text: /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "apply.h"
  
  #include <assert.h>
  
  #include "git2/patch.h"
  #include "git2/filter.h"
  #include "array.h"
  #include "patch.h"
  #include "fileops.h"
  #include "delta.h"
  #include "zstream.h"
  
  #define apply_err(...) \
  	( giterr_set(GITERR_PATCH, __VA_ARGS__), -1 )
  
  typedef struct {
  	/* The lines that we allocate ourself are allocated out of the pool.
  	 * (Lines may have been allocated out of the diff.)
  	 */
  	git_pool pool;
  	git_vector lines;
  } patch_image;
  
  static void patch_line_init(
  	git_diff_line *out,
  	const char *in,
  	size_t in_len,
  	size_t in_offset)
  {
  	out->content = in;
  	out->content_len = in_len;
  	out->content_offset = in_offset;
  }
  
  #define PATCH_IMAGE_INIT { GIT_POOL_INIT, GIT_VECTOR_INIT }
  
  static int patch_image_init_fromstr(
  	patch_image *out, const char *in, size_t in_len)
  {
  	git_diff_line *line;
  	const char *start, *end;
  
  	memset(out, 0x0, sizeof(patch_image));
  
  	git_pool_init(&out->pool, sizeof(git_diff_line));
  
  	for (start = in; start < in + in_len; start = end) {
  		end = memchr(start, '\n', in_len);
  
  		if (end == NULL)
  			end = in + in_len;
  
  		else if (end < in + in_len)
  			end++;
  
  		line = git_pool_mallocz(&out->pool, 1);
  		GITERR_CHECK_ALLOC(line);
  
  		if (git_vector_insert(&out->lines, line) < 0)
  			return -1;
  
  		patch_line_init(line, start, (end - start), (start - in));
  	}
  
  	return 0;
  }
  
  static void patch_image_free(patch_image *image)
  {
  	if (image == NULL)
  		return;
  
  	git_pool_clear(&image->pool);
  	git_vector_free(&image->lines);
  }
  
  static bool match_hunk(
  	patch_image *image,
  	patch_image *preimage,
  	size_t linenum)
  {
  	bool match = 0;
  	size_t i;
  
  	/* Ensure this hunk is within the image boundaries. */
  	if (git_vector_length(&preimage->lines) + linenum >
  		git_vector_length(&image->lines))
  		return 0;
  
  	match = 1;
  
  	/* Check exact match. */
  	for (i = 0; i < git_vector_length(&preimage->lines); i++) {
  		git_diff_line *preimage_line = git_vector_get(&preimage->lines, i);
  		git_diff_line *image_line = git_vector_get(&image->lines, linenum + i);
  
  		if (preimage_line->content_len != image_line->content_len ||
  			memcmp(preimage_line->content, image_line->content, image_line->content_len) != 0) {
  			match = 0;
  			break;
  		}
  	}
  
  	return match;
  }
  
  static bool find_hunk_linenum(
  	size_t *out,
  	patch_image *image,
  	patch_image *preimage,
  	size_t linenum)
  {
  	size_t max = git_vector_length(&image->lines);
  	bool match;
  
  	if (linenum > max)
  		linenum = max;
  
  	match = match_hunk(image, preimage, linenum);
  
  	*out = linenum;
  	return match;
  }
  
  static int update_hunk(
  	patch_image *image,
  	unsigned int linenum,
  	patch_image *preimage,
  	patch_image *postimage)
  {
  	size_t postlen = git_vector_length(&postimage->lines);
  	size_t prelen = git_vector_length(&preimage->lines);
  	size_t i;
  	int error = 0;
  
  	if (postlen > prelen)
  		error = git_vector_insert_null(
  			&image->lines, linenum, (postlen - prelen));
  	else if (prelen > postlen)
  		error = git_vector_remove_range(
  			&image->lines, linenum, (prelen - postlen));
  
  	if (error) {
  		giterr_set_oom();
  		return -1;
  	}
  
  	for (i = 0; i < git_vector_length(&postimage->lines); i++) {
  		image->lines.contents[linenum + i] =
  			git_vector_get(&postimage->lines, i);
  	}
  
  	return 0;
  }
  
  static int apply_hunk(
  	patch_image *image,
  	git_patch *patch,
  	git_patch_hunk *hunk)
  {
  	patch_image preimage = PATCH_IMAGE_INIT, postimage = PATCH_IMAGE_INIT;
  	size_t line_num, i;
  	int error = 0;
  
  	for (i = 0; i < hunk->line_count; i++) {
  		size_t linenum = hunk->line_start + i;
  		git_diff_line *line = git_array_get(patch->lines, linenum);
  
  		if (!line) {
  			error = apply_err("preimage does not contain line %"PRIuZ, linenum);
  			goto done;
  		}
  
  		if (line->origin == GIT_DIFF_LINE_CONTEXT ||
  			line->origin == GIT_DIFF_LINE_DELETION) {
  			if ((error = git_vector_insert(&preimage.lines, line)) < 0)
  				goto done;
  		}
  
  		if (line->origin == GIT_DIFF_LINE_CONTEXT ||
  			line->origin == GIT_DIFF_LINE_ADDITION) {
  			if ((error = git_vector_insert(&postimage.lines, line)) < 0)
  				goto done;
  		}
  	}
  
