Second try at fixing numeric data passed through an ECPG SQLDA.

In commit ecfd55795, I removed sqlda.c's checks for ndigits != 0 on the
grounds that we should duplicate the state of the numeric value's digit
buffer even when all the digits are zeroes.  However, that still isn't
quite right, because another possible state of the digit buffer is
buf == digits == NULL (this occurs for a NaN).  As the code now stands,
it'll invoke memcpy with a NULL source address and zero bytecount,
which we know a few platforms crash on.  Hence, reinstate the no-copy
short-circuit, but make it test specifically for buf != NULL rather than
some other condition.  In hindsight, the ndigits test (added by commit
f2ae9f9c3) was almost certainly meant to fix the NaN case not the
all-zeroes case as the associated thread alleged.

As before, back-patch to all supported versions.

Discussion: https://postgr.es/m/1803D792815FC24D871C00D17AE95905C71161@g01jpexmbkw24

1 files changed, 16 insertions, 9 deletions

diff --git a/src/interfaces/ecpg/ecpglib/sqlda.c b/src/interfaces/ecpg/ecpglib/sqlda.c
index 30645a18572..701a5da844d 100644
--- a/src/interfaces/ecpg/ecpglib/sqlda.c
+++ b/src/interfaces/ecpg/ecpglib/sqlda.c
@@ -122,7 +122,8 @@ sqlda_common_total_size(const PGresult *res, int row, enum COMPAT_MODE compat, l
 					num = PGTYPESnumeric_from_asc(val, NULL);
 					if (!num)
 						break;
-					ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
+					if (num->buf)
+						ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
 					PGTYPESnumeric_free(num);
 				}
 				break;
@@ -346,11 +347,14 @@ ecpg_set_compat_sqlda(int lineno, struct sqlda_compat ** _sqlda, const PGresult
 
 					memcpy(sqlda->sqlvar[i].sqldata, num, sizeof(numeric));
 
-					ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
-					memcpy((char *) sqlda + offset, num->buf, num->digits - num->buf + num->ndigits);
+					if (num->buf)
+					{
+						ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
+						memcpy((char *) sqlda + offset, num->buf, num->digits - num->buf + num->ndigits);
 
-					((numeric *) sqlda->sqlvar[i].sqldata)->buf = (NumericDigit *) sqlda + offset;
-					((numeric *) sqlda->sqlvar[i].sqldata)->digits = (NumericDigit *) sqlda + offset + (num->digits - num->buf);
+						((numeric *) sqlda->sqlvar[i].sqldata)->buf = (NumericDigit *) sqlda + offset;
+						((numeric *) sqlda->sqlvar[i].sqldata)->digits = (NumericDigit *) sqlda + offset + (num->digits - num->buf);
+					}
 
 					PGTYPESnumeric_free(num);
 
@@ -532,11 +536,14 @@ ecpg_set_native_sqlda(int lineno, struct sqlda_struct ** _sqlda, const PGresult
 
 					memcpy(sqlda->sqlvar[i].sqldata, num, sizeof(numeric));
 
-					ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
-					memcpy((char *) sqlda + offset, num->buf, num->digits - num->buf + num->ndigits);
+					if (num->buf)
+					{
+						ecpg_sqlda_align_add_size(next_offset, sizeof(int), num->digits - num->buf + num->ndigits, &offset, &next_offset);
+						memcpy((char *) sqlda + offset, num->buf, num->digits - num->buf + num->ndigits);
 
-					((numeric *) sqlda->sqlvar[i].sqldata)->buf = (NumericDigit *) sqlda + offset;
-					((numeric *) sqlda->sqlvar[i].sqldata)->digits = (NumericDigit *) sqlda + offset + (num->digits - num->buf);
+						((numeric *) sqlda->sqlvar[i].sqldata)->buf = (NumericDigit *) sqlda + offset;
+						((numeric *) sqlda->sqlvar[i].sqldata)->digits = (NumericDigit *) sqlda + offset + (num->digits - num->buf);
+					}
 
 					PGTYPESnumeric_free(num);