thodg/libgit2/src/libgit2/merge_driver.c

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• Hash : ef4ab298
  Author :
  Date : 2021-11-14T08:47:40
  

  refactor: `src` is now `src/libgit2`
  

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• src/libgit2/merge_driver.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 "merge_driver.h"
  
  #include "vector.h"
  #include "runtime.h"
  #include "merge.h"
  #include "git2/merge.h"
  #include "git2/sys/merge.h"
  
  static const char *merge_driver_name__text = "text";
  static const char *merge_driver_name__union = "union";
  static const char *merge_driver_name__binary = "binary";
  
  struct merge_driver_registry {
  	git_rwlock lock;
  	git_vector drivers;
  };
  
  typedef struct {
  	git_merge_driver *driver;
  	int initialized;
  	char name[GIT_FLEX_ARRAY];
  } git_merge_driver_entry;
  
  static struct merge_driver_registry merge_driver_registry;
  
  static void git_merge_driver_global_shutdown(void);
  
  git_repository *git_merge_driver_source_repo(
  	const git_merge_driver_source *src)
  {
  	GIT_ASSERT_ARG_WITH_RETVAL(src, NULL);
  	return src->repo;
  }
  
  const git_index_entry *git_merge_driver_source_ancestor(
  	const git_merge_driver_source *src)
  {
  	GIT_ASSERT_ARG_WITH_RETVAL(src, NULL);
  	return src->ancestor;
  }
  
  const git_index_entry *git_merge_driver_source_ours(
  	const git_merge_driver_source *src)
  {
  	GIT_ASSERT_ARG_WITH_RETVAL(src, NULL);
  	return src->ours;
  }
  
  const git_index_entry *git_merge_driver_source_theirs(
  	const git_merge_driver_source *src)
  {
  	GIT_ASSERT_ARG_WITH_RETVAL(src, NULL);
  	return src->theirs;
  }
  
  const git_merge_file_options *git_merge_driver_source_file_options(
  	const git_merge_driver_source *src)
  {
  	GIT_ASSERT_ARG_WITH_RETVAL(src, NULL);
  	return src->file_opts;
  }
  
  int git_merge_driver__builtin_apply(
  	git_merge_driver *self,
  	const char **path_out,
  	uint32_t *mode_out,
  	git_buf *merged_out,
  	const char *filter_name,
  	const git_merge_driver_source *src)
  {
  	git_merge_driver__builtin *driver = (git_merge_driver__builtin *)self;
  	git_merge_file_options file_opts = GIT_MERGE_FILE_OPTIONS_INIT;
  	git_merge_file_result result = {0};
  	int error;
  
  	GIT_UNUSED(filter_name);
  
  	if (src->file_opts)
  		memcpy(&file_opts, src->file_opts, sizeof(git_merge_file_options));
  
  	if (driver->favor)
  		file_opts.favor = driver->favor;
  
  	if ((error = git_merge_file_from_index(&result, src->repo,
  		src->ancestor, src->ours, src->theirs, &file_opts)) < 0)
  		goto done;
  
  	if (!result.automergeable &&
  		!(file_opts.flags & GIT_MERGE_FILE_ACCEPT_CONFLICTS)) {
  		error = GIT_EMERGECONFLICT;
  		goto done;
  	}
  
  	*path_out = git_merge_file__best_path(
  		src->ancestor ? src->ancestor->path : NULL,
  		src->ours ? src->ours->path : NULL,
  		src->theirs ? src->theirs->path : NULL);
  
  	*mode_out = git_merge_file__best_mode(
  		src->ancestor ? src->ancestor->mode : 0,
  		src->ours ? src->ours->mode : 0,
  		src->theirs ? src->theirs->mode : 0);
  
  	merged_out->ptr = (char *)result.ptr;
  	merged_out->size = result.len;
  	merged_out->reserved = 0;
  	result.ptr = NULL;
  
  done:
  	git_merge_file_result_free(&result);
  	return error;
  }
  
  static int merge_driver_binary_apply(
  	git_merge_driver *self,
  	const char **path_out,
  	uint32_t *mode_out,
  	git_buf *merged_out,
  	const char *filter_name,
  	const git_merge_driver_source *src)
  {
  	GIT_UNUSED(self);
  	GIT_UNUSED(path_out);
  	GIT_UNUSED(mode_out);
  	GIT_UNUSED(merged_out);
  	GIT_UNUSED(filter_name);
  	GIT_UNUSED(src);
  