  	line_num = hunk->hunk.new_start ? hunk->hunk.new_start - 1 : 0;
  
  	if (!find_hunk_linenum(&line_num, image, &preimage, line_num)) {
  		error = apply_err("hunk at line %d did not apply",
  			hunk->hunk.new_start);
  		goto done;
  	}
  
  	error = update_hunk(image, line_num, &preimage, &postimage);
  
  done:
  	patch_image_free(&preimage);
  	patch_image_free(&postimage);
  
  	return error;
  }
  
  static int apply_hunks(
  	git_buf *out,
  	const char *source,
  	size_t source_len,
  	git_patch *patch)
  {
  	git_patch_hunk *hunk;
  	git_diff_line *line;
  	patch_image image;
  	size_t i;
  	int error = 0;
  
  	if ((error = patch_image_init_fromstr(&image, source, source_len)) < 0)
  		goto done;
  
  	git_array_foreach(patch->hunks, i, hunk) {
  		if ((error = apply_hunk(&image, patch, hunk)) < 0)
  			goto done;
  	}
  
  	git_vector_foreach(&image.lines, i, line)
  		git_buf_put(out, line->content, line->content_len);
  
  done:
  	patch_image_free(&image);
  
  	return error;
  }
  
  static int apply_binary_delta(
  	git_buf *out,
  	const char *source,
  	size_t source_len,
  	git_diff_binary_file *binary_file)
  {
  	git_buf inflated = GIT_BUF_INIT;
  	int error = 0;
  
  	/* no diff means identical contents */
  	if (binary_file->datalen == 0)
  		return git_buf_put(out, source, source_len);
  
  	error = git_zstream_inflatebuf(&inflated,
  		binary_file->data, binary_file->datalen);
  
  	if (!error && inflated.size != binary_file->inflatedlen) {
  		error = apply_err("inflated delta does not match expected length");
  		git_buf_free(out);
  	}
  
  	if (error < 0)
  		goto done;
  
  	if (binary_file->type == GIT_DIFF_BINARY_DELTA) {
  		void *data;
  		size_t data_len;
  
  		error = git_delta_apply(&data, &data_len, (void *)source, source_len,
  			(void *)inflated.ptr, inflated.size);
  
  		out->ptr = data;
  		out->size = data_len;
  		out->asize = data_len;
  	}
  	else if (binary_file->type == GIT_DIFF_BINARY_LITERAL) {
  		git_buf_swap(out, &inflated);
  	}
  	else {
  		error = apply_err("unknown binary delta type");
  		goto done;
  	}
  
  done:
  	git_buf_free(&inflated);
  	return error;
  }
  
  static int apply_binary(
  	git_buf *out,
  	const char *source,
  	size_t source_len,
  	git_patch *patch)
  {
  	git_buf reverse = GIT_BUF_INIT;
  	int error = 0;
  
  	if (!patch->binary.contains_data) {
  		error = apply_err("patch does not contain binary data");
  		goto done;
  	}
  
  	if (!patch->binary.old_file.datalen && !patch->binary.new_file.datalen)
  		goto done;
  
  	/* first, apply the new_file delta to the given source */
  	if ((error = apply_binary_delta(out, source, source_len,
  			&patch->binary.new_file)) < 0)
  		goto done;
  
  	/* second, apply the old_file delta to sanity check the result */
  	if ((error = apply_binary_delta(&reverse, out->ptr, out->size,
  			&patch->binary.old_file)) < 0)
  		goto done;
  
  	if (source_len != reverse.size ||
  		memcmp(source, reverse.ptr, source_len) != 0) {
  		error = apply_err("binary patch did not apply cleanly");
  		goto done;
  	}
  
  done:
  	if (error < 0)
  		git_buf_free(out);
  
  	git_buf_free(&reverse);
  	return error;
  }
  
  int git_apply__patch(
  	git_buf *contents_out,
  	char **filename_out,
  	unsigned int *mode_out,
  	const char *source,
  	size_t source_len,
  	git_patch *patch)
  {
  	char *filename = NULL;
  	unsigned int mode = 0;
  	int error = 0;
  
  	assert(contents_out && filename_out && mode_out && (source || !source_len) && patch);
  
  	*filename_out = NULL;
  	*mode_out = 0;
  
  	if (patch->delta->status != GIT_DELTA_DELETED) {
  		const git_diff_file *newfile = &patch->delta->new_file;
  
  		filename = git__strdup(newfile->path);
  		mode = newfile->mode ?
  			newfile->mode : GIT_FILEMODE_BLOB;
  	}
  
  	if (patch->delta->flags & GIT_DIFF_FLAG_BINARY)
  		error = apply_binary(contents_out, source, source_len, patch);
  	else if (patch->hunks.size)
  		error = apply_hunks(contents_out, source, source_len, patch);
  	else
  		error = git_buf_put(contents_out, source, source_len);
  
  	if (error)
  		goto done;
  
  	if (patch->delta->status == GIT_DELTA_DELETED &&
  		git_buf_len(contents_out) > 0) {
  		error = apply_err("removal patch leaves file contents");
  		goto done;
  	}
  
  	*filename_out = filename;
  	*mode_out = mode;
  
  done:
  	if (error < 0)
  		git__free(filename);
  
  	return error;
  }
  