forked from Telodendria/Telodendria
70 lines
2.1 KiB
Groff
70 lines
2.1 KiB
Groff
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.Dd $Mdocdate: November 30 2022 $
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.Dt CANONICALJSON 3
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.Os Telodendria Project
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.Sh NAME
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.Nm CanonicalJson
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.Nd An extension of JSON that produces the Matrix spec's "canonical" JSON.
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.Sh SYNOPSIS
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.In CanonicalJson.h
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.Ft int
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.Fn CanonicalJsonEncode "HashMap *" "FILE *"
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.Ft char *
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.Fn CanonicalJsonEncodeToString "HashMap *"
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.Sh DESCRIPTION
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.Pp
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.Nm
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is an extension of
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.Xr Json 3
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that is specifically designed to produce the Matrix specification's
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"canonical" JSON.
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.Pp
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Canonical JSON is defined as JSON that:
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.Bl -bullet -offset indent
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.It
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Does not have any unecessary whitespace.
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.It
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Has all object keys lexicographically sorted.
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.It
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Does not contain any floating point numerical values.
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.El
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.Pp
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The regular JSON encoder has no such rules, because normally they are
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not needed. However, Canonical JSON is needed to consistently sign JSON
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objects.
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.Pp
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.Fn CanonicalJsonEncode
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encodes a JSON object following the rules of Canonical Json. See the
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documentation for
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.Fn JsonEncode ,
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documented in
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.Xr Json 3
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for more details on how JSON encoding operates. This function exists
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as an alternative to
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.Fn JsonEncode ,
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but should not be preferred to it in most circumstances. It is a lot
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more costly, as it must lexicographically sort all keys and strip out
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float values. If at all possible, use
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.Fn JsonEncode
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because it is much cheaper both in terms of memory and CPU time.
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.Pp
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.Fn CanonicalJsonEncodeToString
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encodes a JSON object to a string.
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.Xr Json 3
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doesn't have any way to send JSON to a string, because there's
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absolutely no reason to handle JSON strings in most cases. However,
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the sole reason Canonical JSON exists is so that JSON objects can
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be signed in a consistent way. Thus, you need a string to pass to
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the signing function.
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.Sh RETURN VALUES
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.Pp
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.Fn CanonicalJsonEncode
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returns whether or not the JSON encoding operation was sucessful.
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This function will fail only if NULL was given for any parameter.
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Otherwise, if an invalid pointer is given, undefined behavior results.
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.Pp
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.Fn CanonicalJsonEncodeToString
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returns a C string containing the canonical JSON representation of
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the given object, or NULL if the encoding failed.
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.Sh SEE ALSO
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.Xr Json 3
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