diff --git a/src/liblimb/fdpatrim.h/fdpatrim_add.c b/src/liblimb/fdpatrim.h/fdpatrim_add.c
new file mode 100644
index 0000000..6bde27f
--- /dev/null
+++ b/src/liblimb/fdpatrim.h/fdpatrim_add.c
@@ -0,0 +1,22 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#include <skalibs/allreadwrite.h>
+#include <limb/fdpatrim.h>
+#include <limb/patrim.h>
+
+int
+fdpatrim_add(int fd, u64 id, u64 u, const char *data)
+{
+    char buf[18];
+    int n;
+
+    n = patrim_put(buf, sizeof(buf), 0, id, u);
+    if (fd_write(fd, buf, n) != n)
+        return 0;
+
+    if (patrim_isblob(id) && fd_write(fd, data, (size_t) u) != (ssize_t) u)
+        return 0;
+
+    return 1;
+}
diff --git a/src/liblimb/fdpatrim.h/fdpatrim_addv.c b/src/liblimb/fdpatrim.h/fdpatrim_addv.c
new file mode 100644
index 0000000..fab71f1
--- /dev/null
+++ b/src/liblimb/fdpatrim.h/fdpatrim_addv.c
@@ -0,0 +1,25 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <limb/fdpatrim.h>
+#include <limb/patrim.h>
+#include <limb/siovec.h>
+
+int
+fdpatrim_addv(int fd, u64 id, const struct iovec v[], unsigned int n)
+{
+    char buf[18];
+    u64 l;
+    int r;
+
+    if (!patrim_isblob(id)) return (errno = EINVAL, 0);
+
+    l = siov_len(v, n);
+    r = patrim_put(buf, sizeof(buf), 0, id, l);
+    if (fd_write(fd, buf, r) != r || fd_writev(fd, v, n) != (ssize_t) l)
+        return 0;
+
+    return 1;
+}
diff --git a/src/liblimb/fdpatrim.h/fdpatrim_get.c b/src/liblimb/fdpatrim.h/fdpatrim_get.c
new file mode 100644
index 0000000..7622dc4
--- /dev/null
+++ b/src/liblimb/fdpatrim.h/fdpatrim_get.c
@@ -0,0 +1,25 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#include <skalibs/allreadwrite.h>
+#include <limb/fdpatrim.h>
+#include <limb/u64.h>
+
+int
+fdpatrim_get(int fd, u64 *id, u64 *u)
+{
+    char buf[9];
+    int r = 0;
+
+    for (;;) {
+        if (fd_read(fd, buf + r++, 1) != 1)
+            return 0;
+        if (u64_unpack_trim(id, buf, r) == r) {
+            if (id == u) break;
+            id = u;
+            r = 0;
+        }
+    }
+
+    return 1;
+}
diff --git a/src/liblimb/fdpatrim.h/fdpatrim_initr.c b/src/liblimb/fdpatrim.h/fdpatrim_initr.c
new file mode 100644
index 0000000..aaac438
--- /dev/null
+++ b/src/liblimb/fdpatrim.h/fdpatrim_initr.c
@@ -0,0 +1,30 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <limb/fdpatrim.h>
+#include <limb/u32.h>
+#include <limb/u64.h>
+
+int
+fdpatrim_initr(int fd, u32 *magic, u64 *ver)
+{
+    if (fd_read(fd, (char *) magic, sizeof(u32)) != sizeof(u32))
+        return 0;
+    u32p_be(magic);
+
+    if (*magic & 0xf0f0f000 != 0xa0e0f000)
+        return (errno = EINVAL, 0);
+
+    char buf[9];
+    int r = 0;
+    for (;;) {
+        if (fd_read(fd, buf + r++, 1) != 1)
+            return 0;
+        if (u64_unpack_trim(ver, buf, r) == r)
+            break;
+    }
+
+    return 1;
+}
diff --git a/src/liblimb/fdpatrim.h/fdpatrim_initw.c b/src/liblimb/fdpatrim.h/fdpatrim_initw.c
new file mode 100644
index 0000000..9155498
--- /dev/null
+++ b/src/liblimb/fdpatrim.h/fdpatrim_initw.c
@@ -0,0 +1,28 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <limb/fdpatrim.h>
+#include <limb/siovec.h>
+#include <limb/u32.h>
+#include <limb/u64.h>
+
+int
+fdpatrim_initw(int fd, u32 magic, u64 ver)
+{
+    char buf[9];
+    struct iovec v[2];
+
+    if (magic & 0xf0f0f000 != 0xa0e0f000)
+        return (errno = EINVAL, -1);
+
+    u32p_be(&magic);
+    v[0].iov_base = &magic;
+    v[0].iov_len = sizeof(u32);
+
+    v[1].iov_base = buf;
+    v[1].iov_len = u64_pack_trim(buf, sizeof(buf), ver);
+
+    return fd_writev(fd, v, 2) == (ssize_t) siov_len(v, 2);
+}
diff --git a/src/liblimb/include/limb/fdpatrim.h b/src/liblimb/include/limb/fdpatrim.h
new file mode 100644
index 0000000..89fba54
--- /dev/null
+++ b/src/liblimb/include/limb/fdpatrim.h
@@ -0,0 +1,17 @@
+/* This file is part of limb                           https://lila.oss/limb
+ * Copyright (C) 2023 Olivier Brunel                          jjk@jjacky.com */
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef LIMB_FDPATRIM_H
+#define LIMB_FDPATRIM_H
+
+#include <limb/int.h>
+#include <limb/siovec.h>
+
+extern int fdpatrim_initw(int fd, u32 magic, u64 ver);
+extern int fdpatrim_add(int fd, u64 id, u64 u, const char *data);
+extern int fdpatrim_addv(int fd, u64 id, const struct iovec v[], unsigned int n);
+
+extern int fdpatrim_initr(int fd, u32 *magic, u64 *ver);
+extern int fdpatrim_get(int fd, u64 *id, u64 *u);
+
+#endif /* LIMB_FDPATRIM_H */