# BST-TIMEOUT: 300   # ~55 cases, but ~35 of them are an exec and an exec is a
#                    # fresh wasm module instantiation (~2-3 s) on this arm, so
#                    # the floor is ~90 s before any work. 300 is the headroom
#                    # the nightly needs on a loaded host.
. "$BST_LIB"

# ifmetric 0.3 (meta-networking recipes-support) -- Lennart Poettering's
# rtnetlink tool that sets the metric of EVERY IPv4 main-table route attached to
# a named interface in one call. One sbin program, 446 lines of plain C, no
# library dependency. It builds this arm unchanged; what this suite adds is the
# evidence.
#
# ---------------------------------------------------------------------------
# THE PACKAGE HAS TWO HALVES AND THEY FAIL FOR DIFFERENT REASONS.
#
#   * THE ARGV HALF -- the usage text and its two triggers, the basename printed
#     in it, the exit status and diagnostic for an interface that does not
#     exist, atoi()'s silent acceptance of a non-numeric metric, and the
#     ignoring of argv[3] onward. All of it is arithmetic on argv and strings,
#     identical on every architecture, and it touches no descriptor. A wasm32
#     build that got it wrong has no environmental excuse available.
#
#   * THE NETLINK HALF -- netlink_open -> getifn -> enumerate -> delete/add.
#     Four requests over an AF_NETLINK socket, and this is where the arm can
#     genuinely differ.
#
# ---------------------------------------------------------------------------
# WHY THERE IS A PROBE, AND WHY THE CLI COULD NOT REPLACE IT.
#
# Every failure in the netlink half surfaces as one of exactly two things:
# "Interface 'X' not existent." or a bare non-zero exit. So a kernel that
# REFUSED the dump, a kernel that answered an EMPTY dump, and a kernel that
# answered perfectly but has no route on that interface to re-weight are
# indistinguishable from outside -- three different verdicts about this arm, and
# only one of them is a defect. /usr/libexec/ifmetric-tests/ifmetric-probe issues
# the same four requests ifmetric issues, byte for byte including the flag word,
# and reports each one's rc, errno NAME and reply count separately.
#
# THE FLAG WORD IS THE HINGE. ifmetric spells both dump requests
# NLM_F_REQUEST|NLM_F_MATCH (0x201) and never sets NLM_F_ROOT, so its flag word
# is HALF of NLM_F_DUMP (== ROOT|MATCH == 0x300). It has worked on Linux for
# twenty years only because rtnetlink_rcv_msg tests `flags & NLM_F_DUMP` as a
# NON-ZERO test rather than an equality. That is a reading of a different
# kernel's source, so the probe issues BOTH spellings and the cases below
# compare them: agreeing means the spelling is not the story, disagreeing is a
# fact about this arm's rtnetlink that no amount of CLI output would have named.
#
# THE SECOND HINGE IS A REAL RISK, not a hypothetical. getifn() attaches an
# IFLA_IFNAME attribute of IFNAMSIZ+1 = 17 payload bytes; ifla_policy declares
# that attribute NLA_STRING with .len = IFNAMSIZ-1 = 15, and NLA_STRING
# validation drops one trailing NUL and then refuses a payload longer than .len.
# A STRICT parse of getifn's request is therefore -EINVAL, and whether the dump
# path reaches that parse depends on netlink_strict_get_check(), off unless a
# caller asks for it. The probe issues getifn's request WITH the attribute and
# the same request WITHOUT it, so an EINVAL is attributable to the attribute
# rather than to the dump.
#
# THE PROBE'S ORACLE IS A NATIVE x86-64 RUN OF THE SAME BINARY. Every line comes
# back rc=0 there, both dump spellings agree (11 links, 36 routes), and getifn's
# 17-byte attribute is accepted. A probe that cannot report success has not
# measured anything, and this one was checked in the direction that catches
# that.
#
# ---------------------------------------------------------------------------
# THE REWRITE IS ASSERTED FOR REAL. NOTHING HERE IS SKIPPED FOR WANT OF AN
# INTERFACE.
#
# The ticket's framing says this image has one virtio interface and a routing
# table with nothing to re-weight. Half of that is wrong and the other half does
# not have the consequence it looks like it has:
#
#   * There is NO virtio interface. `lo` is the only interface on this image and
#     no virtio-net device is registered -- 60-net-tools.test already asserts
#     `ifconfig -a` lists lo alone. The census below records what is really
#     there rather than repeating either claim.
#
#   * The main table IS empty at boot, and that does not make the rewrite
#     untestable: a route can be PUT on lo and re-weighted there. 60-net-tools
#     has been adding and deleting one on lo since it landed. So this suite adds
#     its own, drives ifmetric over them, and reads the result back.
#
# THE ORACLE FOR THE WRITES IS iproute2, WHICH IS THE POINT. `ip` is on this
# image and is an INDEPENDENT implementation of the same protocol, so
# `ip route show` reporting a metric ifmetric wrote is real end-to-end evidence.
# A probe that both wrote and read would round-trip through its own mistakes and
# report every value correct.
#
# WHAT IT CANNOT DAMAGE. ifmetric filters on `rtm_table != RT_TABLE_MAIN`, and
# lo's own 127.0.0.0/8, 127.0.0.1/32 and 127.255.255.255/32 live in table LOCAL
# (255), not MAIN (254) -- confirmed by the probe's route census on the native
# control. So the only routes any invocation below can touch are the ones this
# suite put there, and the cleanup group asserts they are gone again.
#
# ---------------------------------------------------------------------------
# TWO CASES THIS SUITE DELIBERATELY DOES NOT DRIVE, SAID RATHER THAN OMITTED.
#
#   * A NEGATIVE METRIC. `ifmetric lo -1` reaches addattr32 with -1 and asks the
#     kernel for priority 0xffffffff. ifmetric DELETES each route before it
#     re-adds it, so a refused add loses the route outright -- and the tool
#     reports that as "NETLINK: Error: ..." on a run whose exit status is still
#     0, because add_route()'s return value is discarded in go()'s loop. Driving
#     an undocumented input whose failure mode is silent data loss buys less
#     than it costs. It is upstream behaviour and it is not arm-specific.
#
#   * THE MAX_ROUTES CEILING. enumerate_callback stops at 64 routes per
#     interface with "Found too many routes." on stderr. Reaching it needs 65
#     `ip route add` calls, which at ~2-3 s per exec on this arm is most of the
#     suite's time budget for one message.

