, "stderr", &isstderr));
    PetscCall(PetscStrcmp(name, "stdout", &isstdout));
    /* empty filename means stdout */
    if (name[0] == 0) isstdout = PETSC_TRUE;
    if (isstderr) vascii->fd = PETSC_STDERR;
    else if (isstdout) vascii->fd = PETSC_STDOUT;
    else {
      PetscCall(PetscFixFilename(name, fname));
      switch (vascii->mode) {
      case FILE_MODE_READ:
        vascii->fd = fopen(fname, "r");
        break;
      case FILE_MODE_WRITE:
        vascii->fd = fopen(fname, "w");
        break;
      case FILE_MODE_APPEND:
        vascii->fd = fopen(fname, "a");
        break;
      case FILE_MODE_UPDATE:
        vascii->fd = fopen(fname, "r+");
        if (!vascii->fd) vascii->fd = fopen(fname, "w+");
        break;
      case FILE_MODE_APPEND_UPDATE:
        /* I really want a file which is opened at the end for updating,
           not a+, which opens at the beginning, but makes writes at the end.
        */
        vascii->fd = fopen(fname, "r+");
        if (!vascii->fd) vascii->fd = fopen(fname, "w+");
        else {
          int ret = fseek(vascii->fd, 0, SEEK_END);
          PetscCheck(!ret, PETSC_COMM_SELF, PETSC_ERR_LIB, "fseek() failed with error code %d", ret);
        }
        break;
      default:
        SETERRQ(PetscObjectComm((PetscObject)viewer), PETSC_ERR_SUP, "Unsupported file mode %s", PetscFileModes[vascii->mode]);
      }
      PetscCheck(vascii->fd, PETSC_COMM_SELF, PETSC_ERR_FILE_OPEN, "Cannot open PetscViewer file: %s", fname);
    }
  }
#if defined(PETSC_USE_LOG)
  PetscCall(PetscLogObjectState((PetscObject)viewer, "File: %s", name));
#endif
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerGetSubViewer_ASCII(PetscViewer viewer, MPI_Comm subcomm, PetscViewer *outviewer)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data, *ovascii;

  PetscFunctionBegin;
  PetscCall(PetscViewerASCIIPushSynchronized(viewer));
  PetscCheck(!vascii->sviewer, PETSC_COMM_SELF, PETSC_ERR_ORDER, "SubViewer already obtained from PetscViewer and not restored");
  /*
     The following line is a bug; it does another PetscViewerASCIIPushSynchronized() on viewer, but if it is removed the code won't work
     because it relies on this behavior in other places. In particular this line causes the synchronized flush to occur when the viewer is destroyed
     (since the count never gets to zero) in some examples this displays information that otherwise would be lost

     This code also means another call to PetscViewerASCIIPopSynchronized() must be made after the PetscViewerRestoreSubViewer(), see, for example,
     PCView_GASM().
  */
  PetscCall(PetscViewerASCIIPushSynchronized(viewer));
  PetscCall(PetscViewerCreate(subcomm, outviewer));
  PetscCall(PetscViewerSetType(*outviewer, PETSCVIEWERASCII));
  PetscCall(PetscViewerASCIIPushSynchronized(*outviewer));
  ovascii            = (PetscViewer_ASCII *)(*outviewer)->data;
  ovascii->fd        = vascii->fd;
  ovascii->tab       = vascii->tab;
  ovascii->closefile = PETSC_FALSE;

  vascii->sviewer                                      = *outviewer;
  (*outviewer)->format                                 = viewer->format;
  ((PetscViewer_ASCII *)((*outviewer)->data))->bviewer = viewer;
  (*outviewer)->ops->destroy                           = PetscViewerDestroy_ASCII_SubViewer;
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerRestoreSubViewer_ASCII(PetscViewer viewer, MPI_Comm comm, PetscViewer *outviewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)viewer->data;

  PetscFunctionBegin;
  PetscCheck(ascii->sviewer, PETSC_COMM_SELF, PETSC_ERR_ORDER, "SubViewer never obtained from PetscViewer");
  PetscCheck(ascii->sviewer == *outviewer, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "This PetscViewer did not generate this SubViewer");

