seedrng: compress format strings with %s arguments

- Avoid an xstrdup call with seed_dir.
- Compress format strings with %s arguments.
- Open /dev/urandom for add entropy ioctl rather than /dev/random, so that
  /dev/random is only used for the already-sightly-flawed poll() check for
  creditability.

function                                             old     new   delta
seedrng_main                                         948     958     +10
seed_from_file_if_exists                             410     417      +7
.rodata                                           108338  108206    -132
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/1 up/down: 17/-132)          Total: -115 bytes
   text	   data	    bss	    dec	    hex	filename
 975829	   4227	   1816	 981872	  efb70	busybox_old
 975714	   4227	   1816	 981757	  efafd	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, 10 insertions, 12 deletions

diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c
index 5735dc059..5a41addf0 100644
--- a/util-linux/seedrng.c
+++ b/util-linux/seedrng.c
@@ -129,7 +129,7 @@ static int seed_rng(uint8_t *seed, size_t len, bool credit)
         }
         memcpy(req.buffer, seed, len);
 
-        random_fd = open("/dev/random", O_RDONLY);
+        random_fd = open("/dev/urandom", O_RDONLY);
         if (random_fd < 0)
                 return -1;
         ret = ioctl(random_fd, RNDADDENTROPY, &req);
@@ -150,11 +150,11 @@ static int seed_from_file_if_exists(const char *filename, int dfd, bool credit,
         if (seed_len < 0) {
                 if (errno == ENOENT)
                         return 0;
-                bb_simple_perror_msg("unable to read seed file");
+                bb_perror_msg("unable to%s seed", " read");
                 return -1;
         }
         if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
-                bb_simple_perror_msg("unable to remove seed, so not seeding");
+                bb_perror_msg("unable to%s seed", " remove");
                 return -1;
         } else if (!seed_len)
                 return 0;
@@ -164,7 +164,7 @@ static int seed_from_file_if_exists(const char *filename, int dfd, bool credit,
 
         printf("Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without");
         if (seed_rng(seed, seed_len, credit) < 0) {
-                bb_simple_perror_msg("unable to seed");
+                bb_perror_msg("unable to%s seed", "");
                 return -1;
         }
         return 0;
@@ -173,7 +173,7 @@ static int seed_from_file_if_exists(const char *filename, int dfd, bool credit,
 int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
 int seedrng_main(int argc UNUSED_PARAM, char *argv[])
 {
-        char *seed_dir, *creditable_seed, *non_creditable_seed;
+        const char *seed_dir = DEFAULT_SEED_DIR, *creditable_seed, *non_creditable_seed;
         int ret, fd = -1, dfd = -1, program_ret = 0;
         uint8_t new_seed[MAX_SEED_LEN];
         size_t new_seed_len;
@@ -195,8 +195,6 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
 #endif
 
         opt = getopt32long(argv, "d:n", longopts, &seed_dir);
-        if (!(opt & OPT_d) || !seed_dir)
-                seed_dir = xstrdup(DEFAULT_SEED_DIR);
         skip_credit = opt & OPT_n;
         creditable_seed = concat_path_file(seed_dir, CREDITABLE_SEED_NAME);
         non_creditable_seed = concat_path_file(seed_dir, NON_CREDITABLE_SEED_NAME);
@@ -206,11 +204,11 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
                 bb_simple_error_msg_and_die(bb_msg_you_must_be_root);
 
         if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
-                bb_simple_perror_msg_and_die("unable to create seed directory");
+                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_simple_perror_msg("unable to lock seed directory");
+                bb_perror_msg("unable to %s seed directory", "lock");
                 program_ret = 1;
                 goto out;
         }
@@ -232,7 +230,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         new_seed_len = determine_optimal_seed_len();
         ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable);
         if (ret < 0) {
-                bb_simple_perror_msg("unable to read new seed");
+                bb_perror_msg("unable to%s seed", " read new");
                 new_seed_len = SHA256_OUTSIZE;
                 memset(new_seed, 0, SHA256_OUTSIZE);
                 program_ret |= 1 << 3;
@@ -241,10 +239,10 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         sha256_hash(&hash, new_seed, new_seed_len);
         sha256_end(&hash, new_seed + new_seed_len - SHA256_OUTSIZE);
 
-        printf("Saving %zu bits of %s seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
+        printf("Saving %zu bits of %screditable seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "" : "non-");
         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_simple_perror_msg("unable to write seed file");
+                bb_perror_msg("unable to%s seed", " write");
                 program_ret |= 1 << 4;
                 goto out;
         }