Merging upstream version 1.70.0+dfsg2.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 70 insertions, 0 deletions

diff --git a/vendor/gix-pack/src/data/delta.rs b/vendor/gix-pack/src/data/delta.rs
new file mode 100644
index 000000000..a898e4aaf
--- /dev/null
+++ b/vendor/gix-pack/src/data/delta.rs
@@ -0,0 +1,70 @@
+/// Given the decompressed pack delta `d`, decode a size in bytes (either the base object size or the result object size)
+/// Equivalent to [this canonical git function](https://github.com/git/git/blob/311531c9de557d25ac087c1637818bd2aad6eb3a/delta.h#L89)
+pub fn decode_header_size(d: &[u8]) -> (u64, usize) {
+    let mut i = 0;
+    let mut size = 0u64;
+    let mut consumed = 0;
+    for cmd in d.iter() {
+        consumed += 1;
+        size |= (*cmd as u64 & 0x7f) << i;
+        i += 7;
+        if *cmd & 0x80 == 0 {
+            break;
+        }
+    }
+    (size, consumed)
+}
+
+pub fn apply(base: &[u8], mut target: &mut [u8], data: &[u8]) {
+    let mut i = 0;
+    while let Some(cmd) = data.get(i) {
+        i += 1;
+        match cmd {
+            cmd if cmd & 0b1000_0000 != 0 => {
+                let (mut ofs, mut size): (u32, u32) = (0, 0);
+                if cmd & 0b0000_0001 != 0 {
+                    ofs = data[i] as u32;
+                    i += 1;
+                }
+                if cmd & 0b0000_0010 != 0 {
+                    ofs |= (data[i] as u32) << 8;
+                    i += 1;
+                }
+                if cmd & 0b0000_0100 != 0 {
+                    ofs |= (data[i] as u32) << 16;
+                    i += 1;
+                }
+                if cmd & 0b0000_1000 != 0 {
+                    ofs |= (data[i] as u32) << 24;
+                    i += 1;
+                }
+                if cmd & 0b0001_0000 != 0 {
+                    size = data[i] as u32;
+                    i += 1;
+                }
+                if cmd & 0b0010_0000 != 0 {
+                    size |= (data[i] as u32) << 8;
+                    i += 1;
+                }
+                if cmd & 0b0100_0000 != 0 {
+                    size |= (data[i] as u32) << 16;
+                    i += 1;
+                }
+                if size == 0 {
+                    size = 0x10000; // 65536
+                }
+                let ofs = ofs as usize;
+                std::io::Write::write(&mut target, &base[ofs..ofs + size as usize])
+                    .expect("delta copy from base: byte slices must match");
+            }
+            0 => panic!("encountered unsupported command code: 0"),
+            size => {
+                std::io::Write::write(&mut target, &data[i..i + *size as usize])
+                    .expect("delta copy data: slice sizes to match up");
+                i += *size as usize;
+            }
+        }
+    }
+    assert_eq!(i, data.len());
+    assert_eq!(target.len(), 0);
+}