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doc/developer: improve printfrr extension docs
The table is getting rather clunky, let's just break this out and make it pretty there. Signed-off-by: David Lamparter <equinox@diac24.net>
This commit is contained in:
David Lamparter
parent
2c12c904ea
commit
19b1a1c6a9
@ -214,6 +214,22 @@ pre {
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.highlight .na { color: var(--primary-2); }
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.highlight .nv { color: var(--complement-0); }
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.rst-content code.frrfmtout {
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background-color: var(--secondary-1-9);
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border-color: var(--secondary-1-1);
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font-size:100%;
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}
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.rst-content code.frrfmtout::before {
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content: "⇒ \"";
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}
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.rst-content code.frrfmtout::after {
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content: "\"";
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}
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.rst-content code.frrfmtout span {
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color: var(--secondary-1-4);
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font-size:100%;
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}
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strong {
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font-weight:500;
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}
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@ -17,6 +17,8 @@ import os
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import re
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import pygments
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from sphinx.highlighting import lexers
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from sphinx.util import logging
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logger = logging.getLogger(__name__)
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# If extensions (or modules to document with autodoc) are in another directory,
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# add these directories to sys.path here. If the directory is relative to the
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@ -362,11 +364,37 @@ texinfo_documents = [
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with open("../extra/frrlexer.py", "rb") as lex:
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frrlexerpy = lex.read()
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frrfmt_re = re.compile(r'^\s*%(?P<spec>[^\s]+)\s+\((?P<types>.*)\)\s*$')
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def parse_frrfmt(env, text, node):
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from sphinx import addnodes
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m = frrfmt_re.match(text)
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if not m:
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logger.warning('could not parse frrfmt:: %r' % (text), location=node)
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node += addnodes.desc_name(text, text)
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return text
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spec, types = m.group('spec'), m.group('types')
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node += addnodes.desc_sig_operator('%', '%')
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node += addnodes.desc_name(spec + ' ', spec + ' ')
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plist = addnodes.desc_parameterlist()
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for typ in types.split(','):
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typ = typ.strip()
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plist += addnodes.desc_parameter(typ, typ)
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node += plist
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return '%' + spec
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# custom extensions here
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def setup(app):
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# object type for FRR CLI commands, can be extended to document parent CLI
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# node later on
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app.add_object_type("clicmd", "clicmd")
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# printfrr extensions
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app.add_object_type("frrfmt", "frrfmt", parse_node=parse_frrfmt)
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# css overrides for HTML theme
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app.add_stylesheet("overrides.css")
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# load Pygments lexer for FRR config syntax
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@ -1,5 +1,7 @@
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.. _logging:
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.. highlight:: c
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Logging
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=======
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@ -52,68 +54,30 @@ are available:
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if (ret != buf)
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XFREE(MTYPE_FOO, ret);
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Extensions
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^^^^^^^^^^
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.. c:function:: ssize_t bprintfrr(struct fbuf *fb, const char *fmt, ...)
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.. c:function:: ssize_t vbprintfrr(struct fbuf *fb, const char *fmt, va_list)
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``printfrr()`` format strings can be extended with suffixes after `%p` or
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`%d`. The following extended format specifiers are available:
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These are the "lowest level" functions, which the other variants listed
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above use to implement their functionality on top. Mainly useful for
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implementing printfrr extensions since those get a ``struct fbuf *`` to
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write their output to.
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+-----------+--------------------------+----------------------------------------------+
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| Specifier | Argument | Output |
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+===========+==========================+==============================================+
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| ``%Lu`` | ``uint64_t`` | ``12345`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%Ld`` | ``int64_t`` | ``-12345`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pVA`` | ``struct va_format *`` | (recursive printfrr) |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pI4`` | ``struct in_addr *`` | ``1.2.3.4`` |
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| | | |
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| | ``in_addr_t *`` | |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pI6`` | ``struct in6_addr *`` | ``fe80::1234`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pIA`` | ``struct ipaddr *`` | ``1.2.3.4`` |
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| | | |
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| | | ``fe80::1234`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pFX`` | ``struct prefix *`` | ``fe80::1234/64`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pSG4`` | ``struct prefix_sg *`` | ``(*,1.2.3.4)`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pRN`` | ``struct route_node *`` | ``192.168.1.0/24`` (dst-only node) |
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| | | |
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| | | ``2001:db8::/32 from fe80::/64`` (SADR node) |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pNHv`` | ``struct nexthop *`` | ``1.2.3.4, via eth0`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pNHs`` | ``struct nexthop *`` | ``1.2.3.4 if 15`` |
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+-----------+--------------------------+----------------------------------------------+
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| ``%pFX`` | ``struct bgp_dest *`` | ``fe80::1234/64`` (available in BGP only) |
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+-----------+--------------------------+----------------------------------------------+
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| ``%.*pHX``| ``int len, void *ptr`` | ``12 34 56 78`` (hexdump) |
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+-----------+--------------------------+----------------------------------------------+
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.. c:macro:: FMT_NSTD(expr)
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Printf features like field lengths can be used normally with these extensions,
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e.g. ``%-15pI4`` works correctly.
