Introduce git_apply_patch

The beginnings of patch application from an existing (diff-created)
git_patch object: applies the hunks of a git_patch to a buffer.

2 files changed, 462 insertions, 0 deletions

diff --git a/tests/apply/apply_common.h b/tests/apply/apply_common.h
new file mode 100644
index 000000000..8226cc1da
--- /dev/null
+++ b/tests/apply/apply_common.h
@@ -0,0 +1,286 @@
+/* The original file contents */
+
+#define FILE_ORIGINAL \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+/* A change in the middle of the file (and the resultant patch) */
+
+#define FILE_CHANGE_MIDDLE \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(THIS line is changed!)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_CHANGE_MIDDLE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..cd8fd12 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -3,7 +3,7 @@ this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n" \
+	" yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	" below it!\n"
+
+#define PATCH_ORIGINAL_TO_CHANGE_MIDDLE_NOCONTEXT \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..cd8fd12 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -6 +6 @@ yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n"
+
+/* A change of the first line (and the resultant patch) */
+
+#define FILE_CHANGE_FIRSTLINE \
+	"hey, change in head!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_CHANGE_FIRSTLINE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..c81df1d 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-hey!\n" \
+	"+hey, change in head!\n" \
+	" this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n"
+
+/* A change of the last line (and the resultant patch) */
+
+#define FILE_CHANGE_LASTLINE \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"change to the last line.\n"
+
+#define PATCH_ORIGINAL_TO_CHANGE_LASTLINE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..f70db1c 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -6,4 +6,4 @@ yes it is!\n" \
+	" (this line is changed)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	"-below it!\n" \
+	"+change to the last line.\n"
+
+/* An insertion at the beginning of the file (and the resultant patch) */
+
+#define FILE_PREPEND \
+	"insert at front\n" \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n"
+
+#define PATCH_ORIGINAL_TO_PREPEND \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..0f39b9a 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,3 +1,4 @@\n" \
+	"+insert at front\n" \
+	" hey!\n" \
+	" this is some context!\n" \
+	" around some lines\n"
+
+#define PATCH_ORIGINAL_TO_PREPEND_NOCONTEXT \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..0f39b9a 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -0,0 +1 @@\n" \
+	"+insert at front\n"
+
+/* An insertion at the end of the file (and the resultant patch) */
+
+#define FILE_APPEND \
+	"hey!\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"below it!\n" \
+	"insert at end\n"
+
+#define PATCH_ORIGINAL_TO_APPEND \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..72788bb 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -7,3 +7,4 @@ yes it is!\n" \
+	" and this\n" \
+	" is additional context\n" \
+	" below it!\n" \
+	"+insert at end\n"
+
+#define PATCH_ORIGINAL_TO_APPEND_NOCONTEXT \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..72788bb 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -9,0 +10 @@ below it!\n" \
+	"+insert at end\n"
+