  PetscCall(PetscViewerASCIIPopSynchronized(*outviewer));
  ascii->sviewer             = NULL;
  (*outviewer)->ops->destroy = PetscViewerDestroy_ASCII;
  PetscCall(PetscViewerDestroy(outviewer));
  PetscCall(PetscViewerASCIIPopSynchronized(viewer));
  PetscFunctionReturn(PETSC_SUCCESS);
}

PetscErrorCode PetscViewerView_ASCII(PetscViewer v, PetscViewer viewer)
{
  PetscViewer_ASCII *ascii = (PetscViewer_ASCII *)v->data;

  PetscFunctionBegin;
  if (ascii->filename) PetscCall(PetscViewerASCIIPrintf(viewer, "Filename: %s\n", ascii->filename));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*MC
   PETSCVIEWERASCII - A viewer that prints to stdout or an ASCII file

  Level: beginner

.seealso: [](sec_viewers), `PETSC_VIEWER_STDOUT_()`, `PETSC_VIEWER_STDOUT_SELF`, `PETSC_VIEWER_STDOUT_WORLD`, `PetscViewerCreate()`, `PetscViewerASCIIOpen()`,
          `PetscViewerMatlabOpen()`, `VecView()`, `DMView()`, `PetscViewerMatlabPutArray()`, `PETSCVIEWERBINARY`, `PETSCVIEWERMATLAB`,
          `PetscViewerFileSetName()`, `PetscViewerFileSetMode()`, `PetscViewerFormat`, `PetscViewerType`, `PetscViewerSetType()`
M*/
PETSC_EXTERN PetscErrorCode PetscViewerCreate_ASCII(PetscViewer viewer)
{
  PetscViewer_ASCII *vascii;

  PetscFunctionBegin;
  PetscCall(PetscNew(&vascii));
  viewer->data = (void *)vascii;

  viewer->ops->destroy          = PetscViewerDestroy_ASCII;
  viewer->ops->flush            = PetscViewerFlush_ASCII;
  viewer->ops->getsubviewer     = PetscViewerGetSubViewer_ASCII;
  viewer->ops->restoresubviewer = PetscViewerRestoreSubViewer_ASCII;
  viewer->ops->view             = PetscViewerView_ASCII;
  viewer->ops->read             = PetscViewerASCIIRead;

  /* defaults to stdout unless set with PetscViewerFileSetName() */
  vascii->fd        = PETSC_STDOUT;
  vascii->mode      = FILE_MODE_WRITE;
  vascii->bviewer   = NULL;
  vascii->subviewer = NULL;
  vascii->sviewer   = NULL;
  vascii->tab       = 0;
  vascii->tab_store = 0;
  vascii->filename  = NULL;
  vascii->closefile = PETSC_TRUE;

  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileSetName_C", PetscViewerFileSetName_ASCII));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileGetName_C", PetscViewerFileGetName_ASCII));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileGetMode_C", PetscViewerFileGetMode_ASCII));
  PetscCall(PetscObjectComposeFunction((PetscObject)viewer, "PetscViewerFileSetMode_C", PetscViewerFileSetMode_ASCII));
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
    PetscViewerASCIISynchronizedPrintf - Prints synchronized output to the specified `PETSCVIEWERASCII` file from
    several processors.  Output of the first processor is followed by that of the
    second, etc.

    Not Collective, must call collective `PetscViewerFlush()` to get the results flushed

    Input Parameters:
+   viewer - the `PETSCVIEWERASCII` `PetscViewer`
-   format - the usual printf() format string

    Level: intermediate

    Notes:
    You must have previously called `PetscViewerASCIIPushSynchronized()` to allow this routine to be called.
    Then you can do multiple independent calls to this routine.

    The actual synchronized print is then done using `PetscViewerFlush()`.
    `PetscViewerASCIIPopSynchronized()` should be then called if we are already done with the synchronized output
    to conclude the "synchronized session".

