@@ -1307,7 +1307,9 @@ LIB_OBJS += urlmatch.o
 LIB_OBJS += usage.o
 LIB_OBJS += userdiff.o
 LIB_OBJS += utf8.o
+ifndef WITH_RUST
 LIB_OBJS += varint.o
+endif
 LIB_OBJS += version.o
 LIB_OBJS += versioncmp.o
 LIB_OBJS += walker.o

@@ -1499,6 +1501,7 @@ CLAR_TEST_OBJS += $(UNIT_TEST_DIR)/unit-test.o
 UNIT_TEST_OBJS += $(UNIT_TEST_DIR)/test-lib.o
 
 RUST_SOURCES += src/lib.rs
+RUST_SOURCES += src/varint.rs
 
 GIT-VERSION-FILE: FORCE
 	@OLD=$$(cat $@ 2>/dev/null || :) && \

@@ -522,7 +522,6 @@ libgit_sources = [
   'usage.c',
   'userdiff.c',
   'utf8.c',
-  'varint.c',
   'version.c',
   'versioncmp.c',
   'walker.c',

@@ -1707,6 +1706,10 @@ rust_option = get_option('rust').disable_auto_if(not cargo.found())
 if rust_option.allowed()
   subdir('src')
   libgit_c_args += '-DWITH_RUST'
+else
+  libgit_sources += [
+    'varint.c',
+  ]
 endif
 
 libgit = declare_dependency(

@@ -0,0 +1 @@
+pub mod varint;

@@ -1,5 +1,6 @@
 libgit_rs_sources = [
   'lib.rs',
+  'varint.rs',
 ]
 
 # Unfortunately we must use a wrapper command to move the output file into the

@@ -0,0 +1,92 @@
+#[no_mangle]
+pub unsafe extern "C" fn decode_varint(bufp: *mut *const u8) -> usize {
+    let mut buf = *bufp;
+    let mut c = *buf;
+    let mut val = usize::from(c & 127);
+
+    buf = buf.add(1);
+
+    while (c & 128) != 0 {
+        val = val.wrapping_add(1);
+        if val == 0 || val.leading_zeros() < 7 {
+            return 0; // overflow
+        }
+
+        c = *buf;
+        buf = buf.add(1);
+
+        val = (val << 7) + usize::from(c & 127);
+    }
+
+    *bufp = buf;
+    val
+}
+
+#[no_mangle]
+pub unsafe extern "C" fn encode_varint(value: usize, buf: *mut u8) -> u8 {
+    let mut varint: [u8; 16] = [0; 16];
+    let mut pos = varint.len() - 1;
+
+    varint[pos] = (value & 127) as u8;
+
+    let mut value = value >> 7;
+    while value != 0 {
+        pos -= 1;
+        value -= 1;
+        varint[pos] = 128 | (value & 127) as u8;
+        value >>= 7;
+    }
+
+    if !buf.is_null() {
+        std::ptr::copy_nonoverlapping(varint.as_ptr().add(pos), buf, varint.len() - pos);
+    }
+
+    (varint.len() - pos) as u8
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_decode_varint() {
+        unsafe {
+            assert_eq!(decode_varint(&mut [0x00].as_slice().as_ptr()), 0);
+            assert_eq!(decode_varint(&mut [0x01].as_slice().as_ptr()), 1);
+            assert_eq!(decode_varint(&mut [0x7f].as_slice().as_ptr()), 127);
+            assert_eq!(decode_varint(&mut [0x80, 0x00].as_slice().as_ptr()), 128);
+            assert_eq!(decode_varint(&mut [0x80, 0x01].as_slice().as_ptr()), 129);
+            assert_eq!(decode_varint(&mut [0x80, 0x7f].as_slice().as_ptr()), 255);
+
+            // Overflows are expected to return 0.
+            assert_eq!(decode_varint(&mut [0x88; 16].as_slice().as_ptr()), 0);
+        }
+    }
+
+    #[test]
+    fn test_encode_varint() {
+        unsafe {
+            let mut varint: [u8; 16] = [0; 16];
+
+            assert_eq!(encode_varint(0, std::ptr::null_mut()), 1);
+
+            assert_eq!(encode_varint(0, varint.as_mut_slice().as_mut_ptr()), 1);
+            assert_eq!(varint, [0; 16]);
+
+            assert_eq!(encode_varint(10, varint.as_mut_slice().as_mut_ptr()), 1);
+            assert_eq!(varint, [10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+
+            assert_eq!(encode_varint(127, varint.as_mut_slice().as_mut_ptr()), 1);
+            assert_eq!(varint, [127, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+
+            assert_eq!(encode_varint(128, varint.as_mut_slice().as_mut_ptr()), 2);
+            assert_eq!(varint, [128, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+
+            assert_eq!(encode_varint(129, varint.as_mut_slice().as_mut_ptr()), 2);
+            assert_eq!(varint, [128, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+
+            assert_eq!(encode_varint(255, varint.as_mut_slice().as_mut_ptr()), 2);
+            assert_eq!(varint, [128, 127, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]);
+        }
+    }
+}