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db: Fix db_get_field() on an empty array field.

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This fixes a bug introduced with the dynamic-array branch.
The new version of db_get_field() was using the dbr_size_n() macro to
calculate the offset to the start of the buffer area to be zeroed, but
when nRequest is zero this gives the wrong result; the dbr_ structures
always contain at least one value element, and dbr_size_n() thus has
to include that in its size calculation.
This commit is contained in:
Andrew Johnson
2010-10-27 13:26:56 -05:00
parent a5d4572691
commit 2bb3074fab
1 changed files with 10 additions and 6 deletions
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16
src/db/db_access.c
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@@ -152,12 +152,16 @@ int epicsShareAPI db_get_field(struct dbAddr *paddr,
long nRequest = no_elements;
int result = db_get_field_and_count(
paddr, buffer_type, pbuffer, &nRequest, pfl);
if (nRequest < no_elements)
/* If the database request returned fewer elements than requested then
* fill out the remainder of the array with zeros. */
memset(
(char *)pbuffer + dbr_size_n(buffer_type, nRequest), 0,
(no_elements - nRequest) * dbr_value_size[buffer_type]);
if (nRequest < no_elements) {
/* The database request returned fewer elements than requested, so
* fill the remainder of the buffer with zeros.
*/
int val_size = dbr_value_size[buffer_type];
int offset = dbr_size[buffer_type] + (nRequest - 1) * val_size;
int nbytes = (no_elements - nRequest) * val_size;
memset((char *)pbuffer + offset, 0, nbytes);
}
return result;
}