Function StringAppendV

module/src/main/cpp/external/fdutils/stringprintf.cpp:22–56

namespace android::base {
	void StringAppendV(std::string* dst, const char* format, va_list ap) {
		// First try with a small fixed size buffer
		char space[1024] __attribute__((__uninitialized__));
		// It's possible for methods that use a va_list to invalidate
		// the data in it upon use.  The fix is to make a copy
		// of the structure before using it and use that copy instead.
		va_list backup_ap;
		va_copy(backup_ap, ap);
		int result = vsnprintf(space, sizeof(space), format, backup_ap);
		va_end(backup_ap);
		if (result < static_cast<int>(sizeof(space))) {
			if (result >= 0) {
				// Normal case -- everything fit.
				dst->append(space, result);
				return;
			}
			if (result < 0) {
				// Just an error.
				return;
			}
		}
		// Increase the buffer size to the size requested by vsnprintf,
		// plus one for the closing \0.
		int length = result + 1;
		char* buf = new char[length];
		// Restore the va_list before we use it again
		va_copy(backup_ap, ap);
		result = vsnprintf(buf, length, format, backup_ap);
		va_end(backup_ap);
		if (result >= 0 && result < length) {
			// It fit
			dst->append(buf, result);
		}
		delete[] buf;
	}
	std::string StringPrintf(const char* fmt, ...) {
		va_list ap;
		va_start(ap, fmt);