  	return GIT_EMERGECONFLICT;
  }
  
  static int merge_driver_entry_cmp(const void *a, const void *b)
  {
  	const git_merge_driver_entry *entry_a = a;
  	const git_merge_driver_entry *entry_b = b;
  
  	return strcmp(entry_a->name, entry_b->name);
  }
  
  static int merge_driver_entry_search(const void *a, const void *b)
  {
  	const char *name_a = a;
  	const git_merge_driver_entry *entry_b = b;
  
  	return strcmp(name_a, entry_b->name);
  }
  
  git_merge_driver__builtin git_merge_driver__text = {
  	{
  		GIT_MERGE_DRIVER_VERSION,
  		NULL,
  		NULL,
  		git_merge_driver__builtin_apply,
  	},
  	GIT_MERGE_FILE_FAVOR_NORMAL
  };
  
  git_merge_driver__builtin git_merge_driver__union = {
  	{
  		GIT_MERGE_DRIVER_VERSION,
  		NULL,
  		NULL,
  		git_merge_driver__builtin_apply,
  	},
  	GIT_MERGE_FILE_FAVOR_UNION
  };
  
  git_merge_driver git_merge_driver__binary = {
  	GIT_MERGE_DRIVER_VERSION,
  	NULL,
  	NULL,
  	merge_driver_binary_apply
  };
  
  /* Note: callers must lock the registry before calling this function */
  static int merge_driver_registry_insert(
  	const char *name, git_merge_driver *driver)
  {
  	git_merge_driver_entry *entry;
  
  	entry = git__calloc(1, sizeof(git_merge_driver_entry) + strlen(name) + 1);
  	GIT_ERROR_CHECK_ALLOC(entry);
  
  	strcpy(entry->name, name);
  	entry->driver = driver;
  
  	return git_vector_insert_sorted(
  		&merge_driver_registry.drivers, entry, NULL);
  }
  
  int git_merge_driver_global_init(void)
  {
  	int error;
  
  	if (git_rwlock_init(&merge_driver_registry.lock) < 0)
  		return -1;
  
  	if ((error = git_vector_init(&merge_driver_registry.drivers, 3,
  		merge_driver_entry_cmp)) < 0)
  		goto done;
  
  	if ((error = merge_driver_registry_insert(
  			merge_driver_name__text, &git_merge_driver__text.base)) < 0 ||
  		(error = merge_driver_registry_insert(
  			merge_driver_name__union, &git_merge_driver__union.base)) < 0 ||
  		(error = merge_driver_registry_insert(
  			merge_driver_name__binary, &git_merge_driver__binary)) < 0)
  		goto done;
  
  	error = git_runtime_shutdown_register(git_merge_driver_global_shutdown);
  
  done:
  	if (error < 0)
  		git_vector_free_deep(&merge_driver_registry.drivers);
  
  	return error;
  }
  
  static void git_merge_driver_global_shutdown(void)
  {
  	git_merge_driver_entry *entry;
  	size_t i;
  
  	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0)
  		return;
  
  	git_vector_foreach(&merge_driver_registry.drivers, i, entry) {
  		if (entry->driver->shutdown)
  			entry->driver->shutdown(entry->driver);
  
  		git__free(entry);
  	}
  
  	git_vector_free(&merge_driver_registry.drivers);
  
  	git_rwlock_wrunlock(&merge_driver_registry.lock);
  	git_rwlock_free(&merge_driver_registry.lock);
  }
  
  /* Note: callers must lock the registry before calling this function */
  static int merge_driver_registry_find(size_t *pos, const char *name)
  {
  	return git_vector_search2(pos, &merge_driver_registry.drivers,
  		merge_driver_entry_search, name);
  }
  
  /* Note: callers must lock the registry before calling this function */
  static git_merge_driver_entry *merge_driver_registry_lookup(
  	size_t *pos, const char *name)
  {
  	git_merge_driver_entry *entry = NULL;
  
  	if (!merge_driver_registry_find(pos, name))
  		entry = git_vector_get(&merge_driver_registry.drivers, *pos);
  
  	return entry;
  }
  
  int git_merge_driver_register(const char *name, git_merge_driver *driver)
  {
  	int error;
  
  	GIT_ASSERT_ARG(name);
  	GIT_ASSERT_ARG(driver);
  
