Rename 'free' variable to 'nfree' to not clash with free()

The beauty and horrors of the C - the compiler properly detects variable
shadowing, but you can freely shadow a standard function 'free()' with
variable called 'free'.  And if you reference 'free()' just as 'free'
you get the function pointer which means you can do also pointer
arithmetics, so 'free > 0' is always valid even when you delete the
local variable.

Replace the local variables 'free' with a name that doesn't shadow the
'free()' function to prevent future hard to detect bugs.

diff --git a/lib/dns/qp.c b/lib/dns/qp.c
index 6cd99381659c169833ef69a0ed466d5eb8990c4d..d3930677c69ef63e460f229530e3670488efa89b 100644 (file)
--- a/lib/dns/qp.c
+++ b/lib/dns/qp.c
@@ -716,7 +716,7 @@ chunk_free(dns_qp_t *qp, dns_qpchunk_t chunk) {
  */
 static void
 recycle(dns_qp_t *qp) {
-       unsigned int free = 0;
+       unsigned int nfree = 0;
 
        isc_nanosecs_t start = isc_time_monotonic();
 
@@ -725,15 +725,15 @@ recycle(dns_qp_t *qp) {
                    qp->usage[chunk].exists && !qp->usage[chunk].immutable)
                {
                        chunk_free(qp, chunk);
-                       free++;
+                       nfree++;
                }
        }
 
        isc_nanosecs_t time = isc_time_monotonic() - start;
        atomic_fetch_add_relaxed(&recycle_time, time);
 
-       if (free > 0) {
-               LOG_STATS("qp recycle" PRItime "free %u chunks", time, free);
+       if (nfree > 0) {
+               LOG_STATS("qp recycle" PRItime "free %u chunks", time, nfree);
                LOG_STATS("qp recycle leaf %u live %u used %u free %u hold %u",
                          qp->leaf_count, qp->used_count - qp->free_count,
                          qp->used_count, qp->free_count, qp->hold_count);
@@ -757,7 +757,7 @@ reclaim_chunks_cb(struct rcu_head *arg) {
         * If chunk_max is zero, chunks have already been freed.
         */
        if (qp->chunk_max != 0) {
-               unsigned int free = 0;
+               unsigned int nfree = 0;
                isc_nanosecs_t start = isc_time_monotonic();
 
                INSIST(QP_VALID(qp));
@@ -769,16 +769,16 @@ reclaim_chunks_cb(struct rcu_head *arg) {
                                qp->usage[chunk].snapfree = true;
                        } else {
                                chunk_free(qp, chunk);
-                               free++;
+                               nfree++;
                        }
                }
 
                isc_nanosecs_t time = isc_time_monotonic() - start;
                recycle_time += time;
 
-               if (free > 0) {
+               if (nfree > 0) {
                        LOG_STATS("qp reclaim" PRItime "free %u chunks", time,
-                                 free);
+                                 nfree);
                        LOG_STATS(
                                "qp reclaim leaf %u live %u used %u free %u "
                                "hold %u",
@@ -852,7 +852,7 @@ reclaim_chunks(dns_qpmulti_t *multi) {
  */
 static void
 marksweep_chunks(dns_qpmulti_t *multi) {
-       unsigned int free = 0;
+       unsigned int nfree = 0;
 
        isc_nanosecs_t start = isc_time_monotonic();
 
@@ -873,15 +873,15 @@ marksweep_chunks(dns_qpmulti_t *multi) {
                qpw->usage[chunk].snapmark = false;
                if (qpw->usage[chunk].snapfree && !qpw->usage[chunk].snapshot) {
                        chunk_free(qpw, chunk);
-                       free++;
+                       nfree++;
                }
        }
 
        isc_nanosecs_t time = isc_time_monotonic() - start;
        recycle_time += time;
 
-       if (free > 0) {
-               LOG_STATS("qp marksweep" PRItime "free %u chunks", time, free);
+       if (nfree > 0) {
+               LOG_STATS("qp marksweep" PRItime "free %u chunks", time, nfree);
                LOG_STATS(
                        "qp marksweep leaf %u live %u used %u free %u hold %u",
                        qpw->leaf_count, qpw->used_count - qpw->free_count,
@@ -1319,7 +1319,7 @@ dns_qpmulti_commit(dns_qpmulti_t *multi, dns_qp_t **qptp) {
  */
 void
 dns_qpmulti_rollback(dns_qpmulti_t *multi, dns_qp_t **qptp) {
-       unsigned int free = 0;
+       unsigned int nfree = 0;
 
        REQUIRE(QPMULTI_VALID(multi));
        REQUIRE(multi->writer.transaction_mode == QP_UPDATE);
@@ -1342,7 +1342,7 @@ dns_qpmulti_rollback(dns_qpmulti_t *multi, dns_qp_t **qptp) {
                                INSIST(!multi->rollback->usage[chunk].exists);
                                multi->rollback->base->ptr[chunk] = NULL;
                        }
-                       free++;
+                       nfree++;
                }
        }
 
@@ -1365,7 +1365,7 @@ dns_qpmulti_rollback(dns_qpmulti_t *multi, dns_qp_t **qptp) {
        isc_nanosecs_t time = isc_time_monotonic() - start;
        atomic_fetch_add_relaxed(&rollback_time, time);
 
-       LOG_STATS("qp rollback" PRItime "free %u chunks", time, free);
+       LOG_STATS("qp rollback" PRItime "free %u chunks", time, nfree);
 
        *qptp = NULL;
        UNLOCK(&multi->mutex);

diff --git a/tests/libtest/qp.c b/tests/libtest/qp.c
index 4a6a9ff943911f275263795be31c787965578171..ce29c67b393930d550976ba1f4f620d38e36499d 100644 (file)
--- a/tests/libtest/qp.c
+++ b/tests/libtest/qp.c
@@ -177,8 +177,8 @@ qp_test_dumpmulti(dns_qpmulti_t *multi) {
 
 void
 qp_test_dumpchunks(dns_qp_t *qp) {
-       dns_qpcell_t used = 0;
-       dns_qpcell_t free = 0;
+       dns_qpcell_t used_count = 0;
+       dns_qpcell_t free_count = 0;
        dumpqp(qp, "qp");
        for (dns_qpchunk_t c = 0; c < qp->chunk_max; c++) {
                printf("qp %p chunk %u base %p "
@@ -186,10 +186,11 @@ qp_test_dumpchunks(dns_qp_t *qp) {
                       qp, c, qp->base->ptr[c], qp->usage[c].used,
                       qp->usage[c].free, qp->usage[c].immutable,
                       qp->usage[c].discounted);
-               used += qp->usage[c].used;
-               free += qp->usage[c].free;
+               used_count += qp->usage[c].used;
+               free_count += qp->usage[c].free;
        }
-       printf("qp %p total used %u free %u\n", qp, used, free);
+       printf("qp %p total used %" PRIu32 " free %" PRIu32 "\n", qp,
+              used_count, free_count);
        fflush(stdout);
 }