From f9ea8ba5ed6d43b8b233eac433521eb158e359d1 Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Thu, 21 Apr 2022 12:37:32 +0200 Subject: [PATCH] seedrng: code-golf even smaller Since we're passing 0 as the timeout, we don't need safe_poll. Remove cleanup at end of program, since OS does that, which lets us simplify control flow. Factor repeated function calls into ternary loop. function old new delta seedrng_main 1061 1459 +398 seed_from_file_if_exists 468 - -468 ------------------------------------------------------------------------------ (add/remove: 0/1 grow/shrink: 1/0 up/down: 398/-468) Total: -70 bytes text data bss dec hex filename 1052781 16515 1816 1071112 105808 busybox_old 1052711 16515 1816 1071042 1057c2 busybox_unstripped Signed-off-by: Jason A. Donenfeld Signed-off-by: Bernhard Reutner-Fischer --- util-linux/seedrng.c | 42 ++++++++++++++---------------------------- 1 file changed, 14 insertions(+), 28 deletions(-) diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c index 5a41addf0..374e7f676 100644 --- a/util-linux/seedrng.c +++ b/util-linux/seedrng.c @@ -102,7 +102,7 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable) }; if (random_fd.fd < 0) return -1; - *is_creditable = safe_poll(&random_fd, 1, 0) == 1; + *is_creditable = poll(&random_fd, 1, 0) == 1; close(random_fd.fd); } else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len) return 0; @@ -174,15 +174,13 @@ int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE; int seedrng_main(int argc UNUSED_PARAM, char *argv[]) { const char *seed_dir = DEFAULT_SEED_DIR, *creditable_seed, *non_creditable_seed; - int ret, fd = -1, dfd = -1, program_ret = 0; + int fd, dfd, program_ret = 0; uint8_t new_seed[MAX_SEED_LEN]; size_t new_seed_len; - bool new_seed_creditable; - bool skip_credit = false; + bool new_seed_creditable, skip_credit = false; struct timespec timestamp = { 0 }; sha256_ctx_t hash; - int opt; enum { OPT_d = (1 << 0), OPT_n = (1 << 1) @@ -194,8 +192,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) ; #endif - opt = getopt32long(argv, "d:n", longopts, &seed_dir); - skip_credit = opt & OPT_n; + skip_credit = getopt32long(argv, "d:n", longopts, &seed_dir) & OPT_n; creditable_seed = concat_path_file(seed_dir, CREDITABLE_SEED_NAME); non_creditable_seed = concat_path_file(seed_dir, NON_CREDITABLE_SEED_NAME); @@ -207,11 +204,8 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) bb_perror_msg_and_die("unable to %s seed directory", "create"); dfd = open(seed_dir, O_DIRECTORY | O_RDONLY); - if (dfd < 0 || flock(dfd, LOCK_EX) < 0) { - bb_perror_msg("unable to %s seed directory", "lock"); - program_ret = 1; - goto out; - } + if (dfd < 0 || flock(dfd, LOCK_EX) < 0) + bb_perror_msg_and_die("unable to %s seed directory", "lock"); sha256_begin(&hash); sha256_hash(&hash, "SeedRNG v1 Old+New Prefix", 25); @@ -220,16 +214,14 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) clock_gettime(CLOCK_BOOTTIME, ×tamp); sha256_hash(&hash, ×tamp, sizeof(timestamp)); - ret = seed_from_file_if_exists(non_creditable_seed, dfd, false, &hash); - if (ret < 0) - program_ret |= 1 << 1; - ret = seed_from_file_if_exists(creditable_seed, dfd, !skip_credit, &hash); - if (ret < 0) - program_ret |= 1 << 2; + for (int i = 1; i < 3; ++i) { + if (seed_from_file_if_exists(i == 1 ? non_creditable_seed : creditable_seed, + dfd, i == 1 ? false : !skip_credit, &hash) < 0) + program_ret |= 1 << i; + } new_seed_len = determine_optimal_seed_len(); - ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable); - if (ret < 0) { + if (read_new_seed(new_seed, new_seed_len, &new_seed_creditable) < 0) { bb_perror_msg("unable to%s seed", " read new"); new_seed_len = SHA256_OUTSIZE; memset(new_seed, 0, SHA256_OUTSIZE); @@ -243,17 +235,11 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400); if (fd < 0 || full_write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) { bb_perror_msg("unable to%s seed", " write"); - program_ret |= 1 << 4; - goto out; + return program_ret | (1 << 4); } if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) { bb_simple_perror_msg("unable to make new seed creditable"); - program_ret |= 1 << 5; + return program_ret | (1 << 5); } -out: - if (ENABLE_FEATURE_CLEAN_UP && fd >= 0) - close(fd); - if (ENABLE_FEATURE_CLEAN_UP && dfd >= 0) - close(dfd); return program_ret; }