# ---------------------------------------------------------------- 0. the decoy
# The first result line of every suite is eaten in transport
# (brintos/linux#96 / BRINTOS-1149) and the harness counts a dropped line as a
# PASS, so the eaten position must never carry an assertion anyone depends on.
bst_ok ifmetric/suite-canary

require ifmetric ifmetric/present

IFACE=lo
NET1=10.99.0.0/24
NET2=10.98.0.0/24
NET3=10.97.0.0/24
ALTTABLE=100

# ------------------------------------------------------------- 1. packaging ---
# Where it is matters: Makefile.am declares `sbin_PROGRAMS`, so a build that
# quietly relocated it to ${bindir} would still satisfy `require` through PATH
# while breaking every caller that names the path.
check ifmetric/pkg/sbin-path test -x /usr/sbin/ifmetric

# -doc is the one man page upstream installs. Either spelling, because whether
# the distro compresses man pages is a policy this port does not own.
if [ -f /usr/share/man/man8/ifmetric.8 ] || [ -f /usr/share/man/man8/ifmetric.8.gz ]; then
	bst_ok ifmetric/pkg/man8
else
	bst_notok ifmetric/pkg/man8 "neither /usr/share/man/man8/ifmetric.8 nor .gz -- ifmetric-doc is not installed"
fi

# No busybox or toybox applet carries this name, so a bare `ifmetric` resolving
# to anything else would be a surprise worth catching rather than an
# alternatives race.
WHICH=$(command -v ifmetric 2>/dev/null)
check_eq ifmetric/pkg/which /usr/sbin/ifmetric "$WHICH"

# --------------------------------------------------- 2. the argv half, no kernel
# main() prints usage for argc <= 1 and for argv[1] in {-h, --help}, and returns
# 0 from all three. check_out asserts the zero exit as well as the needle.
check_out ifmetric/argv/usage-noargs "Usage: ifmetric <iface> [metric]" ifmetric
check_out ifmetric/argv/usage-h      "Usage: ifmetric <iface> [metric]" ifmetric -h
check_out ifmetric/argv/usage-help   "Usage: ifmetric <iface> [metric]" ifmetric --help
check_out ifmetric/argv/usage-body \
	"tool for setting the metrics of all IPv4 routes" ifmetric --help
check_out ifmetric/argv/usage-default-metric "The new metric (default: 0)" ifmetric --help

