thodg/libgit2/src/diff_file.c

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• Hash : 3a197ea7
  Author :
  Date : 2020-06-27T12:33:32
  

  Make the tests pass cleanly with MemorySanitizer This change: * Initializes a few variables that were being read before being initialized. * Includes https://github.com/madler/zlib/pull/393. As such, it only works reliably with `-DUSE_BUNDLED_ZLIB=ON`.

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• src/diff_file.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 "diff_file.h"
  
  #include "git2/blob.h"
  #include "git2/submodule.h"
  #include "diff.h"
  #include "diff_generate.h"
  #include "odb.h"
  #include "futils.h"
  #include "filter.h"
  
  #define DIFF_MAX_FILESIZE 0x20000000
  
  static bool diff_file_content_binary_by_size(git_diff_file_content *fc)
  {
  	/* if we have diff opts, check max_size vs file size */
  	if ((fc->file->flags & DIFF_FLAGS_KNOWN_BINARY) == 0 &&
  		fc->opts_max_size > 0 &&
  		fc->file->size > fc->opts_max_size)
  		fc->file->flags |= GIT_DIFF_FLAG_BINARY;
  
  	return ((fc->file->flags & GIT_DIFF_FLAG_BINARY) != 0);
  }
  
  static void diff_file_content_binary_by_content(git_diff_file_content *fc)
  {
  	if ((fc->file->flags & DIFF_FLAGS_KNOWN_BINARY) != 0)
  		return;
  
  	switch (git_diff_driver_content_is_binary(
  		fc->driver, fc->map.data, fc->map.len)) {
  	case 0: fc->file->flags |= GIT_DIFF_FLAG_NOT_BINARY; break;
  	case 1: fc->file->flags |= GIT_DIFF_FLAG_BINARY; break;
  	default: break;
  	}
  }
  
  static int diff_file_content_init_common(
  	git_diff_file_content *fc, const git_diff_options *opts)
  {
  	fc->opts_flags = opts ? opts->flags : GIT_DIFF_NORMAL;
  
  	if (opts && opts->max_size >= 0)
  		fc->opts_max_size = opts->max_size ?
  			opts->max_size : DIFF_MAX_FILESIZE;
  
  	if (fc->src == GIT_ITERATOR_EMPTY)
  		fc->src = GIT_ITERATOR_TREE;
  
  	if (!fc->driver &&
  		git_diff_driver_lookup(&fc->driver, fc->repo,
  		    NULL, fc->file->path) < 0)
  		return -1;
  
  	/* give driver a chance to modify options */
  	git_diff_driver_update_options(&fc->opts_flags, fc->driver);
  
  	/* make sure file is conceivable mmap-able */
  	if ((size_t)fc->file->size != fc->file->size)
  		fc->file->flags |= GIT_DIFF_FLAG_BINARY;
  	/* check if user is forcing text diff the file */
  	else if (fc->opts_flags & GIT_DIFF_FORCE_TEXT) {
  		fc->file->flags &= ~GIT_DIFF_FLAG_BINARY;
  		fc->file->flags |= GIT_DIFF_FLAG_NOT_BINARY;
  	}
  	/* check if user is forcing binary diff the file */
  	else if (fc->opts_flags & GIT_DIFF_FORCE_BINARY) {
  		fc->file->flags &= ~GIT_DIFF_FLAG_NOT_BINARY;
  		fc->file->flags |= GIT_DIFF_FLAG_BINARY;
  	}
  
  	diff_file_content_binary_by_size(fc);
  
  	if ((fc->flags & GIT_DIFF_FLAG__NO_DATA) != 0) {
  		fc->flags |= GIT_DIFF_FLAG__LOADED;
  		fc->map.len  = 0;
  		fc->map.data = "";
  	}
  
  	if ((fc->flags & GIT_DIFF_FLAG__LOADED) != 0)
  		diff_file_content_binary_by_content(fc);
  
  	return 0;
  }
  
  int git_diff_file_content__init_from_diff(
  	git_diff_file_content *fc,
  	git_diff *diff,
  	git_diff_delta *delta,
  	bool use_old)
  {
  	bool has_data = true;
  
  	memset(fc, 0, sizeof(*fc));
  	fc->repo = diff->repo;
  	fc->file = use_old ? &delta->old_file : &delta->new_file;
  	fc->src  = use_old ? diff->old_src : diff->new_src;
  
  	if (git_diff_driver_lookup(&fc->driver, fc->repo,
  		    &diff->attrsession, fc->file->path) < 0)
  		return -1;
  
