[GRASS-dev] [GRASS GIS] #2762: more informative error messages in lib/rast/get_row.c

[GRASS GIS]

#2762: more informative error messages in lib/rast/get_row.c
---------------------------+-------------------------
 Reporter:  dylan          |      Owner:  grass-dev@…
     Type:  enhancement    |     Status:  new
 Priority:  minor          |  Milestone:  7.1.0
Component:  Raster         |    Version:  svn-trunk
 Keywords:  error message  |        CPU:  All
 Platform:  All            |
---------------------------+-------------------------
 In the file lib/rast/get_row.c there are several places in which the
 "Error reading raster data..." error message can be generated (grass_trunk
 r66508):

 {{{
 95:     G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 101:    G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 135:    G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 142:    G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 177:    G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 181:    G_fatal_error(_("Error reading raster data for row %d of <%s>"),
 217:    G_fatal_error(_("Error reading raster data via GDAL for row %d of
 <%s>"),
 }}}

 It might be nice to know what exactly triggered these kind of messages,
 especially afer encountering these errors [http://osgeo-
 org.1560.x6.nabble.com/Error-reading-raster-data-for-row-xxx-only-when-
 using-r-series-and-t-rast-series-td5229569.html on a couple] of
 [http://lists.osgeo.org/pipermail/grass-dev/2015-July/075627.html
 occasions].

 I would offer some text, but I don't really understand what is going on in
 code like this:

 {{{
 if (lseek(fcb->data_fd, t1, SEEK_SET) < 0)
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
 }}}

 Something as simple as "Error reading raster data for row %d of <%s>\n
 file offset less than 0, ... blah blah blah" would IMHO help with
 debugging those modules that may have created such a file.

 I would be happy to make the changes if someone is willing to comments on
 the meaning and implications of each case, outlined below:

 {{{
 if (lseek(fcb->data_fd, t1, SEEK_SET) < 0)
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
 }}}

 {{{
  if ((size_t) G_zlib_read(fcb->data_fd, readamount, data_buf, bufsize) !=
 bufsize)
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
 }}}

 {{{
  if (read(fcb->data_fd, cmp, readamount) != readamount) {
         G_freea(cmp);
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
     }
 }}}

 {{{
 if (lseek(fcb->data_fd, (off_t) row * bufsize, SEEK_SET) == -1)
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
 }}}

 {{{
 if (read(fcb->data_fd, data_buf, bufsize) != bufsize)
         G_fatal_error(_("Error reading raster data for row %d of <%s>"),
                       row, fcb->name);
 }}}


 {{{
  if (err != CE_None)
         G_fatal_error(_("Error reading raster data via GDAL for row %d of
 <%s>"),
                       row, fcb->name);
 }}}

--
Ticket URL: <https://trac.osgeo.org/grass/ticket/2762>
GRASS GIS <https://grass.osgeo.org>