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 <Jason@zx2c4.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files 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, &timestamp);
         sha256_hash(&hash, &timestamp, 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;
 }