# The usage text names argv[0]'s BASENAME, via strrchr(argv[0], '/'). Invoked
# through PATH or by absolute path both yield "ifmetric", so neither exercises
# the strrchr arm; a symlink under another name does, and it is the only way to
# tell the two apart from outside.
tmp=${TMPDIR:-/tmp}
alias_name=bst-ifm-alias.$$
alias_path=$tmp/$alias_name
if ln -s /usr/sbin/ifmetric "$alias_path" 2>/dev/null; then
	check_out ifmetric/argv/usage-basename "Usage: $alias_name <iface>" "$alias_path"
else
	bst_notok ifmetric/argv/usage-basename "could not create the symlink $alias_path"
fi
rm -f "$alias_path"

# THERE IS NO VERSION ARM. This case pins the ABSENCE: --version is not
# recognised, so it is taken as an interface name and fails as one. If a future
# ifmetric grows --version this reddens, which is the correct signal -- the
# ticket asked for version text and there is none to assert.
vout=$(ifmetric --version 2>&1); vrc=$?
check_eq ifmetric/argv/no-version-rc 1 "$vrc"
case "$vout" in
	*"Interface '--version' not existent."*) bst_ok ifmetric/argv/no-version-text ;;
	*) bst_notok ifmetric/argv/no-version-text \
		"--version was not treated as an interface name: $(_bst_1line "$vout")" ;;
esac

# The documented failure: man 8 ifmetric's RETURN VALUES section gives 0 for
# success and 1 for failure, and getifn() is where an unknown name stops.
uout=$(ifmetric nosuchif0 2>&1); urc=$?
check_eq ifmetric/argv/unknown-iface-rc 1 "$urc"
case "$uout" in
	*"Interface 'nosuchif0' not existent."*) bst_ok ifmetric/argv/unknown-iface-msg ;;
	*) bst_notok ifmetric/argv/unknown-iface-msg \
		"expected the not-existent diagnostic, got: $(_bst_1line "$uout")" ;;
esac

# strncpy(gi.ifname, iface, IFNAMSIZ) truncates a name longer than 16, but the
# DIAGNOSTIC prints the caller's full string. Both halves are asserted, because
# a build that printed the truncated form would be a real difference and would
# look like nothing in a rc-only test.
lout=$(ifmetric averyveryverylongifname 1 2>&1); lrc=$?
check_eq ifmetric/argv/long-iface-rc 1 "$lrc"
case "$lout" in
	*"Interface 'averyveryverylongifname' not existent."*)
		bst_ok ifmetric/argv/long-iface-msg ;;
	*) bst_notok ifmetric/argv/long-iface-msg \
		"expected the caller's full name in the diagnostic, got: $(_bst_1line "$lout")" ;;
esac

# ------------------------------------------------------------------ 3. the probe
P=/usr/libexec/ifmetric-tests/ifmetric-probe
probe_ok=no
if [ ! -x "$P" ]; then
	bst_notok ifmetric/probe/present \
		"no probe at $P -- ifmetric-tests is not installed, so nothing below can be attributed"
else
	PO=$("$P" "$IFACE" 2>&1); prc=$?
	if bst_execfail "$PO"; then
		bst_unrun ifmetric/probe/runs "$PO"
	else
		case "$PO" in
			*"probe end"*) bst_ok ifmetric/probe/runs; probe_ok=yes ;;
			*) bst_notok ifmetric/probe/runs \
				"rc=$prc, no 'probe end' -- the probe did not finish, so its values below are partial: $(_bst_1line "$PO")" ;;
		esac
	fi
fi

if [ "$probe_ok" = yes ]; then
	# field <line-key> <field-name>. Reads from a VARIABLE, never a redirect: a
	# top-level stdin redirect on the virtiofs root makes dup2(2) return 513 and
	# ash exits, ending the suite silently (brintos/linux#73).
	field() {
		printf '%s\n' "$PO" | sed -n "s/^$1 /  /p" \
			| sed -n "s/.*[ ]$2=\\([^ ]*\\).*/\\1/p" | sed -n 1p
	}

	inet_rc=$(field inet-dgram rc)
	raw_rc=$(field nl-open-raw rc);     raw_name=$(field nl-open-raw name)
	dgram_rc=$(field nl-open-dgram rc); dgram_name=$(field nl-open-dgram name)

