Fix ncdump bug when printing VLENs with basetype char

RELEASE_NOTES.md

@@ -7,6 +7,8 @@ This file contains a high-level description of this package's evolution. Release
 
 ## 4.8.1 - TBD
 
+
+* [Bug Fix] Fix ncdump bug when printing VLENs with basetype char. See [Github #1986](https://github.com/Unidata/netcdf-c/issues/1986).  
 * [Bug Fixes] The netcdf-c library was incorrectly determining the scope of types referred to by nc_inq_type_equal. See [Github #1959](https://github.com/Unidata/netcdf-c/pull/1959) for more information.
 * [Bug Fix] Fix bug in use of XGetopt when building under Mingw. See [Github #2009](https://github.com/Unidata/netcdf-c/issues/2009).
 * [Enhancement] Improve the error reporting when attempting to use a filter for which no implementation can be found in HDF5_PLUGIN_PATH. See [Github #2000](https://github.com/Unidata/netcdf-c/pull/2000) for more information.

nc_test4/CMakeLists.txt

@@ -28,6 +28,7 @@ IF(BUILD_UTILITIES)
   SET(NC4_TESTS ${NC4_TESTS} tst_xplatform)
   build_bin_test(renamegroup)
   add_sh_test(nc_test4 run_grp_rename)
+  build_bin_test(tst_charvlenbug)
   ADD_SH_TEST(nc_test4 tst_misc)
   build_bin_test(tst_fillonly)
   ADD_SH_TEST(nc_test4 test_fillonly)

nc_test4/Makefile.am

@@ -35,7 +35,7 @@ tst_h_scalar tst_rename tst_rename2 tst_rename3 tst_h5_endians		\
 tst_atts_string_rewrite tst_hdf5_file_compat tst_fill_attr_vanish	\
 tst_rehash tst_filterparser tst_bug324 tst_types tst_atts3		\
 tst_put_vars tst_elatefill tst_udf tst_put_vars_two_unlim_dim		\
-tst_bug1442
+tst_bug1442 tst_charvlenbug
 
