105 lines
2.9 KiB
C
105 lines
2.9 KiB
C
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/*
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* vim:ts=4:sw=4:expandtab
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*
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* i3bar - an xcb-based status- and ws-bar for i3
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* © 2010-2012 Axel Wagner and contributors (see also: LICENSE)
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*
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* determine_json_version.c: Determines the JSON protocol version based on the
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* first line of input from a child program.
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*
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*/
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <signal.h>
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#include <stdio.h>
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#include <fcntl.h>
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#include <string.h>
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#include <errno.h>
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#include <err.h>
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#include <ev.h>
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#include <stdbool.h>
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#include <stdint.h>
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#include <yajl/yajl_common.h>
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#include <yajl/yajl_parse.h>
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#include <yajl/yajl_version.h>
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static bool version_key;
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static int32_t version_number;
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#if YAJL_MAJOR >= 2
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static int version_integer(void *ctx, long long val) {
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#else
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static int version_integer(void *ctx, long val) {
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#endif
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if (version_key)
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version_number = (uint32_t)val;
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return 1;
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}
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#if YAJL_MAJOR >= 2
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static int version_map_key(void *ctx, const unsigned char *stringval, size_t stringlen) {
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#else
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static int version_map_key(void *ctx, const unsigned char *stringval, unsigned int stringlen) {
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#endif
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version_key = (stringlen == strlen("version") &&
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strncmp((const char*)stringval, "version", strlen("version")) == 0);
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return 1;
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}
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static yajl_callbacks version_callbacks = {
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NULL, /* null */
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NULL, /* boolean */
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&version_integer,
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NULL, /* double */
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NULL, /* number */
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NULL, /* string */
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NULL, /* start_map */
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&version_map_key,
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NULL, /* end_map */
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NULL, /* start_array */
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NULL /* end_array */
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};
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/*
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* Determines the JSON i3bar protocol version from the given buffer. In case
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* the buffer does not contain valid JSON, or no version field is found, this
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* function returns -1. The amount of bytes consumed by parsing the header is
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* returned in *consumed (if non-NULL).
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*
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* The return type is an int32_t to avoid machines with different sizes of
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* 'int' to allow different values here. It’s highly unlikely we ever exceed
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* even an int8_t, but still…
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*
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*/
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int32_t determine_json_version(const unsigned char *buffer, int length, unsigned int *consumed) {
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#if YAJL_MAJOR >= 2
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yajl_handle handle = yajl_alloc(&version_callbacks, NULL, NULL);
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/* Allow trailing garbage. yajl 1 always behaves that way anyways, but for
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* yajl 2, we need to be explicit. */
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yajl_config(handle, yajl_allow_trailing_garbage, 1);
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#else
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yajl_parser_config parse_conf = { 0, 0 };
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yajl_handle handle = yajl_alloc(&version_callbacks, &parse_conf, NULL, NULL);
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#endif
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version_key = false;
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version_number = -1;
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yajl_status state = yajl_parse(handle, buffer, length);
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if (state != yajl_status_ok) {
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version_number = -1;
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if (consumed != NULL)
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*consumed = 0;
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} else {
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if (consumed != NULL)
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*consumed = yajl_get_bytes_consumed(handle);
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}
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yajl_free(handle);
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return version_number;
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}
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