	gl_match_rc=$(field getlink-match-only rc); gl_match_n=$(field getlink-match-only links)
	gl_dump_rc=$(field getlink-full-dump rc);   gl_dump_n=$(field getlink-full-dump links)
	gl_attr_rc=$(field getlink-getifn rc);      gl_attr_n=$(field getlink-getifn links)
	gl_attr_name=$(field getlink-getifn name)

	gr_match_rc=$(field getroute-match-only rc); gr_match_n=$(field getroute-match-only routes)
	gr_dump_rc=$(field getroute-full-dump rc);   gr_dump_n=$(field getroute-full-dump routes)
	gr_dump_name=$(field getroute-full-dump name)

	if_n=$(field ifcensus n)
	resolve_idx=$(field resolve idx)
	rt_main=$(field rtcensus main)

	# Echo what the probe answered, prefixed so it is greppable and plainly not
	# a result line. Every branch below is a function of these values, and
	# without them a stored dump records the verdicts without the evidence.
	printf '%s\n' "$PO" | while read -r _dl; do
		[ -n "$_dl" ] && printf '#diag: ifmetric probe: %s\n' "$_dl"
	done

	# --- the controls ---------------------------------------------------
	# Three things this kernel certainly does. They are ASSERTED, not
	# recorded: while they pass, a refusal below is a fact about rtnetlink;
	# if they fail, the reading is about the process and nothing below may be
	# attributed to the kernel.
	check_eq ifmetric/control/inet-dgram   0 "$inet_rc"
	check_eq ifmetric/control/nl-open-raw  0 "$raw_rc"
	# ifmetric's OWN socket, and it is the unusual spelling: SOCK_DGRAM rather
	# than the SOCK_RAW everything else opens, plus an explicit bind naming
	# getpid() as the netlink port id. netlink_create accepts both types, so
	# this passing while nl-open-raw also passes says the type is not the
	# story; this failing ALONE would localise the fault to ifmetric's choice.
	check_eq ifmetric/control/nl-open-dgram 0 "$dgram_rc"
	check_eq ifmetric/control/nl-open-dgram-errno OK "$dgram_name"

	# --- hinge 1: the half-spelled dump flag ----------------------------
	check_eq ifmetric/nl/getlink-match-only-rc 0 "$gl_match_rc"
	check_eq ifmetric/nl/getlink-full-dump-rc  0 "$gl_dump_rc"
	# The comparison IS the assertion. If MATCH-alone stopped selecting the
	# dump path on this arm, the first would come back with zero links while
	# the second still listed them -- and ifmetric would report every
	# interface non-existent with no other symptom.
	check_eq ifmetric/nl/dump-flag-equivalence "$gl_dump_n" "$gl_match_n"
	if [ -n "$gl_match_n" ] && [ "$gl_match_n" -gt 0 ] 2>/dev/null; then
		bst_ok ifmetric/nl/getlink-nonempty
	else
		bst_notok ifmetric/nl/getlink-nonempty \
			"ifmetric's own RTM_GETLINK spelling returned $gl_match_n links -- getifn() cannot resolve any name on this arm"
	fi

	# --- hinge 2: getifn's 17-byte IFLA_IFNAME --------------------------
	check_eq ifmetric/nl/getifn-attr-rc    0 "$gl_attr_rc"
	check_eq ifmetric/nl/getifn-attr-errno OK "$gl_attr_name"
	# Same request, one attribute apart. A difference here localises the fault
	# to the attribute; no difference means the over-long IFLA_IFNAME is
	# tolerated on this arm and getifn needs no patch.
	check_eq ifmetric/nl/getifn-attr-equivalence "$gl_match_n" "$gl_attr_n"

	# --- what getifn would have resolved --------------------------------
	check_eq ifmetric/nl/census-has-lo "$IFACE" \
		"$(printf '%s\n' "$PO" | sed -n "s/^iface .* name=\\($IFACE\\)$/\\1/p" | sed -n 1p)"
	if [ -n "$resolve_idx" ] && [ "$resolve_idx" -ge 1 ] 2>/dev/null; then
		bst_ok ifmetric/nl/resolve-index
	else
		bst_notok ifmetric/nl/resolve-index \
			"getifn's own request resolved $IFACE to index '$resolve_idx'"
	fi
	# Recorded, not asserted: the interface count is 60-net-tools.test's pin,
	# and re-pinning it here would make one image change red in two places
	# saying the same thing.
	printf '#diag: ifmetric: interface census n=%s, main-table routes at entry=%s\n' \
		"$if_n" "$rt_main"

