thodg/libgit2/src/diff_xdiff.c

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• Hash : 6c014bcc
  Author :
  Date : 2015-09-29T12:18:17
  

  diff: don't feed large files to xdiff

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• src/diff_xdiff.c

• /*
   * 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 "git2/errors.h"
  #include "common.h"
  #include "diff.h"
  #include "diff_driver.h"
  #include "diff_patch.h"
  #include "diff_xdiff.h"
  
  static int git_xdiff_scan_int(const char **str, int *value)
  {
  	const char *scan = *str;
  	int v = 0, digits = 0;
  	/* find next digit */
  	for (scan = *str; *scan && !git__isdigit(*scan); scan++);
  	/* parse next number */
  	for (; git__isdigit(*scan); scan++, digits++)
  		v = (v * 10) + (*scan - '0');
  	*str = scan;
  	*value = v;
  	return (digits > 0) ? 0 : -1;
  }
  
  static int git_xdiff_parse_hunk(git_diff_hunk *hunk, const char *header)
  {
  	/* expect something of the form "@@ -%d[,%d] +%d[,%d] @@" */
  	if (*header != '@')
  		goto fail;
  	if (git_xdiff_scan_int(&header, &hunk->old_start) < 0)
  		goto fail;
  	if (*header == ',') {
  		if (git_xdiff_scan_int(&header, &hunk->old_lines) < 0)
  			goto fail;
  	} else
  		hunk->old_lines = 1;
  	if (git_xdiff_scan_int(&header, &hunk->new_start) < 0)
  		goto fail;
  	if (*header == ',') {
  		if (git_xdiff_scan_int(&header, &hunk->new_lines) < 0)
  			goto fail;
  	} else
  		hunk->new_lines = 1;
  	if (hunk->old_start < 0 || hunk->new_start < 0)
  		goto fail;
  
  	return 0;
  
  fail:
  	giterr_set(GITERR_INVALID, "Malformed hunk header from xdiff");
  	return -1;
  }
  
  typedef struct {
  	git_xdiff_output *xo;
  	git_patch *patch;
  	git_diff_hunk hunk;
  	int old_lineno, new_lineno;
  	mmfile_t xd_old_data, xd_new_data;
  } git_xdiff_info;
  
  static int diff_update_lines(
  	git_xdiff_info *info,
  	git_diff_line *line,
  	const char *content,
  	size_t content_len)
  {
  	const char *scan = content, *scan_end = content + content_len;
  
  	for (line->num_lines = 0; scan < scan_end; ++scan)
  		if (*scan == '\n')
  			++line->num_lines;
  
  	line->content     = content;
  	line->content_len = content_len;
  
  	/* expect " "/"-"/"+", then data */
  	switch (line->origin) {
  	case GIT_DIFF_LINE_ADDITION:
  	case GIT_DIFF_LINE_DEL_EOFNL:
  		line->old_lineno = -1;
  		line->new_lineno = info->new_lineno;
  		info->new_lineno += (int)line->num_lines;
  		break;
  	case GIT_DIFF_LINE_DELETION:
  	case GIT_DIFF_LINE_ADD_EOFNL:
  		line->old_lineno = info->old_lineno;
  		line->new_lineno = -1;
  		info->old_lineno += (int)line->num_lines;
  		break;
  	case GIT_DIFF_LINE_CONTEXT:
  	case GIT_DIFF_LINE_CONTEXT_EOFNL:
  		line->old_lineno = info->old_lineno;
  		line->new_lineno = info->new_lineno;
  		info->old_lineno += (int)line->num_lines;
  		info->new_lineno += (int)line->num_lines;
  		break;
  	default:
  		giterr_set(GITERR_INVALID, "Unknown diff line origin %02x",
  			(unsigned int)line->origin);
  		return -1;
  	}
  
  	return 0;
  }
  
  static int git_xdiff_cb(void *priv, mmbuffer_t *bufs, int len)
  {
  	git_xdiff_info *info = priv;
  	git_patch *patch = info->patch;
  	const git_diff_delta *delta = git_patch_get_delta(patch);
  	git_diff_output *output = &info->xo->output;
  	git_diff_line line;
  
  	if (len == 1) {
  		output->error = git_xdiff_parse_hunk(&info->hunk, bufs[0].ptr);
  		if (output->error < 0)
  			return output->error;
  
  		info->hunk.header_len = bufs[0].size;
  		if (info->hunk.header_len >= sizeof(info->hunk.header))
  			info->hunk.header_len = sizeof(info->hunk.header) - 1;
  		memcpy(info->hunk.header, bufs[0].ptr, info->hunk.header_len);
  		info->hunk.header[info->hunk.header_len] = '\0';
  
  		if (output->hunk_cb != NULL &&
  			(output->error = output->hunk_cb(
  				delta, &info->hunk, output->payload)))
  			return output->error;
  
