diff --git a/misc/subr.c b/misc/subr.c
index 729d588..e16a7dc 100644
--- a/misc/subr.c
+++ b/misc/subr.c
@@ -174,3 +174,35 @@ rand_between(long min, long max)
 {
     return min + (long)rint((double)random() * (max - min) / RAND_MAX);
 }
+
+int
+write_fully(int fd, const void *buf, size_t len)
+{
+    ssize_t nw;
+    size_t off = 0;
+
+    while (off < len) {
+        nw = write(fd, buf + off, len - off);
+        if (nw == -1)
+            return errno;
+        off += nw;
+    }
+    return 0;
+}
+
+int
+read_fully(int fd, void *buf, size_t len)
+{
+    ssize_t nread;
+    size_t off = 0;
+
+    while (off < len) {
+        nread = read(fd, buf + off, len - off);
+        if (nread == 0)
+            return ECONNRESET;
+        else if (nread == -1)
+            return errno;
+        off += nread;
+    }
+    return 0;
+}
diff --git a/misc/subr.h b/misc/subr.h
index 8ad42c2..0a6223a 100644
--- a/misc/subr.h
+++ b/misc/subr.h
@@ -24,4 +24,7 @@ int canon_path(const char *path, char **res);
 
 long rand_between(long min, long max);
 
+int read_fully(int fd, void *buf, size_t len);
+int write_fully(int fd, const void *buf, size_t len);
+
 #endif