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glib-aux: simplify logic in nm_utils_random_bytes()

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There should be no change in behavior.

(cherry picked from commit 62c60653a7)
This commit is contained in:
Thomas Haller 2021-07-09 07:56:29 +02:00
parent 139fc5c81e
commit f84ebc4611
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GPG key ID: 29C2366E4DFC5728
1 changed files with 27 additions and 38 deletions
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65
src/libnm-glib-aux/nm-random-utils.c
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@ -190,9 +190,7 @@ nm_utils_random_bytes(void *p, size_t n)
int fd;
int r;
gboolean has_high_quality = TRUE;
gboolean urandom_success;
guint8 * buf = p;
gboolean avoid_urandom = FALSE;
guint8 * buf = p;
g_return_val_if_fail(p, FALSE);
g_return_val_if_fail(n > 0, FALSE);
@ -213,7 +211,6 @@ nm_utils_random_bytes(void *p, size_t n)
nm_assert(r < n);
buf += r;
n -= r;
has_high_quality = FALSE;
/* At this point, we don't want to read /dev/urandom, because
* the entropy pool is low (early boot?), and asking for more
@ -223,47 +220,39 @@ nm_utils_random_bytes(void *p, size_t n)
* itself with g_rand_new(). That also will read /dev/urandom, but as
* we do that only once, we don't care. But in general, we are here in
* a situation where we want to avoid reading /dev/urandom too much. */
avoid_urandom = TRUE;
goto out_bad_random;
}
if (errno == ENOSYS) {
/* no support for getrandom(). We don't know whether
* we urandom will give us good quality. Assume yes. */
have_syscall = FALSE;
} else {
if (errno == ENOSYS) {
/* no support for getrandom(). We don't know whether
* we urandom will give us good quality. Assume yes. */
have_syscall = FALSE;
} else {
/* unknown error. We'll read urandom below, but we don't have
* high-quality randomness. */
has_high_quality = FALSE;
}
/* unknown error. We'll read urandom below, but we don't have
* high-quality randomness. */
has_high_quality = FALSE;
}
}
}
#endif
urandom_success = FALSE;
if (!avoid_urandom) {
fd_open:
fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOCTTY);
if (fd < 0) {
r = errno;
if (r == EINTR)
goto fd_open;
} else {
r = nm_utils_fd_read_loop_exact(fd, buf, n, TRUE);
nm_close(fd);
if (r >= 0)
urandom_success = TRUE;
}
fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC | O_NOCTTY);
if (fd < 0) {
if (errno == EINTR)
goto fd_open;
goto out_bad_random;
}
r = nm_utils_fd_read_loop_exact(fd, buf, n, TRUE);
nm_close(fd);
if (r >= 0)
return has_high_quality;
if (!urandom_success) {
/* we failed to fill the bytes reading from urandom.
* Fill the bits using our pseudo random numbers.
*
* We don't have good quality.
*/
has_high_quality = FALSE;
_bad_random_bytes(buf, n);
}
return has_high_quality;
out_bad_random:
/* we failed to fill the bytes reading from urandom.
* Fill the bits using our pseudo random numbers.
*
* We don't have good quality.
*/
_bad_random_bytes(buf, n);
return FALSE;
}