  		info->old_lineno = info->hunk.old_start;
  		info->new_lineno = info->hunk.new_start;
  	}
  
  	if (len == 2 || len == 3) {
  		/* expect " "/"-"/"+", then data */
  		line.origin =
  			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_ADDITION :
  			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_DELETION :
  			GIT_DIFF_LINE_CONTEXT;
  
  		if (line.origin == GIT_DIFF_LINE_ADDITION)
  			line.content_offset = bufs[1].ptr - info->xd_new_data.ptr;
  		else if (line.origin == GIT_DIFF_LINE_DELETION)
  			line.content_offset = bufs[1].ptr - info->xd_old_data.ptr;
  		else
  			line.content_offset = -1;
  
  		output->error = diff_update_lines(
  			info, &line, bufs[1].ptr, bufs[1].size);
  
  		if (!output->error && output->data_cb != NULL)
  			output->error = output->data_cb(
  				delta, &info->hunk, &line, output->payload);
  	}
  
  	if (len == 3 && !output->error) {
  		/* If we have a '+' and a third buf, then we have added a line
  		 * without a newline and the old code had one, so DEL_EOFNL.
  		 * If we have a '-' and a third buf, then we have removed a line
  		 * with out a newline but added a blank line, so ADD_EOFNL.
  		 */
  		line.origin =
  			(*bufs[0].ptr == '+') ? GIT_DIFF_LINE_DEL_EOFNL :
  			(*bufs[0].ptr == '-') ? GIT_DIFF_LINE_ADD_EOFNL :
  			GIT_DIFF_LINE_CONTEXT_EOFNL;
  
  		line.content_offset = -1;
  
  		output->error = diff_update_lines(
  			info, &line, bufs[2].ptr, bufs[2].size);
  
  		if (!output->error && output->data_cb != NULL)
  			output->error = output->data_cb(
  				delta, &info->hunk, &line, output->payload);
  	}
  
  	return output->error;
  }
  
  static int git_xdiff(git_diff_output *output, git_patch *patch)
  {
  	git_xdiff_output *xo = (git_xdiff_output *)output;
  	git_xdiff_info info;
  	git_diff_find_context_payload findctxt;
  
  	memset(&info, 0, sizeof(info));
  	info.patch = patch;
  	info.xo    = xo;
  
  	xo->callback.priv = &info;
  
  	git_diff_find_context_init(
  		&xo->config.find_func, &findctxt, git_patch__driver(patch));
  	xo->config.find_func_priv = &findctxt;
  
  	if (xo->config.find_func != NULL)
  		xo->config.flags |= XDL_EMIT_FUNCNAMES;
  	else
  		xo->config.flags &= ~XDL_EMIT_FUNCNAMES;
  
  	/* TODO: check ofile.opts_flags to see if driver-specific per-file
  	 * updates are needed to xo->params.flags
  	 */
  
  	git_patch__old_data(&info.xd_old_data.ptr, &info.xd_old_data.size, patch);
  	git_patch__new_data(&info.xd_new_data.ptr, &info.xd_new_data.size, patch);
  
  	if (info.xd_old_data.size > GIT_XDIFF_MAX_SIZE ||
  		info.xd_new_data.size > GIT_XDIFF_MAX_SIZE) {
  		giterr_set(GITERR_INVALID, "files too large for diff");
  		return -1;
  	}
  
  	xdl_diff(&info.xd_old_data, &info.xd_new_data,
  		&xo->params, &xo->config, &xo->callback);
  
  	git_diff_find_context_clear(&findctxt);
  
  	return xo->output.error;
  }
  
  void git_xdiff_init(git_xdiff_output *xo, const git_diff_options *opts)
  {
  	uint32_t flags = opts ? opts->flags : 0;
  
  	xo->output.diff_cb = git_xdiff;
  
  	xo->config.ctxlen = opts ? opts->context_lines : 3;
  	xo->config.interhunkctxlen = opts ? opts->interhunk_lines : 0;
  
  	if (flags & GIT_DIFF_IGNORE_WHITESPACE)
  		xo->params.flags |= XDF_WHITESPACE_FLAGS;
  	if (flags & GIT_DIFF_IGNORE_WHITESPACE_CHANGE)
  		xo->params.flags |= XDF_IGNORE_WHITESPACE_CHANGE;
  	if (flags & GIT_DIFF_IGNORE_WHITESPACE_EOL)
  		xo->params.flags |= XDF_IGNORE_WHITESPACE_AT_EOL;
  
  	if (flags & GIT_DIFF_PATIENCE)
  		xo->params.flags |= XDF_PATIENCE_DIFF;
  	if (flags & GIT_DIFF_MINIMAL)
  		xo->params.flags |= XDF_NEED_MINIMAL;
  
  	xo->callback.outf = git_xdiff_cb;
  }
  

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