    So the typical calling sequence looks like
.vb
    PetscViewerASCIIPushSynchronized(viewer);
    PetscViewerASCIISynchronizedPrintf(viewer, ...);
    PetscViewerASCIISynchronizedPrintf(viewer, ...);
    ...
    PetscViewerFlush(viewer);
    PetscViewerASCIISynchronizedPrintf(viewer, ...);
    PetscViewerASCIISynchronizedPrintf(viewer, ...);
    ...
    PetscViewerFlush(viewer);
   PetscViewerASCIIPopSynchronized(viewer);
.ve

    Fortran Note:
      Can only print a single character* string

.seealso: [](sec_viewers), `PetscViewerASCIIPushSynchronized()`, `PetscViewerFlush()`, `PetscViewerASCIIPopSynchronized()`,
          `PetscSynchronizedPrintf()`, `PetscViewerASCIIPrintf()`, `PetscViewerASCIIOpen()`,
          `PetscViewerCreate()`, `PetscViewerDestroy()`, `PetscViewerSetType()`
@*/
PetscErrorCode PetscViewerASCIISynchronizedPrintf(PetscViewer viewer, const char format[], ...)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  PetscMPIInt        rank;
  PetscInt           tab = vascii->tab;
  MPI_Comm           comm;
  FILE              *fp;
  PetscBool          iascii, hasbviewer = PETSC_FALSE;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscValidCharPointer(format, 2);
  PetscCall(PetscObjectTypeCompare((PetscObject)viewer, PETSCVIEWERASCII, &iascii));
  PetscCheck(iascii, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Not ASCII PetscViewer");
  PetscCheck(vascii->allowsynchronized, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONGSTATE, "First call PetscViewerASCIIPushSynchronized() to allow this call");

  PetscCall(PetscObjectGetComm((PetscObject)viewer, &comm));
  PetscCallMPI(MPI_Comm_rank(comm, &rank));

  if (vascii->bviewer) {
    hasbviewer = PETSC_TRUE;
    if (rank == 0) {
      vascii = (PetscViewer_ASCII *)vascii->bviewer->data;
      PetscCall(PetscObjectGetComm((PetscObject)viewer, &comm));
      PetscCallMPI(MPI_Comm_rank(comm, &rank));
    }
  }

  fp = vascii->fd;

  if (rank == 0 && !hasbviewer) { /* First processor prints immediately to fp */
    va_list Argp;
    /* flush my own messages that I may have queued up */
    PrintfQueue next = vascii->petsc_printfqueuebase, previous;
    PetscInt    i;
    for (i = 0; i < vascii->petsc_printfqueuelength; i++) {
      PetscCall(PetscFPrintf(comm, fp, "%s", next->string));
      previous = next;
      next     = next->next;
      PetscCall(PetscFree(previous->string));
      PetscCall(PetscFree(previous));
    }
    vascii->petsc_printfqueue       = NULL;
    vascii->petsc_printfqueuelength = 0;

    while (tab--) PetscCall(PetscFPrintf(PETSC_COMM_SELF, fp, "  "));

    va_start(Argp, format);
    PetscCall((*PetscVFPrintf)(fp, format, Argp));
    va_end(Argp);
    PetscCall(PetscFFlush(fp));
    if (petsc_history) {
      va_start(Argp, format);
      PetscCall((*PetscVFPrintf)(petsc_history, format, Argp));
      va_end(Argp);
      PetscCall(PetscFFlush(petsc_history));
    }
    va_end(Argp);
  } else { /* other processors add to queue */
    char       *string;
    va_list     Argp;
    size_t      fullLength;
    PrintfQueue next;

    PetscCall(PetscNew(&next));
    if (vascii->petsc_printfqueue) {
      vascii->petsc_printfqueue->next = next;
      vascii->petsc_printfqueue       = next;
    } else {
      vascii->petsc_printfqueuebase = vascii->petsc_printfqueue = next;
    }
    vascii->petsc_printfqueuelength++;
    next->size = QUEUESTRINGSIZE;
    PetscCall(PetscCalloc1(next->size, &next->string));
    string = next->string;
    tab *= 2;
    while (tab--) *string++ = ' ';
    va_start(Argp, format);
    PetscCall(PetscVSNPrintf(string, next->size - 2 * vascii->tab, format, &fullLength, Argp));
    va_end(Argp);
    if (fullLength > (size_t)(next->size - 2 * vascii->tab)) {
      PetscCall(PetscFree(next->string));
      next->size = fullLength + 2 * vascii->tab;
      PetscCall(PetscCalloc1(next->size, &next->string));
      string = next->string;
      tab    = 2 * vascii->tab;
      while (tab--) *string++ = ' ';
      va_start(Argp, format);
      PetscCall(PetscVSNPrintf(string, next->size - 2 * vascii->tab, format, NULL, Argp));
      va_end(Argp);
    }
  }
  PetscFunctionReturn(PETSC_SUCCESS);
}

