While parsing patch header lines, we iterate over each line and check if
the line has trailing garbage. What we do not check though is that the
line is actually a line ending with a trailing newline.
Fix this by checking the return code of `parse_advance_expected_str`.
In a diff, the shortest possible hunk with a modification (that is, no
deletion) results from a file with only one line with a single character
which is removed. Thus the following hunk
@@ -1 +1 @@
-a
+
is the shortest valid hunk modifying a line. The function parsing the
hunk body though assumes that there must always be at least 4 bytes
present to make up a valid hunk, which is obviously wrong in this case.
The absolute minimum number of bytes required for a modification is
actually 2 bytes, that is the "+" and the following newline. Note: if
there is no trailing newline, the assumption will not be offended as the
diff will have a line "\ No trailing newline" at its end.
This patch fixes the issue by lowering the amount of bytes required.
When creating and printing diffs, deal with binary deltas that have
binary data specially, versus diffs that have a binary file but lack the
actual binary data.
When showing copy information because we are duplicating contents,
for example, when performing a `diff --find-copies-harder -M100 -B100`,
then show copy from/to lines in a patch, and do not show context.
Ensure that we can also parse such patches.
When a text file is added or deleted, use the file names from the
`diff --git` header instead of the `---` or `+++` lines. This is
for compatibility with git.
Now that `git_diff_delta` data can be produced by reading patch
file data, which may have an abbreviated oid, allow consumers to
know that the id is abbreviated.
Patches can now come from a variety of sources - either internally
generated (from diffing two commits) or as the results of parsing
some external data.
