452 lines
16 KiB
C
452 lines
16 KiB
C
#undef I3__FILE__
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#define I3__FILE__ "commands_parser.c"
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/*
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* vim:ts=4:sw=4:expandtab
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*
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* i3 - an improved dynamic tiling window manager
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* © 2009-2012 Michael Stapelberg and contributors (see also: LICENSE)
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*
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* commands_parser.c: hand-written parser to parse commands (commands are what
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* you bind on keys and what you can send to i3 using the IPC interface, like
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* 'move left' or 'workspace 4').
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*
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* We use a hand-written parser instead of lex/yacc because our commands are
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* easy for humans, not for computers. Thus, it’s quite hard to specify a
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* context-free grammar for the commands. A PEG grammar would be easier, but
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* there’s downsides to every PEG parser generator I have come across so far.
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*
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* This parser is basically a state machine which looks for literals or strings
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* and can push either on a stack. After identifying a literal or string, it
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* will either transition to the current state, to a different state, or call a
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* function (like cmd_move()).
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*
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* Special care has been taken that error messages are useful and the code is
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* well testable (when compiled with -DTEST_PARSER it will output to stdout
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* instead of actually calling any function).
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include "all.h"
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// Macros to make the YAJL API a bit easier to use.
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#define y(x, ...) yajl_gen_ ## x (command_output.json_gen, ##__VA_ARGS__)
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#define ystr(str) yajl_gen_string(command_output.json_gen, (unsigned char*)str, strlen(str))
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/*******************************************************************************
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* The data structures used for parsing. Essentially the current state and a
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* list of tokens for that state.
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*
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* The GENERATED_* files are generated by generate-commands-parser.pl with the
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* input parser-specs/commands.spec.
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******************************************************************************/
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#include "GENERATED_command_enums.h"
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typedef struct token {
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char *name;
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char *identifier;
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/* This might be __CALL */
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cmdp_state next_state;
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union {
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uint16_t call_identifier;
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} extra;
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} cmdp_token;
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typedef struct tokenptr {
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cmdp_token *array;
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int n;
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} cmdp_token_ptr;
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#include "GENERATED_command_tokens.h"
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/*******************************************************************************
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* The (small) stack where identified literals are stored during the parsing
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* of a single command (like $workspace).
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******************************************************************************/
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struct stack_entry {
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/* Just a pointer, not dynamically allocated. */
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const char *identifier;
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char *str;
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};
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/* 10 entries should be enough for everybody. */
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static struct stack_entry stack[10];
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/*
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* Pushes a string (identified by 'identifier') on the stack. We simply use a
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* single array, since the number of entries we have to store is very small.
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*
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*/
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static void push_string(const char *identifier, char *str) {
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for (int c = 0; c < 10; c++) {
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if (stack[c].identifier != NULL)
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continue;
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/* Found a free slot, let’s store it here. */
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stack[c].identifier = identifier;
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stack[c].str = str;
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return;
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}
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/* When we arrive here, the stack is full. This should not happen and
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* means there’s either a bug in this parser or the specification
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* contains a command with more than 10 identified tokens. */
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fprintf(stderr, "BUG: commands_parser stack full. This means either a bug "
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"in the code, or a new command which contains more than "
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"10 identified tokens.\n");
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exit(1);
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}
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// XXX: ideally, this would be const char. need to check if that works with all
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// called functions.
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static char *get_string(const char *identifier) {
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for (int c = 0; c < 10; c++) {
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if (stack[c].identifier == NULL)
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break;
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if (strcmp(identifier, stack[c].identifier) == 0)
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return stack[c].str;
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}
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return NULL;
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}
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static void clear_stack(void) {
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for (int c = 0; c < 10; c++) {
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if (stack[c].str != NULL)
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free(stack[c].str);
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stack[c].identifier = NULL;
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stack[c].str = NULL;
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}
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}
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// TODO: remove this if it turns out we don’t need it for testing.
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#if 0
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/*******************************************************************************
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* A dynamically growing linked list which holds the criteria for the current
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* command.
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******************************************************************************/
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typedef struct criterion {
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char *type;
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char *value;
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TAILQ_ENTRY(criterion) criteria;
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} criterion;
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static TAILQ_HEAD(criteria_head, criterion) criteria =
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TAILQ_HEAD_INITIALIZER(criteria);
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/*
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* Stores the given type/value in the list of criteria.
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* Accepts a pointer as first argument, since it is 'call'ed by the parser.