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This macro turns off/on format warnings as needed when non-ISO-C
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compatible printfrr extensions are used (e.g. ``%.*p`` or ``%Ld``.)::
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The extension specifier after ``%p`` or ``%d`` is always an uppercase letter;
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by means of established pattern uppercase letters and numbers form the type
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identifier which may be followed by lowercase flags.
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vty_out(vty, "standard compatible %pI4\n", &addr);
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FMT_NSTD(vty_out(vty, "non-standard %-47.*pHX\n", (int)len, buf));
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You can grep the FRR source for ``printfrr_ext_autoreg`` to see all extended
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printers and what exactly they do. More printers are likely to be added as
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needed/useful, so the list above may become outdated.
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``%Ld`` is not an "extension" for printfrr; it's wired directly into the main
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printf logic.
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When the frr-format plugin is in use, this macro is a no-op since the
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frr-format plugin supports all printfrr extensions. Since the FRR CI
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includes a system with the plugin enabled, this means format errors will
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not slip by undetected even with FMT_NSTD.
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.. note::
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The ``zlog_*``/``flog_*`` and ``vty_out`` functions all use printfrr
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internally, so these extensions are available there. However, they are
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**not** available when calling ``snprintf`` directly. You need to call
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``snprintfrr`` instead.
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``printfrr()`` does not support the ``%n`` format.
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AS-Safety
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^^^^^^^^^
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@ -126,6 +90,243 @@ AS-Safety
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while AS-Safe)
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* extensions are only AS-Safe if their printer is AS-Safe
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printfrr Extensions
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-------------------
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``printfrr()`` format strings can be extended with suffixes after `%p` or `%d`.
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Printf features like field lengths can be used normally with these extensions,
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e.g. ``%-15pI4`` works correctly, **except if the extension consumes the
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width or precision**. Extensions that do so are listed below as ``%*pXX``
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rather than ``%pXX``.
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The extension specifier after ``%p`` or ``%d`` is always an uppercase letter;
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by means of established pattern uppercase letters and numbers form the type
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identifier which may be followed by lowercase flags.
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You can grep the FRR source for ``printfrr_ext_autoreg`` to see all extended
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printers and what exactly they do. More printers are likely to be added as
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needed/useful, so the list here may be outdated.
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.. note::
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The ``zlog_*``/``flog_*`` and ``vty_out`` functions all use printfrr
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internally, so these extensions are available there. However, they are
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**not** available when calling ``snprintf`` directly. You need to call
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``snprintfrr`` instead.
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Networking data types
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^^^^^^^^^^^^^^^^^^^^^
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.. role:: frrfmtout(code)
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.. frrfmt:: %pI4 (struct in_addr *, in_addr_t *)
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:frrfmtout:`1.2.3.4`
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.. frrfmt:: %pI6 (struct in6_addr *)
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:frrfmtout:`fe80::1234`
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.. frrfmt:: %pEA (struct ethaddr *)
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:frrfmtout:`01:23:45:67:89:ab`
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.. frrfmt:: %pIA (struct ipaddr *)
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:frrfmtout:`1.2.3.4` / :frrfmtout:`fe80::1234`
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.. frrfmt:: %pFX (struct prefix *)
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:frrfmtout:`1.2.3.0/24` / :frrfmtout:`fe80::1234/64`
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This accepts the following types:
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- :c:struct:`prefix`
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- :c:struct:`prefix_ipv4`
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- :c:struct:`prefix_ipv6`
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- :c:struct:`prefix_eth`
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- :c:struct:`prefix_evpn`
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- :c:struct:`prefix_fs`
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It does **not** accept the following types:
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- :c:struct:`prefix_ls`
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- :c:struct:`prefix_rd`
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- :c:struct:`prefix_ptr`
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- :c:struct:`prefix_sg` (use :frrfmt:`%pSG4`)
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- :c:union:`prefixptr` (dereference to get :c:struct:`prefix`)
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- :c:union:`prefixconstptr` (dereference to get :c:struct:`prefix`)
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.. frrfmt:: %pSG4 (struct prefix_sg *)
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:frrfmtout:`(*,1.2.3.4)`
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This is *(S,G)* output for use in pimd. (Note prefix_sg is not a prefix
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"subclass" like the other prefix_* structs.)
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.. frrfmt:: %pSU (union sockunion *)
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``%pSU``: :frrfmtout:`1.2.3.4` / :frrfmtout:`fe80::1234`
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``%pSUs``: :frrfmtout:`1.2.3.4` / :frrfmtout:`fe80::1234%89`
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(adds IPv6 scope ID as integer)
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``%pSUp``: :frrfmtout:`1.2.3.4:567` / :frrfmtout:`[fe80::1234]:567`
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(adds port)
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``%pSUps``: :frrfmtout:`1.2.3.4:567` / :frrfmtout:`[fe80::1234%89]:567`
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(adds port and scope ID)
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.. frrfmt:: %pRN (struct route_node *, struct bgp_node *, struct agg_node *)
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:frrfmtout:`192.168.1.0/24` (dst-only node)
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:frrfmtout:`2001:db8::/32 from fe80::/64` (SADR node)
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.. frrfmt:: %pNH (struct nexthop *)
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``%pNHvv``: :frrfmtout:`via 1.2.3.4, eth0` — verbose zebra format
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``%pNHv``: :frrfmtout:`1.2.3.4, via eth0` — slightly less verbose zebra format
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``%pNHs``: :frrfmtout:`1.2.3.4 if 15` — same as :c:func:`nexthop2str()`
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.. frrfmt:: %pBD (struct bgp_dest *)
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:frrfmtout:`fe80::1234/64`
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(only available in bgpd.)
