Enable ctl on partial mib and partial name

include/jemalloc/internal/ctl.h

@@ -102,6 +102,8 @@ int ctl_bymib(tsd_t *tsd, const size_t *mib, size_t miblen, void *oldp,
     size_t *oldlenp, void *newp, size_t newlen);
 int ctl_mibnametomib(tsd_t *tsd, size_t *mib, size_t miblen, const char *name,
     size_t *miblenp);
+int ctl_bymibname(tsd_t *tsd, size_t *mib, size_t miblen, const char *name,
+    size_t *miblenp, void *oldp, size_t *oldlenp, void *newp, size_t newlen);
 bool ctl_boot(void);
 void ctl_prefork(tsdn_t *tsdn);
 void ctl_postfork_parent(tsdn_t *tsdn);

src/ctl.c

@@ -1558,6 +1558,51 @@ label_return:
 	return(ret);
 }
 
+int
+ctl_bymibname(tsd_t *tsd, size_t *mib, size_t miblen, const char *name,
+    size_t *miblenp, void *oldp, size_t *oldlenp, void *newp, size_t newlen) {
+	int ret;
+	const ctl_named_node_t *node;
+
+	if (!ctl_initialized && ctl_init(tsd)) {
+		ret = EAGAIN;
+		goto label_return;
+	}
+
+	ret = ctl_lookupbymib(tsd_tsdn(tsd), &node, mib, miblen);
+	if (ret != 0) {
+		goto label_return;
+	}
+	if (node == NULL || node->ctl != NULL) {
+		ret = ENOENT;
+		goto label_return;
+	}
+
+	assert(miblenp != NULL);
+	assert(*miblenp >= miblen);
+	*miblenp -= miblen;
+	/*
+	 * The same node supplies the starting node and stores the ending node.
+	 */
+	ret = ctl_lookup(tsd_tsdn(tsd), node, name, &node, mib + miblen,
+	    miblenp);
+	*miblenp += miblen;
+	if (ret != 0) {
+		goto label_return;
+	}
+
+	if (node != NULL && node->ctl) {
+		ret = node->ctl(tsd, mib, *miblenp, oldp, oldlenp, newp,
+		    newlen);
+	} else {
+		/* The name refers to a partial path through the ctl tree. */
+		ret = ENOENT;
+	}
+
+label_return:
+	return(ret);
+}
+
 bool
 ctl_boot(void) {
 	if (malloc_mutex_init(&ctl_mtx, "ctl", WITNESS_RANK_CTL,

test/unit/mallctl.c

@@ -187,6 +187,56 @@ TEST_BEGIN(test_mallctlmibnametomib) {
 }
 TEST_END
 
+TEST_BEGIN(test_mallctlbymibname) {
+	size_t mib[4];
+	size_t miblen = 4;
+	uint32_t result, result_ref;
+	size_t len_result = sizeof(uint32_t);
+
+	tsd_t *tsd = tsd_fetch();
+
+	/* Error cases. */
+
+	assert_d_eq(mallctlnametomib("arenas", mib, &miblen), 0,
+	    "Unexpected mallctlnametomib() failure");
+	assert_zu_eq(miblen, 1, "");
+
+	miblen = 4;
+	assert_d_eq(ctl_bymibname(tsd, mib, 1, "bin.0", &miblen,
+	    &result, &len_result, NULL, 0), ENOENT, "");
+	miblen = 4;
+	assert_d_eq(ctl_bymibname(tsd, mib, 1, "bin.0.bob", &miblen,
+	    &result, &len_result, NULL, 0), ENOENT, "");
+	assert_zu_eq(miblen, 4, "");
+
+	/* Valid cases. */
+
+	assert_d_eq(mallctl("arenas.bin.0.nregs", &result_ref, &len_result,
+	    NULL, 0), 0, "Unexpected mallctl() failure");
+	miblen = 4;
+
+	assert_d_eq(ctl_bymibname(tsd, mib, 0, "arenas.bin.0.nregs", &miblen,
+	    &result, &len_result, NULL, 0), 0, "");
+	assert_zu_eq(miblen, 4, "");
+	expect_zu_eq(result, result_ref, "Unexpected result");
+
+	assert_d_eq(ctl_bymibname(tsd, mib, 1, "bin.0.nregs", &miblen, &result,
+	    &len_result, NULL, 0), 0, "");
+	assert_zu_eq(miblen, 4, "");
+	expect_zu_eq(result, result_ref, "Unexpected result");
+
+	assert_d_eq(ctl_bymibname(tsd, mib, 2, "0.nregs", &miblen, &result,
+	    &len_result, NULL, 0), 0, "");
+	assert_zu_eq(miblen, 4, "");
+	expect_zu_eq(result, result_ref, "Unexpected result");
+
+	assert_d_eq(ctl_bymibname(tsd, mib, 3, "nregs", &miblen, &result,
+	    &len_result, NULL, 0), 0, "");
+	assert_zu_eq(miblen, 4, "");
+	expect_zu_eq(result, result_ref, "Unexpected result");
+}
+TEST_END
+
 TEST_BEGIN(test_mallctl_config) {
 #define TEST_MALLCTL_CONFIG(config, t) do {				\
 	t oldval;							\
@@ -1178,6 +1228,7 @@ main(void) {
 	    test_mallctlnametomib_short_mib,
 	    test_mallctlnametomib_short_name,
 	    test_mallctlmibnametomib,
+	    test_mallctlbymibname,
 	    test_mallctl_config,
 	    test_mallctl_opt,
 	    test_manpage_example,