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*
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*/
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static void push_criterion(void *unused_criteria, const char *type,
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const char *value) {
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struct criterion *criterion = malloc(sizeof(struct criterion));
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criterion->type = strdup(type);
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criterion->value = strdup(value);
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TAILQ_INSERT_TAIL(&criteria, criterion, criteria);
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}
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/*
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* Clears the criteria linked list.
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* Accepts a pointer as first argument, since it is 'call'ed by the parser.
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*
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*/
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static void clear_criteria(void *unused_criteria) {
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struct criterion *criterion;
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while (!TAILQ_EMPTY(&criteria)) {
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criterion = TAILQ_FIRST(&criteria);
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free(criterion->type);
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free(criterion->value);
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TAILQ_REMOVE(&criteria, criterion, criteria);
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free(criterion);
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}
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}
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#endif
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/*******************************************************************************
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* The parser itself.
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******************************************************************************/
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static cmdp_state state;
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#ifndef TEST_PARSER
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static Match current_match;
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#endif
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static struct CommandResult subcommand_output;
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static struct CommandResult command_output;
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#include "GENERATED_command_call.h"
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static void next_state(const cmdp_token *token) {
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if (token->next_state == __CALL) {
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subcommand_output.json_gen = command_output.json_gen;
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subcommand_output.needs_tree_render = false;
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GENERATED_call(token->extra.call_identifier, &subcommand_output);
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state = subcommand_output.next_state;
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/* If any subcommand requires a tree_render(), we need to make the
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* whole parser result request a tree_render(). */
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if (subcommand_output.needs_tree_render)
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command_output.needs_tree_render = true;
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clear_stack();
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return;
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}
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state = token->next_state;
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if (state == INITIAL) {
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clear_stack();
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}
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}
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struct CommandResult *parse_command(const char *input) {
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DLOG("COMMAND: *%s*\n", input);
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state = INITIAL;
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/* A YAJL JSON generator used for formatting replies. */
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#if YAJL_MAJOR >= 2
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command_output.json_gen = yajl_gen_alloc(NULL);
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#else
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command_output.json_gen = yajl_gen_alloc(NULL, NULL);
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#endif
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y(array_open);
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command_output.needs_tree_render = false;
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const char *walk = input;
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const size_t len = strlen(input);
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int c;
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const cmdp_token *token;
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bool token_handled;
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// TODO: make this testable
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#ifndef TEST_PARSER
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cmd_criteria_init(¤t_match, &subcommand_output);
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#endif
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/* The "<=" operator is intentional: We also handle the terminating 0-byte
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* explicitly by looking for an 'end' token. */
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while ((size_t)(walk - input) <= len) {
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/* skip whitespace and newlines before every token */
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while ((*walk == ' ' || *walk == '\t' ||
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*walk == '\r' || *walk == '\n') && *walk != '\0')
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walk++;
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cmdp_token_ptr *ptr = &(tokens[state]);
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token_handled = false;
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for (c = 0; c < ptr->n; c++) {
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token = &(ptr->array[c]);
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/* A literal. */
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if (token->name[0] == '\'') {
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if (strncasecmp(walk, token->name + 1, strlen(token->name) - 1) == 0) {
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if (token->identifier != NULL)
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push_string(token->identifier, sstrdup(token->name + 1));
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walk += strlen(token->name) - 1;
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next_state(token);
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token_handled = true;
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break;
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}
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continue;
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}
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if (strcmp(token->name, "string") == 0 ||
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strcmp(token->name, "word") == 0) {
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const char *beginning = walk;
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/* Handle quoted strings (or words). */
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if (*walk == '"') {
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beginning++;
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walk++;
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while (*walk != '\0' && (*walk != '"' || *(walk-1) == '\\'))
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walk++;
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} else {
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if (token->name[0] == 's') {
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/* For a string (starting with 's'), the delimiters are
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* comma (,) and semicolon (;) which introduce a new
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* operation or command, respectively. Also, newlines
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* end a command. */
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while (*walk != ';' && *walk != ',' &&
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*walk != '\0' && *walk != '\r' &&
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*walk != '\n')
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walk++;
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} else {
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/* For a word, the delimiters are white space (' ' or
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* '\t'), closing square bracket (]), comma (,) and
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* semicolon (;). */
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while (*walk != ' ' && *walk != '\t' &&
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*walk != ']' && *walk != ',' &&
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*walk != ';' && *walk != '\r' &&
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*walk != '\n' && *walk != '\0')
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walk++;
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}
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}
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if (walk != beginning) {
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char *str = scalloc(walk-beginning + 1);
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/* We copy manually to handle escaping of characters. */
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int inpos, outpos;
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for (inpos = 0, outpos = 0;
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inpos < (walk-beginning);
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inpos++, outpos++) {
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/* We only handle escaped double quotes to not break