	# --- enumerate()'s request ------------------------------------------
	check_eq ifmetric/nl/getroute-match-only-rc 0 "$gr_match_rc"
	check_eq ifmetric/nl/getroute-full-dump-rc  0 "$gr_dump_rc"
	check_eq ifmetric/nl/getroute-errno         OK "$gr_dump_name"
	check_eq ifmetric/nl/route-dump-equivalence "$gr_dump_n" "$gr_match_n"
else
	for c in inet-dgram nl-open-raw nl-open-dgram; do
		bst_notok "ifmetric/control/$c" "the probe did not run, so this control was never taken"
	done
	for c in getlink-match-only-rc getlink-full-dump-rc dump-flag-equivalence \
	         getlink-nonempty getifn-attr-rc getifn-attr-equivalence resolve-index \
	         getroute-match-only-rc getroute-full-dump-rc route-dump-equivalence; do
		bst_notok "ifmetric/nl/$c" "the probe did not run, so this measurement does not exist"
	done
fi

# ------------------------------------------------- 4. the rewrite, for real ---
# Everything below needs iproute2, and it needs it as an ORACLE rather than as a
# convenience -- it is the independent reader that makes a metric ifmetric wrote
# into evidence rather than a claim.
if ! command -v ip >/dev/null 2>&1; then
	bst_skip ifmetric/rewrite/oracle \
		"iproute2 'ip' is not on this image, so nothing can read back what ifmetric wrote"
	exit 0
fi

# rshow -- the whole main table, read ONCE into a variable. Every assertion that
# follows is a `case` against it, which is a builtin and forks nothing; the
# guest does not return memory on process exit, so a suite's process count is a
# resource budget rather than a performance detail.
MAIN=""
rshow() { MAIN=$(ip -4 route show table main 2>&1); }

# rline <prefix> -- the ONE line of $MAIN describing <prefix>, or the empty
# string. Every metric assertion below scores this rather than the whole table,
# and that is not tidiness: a `case` glob against the whole table spans LINES, so
# `*10.98.0.0/24*metric 5*` is satisfied by 10.98's prefix and a DIFFERENT
# route's metric further down. Measured on the native control -- the no-metric
# premise case passed its glob against a table in which the no-metric route had
# no metric and the next route had one. One awk, not a grep+sed pair: the guest
# does not return memory on process exit, so every avoidable fork is spent
# twice.
# The trailing blanks matter: `ip route show` ends its line with one, so an
# end-anchored `*"metric 7")` never fires against the raw line -- and the metric
# is the LAST field, which is exactly where the anchor has to be if `metric 5`
# is not to be satisfied by `metric 50`. Stripped here, once, rather than in ten
# patterns.
rline() {
	printf '%s\n' "$MAIN" \
		| awk -v p="$1 " 'index($0, p) == 1 { sub(/[ \t]+$/, ""); print; exit }'
}

# THE PREMISE, PROBED RATHER THAN ASSUMED. If a route cannot be put on lo here,
# the rewrite genuinely is untestable and every case below skips WITH the reason
# -- which is the only form of skip this ticket permits.
ip route del "$NET1" 2>/dev/null
add_out=$(ip route add "$NET1" dev "$IFACE" metric 7 2>&1); add_rc=$?
rshow
case "$(rline "$NET1")" in
	?*) can_route=yes ;;
	*) can_route=no ;;
esac

if [ "$can_route" != yes ]; then
	bst_skip ifmetric/rewrite/premise \
		"a route cannot be added to lo on this image (ip route add rc=$add_rc: $(_bst_1line "$add_out")) -- the metric rewrite has no route to act on"
	for c in prio-arm-rc prio-arm-metric prio-arm-survives noprio-premise \
	         noprio-arm-metric all-routes-one-call default-zero atoi-nonnumeric \
	         extra-args-ignored empty-table-ok cleanup; do
		bst_skip "ifmetric/rewrite/$c" "no route could be staged on $IFACE"
	done
	exit 0
fi
bst_ok ifmetric/rewrite/premise