  	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0) {
  		git_error_set(GIT_ERROR_OS, "failed to lock merge driver registry");
  		return -1;
  	}
  
  	if (!merge_driver_registry_find(NULL, name)) {
  		git_error_set(GIT_ERROR_MERGE, "attempt to reregister existing driver '%s'",
  			name);
  		error = GIT_EEXISTS;
  		goto done;
  	}
  
  	error = merge_driver_registry_insert(name, driver);
  
  done:
  	git_rwlock_wrunlock(&merge_driver_registry.lock);
  	return error;
  }
  
  int git_merge_driver_unregister(const char *name)
  {
  	git_merge_driver_entry *entry;
  	size_t pos;
  	int error = 0;
  
  	if (git_rwlock_wrlock(&merge_driver_registry.lock) < 0) {
  		git_error_set(GIT_ERROR_OS, "failed to lock merge driver registry");
  		return -1;
  	}
  
  	if ((entry = merge_driver_registry_lookup(&pos, name)) == NULL) {
  		git_error_set(GIT_ERROR_MERGE, "cannot find merge driver '%s' to unregister",
  			name);
  		error = GIT_ENOTFOUND;
  		goto done;
  	}
  
  	git_vector_remove(&merge_driver_registry.drivers, pos);
  
  	if (entry->initialized && entry->driver->shutdown) {
  		entry->driver->shutdown(entry->driver);
  		entry->initialized = false;
  	}
  
  	git__free(entry);
  
  done:
  	git_rwlock_wrunlock(&merge_driver_registry.lock);
  	return error;
  }
  
  git_merge_driver *git_merge_driver_lookup(const char *name)
  {
  	git_merge_driver_entry *entry;
  	size_t pos;
  	int error;
  
  	/* If we've decided the merge driver to use internally - and not
  	 * based on user configuration (in merge_driver_name_for_path)
  	 * then we can use a hardcoded name to compare instead of bothering
  	 * to take a lock and look it up in the vector.
  	 */
  	if (name == merge_driver_name__text)
  		return &git_merge_driver__text.base;
  	else if (name == merge_driver_name__binary)
  		return &git_merge_driver__binary;
  
  	if (git_rwlock_rdlock(&merge_driver_registry.lock) < 0) {
  		git_error_set(GIT_ERROR_OS, "failed to lock merge driver registry");
  		return NULL;
  	}
  
  	entry = merge_driver_registry_lookup(&pos, name);
  
  	git_rwlock_rdunlock(&merge_driver_registry.lock);
  
  	if (entry == NULL) {
  		git_error_set(GIT_ERROR_MERGE, "cannot use an unregistered filter");
  		return NULL;
  	}
  
  	if (!entry->initialized) {
  		if (entry->driver->initialize &&
  			(error = entry->driver->initialize(entry->driver)) < 0)
  			return NULL;
  
  		entry->initialized = 1;
  	}
  
  	return entry->driver;
  }
  
  static int merge_driver_name_for_path(
  	const char **out,
  	git_repository *repo,
  	const char *path,
  	const char *default_driver)
  {
  	const char *value;
  	int error;
  
  	*out = NULL;
  
  	if ((error = git_attr_get(&value, repo, 0, path, "merge")) < 0)
  		return error;
  
  	/* set: use the built-in 3-way merge driver ("text") */
  	if (GIT_ATTR_IS_TRUE(value))
  		*out = merge_driver_name__text;
  
  	/* unset: do not merge ("binary") */
  	else if (GIT_ATTR_IS_FALSE(value))
  		*out = merge_driver_name__binary;
  
  	else if (GIT_ATTR_IS_UNSPECIFIED(value) && default_driver)
  		*out = default_driver;
  
  	else if (GIT_ATTR_IS_UNSPECIFIED(value))
  		*out = merge_driver_name__text;
  
  	else
  		*out = value;
  
  	return 0;
  }
  
  
  GIT_INLINE(git_merge_driver *) merge_driver_lookup_with_wildcard(
  	const char *name)
  {
  	git_merge_driver *driver = git_merge_driver_lookup(name);
  
  	if (driver == NULL)
  		driver = git_merge_driver_lookup("*");
  
  	return driver;
  }
  
  int git_merge_driver_for_source(
  	const char **name_out,
  	git_merge_driver **driver_out,
  	const git_merge_driver_source *src)
  {
  	const char *path, *driver_name;
  	int error = 0;
  
  	path = git_merge_file__best_path(
  		src->ancestor ? src->ancestor->path : NULL,
  		src->ours ? src->ours->path : NULL,
  		src->theirs ? src->theirs->path : NULL);
  
  	if ((error = merge_driver_name_for_path(
  			&driver_name, src->repo, path, src->default_driver)) < 0)
  		return error;
  
  	*name_out = driver_name;
  	*driver_out = merge_driver_lookup_with_wildcard(driver_name);
  	return error;
  }
  
  

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