+/* An insertion at the beginning and end of file (and the resultant patch) */
+
+#define FILE_PREPEND_AND_APPEND \
+	"first and\n" \
+	"this is some context!\n" \
+	"around some lines\n" \
+	"that will change\n" \
+	"yes it is!\n" \
+	"(this line is changed)\n" \
+	"and this\n" \
+	"is additional context\n" \
+	"last lines\n"
+
+#define PATCH_ORIGINAL_TO_PREPEND_AND_APPEND \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..f282430 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,4 +1,4 @@\n" \
+	"-hey!\n" \
+	"+first and\n" \
+	" this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n" \
+	"@@ -6,4 +6,4 @@ yes it is!\n" \
+	" (this line is changed)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	"-below it!\n" \
+	"+last lines\n"
+
+#define PATCH_ORIGINAL_TO_EMPTY_FILE \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index 9432026..e69de29 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -1,9 +0,0 @@\n" \
+	"-hey!\n" \
+	"-this is some context!\n" \
+	"-around some lines\n" \
+	"-that will change\n" \
+	"-yes it is!\n" \
+	"-(this line is changed)\n" \
+	"-and this\n" \
+	"-is additional context\n" \
+	"-below it!\n"
+
+#define PATCH_EMPTY_FILE_TO_ORIGINAL \
+	"diff --git a/file.txt b/file.txt\n" \
+	"index e69de29..9432026 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/file.txt\n" \
+	"@@ -0,0 +1,9 @@\n" \
+	"+hey!\n" \
+	"+this is some context!\n" \
+	"+around some lines\n" \
+	"+that will change\n" \
+	"+yes it is!\n" \
+	"+(this line is changed)\n" \
+	"+and this\n" \
+	"+is additional context\n" \
+	"+below it!\n"
+
+#define PATCH_ADD_ORIGINAL \
+	"diff --git a/file.txt b/file.txt\n" \
+	"new file mode 100644\n" \
+	"index 0000000..9432026\n" \
+	"--- /dev/null\n" \
+	"+++ b/file.txt\n" \
+	"@@ -0,0 +1,9 @@\n" \
+	"+hey!\n" \
+	"+this is some context!\n" \
+	"+around some lines\n" \
+	"+that will change\n" \
+	"+yes it is!\n" \
+	"+(this line is changed)\n" \
+	"+and this\n" \
+	"+is additional context\n" \
+	"+below it!\n"
+
+#define PATCH_DELETE_ORIGINAL \
+	"diff --git a/file.txt b/file.txt\n" \
+	"deleted file mode 100644\n" \
+	"index 9432026..0000000\n" \
+	"--- a/file.txt\n" \
+	"+++ /dev/null\n" \
+	"@@ -1,9 +0,0 @@\n" \
+	"-hey!\n" \
+	"-this is some context!\n" \
+	"-around some lines\n" \
+	"-that will change\n" \
+	"-yes it is!\n" \
+	"-(this line is changed)\n" \
+	"-and this\n" \
+	"-is additional context\n" \
+	"-below it!\n"
+
+#define PATCH_RENAME_EXACT \
+	"diff --git a/file.txt b/newfile.txt\n" \
+	"similarity index 100%\n" \
+	"rename from file.txt\n" \
+	"rename to newfile.txt\n"
+
+#define PATCH_RENAME_SIMILAR \
+	"diff --git a/file.txt b/newfile.txt\n" \
+	"similarity index 77%\n" \
+	"rename from file.txt\n" \
+	"rename to newfile.txt\n" \
+	"index 9432026..cd8fd12 100644\n" \
+	"--- a/file.txt\n" \
+	"+++ b/newfile.txt\n" \
+	"@@ -3,7 +3,7 @@ this is some context!\n" \
+	" around some lines\n" \
+	" that will change\n" \
+	" yes it is!\n" \
+	"-(this line is changed)\n" \
+	"+(THIS line is changed!)\n" \
+	" and this\n" \
+	" is additional context\n" \
+	" below it!\n"
diff --git a/tests/apply/fromdiff.c b/tests/apply/fromdiff.c
new file mode 100644
index 000000000..64ed9de79
--- /dev/null
+++ b/tests/apply/fromdiff.c
@@ -0,0 +1,176 @@
+#include "clar_libgit2.h"
+#include "git2/sys/repository.h"
+
+#include "apply.h"
+#include "repository.h"
+#include "buf_text.h"
+
+#include "apply_common.h"
+
+static git_repository *repo = NULL;
+
