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Refuse set() on a read-only instance #1700

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Merged
lingol merged 1 commit into from
Oct 26, 2026
Merged

Refuse set() on a read-only instance #1700

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4 changes: 4 additions & 0 deletions Core/MMKV_IO.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -769,6 +769,10 @@ bool MMKV::setDataForKey(MMBuffer &&data, MMKVKey_t key, bool isDataHolder) {
if ((!isDataHolder && data.length() == 0) || isKeyEmpty(key)) {
return false;
}
if (isReadOnly()) {
MMKVWarning("[%s] file readonly", m_mmapID.c_str());
return false;
}
uint32_t ignoredValueLength = 0;
if (!encodedValueLength(data.length(), isDataHolder, ignoredValueLength)) {
MMKVError("[%s] reject value too large to encode: %zu", m_mmapID.c_str(), data.length());
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15 changes: 15 additions & 0 deletions POSIX/demo/UnitTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1182,6 +1182,20 @@ void testReadOnlyExpiration() {
printf("test read-only expiration: passed\n");
}

void testReadOnlyRejectsSet() {
auto kv = MMKV::mmkvWithID("read_only_set");
kv->clearAll();
assert(kv->set("value1", "key"));
kv->close();

kv = MMKV::mmkvWithID("read_only_set", MMKV_SINGLE_PROCESS | MMKV_READ_ONLY);
assert(!kv->set("value2", "key"));
string value;
assert(kv->getString("key", value) && value == "value1");
kv->close();
printf("test read-only set: passed\n");
}

void testFirstWriteAfterReopenPreservesValue() {
const string id = "first-write-expiration";
auto kv = MMKV::mmkvWithID(id);
Expand Down Expand Up @@ -1351,6 +1365,7 @@ int main(int argc, char *argv[]) {
#endif
testFirstReadAfterReopenRespectsExpiration();
testReadOnlyExpiration();
testReadOnlyRejectsSet();
testFirstWriteAfterReopenPreservesValue();
testFirstWriteAfterReopenOverloads();
}