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.. frrfmt:: %dPF (int)
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:frrfmtout:`AF_INET`
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Prints an `AF_*` / `PF_*` constant. ``PF`` is used here to avoid confusion
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with `AFI` constants, even though the FRR codebase prefers `AF_INET` over
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`PF_INET` & co.
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.. frrfmt:: %dSO (int)
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:frrfmtout:`SOCK_STREAM`
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General utility formats
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^^^^^^^^^^^^^^^^^^^^^^^
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.. frrfmt:: %m (no argument)
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:frrfmtout:`Permission denied`
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Prints ``strerror(errno)``. Does **not** consume any input argument, don't
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pass ``errno``!
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(This is a GNU extension not specific to FRR. FRR guarantees it is
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available on all systems in printfrr, though BSDs support it in printf too.)
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.. frrfmt:: %pSQ (char *)
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([S]tring [Q]uote.) Like ``%s``, but produce a quoted string. Options:
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``n`` - treat ``NULL`` as empty string instead.
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``q`` - include ``""`` quotation marks. Note: ``NULL`` is printed as
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``(null)``, not ``"(null)"`` unless ``n`` is used too. This is
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intentional.
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``s`` - use escaping suitable for RFC5424 syslog. This means ``]`` is
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escaped too.
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If a length is specified (``%*pSQ`` or ``%.*pSQ``), null bytes in the input
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string do not end the string and are just printed as ``\x00``.
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.. frrfmt:: %pSE (char *)
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([S]tring [E]scape.) Like ``%s``, but escape special characters.
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Options:
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``n`` - treat ``NULL`` as empty string instead.
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Unlike :frrfmt:`%pSQ`, this escapes many more characters that are fine for
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a quoted string but not on their own.
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If a length is specified (``%*pSE`` or ``%.*pSE``), null bytes in the input
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string do not end the string and are just printed as ``\x00``.
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.. frrfmt:: %pVA (struct va_format *)
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Recursively invoke printfrr, with arguments passed in through:
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.. c:struct:: va_format
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.. c:member:: const char *fmt
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Format string to use for the recursive printfrr call.
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.. c:member:: va_list *va
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Formatting arguments. Note this is passed as a pointer, not - as in
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most other places - a direct struct reference. Internally uses
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``va_copy()`` so repeated calls can be made (e.g. for determining
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output length.)
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.. frrfmt:: %pFB (struct fbuf *)
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Insert text from a ``struct fbuf *``, i.e. the output of a call to
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:c:func:`bprintfrr()`.
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.. frrfmt:: %*pHX (void *, char *, unsigned char *)
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``%pHX``: :frrfmtout:`12 34 56 78`
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``%pHXc``: :frrfmtout:`12:34:56:78` (separate with [c]olon)
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``%pHXn``: :frrfmtout:`12345678` (separate with [n]othing)
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Insert hexdump. This specifier requires a precision or width to be
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specified. A precision (``%.*pHX``) takes precedence, but generates a
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compiler warning since precisions are undefined for ``%p`` in ISO C. If
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no precision is given, the width is used instead (and normal handling of
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the width is suppressed).
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Note that width and precision are ``int`` arguments, not ``size_t``. Use
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like::
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char *buf;
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size_t len;
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snprintfrr(out, sizeof(out), "... %*pHX ...", (int)len, buf);
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/* with padding to width - would generate a warning due to %.*p */
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FMT_NSTD(snprintfrr(out, sizeof(out), "... %-47.*pHX ...", (int)len, buf));
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.. frrfmt:: %*pHS (void *, char *, unsigned char *)
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``%pHS``: :frrfmtout:`hex.dump`
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This is a complementary format for :frrfmt:`%*pHX` to print the text
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representation for a hexdump. Non-printable characters are replaced with
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a dot.
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Integer formats
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^^^^^^^^^^^^^^^
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.. note::
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These formats currently only exist for advanced type checking with the
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``frr-format`` GCC plugin. They should not be used directly since they will
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cause compiler warnings when used without the plugin. Use with
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:c:macro:`FMT_NSTD` if necessary.
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It is possible ISO C23 may introduce another format for these, possibly
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``%w64d`` discussed in `JTC 1/SC 22/WG 14/N2680 <http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2680.pdf>`_.
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.. frrfmt:: %Lu (uint64_t)
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:frrfmtout:`12345`
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.. frrfmt:: %Ld (int64_t)
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:frrfmtout:`-12345`
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Log levels
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----------
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