  	switch (delta->status) {
  	case GIT_DELTA_ADDED:
  		has_data = !use_old; break;
  	case GIT_DELTA_DELETED:
  		has_data = use_old; break;
  	case GIT_DELTA_UNTRACKED:
  		has_data = !use_old &&
  			(diff->opts.flags & GIT_DIFF_SHOW_UNTRACKED_CONTENT) != 0;
  		break;
  	case GIT_DELTA_UNREADABLE:
  	case GIT_DELTA_MODIFIED:
  	case GIT_DELTA_COPIED:
  	case GIT_DELTA_RENAMED:
  		break;
  	default:
  		has_data = false;
  		break;
  	}
  
  	if (!has_data)
  		fc->flags |= GIT_DIFF_FLAG__NO_DATA;
  
  	return diff_file_content_init_common(fc, &diff->opts);
  }
  
  int git_diff_file_content__init_from_src(
  	git_diff_file_content *fc,
  	git_repository *repo,
  	const git_diff_options *opts,
  	const git_diff_file_content_src *src,
  	git_diff_file *as_file)
  {
  	memset(fc, 0, sizeof(*fc));
  	fc->repo = repo;
  	fc->file = as_file;
  
  	if (!src->blob && !src->buf) {
  		fc->flags |= GIT_DIFF_FLAG__NO_DATA;
  	} else {
  		fc->flags |= GIT_DIFF_FLAG__LOADED;
  		fc->file->flags |= GIT_DIFF_FLAG_VALID_ID;
  		fc->file->mode = GIT_FILEMODE_BLOB;
  
  		if (src->blob) {
  			git_blob_dup((git_blob **)&fc->blob, (git_blob *) src->blob);
  			fc->file->size = git_blob_rawsize(src->blob);
  			git_oid_cpy(&fc->file->id, git_blob_id(src->blob));
  			fc->file->id_abbrev = GIT_OID_HEXSZ;
  
  			fc->map.len  = (size_t)fc->file->size;
  			fc->map.data = (char *)git_blob_rawcontent(src->blob);
  
  			fc->flags |= GIT_DIFF_FLAG__FREE_BLOB;
  		} else {
  			int error;
  			if ((error = git_odb_hash(&fc->file->id, src->buf, src->buflen, GIT_OBJECT_BLOB)) < 0)
  				return error;
  			fc->file->size = src->buflen;
  			fc->file->id_abbrev = GIT_OID_HEXSZ;
  
  			fc->map.len  = src->buflen;
  			fc->map.data = (char *)src->buf;
  		}
  	}
  
  	return diff_file_content_init_common(fc, opts);
  }
  
  static int diff_file_content_commit_to_str(
  	git_diff_file_content *fc, bool check_status)
  {
  	char oid[GIT_OID_HEXSZ+1];
  	git_buf content = GIT_BUF_INIT;
  	const char *status = "";
  
  	if (check_status) {
  		int error = 0;
  		git_submodule *sm = NULL;
  		unsigned int sm_status = 0;
  		const git_oid *sm_head;
  
  		if ((error = git_submodule_lookup(&sm, fc->repo, fc->file->path)) < 0) {
  			/* GIT_EEXISTS means a "submodule" that has not been git added */
  			if (error == GIT_EEXISTS) {
  				git_error_clear();
  				error = 0;
  			}
  			return error;
  		}
  
  		if ((error = git_submodule_status(&sm_status, fc->repo, fc->file->path, GIT_SUBMODULE_IGNORE_UNSPECIFIED)) < 0) {
  			git_submodule_free(sm);
  			return error;
  		}
  
  		/* update OID if we didn't have it previously */
  		if ((fc->file->flags & GIT_DIFF_FLAG_VALID_ID) == 0 &&
  			((sm_head = git_submodule_wd_id(sm)) != NULL ||
  			 (sm_head = git_submodule_head_id(sm)) != NULL))
  		{
  			git_oid_cpy(&fc->file->id, sm_head);
  			fc->file->flags |= GIT_DIFF_FLAG_VALID_ID;
  		}
  
  		if (GIT_SUBMODULE_STATUS_IS_WD_DIRTY(sm_status))
  			status = "-dirty";
  
  		git_submodule_free(sm);
  	}
  
  	git_oid_tostr(oid, sizeof(oid), &fc->file->id);
  	if (git_buf_printf(&content, "Subproject commit %s%s\n", oid, status) < 0)
  		return -1;
  
  	fc->map.len  = git_buf_len(&content);
  	fc->map.data = git_buf_detach(&content);
  	fc->flags |= GIT_DIFF_FLAG__FREE_DATA;
  
  	return 0;
  }
  
  static int diff_file_content_load_blob(
  	git_diff_file_content *fc,
  	git_diff_options *opts)
  {
  	int error = 0;
  	git_odb_object *odb_obj = NULL;
  
  	if (git_oid_is_zero(&fc->file->id))
  		return 0;
  
  	if (fc->file->mode == GIT_FILEMODE_COMMIT)
  		return diff_file_content_commit_to_str(fc, false);
  
