thodg/libgit2/src/config_snapshot.c

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• Hash : dadbb33b
  Author :
  Date : 2019-11-01T18:55:54
  

  Fix crash if snapshotting a config_snapshot Signed-off-by: Sven Strickroth <email@cs-ware.de>

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• src/config_snapshot.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 "config.h"
  
  #include "config_entries.h"
  
  typedef struct {
  	git_config_backend parent;
  	git_mutex values_mutex;
  	git_config_entries *entries;
  	git_config_backend *source;
  } config_snapshot_backend;
  
  static int config_error_readonly(void)
  {
  	git_error_set(GIT_ERROR_CONFIG, "this backend is read-only");
  	return -1;
  }
  
  static int config_iterator_new_readonly(
  	git_config_iterator **iter,
  	struct git_config_backend *backend)
  {
  	config_snapshot_backend *b = GIT_CONTAINER_OF(backend, config_snapshot_backend, parent);
  	git_config_entries *entries = NULL;
  	int error;
  
  	if ((error = git_config_entries_dup(&entries, b->entries)) < 0 ||
  	    (error = git_config_entries_iterator_new(iter, entries)) < 0)
  		goto out;
  
  out:
  	/* Let iterator delete duplicated entries when it's done */
  	git_config_entries_free(entries);
  	return error;
  }
  
  /* release the map containing the entry as an equivalent to freeing it */
  static void free_diskfile_entry(git_config_entry *entry)
  {
  	git_config_entries *entries = (git_config_entries *) entry->payload;
  	git_config_entries_free(entries);
  }
  
  static int config_get_readonly(git_config_backend *cfg, const char *key, git_config_entry **out)
  {
  	config_snapshot_backend *b = GIT_CONTAINER_OF(cfg, config_snapshot_backend, parent);
  	git_config_entries *entries = NULL;
  	git_config_entry *entry;
  	int error = 0;
  
  	if (git_mutex_lock(&b->values_mutex) < 0) {
  	    git_error_set(GIT_ERROR_OS, "failed to lock config backend");
  	    return -1;
  	}
  
  	entries = b->entries;
  	git_config_entries_incref(entries);
  	git_mutex_unlock(&b->values_mutex);
  
  	if ((error = (git_config_entries_get(&entry, entries, key))) < 0) {
  		git_config_entries_free(entries);
  		return error;
  	}
  
  	entry->free = free_diskfile_entry;
  	entry->payload = entries;
  	*out = entry;
  
  	return 0;
  }
  
  static int config_set_readonly(git_config_backend *cfg, const char *name, const char *value)
  {
  	GIT_UNUSED(cfg);
  	GIT_UNUSED(name);
  	GIT_UNUSED(value);
  
  	return config_error_readonly();
  }
  
  static int config_set_multivar_readonly(
  	git_config_backend *cfg, const char *name, const char *regexp, const char *value)
  {
  	GIT_UNUSED(cfg);
  	GIT_UNUSED(name);
  	GIT_UNUSED(regexp);
  	GIT_UNUSED(value);
  
  	return config_error_readonly();
  }
  
  static int config_delete_multivar_readonly(git_config_backend *cfg, const char *name, const char *regexp)
  {
  	GIT_UNUSED(cfg);
  	GIT_UNUSED(name);
  	GIT_UNUSED(regexp);
  
  	return config_error_readonly();
  }
  
  static int config_delete_readonly(git_config_backend *cfg, const char *name)
  {
  	GIT_UNUSED(cfg);
  	GIT_UNUSED(name);
  
  	return config_error_readonly();
  }
  
  static int config_lock_readonly(git_config_backend *_cfg)
  {
  	GIT_UNUSED(_cfg);
  
  	return config_error_readonly();
  }
  
  static int config_unlock_readonly(git_config_backend *_cfg, int success)
  {
  	GIT_UNUSED(_cfg);
  	GIT_UNUSED(success);
  
  	return config_error_readonly();
  }
  
  static void backend_readonly_free(git_config_backend *_backend)
  {
  	config_snapshot_backend *backend = GIT_CONTAINER_OF(_backend, config_snapshot_backend, parent);
  
  	if (backend == NULL)
  		return;
  
  	git_config_entries_free(backend->entries);
  	git_mutex_free(&backend->values_mutex);
  	git__free(backend);
  }
  
  static int config_readonly_open(git_config_backend *cfg, git_config_level_t level, const git_repository *repo)
  {
  	config_snapshot_backend *b = GIT_CONTAINER_OF(cfg, config_snapshot_backend, parent);
  	git_config_entries *entries = NULL;
  	git_config_iterator *it = NULL;
  	git_config_entry *entry;
  	int error;
  
  	/* We're just copying data, don't care about the level or repo*/
  	GIT_UNUSED(level);
  	GIT_UNUSED(repo);
  
  	if ((error = git_config_entries_new(&entries)) < 0 ||
  	    (error = b->source->iterator(&it, b->source)) < 0)
  		goto out;
  
  	while ((error = git_config_next(&entry, it)) == 0)
  		if ((error = git_config_entries_dup_entry(entries, entry)) < 0)
  			goto out;
  
  	if (error < 0) {
  		if (error != GIT_ITEROVER)
  			goto out;
  		error = 0;
  	}
  
  	b->entries = entries;
  
  out:
  	git_config_iterator_free(it);
  	if (error)
  		git_config_entries_free(entries);
  	return error;
  }
  
  int git_config_backend_snapshot(git_config_backend **out, git_config_backend *source)
  {
  	config_snapshot_backend *backend;
  
  	backend = git__calloc(1, sizeof(config_snapshot_backend));
  	GIT_ERROR_CHECK_ALLOC(backend);
  
  	backend->parent.version = GIT_CONFIG_BACKEND_VERSION;
  	git_mutex_init(&backend->values_mutex);
  
  	backend->source = source;
  
  	backend->parent.readonly = 1;
  	backend->parent.version = GIT_CONFIG_BACKEND_VERSION;
  	backend->parent.open = config_readonly_open;
  	backend->parent.get = config_get_readonly;
  	backend->parent.set = config_set_readonly;
  	backend->parent.set_multivar = config_set_multivar_readonly;
  	backend->parent.snapshot = git_config_backend_snapshot;
  	backend->parent.del = config_delete_readonly;
  	backend->parent.del_multivar = config_delete_multivar_readonly;
  	backend->parent.iterator = config_iterator_new_readonly;
  	backend->parent.lock = config_lock_readonly;
  	backend->parent.unlock = config_unlock_readonly;
  	backend->parent.free = backend_readonly_free;
  
  	*out = &backend->parent;
  
  	return 0;
  }
  

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