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* backwards compatibility with people using \w in
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* regular expressions etc. */
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if (beginning[inpos] == '\\' && beginning[inpos+1] == '"')
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inpos++;
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str[outpos] = beginning[inpos];
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}
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if (token->identifier)
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push_string(token->identifier, str);
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/* If we are at the end of a quoted string, skip the ending
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* double quote. */
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if (*walk == '"')
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walk++;
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next_state(token);
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token_handled = true;
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break;
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}
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}
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if (strcmp(token->name, "end") == 0) {
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if (*walk == '\0' || *walk == ',' || *walk == ';') {
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next_state(token);
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token_handled = true;
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/* To make sure we start with an appropriate matching
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* datastructure for commands which do *not* specify any
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* criteria, we re-initialize the criteria system after
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* every command. */
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// TODO: make this testable
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#ifndef TEST_PARSER
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if (*walk == '\0' || *walk == ';')
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cmd_criteria_init(¤t_match, &subcommand_output);
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#endif
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walk++;
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break;
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}
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}
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}
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if (!token_handled) {
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/* Figure out how much memory we will need to fill in the names of
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* all tokens afterwards. */
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int tokenlen = 0;
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for (c = 0; c < ptr->n; c++)
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tokenlen += strlen(ptr->array[c].name) + strlen("'', ");
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/* Build up a decent error message. We include the problem, the
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* full input, and underline the position where the parser
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* currently is. */
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char *errormessage;
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char *possible_tokens = smalloc(tokenlen + 1);
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char *tokenwalk = possible_tokens;
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for (c = 0; c < ptr->n; c++) {
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token = &(ptr->array[c]);
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if (token->name[0] == '\'') {
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/* A literal is copied to the error message enclosed with
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* single quotes. */
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*tokenwalk++ = '\'';
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strcpy(tokenwalk, token->name + 1);
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tokenwalk += strlen(token->name + 1);
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*tokenwalk++ = '\'';
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} else {
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/* Any other token is copied to the error message enclosed
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* with angle brackets. */
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*tokenwalk++ = '<';
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strcpy(tokenwalk, token->name);
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tokenwalk += strlen(token->name);
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*tokenwalk++ = '>';
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}
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if (c < (ptr->n - 1)) {
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*tokenwalk++ = ',';
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*tokenwalk++ = ' ';
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}
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}
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*tokenwalk = '\0';
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sasprintf(&errormessage, "Expected one of these tokens: %s",
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possible_tokens);
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free(possible_tokens);
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/* Contains the same amount of characters as 'input' has, but with
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* the unparseable part highlighted using ^ characters. */
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char *position = smalloc(len + 1);
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for (const char *copywalk = input; *copywalk != '\0'; copywalk++)
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position[(copywalk - input)] = (copywalk >= walk ? '^' : ' ');
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position[len] = '\0';
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ELOG("%s\n", errormessage);
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ELOG("Your command: %s\n", input);
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ELOG(" %s\n", position);
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/* Format this error message as a JSON reply. */
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y(map_open);
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ystr("success");
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y(bool, false);
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/* We set parse_error to true to distinguish this from other
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* errors. i3-nagbar is spawned upon keypresses only for parser
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* errors. */
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ystr("parse_error");
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y(bool, true);
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ystr("error");
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ystr(errormessage);
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ystr("input");
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ystr(input);
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ystr("errorposition");
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ystr(position);
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y(map_close);
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free(position);
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free(errormessage);
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clear_stack();
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break;
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}
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}
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y(array_close);
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return &command_output;
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}
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/*******************************************************************************
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* Code for building the stand-alone binary test.commands_parser which is used
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* by t/187-commands-parser.t.
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******************************************************************************/
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#ifdef TEST_PARSER
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/*
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* Logs the given message to stdout while prefixing the current time to it,
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* but only if debug logging was activated.
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* This is to be called by DLOG() which includes filename/linenumber
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*
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*/
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void debuglog(char *fmt, ...) {
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va_list args;
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va_start(args, fmt);
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fprintf(stdout, "# ");
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vfprintf(stdout, fmt, args);
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va_end(args);
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}
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void errorlog(char *fmt, ...) {
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va_list args;
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va_start(args, fmt);
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vfprintf(stderr, fmt, args);
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va_end(args);
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}
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int main(int argc, char *argv[]) {
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if (argc < 2) {
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fprintf(stderr, "Syntax: %s <command>\n", argv[0]);
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return 1;
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}
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parse_command(argv[1]);
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}
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#endif
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