From 25fb26e4f4b7cd50b9a7314400a2f800a4082b71 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 13 Mar 2019 20:47:32 -0700 Subject: [PATCH] crypto: Do not fail for EINTR during qcrypto_random_bytes MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-by: Daniel P. Berrangé Signed-off-by: Richard Henderson --- crypto/random-platform.c | 36 +++++++++++++++--------------------- 1 file changed, 15 insertions(+), 21 deletions(-) diff --git a/crypto/random-platform.c b/crypto/random-platform.c index f995fc0ef1..260b64564d 100644 --- a/crypto/random-platform.c +++ b/crypto/random-platform.c @@ -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; }