/*@C
   PetscViewerASCIIRead - Reads from a `PETSCVIEWERASCII` file

   Only MPI rank 0 in the `PetscViewer` may call this

   Input Parameters:
+  viewer - the `PETSCVIEWERASCII` viewer
.  data - location to write the data, treated as an array of type indicated by `datatype`
.  num - number of items of data to read
-  datatype - type of data to read

   Output Parameter:
.  count - number of items of data actually read, or `NULL`

   Level: beginner

.seealso: [](sec_viewers), `PetscViewerASCIIOpen()`, `PetscViewerPushFormat()`, `PetscViewerDestroy()`, `PetscViewerCreate()`, `PetscViewerFileSetMode()`, `PetscViewerFileSetName()`
          `VecView()`, `MatView()`, `VecLoad()`, `MatLoad()`, `PetscViewerBinaryGetDescriptor()`,
          `PetscViewerBinaryGetInfoPointer()`, `PetscFileMode`, `PetscViewer`, `PetscViewerBinaryRead()`
@*/
PetscErrorCode PetscViewerASCIIRead(PetscViewer viewer, void *data, PetscInt num, PetscInt *count, PetscDataType dtype)
{
  PetscViewer_ASCII *vascii = (PetscViewer_ASCII *)viewer->data;
  FILE              *fd     = vascii->fd;
  PetscInt           i;
  int                ret = 0;
  PetscMPIInt        rank;

  PetscFunctionBegin;
  PetscValidHeaderSpecific(viewer, PETSC_VIEWER_CLASSID, 1);
  PetscCallMPI(MPI_Comm_rank(PetscObjectComm((PetscObject)viewer), &rank));
  PetscCheck(rank == 0, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Can only be called from process 0 in the PetscViewer");
  for (i = 0; i < num; i++) {
    if (dtype == PETSC_CHAR) ret = fscanf(fd, "%c", &(((char *)data)[i]));
    else if (dtype == PETSC_STRING) ret = fscanf(fd, "%s", &(((char *)data)[i]));
    else if (dtype == PETSC_INT) ret = fscanf(fd, "%" PetscInt_FMT, &(((PetscInt *)data)[i]));
    else if (dtype == PETSC_ENUM) ret = fscanf(fd, "%d", &(((int *)data)[i]));
    else if (dtype == PETSC_INT64) ret = fscanf(fd, "%" PetscInt64_FMT, &(((PetscInt64 *)data)[i]));
    else if (dtype == PETSC_LONG) ret = fscanf(fd, "%ld", &(((long *)data)[i]));
    else if (dtype == PETSC_FLOAT) ret = fscanf(fd, "%f", &(((float *)data)[i]));
    else if (dtype == PETSC_DOUBLE) ret = fscanf(fd, "%lg", &(((double *)data)[i]));
#if defined(PETSC_USE_REAL___FLOAT128)
    else if (dtype == PETSC___FLOAT128) {
      double tmp;
      ret                     = fscanf(fd, "%lg", &tmp);
      ((__float128 *)data)[i] = tmp;
    }
#endif
    else
      SETERRQ(PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Data type %d not supported", (int)dtype);
    PetscCheck(ret, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Conversion error for data type %d", (int)dtype);
    if (ret < 0) break; /* Proxy for EOF, need to check for it in configure */
  }
  if (count) *count = i;
  else PetscCheck(ret >= 0, PETSC_COMM_SELF, PETSC_ERR_ARG_WRONG, "Insufficient data, read only %" PetscInt_FMT " < %" PetscInt_FMT " items", i, num);
  PetscFunctionReturn(PETSC_SUCCESS);
}