 # Temporary I hoped, but hoped in vain.
 if !ISCYGWIN

nc_test4/tst_charvlenbug.c

@@ -0,0 +1,111 @@
+#define AFIRST
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "netcdf.h"
+
+#define FILE "tst_charvlenbug.nc"
+
+void checkErrorCode(int status, const char* message){
+    if (status != NC_NOERR){
+        fprintf(stderr,"Error code: %d: %s\n",status,message);
+    }
+}
+
+int
+main(int argc, const char * argv[])
+{
+    int ncid;
+    int retval;
+    int dimid_a;
+    int dimid_b;
+    int dimids[2];
+    int varid;
+    int typeid;
+    int ndims, dimids_read[NC_MAX_VAR_DIMS];
+    size_t dimlen;
+    size_t num_items;
+    ptrdiff_t stride[2] = {1, 1};
+    nc_vlen_t vlenPointers[4];
+    nc_vlen_t* readVlenPointers;
+
+#ifdef AFIRST
+    size_t start[2] = {1, 0};
+    size_t count[2] = {2, 2};
+#else
+    size_t start[2] = {0, 1};
+    size_t count[2] = {2, 2};
+#endif
+
+    // set up data
+
+    vlenPointers[0].len = 1; vlenPointers[0].p = "a";
+    vlenPointers[1].len = 2; vlenPointers[1].p = "aa";
+    vlenPointers[2].len = 1; vlenPointers[2].p = "b";
+    vlenPointers[3].len = 2; vlenPointers[3].p = "bb";
+
+    // -- WRITE --
+
+    retval = nc_create(FILE, NC_NETCDF4, &ncid);
+    checkErrorCode(retval, "nc_create");
+
+    // Define dimensions
+    retval = nc_def_dim(ncid, "a", NC_UNLIMITED, &dimid_a);
+    checkErrorCode(retval, "nc_def_dim for 'a'");
+
+    retval = nc_def_dim(ncid, "b", 4, &dimid_b);
+    checkErrorCode(retval, "nc_def_dim for 'b'");
+
+    /* Define VLEN type */
+    retval = nc_def_vlen(ncid,"str",NC_CHAR,&typeid);
+    checkErrorCode(retval, "nc_def_vlen");
+
+    // Define variable
+#ifdef AFIRST
+    dimids[0] = dimid_a;
+    dimids[1] = dimid_b;
+#else
+    dimids[0] = dimid_b;
+    dimids[1] = dimid_a;
+#endif
+    retval = nc_def_var(ncid, "var", typeid, 2, dimids, &varid);
+    checkErrorCode(retval, "nc_def_var");
+
+    // Put variable
+
+    retval = nc_put_vars(ncid, varid, start, count, stride, vlenPointers);
+//    retval = nc_put_vara_string(ncid, varid, start, count, vlenPointers);
+    checkErrorCode(retval, "nc_put_vars_string");
+
+    retval = nc_close(ncid);
+    checkErrorCode(retval, "nc_close(1)");
+
+    // -- READ --
+    retval = nc_open(FILE, NC_NOWRITE, &ncid);
+    checkErrorCode(retval, "nc_open");
+
+    // get dimensions
+    retval = nc_inq_var(ncid, varid, NULL, NULL, &ndims, dimids_read, NULL);
+    checkErrorCode(retval, "nc_inq_var");
+
+    // calculate num elements to read
+    dimlen = 0;
+    num_items = 1;
+    for ( int j = 0; j < ndims; ++j ) {
+        retval = nc_inq_dimlen(ncid, dimids_read[j], &dimlen);
+        checkErrorCode(retval, "nc_inq_dimlen");
+        num_items *= dimlen;
+    }
+
+    // get var
+    readVlenPointers = (nc_vlen_t*)malloc(sizeof(nc_vlen_t)*num_items);
+    retval = nc_get_var(ncid, varid, readVlenPointers);
+    checkErrorCode(retval, "nc_get_var");
+
+    retval = nc_close(ncid);
+    checkErrorCode(retval, "nc_close(2)");
+
+    free(readVlenPointers);
+    return retval;
+}

nc_test4/tst_misc.sh

@@ -5,16 +5,27 @@ if test "x$srcdir" = x ; then srcdir=`pwd`; fi
 
 set -e
 
+ECODE=0
+
 echo "*** Testing phony dimension creation on pure h5 file"
 rm -f ./tmp
 if $NCDUMP -L0 -K ${srcdir}/tdset.h5 >./tmp ; then
 echo "*** Pass: phony dimension creation"
-ECODE=0
 else
 echo "*** Fail: phony dimension creation"
 ECODE=1
 fi
 
+echo "*** Testing char(*) type printout error in ncdump"
+rm -f ./tst_charvlenbug.nc ./tmp
+${execdir}/tst_charvlenbug
+if $NCDUMP ./tst_charvlenbug.nc 2>1 >./tmp ; then
+    echo "*** Pass: char(*) ncdump printout"
+else
+    echo "*** Fail: char(*) ncdump printout"
+    ECODE=1
+fi
+
 rm -f tmp
 
 exit $ECODE

ncdump/dumplib.c

@@ -696,8 +696,11 @@ ncbyte_typ_tostring(const nctype_t *typ, safebuf_t *sfbf, const void *valp) {
 int
 ncchar_typ_tostring(const nctype_t *typ, safebuf_t *sfbf, const void *valp) {
     char sout[PRIM_LEN];
+    char cstr[2];
     int res;
-    res = snprintf(sout, PRIM_LEN, typ->fmt, *(char *)valp);
+cstr[0] = *(char*)valp;
+cstr[1] = '\0';
+    res = snprintf(sout, PRIM_LEN, typ->fmt, cstr);
     assert(res < PRIM_LEN);
     sbuf_cpy(sfbf, sout);
     return sbuf_len(sfbf);