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Free the non-blocking error array before a raise #613

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Free the non-blocking error array before a raise #613

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7aa35d7
fix(ext): free the non-blocking errors before a raise
navidemad Oct 15, 2026
6909e37
refactor(ext): use the RB_ALLOCV_N and RB_ALLOCV_END macros
navidemad Nov 8, 2026
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
## (unreleased)

* Free the errors that a non-blocking call collects before the extension raises them. Each SQL Server error no longer leaks about 4 KB of native memory.

## 3.4.1

* Register the C globals that hold Ruby classes and modules with the GC, so raising `TinyTds::Error` after GC compaction no longer crashes with a segmentation fault. Fixes #608.
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26 changes: 19 additions & 7 deletions ext/tiny_tds/result.c
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Expand Up @@ -121,16 +121,30 @@ static void nogvl_cleanup(DBPROCESS *client)
exceptions based on errors from SQL Server.
*/
short int i;
short int errors_length = userdata->nonblocking_errors_length;

for (i = 0; i < userdata->nonblocking_errors_length; i++) {
tinytds_errordata error = userdata->nonblocking_errors[i];
/*
A raise longjmps out of this function and skips the code after it.
Thus copy the errors into a buffer that Ruby manages, and free the malloc'd array first.
RB_ALLOCV_N registers the buffer with the GC: if a raise skips RB_ALLOCV_END, the GC frees it.
*/
VALUE errors_buffer;
tinytds_errordata *errors = RB_ALLOCV_N(tinytds_errordata, errors_buffer, errors_length);
MEMCPY(errors, userdata->nonblocking_errors, tinytds_errordata, errors_length);
free(userdata->nonblocking_errors);
userdata->nonblocking_errors = NULL;
userdata->nonblocking_errors_length = 0;
userdata->nonblocking_errors_size = 0;

for (i = 0; i < errors_length; i++) {
tinytds_errordata error = errors[i];

// lookahead to drain any info messages ahead of raising error
if (!error.is_message) {
short int j;

for (j = i; j < userdata->nonblocking_errors_length; j++) {
tinytds_errordata msg_error = userdata->nonblocking_errors[j];
for (j = i; j < errors_length; j++) {
tinytds_errordata msg_error = errors[j];

if (msg_error.is_message) {
rb_tinytds_raise_error(client, msg_error);
Expand All @@ -141,9 +155,7 @@ static void nogvl_cleanup(DBPROCESS *client)
rb_tinytds_raise_error(client, error);
}

free(userdata->nonblocking_errors);
userdata->nonblocking_errors_length = 0;
userdata->nonblocking_errors_size = 0;
RB_ALLOCV_END(errors_buffer);
}

static RETCODE nogvl_dbsqlok(DBPROCESS *client)
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