hashmap: randomize hash functions a bit

[elogind.git] / src / shared / util.c

diff --git a/src/shared/util.c b/src/shared/util.c
index fb42d663a6cfc4cad91a9b0582af35d31eab4627..9be6acfc8f3b45f31be7ec0210cd272d0c053c78 100644 (file)
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2186,8 +2186,10 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
                                         return n > 0 ? n : -errno;
                                 }
 
-                                if (pollfd.revents != POLLIN)
-                                        return n > 0 ? n : -EIO;
+                                /* We knowingly ignore the revents value here,
+                                 * and expect that any error/EOF is reported
+                                 * via read()/write()
+                                 */
 
                                 continue;
                         }
@@ -2234,8 +2236,10 @@ ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
                                         return n > 0 ? n : -errno;
                                 }
 
-                                if (pollfd.revents != POLLOUT)
-                                        return n > 0 ? n : -EIO;
+                                /* We knowingly ignore the revents value here,
+                                 * and expect that any error/EOF is reported
+                                 * via read()/write()
+                                 */
 
                                 continue;
                         }
@@ -2420,6 +2424,25 @@ fallback:
         return random() * RAND_MAX + random();
 }
 
+unsigned random_u(void) {
+        _cleanup_close_ int fd;
+        unsigned u;
+        ssize_t r;
+
+        fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+        if (fd < 0)
+                goto fallback;
+
+        r = loop_read(fd, &u, sizeof(u), true);
+        if (r != sizeof(u))
+                goto fallback;
+
+        return u;
+
+fallback:
+        return random() * RAND_MAX + random();
+}
+
 void rename_process(const char name[8]) {
         assert(name);