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/* Copyright (c) 2001 Matej Pfajfar.
* Copyright (c) 2001-2004, Roger Dingledine.
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* @file typedvar.c
* @brief Functions for accessing a pointer as an object of a given type.
*
* These functions represent a low-level API for accessing a typed variable.
* They are used in the configuration system to examine and set fields in
* configuration objects used by individual modules.
*
* Almost no code should call these directly.
**/
#include "orconfig.h"
#include "lib/conf/conftypes.h"
#include "lib/confmgt/type_defs.h"
#include "lib/confmgt/typedvar.h"
#include "lib/encoding/confline.h"
#include "lib/log/escape.h"
#include "lib/log/log.h"
#include "lib/log/util_bug.h"
#include "lib/malloc/malloc.h"
#include "lib/string/printf.h"
#include "lib/string/util_string.h"
#include "lib/confmgt/var_type_def_st.h"
#include <stddef.h>
#include <string.h>
/**
* Try to parse a string in <b>value</b> that encodes an object of the type
* defined by <b>def</b>.
*
* On success, adjust the lvalue pointed to by <b>target</b> to hold that
* value, and return 0. On failure, set *<b>errmsg</b> to a newly allocated
* string holding an error message, and return -1.
**/
int
typed_var_assign(void *target, const char *value, char **errmsg,
const var_type_def_t *def)
{
if (BUG(!def))
return -1; // LCOV_EXCL_LINE
// clear old value if needed.
typed_var_free(target, def);
tor_assert(def->fns->parse);
return def->fns->parse(target, value, errmsg, def->params);
}
/**
* Try to parse a single line from the head of<b>line</b> that encodes an
* object of the type defined in <b>def</b>. On success and failure, behave as
* typed_var_assign().
*
* All types for which keys are significant should use this function.
*
* Note that although multiple lines may be provided in <b>line</b>,
* only the first one is handled by this function.
**/
int
typed_var_kvassign(void *target, const config_line_t *line,
char **errmsg, const var_type_def_t *def)
{
if (BUG(!def))
return -1; // LCOV_EXCL_LINE
if (def->fns->kv_parse) {
// We do _not_ free the old value here, since linelist options
// sometimes have append semantics.
return def->fns->kv_parse(target, line, errmsg, def->params);
}
int rv = typed_var_assign(target, line->value, errmsg, def);
if (rv < 0 && *errmsg != NULL) {
/* typed_var_assign() didn't know the line's keyword, but we do.
* Let's add it to the error message. */
char *oldmsg = *errmsg;
tor_asprintf(errmsg, "Could not parse %s: %s", line->key, oldmsg);
tor_free(oldmsg);
}
return rv;
}
/**
* Release storage held by a variable in <b>target</b> of type defined by
* <b>def</b>, and set <b>target</b> to a reasonable default.
**/
void
typed_var_free(void *target, const var_type_def_t *def)
{
if (BUG(!def))
return; // LCOV_EXCL_LINE
if (def->fns->clear) {
def->fns->clear(target, def->params);
}
}
/**
* Encode a value of type <b>def</b> pointed to by <b>value</b>, and return
* its result in a newly allocated string. The string may need to be escaped.
*
* Returns NULL if this option has a NULL value, or on internal error.
**/
char *
typed_var_encode(const void *value, const var_type_def_t *def)
{
if (BUG(!def))
return NULL; // LCOV_EXCL_LINE
tor_assert(def->fns->encode);
return def->fns->encode(value, def->params);
}
/**
* As typed_var_encode(), but returns a newly allocated config_line_t
* object. The provided <b>key</b> is used as the key of the lines, unless
* the type is one (line a linelist) that encodes its own keys.
*
* This function may return a list of multiple lines.
*
* Returns NULL if there are no lines to encode, or on internal error.
*/
config_line_t *
typed_var_kvencode(const char *key, const void *value,
const var_type_def_t *def)
{
if (BUG(!def))
return NULL; // LCOV_EXCL_LINE
if (def->fns->kv_encode) {
return def->fns->kv_encode(key, value, def->params);
}
char *encoded_value = typed_var_encode(value, def);
if (!encoded_value)
return NULL;
config_line_t *result = tor_malloc_zero(sizeof(config_line_t));
result->key = tor_strdup(key);
result->value = encoded_value;
return result;
}
/**
* Set <b>dest</b> to contain the same value as <b>src</b>. Both types
* must be as defined by <b>def</b>.
*
* Return 0 on success, and -1 on failure.
**/
int
typed_var_copy(void *dest, const void *src, const var_type_def_t *def)
{
if (BUG(!def))
return -1; // LCOV_EXCL_LINE
if (def->fns->copy) {
// If we have been provided a copy fuction, use it.
return def->fns->copy(dest, src, def);
}
// Otherwise, encode 'src' and parse the result into 'def'.
char *enc = typed_var_encode(src, def);
if (!enc) {
typed_var_free(dest, def);
return 0;
}
char *err = NULL;
int rv = typed_var_assign(dest, enc, &err, def);
if (BUG(rv < 0)) {
// LCOV_EXCL_START
log_warn(LD_BUG, "Encoded value %s was not parseable as a %s: %s",
escaped(enc), def->name, err?err:"");
// LCOV_EXCL_STOP
}
tor_free(err);
tor_free(enc);
return rv;
}
/**
* Return true if <b>a</b> and <b>b</b> are semantically equivalent.
* Both types must be as defined by <b>def</b>.
**/
bool
typed_var_eq(const void *a, const void *b, const var_type_def_t *def)
{
if (BUG(!def))
return false; // LCOV_EXCL_LINE
if (def->fns->eq) {
// Use a provided eq function if we got one.
return def->fns->eq(a, b, def->params);
}
// Otherwise, encode the values and compare them.
char *enc_a = typed_var_encode(a, def);
char *enc_b = typed_var_encode(b, def);
bool eq = !strcmp_opt(enc_a,enc_b);
tor_free(enc_a);
tor_free(enc_b);
return eq;
}
/**
* Check whether <b>value</b> encodes a valid value according to the
* type definition in <b>def</b>.
*/
bool
typed_var_ok(const void *value, const var_type_def_t *def)
{
if (BUG(!def))
return false; // LCOV_EXCL_LINE
if (def->fns->ok)
return def->fns->ok(value, def->params);
return true;
}
/**
* Mark <b>value</b> -- a variable that ordinarily would be extended by
* assignment -- as "fragile", so that it will get replaced by the next
* assignment instead.
**/
void
typed_var_mark_fragile(void *value, const var_type_def_t *def)
{
if (BUG(!def)) {
return; // LCOV_EXCL_LINE
}
if (def->fns->mark_fragile)
def->fns->mark_fragile(value, def->params);
}
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