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[174.21.72.5]) by smtp.gmail.com with ESMTPSA id x23-20020a056a000bd700b006e6b180d87asm1582041pfu.35.2024.04.11.13.07.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 11 Apr 2024 13:07:12 -0700 (PDT) Message-ID: <89453f6f-1ffe-4141-a8aa-fde7319f3e17@linaro.org> Date: Thu, 11 Apr 2024 13:07:10 -0700 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 04/13] hw/mips/malta: Add re-usable rng_seed_hex_new() method To: =?UTF-8?Q?Philippe_Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org Cc: qemu-arm@nongnu.org, qemu-block@nongnu.org, qemu-ppc@nongnu.org, Aurelien Jarno , Jiaxun Yang References: <20240411101550.99392-1-philmd@linaro.org> <20240411101550.99392-5-philmd@linaro.org> Content-Language: en-US From: Richard Henderson In-Reply-To: <20240411101550.99392-5-philmd@linaro.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2607:f8b0:4864:20::429; envelope-from=richard.henderson@linaro.org; helo=mail-pf1-x429.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 4/11/24 03:15, Philippe Mathieu-Daudé wrote: > Extract common code from reinitialize_rng_seed() and > load_kernel() to rng_seed_hex_new(). > > Signed-off-by: Philippe Mathieu-Daudé > --- > hw/mips/malta.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/hw/mips/malta.c b/hw/mips/malta.c > index af74008c82..9fc6a7d313 100644 > --- a/hw/mips/malta.c > +++ b/hw/mips/malta.c > @@ -850,15 +850,24 @@ static void G_GNUC_PRINTF(3, 4) prom_set(uint32_t *prom_buf, int index, > va_end(ap); > } > > -static void reinitialize_rng_seed(void *opaque) > +static char *rng_seed_hex_new(void) > { > - char *rng_seed_hex = opaque; > uint8_t rng_seed[32]; > + char rng_seed_hex[sizeof(rng_seed) * 2 + 1]; > > qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed)); > for (size_t i = 0; i < sizeof(rng_seed); ++i) { > sprintf(rng_seed_hex + i * 2, "%02x", rng_seed[i]); > } > + > + return g_strdup(rng_seed_hex); > +} > + > +static void reinitialize_rng_seed(void *opaque) > +{ > + g_autofree char *rng_seed_hex = rng_seed_hex_new(); > + > + strcpy(opaque, rng_seed_hex); > } Though it isn't deprecated, strcpy isn't really any safer than sprintf. We don't need to be copying text around quite as much as this. How about: #define RNG_SEED_SIZE 32 static void rng_seed_hex_new(char buf[2 * RNG_SEED_SIZE + 1]) { static const char hex = "0123456789abcdef"; uint8_t rng_seed[RNG_SEED_SIZE]; qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed)); for (int i = 0; i < RNG_SEED_SIZE; ++i) { buf[i * 2 + 0] = hex[rng_seed[i] / 16]; buf[i * 2 + 1] = hex[rng_seed[i] % 16]; } buf[RNG_SEED_SIZE * 2] = '\0'; } static void reinitialize_rng_seed(void *opaque) { rng_seed_hex_new(opaque); } with little change in load_kernel. r~