# The staged route carries an explicit metric, so the kernel emits RTA_PRIORITY
# in the dump and set_route_metric() takes its IN-PLACE rewrite arm.
case "$(rline "$NET1")" in
	*"metric 7") bst_ok ifmetric/rewrite/staged-metric-7 ;;
	*) bst_notok ifmetric/rewrite/staged-metric-7 \
		"ip route add reported rc=$add_rc but the table does not show metric 7: $(_bst_1line "$MAIN")" ;;
esac

# --- the in-place RTA_PRIORITY arm ------------------------------------------
out=$(ifmetric "$IFACE" 42 2>&1); rc=$?
check_eq ifmetric/rewrite/prio-arm-rc 0 "$rc"
rshow
N1=$(rline "$NET1")
case "$N1" in
	*"metric 42") bst_ok ifmetric/rewrite/prio-arm-metric ;;
	*) bst_notok ifmetric/rewrite/prio-arm-metric \
		"metric is not 42 after 'ifmetric $IFACE 42' (tool said: $(_bst_1line "$out")); table: $(_bst_1line "$MAIN")" ;;
esac
# ifmetric DELETES each route and re-adds it. A failed re-add loses the route
# outright and go() discards add_route()'s return value, so the tool would exit
# 0 having destroyed the table. This case is the one that catches that, and it
# is not the same assertion as the metric one above.
case "$N1" in
	?*) bst_ok ifmetric/rewrite/prio-arm-survives ;;
	*) bst_notok ifmetric/rewrite/prio-arm-survives \
		"the route is GONE after the delete/re-add cycle -- add_route() failed and go() swallowed it: $(_bst_1line "$MAIN")" ;;
esac
case "$N1" in
	*"dev $IFACE"*) bst_ok ifmetric/rewrite/prio-arm-dev ;;
	*) bst_notok ifmetric/rewrite/prio-arm-dev \
		"the re-added route no longer names dev $IFACE: $(_bst_1line "$MAIN")" ;;
esac

# --- the realloc()+addattr32 arm --------------------------------------------
# A route added with NO metric has priority 0, and the kernel OMITS RTA_PRIORITY
# from the dump for a zero priority (fib_dump_info guards the nla_put on
# fi->fib_priority). set_route_metric() therefore finds no attribute to rewrite
# and takes its realloc()+addattr32 arm instead. That is different code, and
# only a route census can say which arm a given run exercised.
ip route del "$NET2" 2>/dev/null
ip route add "$NET2" dev "$IFACE" 2>/dev/null
rshow
case "$(rline "$NET2")" in
	*"metric"*)
		bst_notok ifmetric/rewrite/noprio-premise \
			"the no-metric route came back WITH a metric, so the addattr32 arm below is not the one being exercised: $(_bst_1line "$MAIN")" ;;
	?*) bst_ok ifmetric/rewrite/noprio-premise ;;
	*) bst_notok ifmetric/rewrite/noprio-premise \
		"$NET2 could not be staged without a metric: $(_bst_1line "$MAIN")" ;;
esac

out=$(ifmetric "$IFACE" 5 2>&1); rc=$?
check_eq ifmetric/rewrite/noprio-arm-rc 0 "$rc"
rshow
case "$(rline "$NET2")" in
	*"metric 5") bst_ok ifmetric/rewrite/noprio-arm-metric ;;
	*) bst_notok ifmetric/rewrite/noprio-arm-metric \
		"the addattr32 arm did not set metric 5 (tool said: $(_bst_1line "$out")); table: $(_bst_1line "$MAIN")" ;;
esac
# THE CASE THAT SEPARATES THIS TOOL FROM `ip route change`. One invocation named
# no prefix at all and re-weighted BOTH routes on the interface, which is the
# whole of what ifmetric is for.
case "$(rline "$NET1")" in
	*"metric 5") bst_ok ifmetric/rewrite/all-routes-one-call ;;
	*) bst_notok ifmetric/rewrite/all-routes-one-call \
		"$NET1 was not re-weighted by the same call that re-weighted $NET2 -- ifmetric acted on one route, not on the interface: $(_bst_1line "$MAIN")" ;;
esac

# --- the default metric, and atoi() -----------------------------------------
# `metric = argc > 2 ? atoi(argv[2]) : 0` -- with no second argument the metric
# is 0, and a zero priority is what makes the kernel omit RTA_PRIORITY again.
out=$(ifmetric "$IFACE" 2>&1); rc=$?
check_eq ifmetric/rewrite/default-zero-rc 0 "$rc"
rshow
case "$(rline "$NET1")$(rline "$NET2")" in
	*"metric"*)
		bst_notok ifmetric/rewrite/default-zero \
			"a bare 'ifmetric $IFACE' should leave metric 0 on both routes, which shows as NO metric field: $(_bst_1line "$MAIN")" ;;
	*) bst_ok ifmetric/rewrite/default-zero ;;
esac

