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crypto: Do not fail for EINTR during qcrypto_random_bytes

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We can always get EINTR for read; /dev/urandom is no exception.

Rearrange the order of tests for likelihood; allow degenerate buflen==0
case to perform a no-op zero-length read.  This means that the normal
success path is a straight line with a single test for success.

Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-03-13 20:47:32 -07:00
parent 14a356f475
commit 25fb26e4f4
1 changed files with 15 additions and 21 deletions
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36
crypto/random-platform.c
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@ -65,29 +65,23 @@ int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED,
"Unable to read random bytes");
return -1;
}
return 0;
#else
int ret = -1;
int got;
while (buflen > 0) {
got = read(fd, buf, buflen);
if (got < 0) {
error_setg_errno(errp, errno,
"Unable to read random bytes");
goto cleanup;
} else if (!got) {
error_setg(errp,
"Unexpected EOF reading random bytes");
goto cleanup;
while (1) {
ssize_t got = read(fd, buf, buflen);
if (likely(got == buflen)) {
return 0;
}
if (got > 0) {
buflen -= got;
buf += got;
} else if (got == 0) {
error_setg(errp, "Unexpected EOF reading random bytes");
return -1;
} else if (errno != EINTR) {
error_setg_errno(errp, errno, "Unable to read random bytes");
return -1;
}
buflen -= got;
buf += got;
}
ret = 0;
cleanup:
return ret;
#endif
return 0;
}