+void test_apply_fromdiff__initialize(void)
+{
+	repo = cl_git_sandbox_init("renames");
+}
+
+void test_apply_fromdiff__cleanup(void)
+{
+	cl_git_sandbox_cleanup();
+}
+
+static int apply_buf(
+	const char *old,
+	const char *oldname,
+	const char *new,
+	const char *newname,
+	const char *patch_expected,
+	const git_diff_options *diff_opts)
+{
+	git_patch *patch;
+	git_buf result = GIT_BUF_INIT;
+	git_buf patchbuf = GIT_BUF_INIT;
+	char *filename;
+	unsigned int mode;
+	int error;
+
+	cl_git_pass(git_patch_from_buffers(&patch,
+		old, old ? strlen(old) : 0, oldname,
+		new, new ? strlen(new) : 0, newname,
+		diff_opts));
+	cl_git_pass(git_patch_to_buf(&patchbuf, patch));
+
+	cl_assert_equal_s(patch_expected, patchbuf.ptr);
+
+	error = git_apply__patch(&result, &filename, &mode, old, old ? strlen(old) : 0, patch);
+
+	if (error == 0 && new == NULL) {
+		cl_assert_equal_i(0, result.size);
+		cl_assert_equal_p(NULL, filename);
+		cl_assert_equal_i(0, mode);
+	} else {
+		cl_assert_equal_s(new, result.ptr);
+		cl_assert_equal_s("file.txt", filename);
+		cl_assert_equal_i(0100644, mode);
+	}
+
+	git__free(filename);
+	git_buf_free(&result);
+	git_buf_free(&patchbuf);
+	git_patch_free(patch);
+
+	return error;
+}
+
+void test_apply_fromdiff__change_middle(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_CHANGE_MIDDLE, "file.txt",
+		PATCH_ORIGINAL_TO_CHANGE_MIDDLE, NULL));
+}
+
+void test_apply_fromdiff__change_middle_nocontext(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_CHANGE_MIDDLE, "file.txt",
+		PATCH_ORIGINAL_TO_CHANGE_MIDDLE_NOCONTEXT, &diff_opts));
+}
+
+void test_apply_fromdiff__change_firstline(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_CHANGE_FIRSTLINE, "file.txt",
+		PATCH_ORIGINAL_TO_CHANGE_FIRSTLINE, NULL));
+}
+
+void test_apply_fromdiff__lastline(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_CHANGE_LASTLINE, "file.txt",
+		PATCH_ORIGINAL_TO_CHANGE_LASTLINE, NULL));
+}
+
+void test_apply_fromdiff__prepend(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND, "file.txt",
+		PATCH_ORIGINAL_TO_PREPEND, NULL));
+}
+
+void test_apply_fromdiff__prepend_nocontext(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND, "file.txt",
+		PATCH_ORIGINAL_TO_PREPEND_NOCONTEXT, &diff_opts));
+}
+
+void test_apply_fromdiff__append(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_APPEND, "file.txt",
+		PATCH_ORIGINAL_TO_APPEND, NULL));
+}
+
+void test_apply_fromdiff__append_nocontext(void)
+{
+	git_diff_options diff_opts = GIT_DIFF_OPTIONS_INIT;
+	diff_opts.context_lines = 0;
+
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_APPEND, "file.txt",
+		PATCH_ORIGINAL_TO_APPEND_NOCONTEXT, &diff_opts));
+}
+
+void test_apply_fromdiff__prepend_and_append(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		FILE_PREPEND_AND_APPEND, "file.txt",
+		PATCH_ORIGINAL_TO_PREPEND_AND_APPEND, NULL));
+}
+
+void test_apply_fromdiff__to_empty_file(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		"", NULL,
+		PATCH_ORIGINAL_TO_EMPTY_FILE, NULL));
+}
+
+void test_apply_fromdiff__from_empty_file(void)
+{
+	cl_git_pass(apply_buf(
+		"", NULL,
+		FILE_ORIGINAL, "file.txt",
+		PATCH_EMPTY_FILE_TO_ORIGINAL, NULL));
+}
+
+void test_apply_fromdiff__add(void)
+{
+	cl_git_pass(apply_buf(
+		NULL, NULL,
+		FILE_ORIGINAL, "file.txt",
+		PATCH_ADD_ORIGINAL, NULL));
+}
+
+void test_apply_fromdiff__delete(void)
+{
+	cl_git_pass(apply_buf(
+		FILE_ORIGINAL, "file.txt",
+		NULL, NULL,
+		PATCH_DELETE_ORIGINAL, NULL));
+}