using array of char pointers gives wrong results

Hi,
When array of char * is used as target for the FETCH statement returning
more than one row, it tries to store all the result in the first element.
PFA test_char_select.pgc, which fetches first 3 relnames from pg_class
ordered by relname. The program prints following result

steps to compile and build the program
ecpg -c -I<ecpg_include_dir> test_char_select.pgc
cc -I<pg installation include dir> -g -c -o test_char_select.o
test_char_select.c
cc -g test_char_select.o -L<pg installation lib dir> -lecpg -lpq
-lpgtypes -o test_char_select

output
./test_char_select
relname=___pg_foreign_table_columns
relname=
relname=

The first three relnames should have been
postgres=# select relname from pg_class order by relname limit 3;
relname
---------------------------
_pg_foreign_data_wrappers
_pg_foreign_servers
_pg_foreign_table_columns

It's obvious that the first element of the array is being overwritten with
an offset of 1.

This happens because, the array of char pointer is dumped as
/* Fetch multiple columns into one structure. */
{ ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_normal, "fetch 3 from cur1",
ECPGt_EOIT,
ECPGt_char,(strings),(long)0,(long)3,*(1)*sizeof(char)*,
ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EORT);

Since the offset is 1, the next result overwrites the previous result
except for the first byte.

PFA patch ecpg_char_ptr_arr.patch to fix this issue. It has changes as
follows
1. Dump array of char pointer with right offset i.e. sizeof(char *)
2. While reading array of char pointer in ecpg_do_prologue(), use the
address instead of the value at that address
3. The pointer arithmetic should treat such variable as char **, instead of
char *

ECPG regression tests do not show any failures with this patch.
--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company