We can always get EINTR for read; /dev/urandom is no exception.
Clean up return paths and avoid unnecessary goto.

Cc: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 crypto/random-platform.c | 33 +++++++++++++--------------------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/crypto/random-platform.c b/crypto/random-platform.c
index f995fc0ef1..0866f216dc 100644
--- a/crypto/random-platform.c
+++ b/crypto/random-platform.c
@@ -65,29 +65,22 @@ 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;
+        ssize_t got = read(fd, buf, buflen);
+        if (unlikely(got <= 0)) {
+            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;
+            }
+        } else {
+            buflen -= got;
+            buf += got;
         }
-        buflen -= got;
-        buf += got;
     }
-
-    ret = 0;
- cleanup:
-    return ret;
 #endif
+    return 0;
 }
-- 
2.17.1

On Wed, Mar 13, 2019 at 09:55:15PM -0700, Richard Henderson wrote:
> We can always get EINTR for read; /dev/urandom is no exception.
> Clean up return paths and avoid unnecessary goto.
> 
> Cc: Daniel P. Berrangé <berrange@redhat.com>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  crypto/random-platform.c | 33 +++++++++++++--------------------
>  1 file changed, 13 insertions(+), 20 deletions(-)
> 
> diff --git a/crypto/random-platform.c b/crypto/random-platform.c
> index f995fc0ef1..0866f216dc 100644
> --- a/crypto/random-platform.c
> +++ b/crypto/random-platform.c
> @@ -65,29 +65,22 @@ 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;
> +        ssize_t got = read(fd, buf, buflen);
> +        if (unlikely(got <= 0)) {

Not seeing a the need for the unlikely() call there - I'd
expect any benefit is dwarved by the read syscall time.

> +            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;
> +            }
> +        } else {
> +            buflen -= got;
> +            buf += got;
>          }
> -        buflen -= got;
> -        buf += got;
>      }
> -
> -    ret = 0;
> - cleanup:
> -    return ret;
>  #endif
> +    return 0;
>  }

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

Regards,
Daniel
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