  	/* if we don't know size, try to peek at object header first */
  	if (!fc->file->size) {
  		if ((error = git_diff_file__resolve_zero_size(
  				fc->file, &odb_obj, fc->repo)) < 0)
  			return error;
  	}
  
  	if ((opts->flags & GIT_DIFF_SHOW_BINARY) == 0 &&
  		diff_file_content_binary_by_size(fc))
  		return 0;
  
  	if (odb_obj != NULL) {
  		error = git_object__from_odb_object(
  			(git_object **)&fc->blob, fc->repo, odb_obj, GIT_OBJECT_BLOB);
  		git_odb_object_free(odb_obj);
  	} else {
  		error = git_blob_lookup(
  			(git_blob **)&fc->blob, fc->repo, &fc->file->id);
  	}
  
  	if (!error) {
  		fc->flags |= GIT_DIFF_FLAG__FREE_BLOB;
  		fc->map.data = (void *)git_blob_rawcontent(fc->blob);
  		fc->map.len  = (size_t)git_blob_rawsize(fc->blob);
  	}
  
  	return error;
  }
  
  static int diff_file_content_load_workdir_symlink_fake(
  	git_diff_file_content *fc, git_buf *path)
  {
  	git_buf target = GIT_BUF_INIT;
  	int error;
  
  	if ((error = git_futils_readbuffer(&target, path->ptr)) < 0)
  		return error;
  
  	fc->map.len = git_buf_len(&target);
  	fc->map.data = git_buf_detach(&target);
  	fc->flags |= GIT_DIFF_FLAG__FREE_DATA;
  
  	git_buf_dispose(&target);
  	return error;
  }
  
  static int diff_file_content_load_workdir_symlink(
  	git_diff_file_content *fc, git_buf *path)
  {
  	ssize_t alloc_len, read_len;
  	int symlink_supported, error;
  
  	if ((error = git_repository__configmap_lookup(
  		&symlink_supported, fc->repo, GIT_CONFIGMAP_SYMLINKS)) < 0)
  		return -1;
  
  	if (!symlink_supported)
  		return diff_file_content_load_workdir_symlink_fake(fc, path);
  
  	/* link path on disk could be UTF-16, so prepare a buffer that is
  	 * big enough to handle some UTF-8 data expansion
  	 */
  	alloc_len = (ssize_t)(fc->file->size * 2) + 1;
  
  	fc->map.data = git__calloc(alloc_len, sizeof(char));
  	GIT_ERROR_CHECK_ALLOC(fc->map.data);
  
  	fc->flags |= GIT_DIFF_FLAG__FREE_DATA;
  
  	read_len = p_readlink(git_buf_cstr(path), fc->map.data, alloc_len);
  	if (read_len < 0) {
  		git_error_set(GIT_ERROR_OS, "failed to read symlink '%s'", fc->file->path);
  		return -1;
  	}
  
  	fc->map.len = read_len;
  	return 0;
  }
  
  static int diff_file_content_load_workdir_file(
  	git_diff_file_content *fc,
  	git_buf *path,
  	git_diff_options *diff_opts)
  {
  	int error = 0;
  	git_filter_list *fl = NULL;
  	git_file fd = git_futils_open_ro(git_buf_cstr(path));
  	git_buf raw = GIT_BUF_INIT;
  
  	if (fd < 0)
  		return fd;
  
  	if (!fc->file->size)
  	    error = git_futils_filesize(&fc->file->size, fd);
  
  	if (error < 0 || !fc->file->size)
  		goto cleanup;
  
  	if ((diff_opts->flags & GIT_DIFF_SHOW_BINARY) == 0 &&
  		diff_file_content_binary_by_size(fc))
  		goto cleanup;
  
  	if ((error = git_filter_list_load(
  			&fl, fc->repo, NULL, fc->file->path,
  			GIT_FILTER_TO_ODB, GIT_FILTER_ALLOW_UNSAFE)) < 0)
  		goto cleanup;
  
