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Handers of a specific form are both designed to be used as callbacks for param(), and also dispose of the command if something goes wrong. Make them return the 'struct command_result *' from command_failed(), or NULL. Renaming them just makes sense: json_tok_XXX is used for non-command-freeing parsers too. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
106 lines
3.4 KiB
C
106 lines
3.4 KiB
C
#ifndef LIGHTNING_COMMON_PARAM_H
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#define LIGHTNING_COMMON_PARAM_H
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#include "config.h"
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#include <common/json.h>
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#include <common/json_tok.h>
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#include <stdbool.h>
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/*~ Greetings adventurer!
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*
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* Do you want to automatically validate json input and unmarshal it into
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* local variables, all using typesafe callbacks? And on error,
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* call command_fail with a proper error message? Then you've come to the
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* right place!
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*
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* Here is a simple example of using the system:
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*
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* unsigned *cltv;
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* u64 *msatoshi;
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* const jsmntok_t *note;
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* u64 *expiry;
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*
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* if (!param(cmd, buffer, params,
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* p_req("cltv", json_tok_number, &cltv),
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* p_opt("msatoshi", json_tok_u64, &msatoshi),
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* p_opt("note", json_tok_tok, ¬e),
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* p_opt_def("expiry", json_tok_u64, &expiry, 3600),
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* NULL))
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* return;
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*
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* If param() returns true then you're good to go.
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*
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* All the command handlers throughout the code use this system.
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* json_invoice() is a great example. The common callbacks can be found in
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* common/json_tok.c. Use them directly or feel free to write your own.
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*/
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struct command;
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/* A dummy type returned by command_ functions, to ensure you return them
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* immediately */
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struct command_result;
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/*
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* Parse the json tokens. @params can be an array of values or an object
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* of named values.
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*/
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bool param(struct command *cmd, const char *buffer,
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const jsmntok_t params[], ...) LAST_ARG_NULL;
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/*
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* The callback signature.
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*
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* Callbacks must return NULL on success. On failure they
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* must return command_fail(...).
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*/
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typedef struct command_result *(*param_cbx)(struct command *cmd,
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const char *name,
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const char *buffer,
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const jsmntok_t *tok,
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void **arg);
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/*
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* Add a required parameter.
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*/
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#define p_req(name, cbx, arg) \
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name"", \
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true, \
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(cbx), \
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(arg) + 0*sizeof((cbx)((struct command *)NULL, \
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(const char *)NULL, \
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(const char *)NULL, \
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(const jsmntok_t *)NULL, \
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(arg)) == (struct command_result *)NULL)
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/*
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* Add an optional parameter. *arg is set to NULL if it isn't found.
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*/
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#define p_opt(name, cbx, arg) \
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name"", \
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false, \
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(cbx), \
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({ *arg = NULL; \
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(arg) + 0*sizeof((cbx)((struct command *)NULL, \
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(const char *)NULL, \
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(const char *)NULL, \
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(const jsmntok_t *)NULL, \
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(arg)) == (struct command_result *)NULL); })
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/*
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* Add an optional parameter. *arg is set to @def if it isn't found.
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*/
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#define p_opt_def(name, cbx, arg, def) \
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name"", \
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false, \
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(cbx), \
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({ (*arg) = tal((cmd), typeof(**arg)); \
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(**arg) = (def); \
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(arg) + 0*sizeof((cbx)((struct command *)NULL, \
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(const char *)NULL, \
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(const char *)NULL, \
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(const jsmntok_t *)NULL, \
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(arg)) == (struct command_result *)NULL); })
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/* Special flag for 'check' which allows any parameters. */
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#define p_opt_any() "", false, NULL, NULL
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#endif /* LIGHTNING_COMMON_PARAM_H */
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