Introduce git_patch_options, handle prefixes

Handle prefixes (in terms of number of path components) for patch
parsing.

include/git2/patch.h

@@ -267,18 +267,31 @@ GIT_EXTERN(int) git_patch_to_buf(
 	git_buf *out,
 	git_patch *patch);
 
+/** Options for parsing patch files. */
+typedef struct {
+	/**
+	 * The length of the prefix (in path segments) for the filenames.
+	 * This prefix will be removed when looking for files.  The default is 1.
+	 */
+	uint32_t prefix_len;
+} git_patch_options;
+
+#define GIT_PATCH_OPTIONS_INIT { 1 }
+
 /**
  * Create a patch from the contents of a patch file.
  *
  * @param out The patch to be created
  * @param patchfile The contents of a patch file
  * @param patchfile_len The length of the patch file
+ * @param opts The git_patch_options
  * @return 0 on success, <0 on failure.
  */
 GIT_EXTERN(int) git_patch_from_patchfile(
 	git_patch **out,
 	const char *patchfile,
-	size_t patchfile_len);
+	size_t patchfile_len,
+	git_patch_options *opts);
 
 GIT_END_DECL
 

tests/patch/parse.c

@@ -8,19 +8,21 @@ void test_patch_parse__original_to_change_middle(void)
 	const git_diff_delta *delta;
 	char idstr[GIT_OID_HEXSZ+1] = {0};
 
-	cl_git_pass(git_patch_from_patchfile(&patch, PATCH_ORIGINAL_TO_CHANGE_MIDDLE, strlen(PATCH_ORIGINAL_TO_CHANGE_MIDDLE)));
+	cl_git_pass(git_patch_from_patchfile(
+		&patch, PATCH_ORIGINAL_TO_CHANGE_MIDDLE,
+		strlen(PATCH_ORIGINAL_TO_CHANGE_MIDDLE), NULL));
 
 	cl_assert((delta = git_patch_get_delta(patch)) != NULL);
 	cl_assert_equal_i(2, delta->nfiles);
 
-	cl_assert_equal_s(delta->old_file.path, "a/file.txt");
+	cl_assert_equal_s(delta->old_file.path, "file.txt");
 	cl_assert(delta->old_file.mode == GIT_FILEMODE_BLOB);
 	cl_assert_equal_i(7, delta->old_file.id_abbrev);
 	git_oid_nfmt(idstr, delta->old_file.id_abbrev, &delta->old_file.id);
 	cl_assert_equal_s(idstr, "9432026");
 	cl_assert_equal_i(0, delta->old_file.size);
 
-	cl_assert_equal_s(delta->new_file.path, "b/file.txt");
+	cl_assert_equal_s(delta->new_file.path, "file.txt");
 	cl_assert(delta->new_file.mode == GIT_FILEMODE_BLOB);
 	cl_assert_equal_i(7, delta->new_file.id_abbrev);
 	git_oid_nfmt(idstr, delta->new_file.id_abbrev, &delta->new_file.id);

tests/patch/print.c

@@ -12,7 +12,7 @@ void patch_print_from_patchfile(const char *data, size_t len)
 	git_patch *patch;
 	git_buf buf = GIT_BUF_INIT;
 
-	cl_git_pass(git_patch_from_patchfile(&patch, data, len));
+	cl_git_pass(git_patch_from_patchfile(&patch, data, len, NULL));
 	cl_git_pass(git_patch_to_buf(&buf, patch));
 
 	cl_assert_equal_s(data, buf.ptr);