  	/* if there are no filters, try to mmap the file */
  	if (fl == NULL) {
  		if (!(error = git_futils_mmap_ro(
  				&fc->map, fd, 0, (size_t)fc->file->size))) {
  			fc->flags |= GIT_DIFF_FLAG__UNMAP_DATA;
  			goto cleanup;
  		}
  
  		/* if mmap failed, fall through to try readbuffer below */
  		git_error_clear();
  	}
  
  	if (!(error = git_futils_readbuffer_fd(&raw, fd, (size_t)fc->file->size))) {
  		git_buf out = GIT_BUF_INIT;
  
  		error = git_filter_list_apply_to_data(&out, fl, &raw);
  
  		if (out.ptr != raw.ptr)
  			git_buf_dispose(&raw);
  
  		if (!error) {
  			fc->map.len  = out.size;
  			fc->map.data = out.ptr;
  			fc->flags |= GIT_DIFF_FLAG__FREE_DATA;
  		}
  	}
  
  cleanup:
  	git_filter_list_free(fl);
  	p_close(fd);
  
  	return error;
  }
  
  static int diff_file_content_load_workdir(
  	git_diff_file_content *fc,
  	git_diff_options *diff_opts)
  {
  	int error = 0;
  	git_buf path = GIT_BUF_INIT;
  
  	if (fc->file->mode == GIT_FILEMODE_COMMIT)
  		return diff_file_content_commit_to_str(fc, true);
  
  	if (fc->file->mode == GIT_FILEMODE_TREE)
  		return 0;
  
  	if (git_buf_joinpath(
  			&path, git_repository_workdir(fc->repo), fc->file->path) < 0)
  		return -1;
  
  	if (S_ISLNK(fc->file->mode))
  		error = diff_file_content_load_workdir_symlink(fc, &path);
  	else
  		error = diff_file_content_load_workdir_file(fc, &path, diff_opts);
  
  	/* once data is loaded, update OID if we didn't have it previously */
  	if (!error && (fc->file->flags & GIT_DIFF_FLAG_VALID_ID) == 0) {
  		error = git_odb_hash(
  			&fc->file->id, fc->map.data, fc->map.len, GIT_OBJECT_BLOB);
  		fc->file->flags |= GIT_DIFF_FLAG_VALID_ID;
  	}
  
  	git_buf_dispose(&path);
  	return error;
  }
  
  int git_diff_file_content__load(
  	git_diff_file_content *fc,
  	git_diff_options *diff_opts)
  {
  	int error = 0;
  
  	if ((fc->flags & GIT_DIFF_FLAG__LOADED) != 0)
  		return 0;
  
  	if ((fc->file->flags & GIT_DIFF_FLAG_BINARY) != 0 &&
  		(diff_opts->flags & GIT_DIFF_SHOW_BINARY) == 0)
  		return 0;
  
  	if (fc->src == GIT_ITERATOR_WORKDIR)
  		error = diff_file_content_load_workdir(fc, diff_opts);
  	else
  		error = diff_file_content_load_blob(fc, diff_opts);
  	if (error)
  		return error;
  
  	fc->flags |= GIT_DIFF_FLAG__LOADED;
  
  	diff_file_content_binary_by_content(fc);
  
  	return 0;
  }
  
  void git_diff_file_content__unload(git_diff_file_content *fc)
  {
  	if ((fc->flags & GIT_DIFF_FLAG__LOADED) == 0)
  		return;
  
  	if (fc->flags & GIT_DIFF_FLAG__FREE_DATA) {
  		git__free(fc->map.data);
  		fc->map.data = "";
  		fc->map.len  = 0;
  		fc->flags &= ~GIT_DIFF_FLAG__FREE_DATA;
  	}
  	else if (fc->flags & GIT_DIFF_FLAG__UNMAP_DATA) {
  		git_futils_mmap_free(&fc->map);
  		fc->map.data = "";
  		fc->map.len  = 0;
  		fc->flags &= ~GIT_DIFF_FLAG__UNMAP_DATA;
  	}
  
  	if (fc->flags & GIT_DIFF_FLAG__FREE_BLOB) {
  		git_blob_free((git_blob *)fc->blob);
  		fc->blob = NULL;
  		fc->flags &= ~GIT_DIFF_FLAG__FREE_BLOB;
  	}
  
  	fc->flags &= ~GIT_DIFF_FLAG__LOADED;
  }
  
  void git_diff_file_content__clear(git_diff_file_content *fc)
  {
  	git_diff_file_content__unload(fc);
  
  	/* for now, nothing else to do */
  }
  

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