# atoi("abc") is 0 and ifmetric neither validates nor complains. This is
# upstream behaviour and the case PINS it rather than wishing it away: a future
# version that started rejecting it would be a real change worth seeing.
ip route del "$NET1" 2>/dev/null
ip route add "$NET1" dev "$IFACE" metric 9 2>/dev/null
out=$(ifmetric "$IFACE" abc 2>&1); rc=$?
check_eq ifmetric/rewrite/atoi-nonnumeric-rc 0 "$rc"
rshow
case "$(rline "$NET1")" in
	*"metric"*)
		bst_notok ifmetric/rewrite/atoi-nonnumeric \
			"'ifmetric $IFACE abc' should be atoi()=0 and clear the metric: $(_bst_1line "$MAIN")" ;;
	*) bst_ok ifmetric/rewrite/atoi-nonnumeric ;;
esac

# main() reads argv[1] and argv[2] and nothing else; there is no getopt and no
# trailing-argument check.
out=$(ifmetric "$IFACE" 3 junk extra 2>&1); rc=$?
check_eq ifmetric/rewrite/extra-args-rc 0 "$rc"
rshow
case "$(rline "$NET1")" in
	*"metric 3") bst_ok ifmetric/rewrite/extra-args-ignored ;;
	*) bst_notok ifmetric/rewrite/extra-args-ignored \
		"argv[3] onward should be ignored and the metric set to 3: $(_bst_1line "$MAIN")" ;;
esac

# --- the table filter -------------------------------------------------------
# enumerate_callback returns early on `r->rtm_table != RT_TABLE_MAIN`, so a
# route in another table must survive untouched. Probed rather than assumed:
# policy routing is CONFIG_IP_MULTIPLE_TABLES and this kernel may not have it.
ip route del "$NET3" table "$ALTTABLE" 2>/dev/null
ip route add "$NET3" dev "$IFACE" metric 3 table "$ALTTABLE" 2>/dev/null
alt=$(ip -4 route show table "$ALTTABLE" 2>&1)
case "$alt" in
	*"10.97.0.0/24"*"metric 3"*)
		out=$(ifmetric "$IFACE" 77 2>&1)
		alt=$(ip -4 route show table "$ALTTABLE" 2>&1)
		case "$alt" in
			*"10.97.0.0/24"*"metric 3"*) bst_ok ifmetric/rewrite/table-filter ;;
			*) bst_notok ifmetric/rewrite/table-filter \
				"a route in table $ALTTABLE was touched by 'ifmetric $IFACE 77' -- the rtm_table filter did not hold: $(_bst_1line "$alt")" ;;
		esac
		ip route del "$NET3" table "$ALTTABLE" 2>/dev/null ;;
	*)
		bst_skip ifmetric/rewrite/table-filter \
			"no second routing table on this kernel (CONFIG_IP_MULTIPLE_TABLES): $(_bst_1line "$alt")" ;;
esac

# --- an interface with nothing to re-weight ---------------------------------
# n_routes == 0 makes go() skip its loop and return 0. "Nothing to re-weight" is
# a SUCCESS in this tool, not a failure, and that is worth pinning because the
# ticket's framing reads as though it were the other way round.
ip route del "$NET1" 2>/dev/null
ip route del "$NET2" 2>/dev/null
rshow
case "$(rline "$NET1")$(rline "$NET2")" in
	?*)
		bst_notok ifmetric/rewrite/cleanup \
			"this suite's routes are still in the main table after ip route del: $(_bst_1line "$MAIN")" ;;
	*) bst_ok ifmetric/rewrite/cleanup ;;
esac

out=$(ifmetric "$IFACE" 11 2>&1); rc=$?
check_eq ifmetric/rewrite/empty-table-rc 0 "$rc"
case "$out" in
	"") bst_ok ifmetric/rewrite/empty-table-quiet ;;
	*) bst_notok ifmetric/rewrite/empty-table-quiet \
		"an interface with no main-table route should produce no output: $(_bst_1line "$out")" ;;
esac