#!/bin/sh
set -eu

: "${CPU_AS:?}" "${CPU_LD:?}" "${CPU_RUN:?}" "${CPU_READELF:?}"

TMP=${TMPDIR:-/tmp}/libmcpu-needed-runtime-$$
mkdir -p "$TMP/lib"
trap 'rm -rf "$TMP"' EXIT HUP INT TERM

cat > "$TMP/main.s" <<'EOS'
.global _life
.extern afoo
.text
_start_life:
        LDI     r64@0x00000, 40
        CALL    afoo
        MOV     r64@0x00018, r64@0x00000
        LDI     r32@0x00030, 0
        EXIT    r32@0x00030
EOS

cat > "$TMP/a.s" <<'EOS'
.global afoo
.extern bfoo
.text
afoo:
        CALL    bfoo
        RET
EOS

cat > "$TMP/b.s" <<'EOS'
.global bfoo
.text
bfoo:
        LDI     r64@0x00008, 2
        IADD    r64@0x00000, r64@0x00000, r64@0x00008
        RET
EOS

"$CPU_AS" -o "$TMP/main.o" "$TMP/main.s"
"$CPU_AS" -o "$TMP/a.o" "$TMP/a.s"
"$CPU_AS" -o "$TMP/b.o" "$TMP/b.s"

# A real recursive graph: main -> liba.so.1 -> libb.so.1.
"$CPU_LD" --shared --soname=libb.so.1 \
  -o "$TMP/lib/libb.so.1.0.0" "$TMP/b.o"
ln -s libb.so.1.0.0 "$TMP/lib/libb.so.1"
ln -s libb.so.1 "$TMP/lib/libb.so"

"$CPU_LD" --shared --soname=liba.so.1 \
  -L"$TMP/lib" -lb -o "$TMP/lib/liba.so.1.0.0" "$TMP/a.o"
ln -s liba.so.1.0.0 "$TMP/lib/liba.so.1"
ln -s liba.so.1 "$TMP/lib/liba.so"

"$CPU_LD" --dynamic --stack-size=4096 --no-heap \
  -L"$TMP/lib" -la -o "$TMP/main" "$TMP/main.o"

"$CPU_READELF" -d "$TMP/main" | grep -q 'NEEDED.*\[liba.so.1\]'
"$CPU_READELF" -d "$TMP/lib/liba.so.1.0.0" | \
  grep -q 'NEEDED.*\[libb.so.1\]'
[ "`"$CPU_RUN" --library-path="$TMP/lib" \
        --int-reg=r64@0x00018 "$TMP/main"`" = 42 ]

# A missing transitive dependency is reported by SONAME, before process load.
mv "$TMP/lib/libb.so.1" "$TMP/lib/libb.so.1.save"
if "$CPU_RUN" --library-path="$TMP/lib" "$TMP/main" \
     >"$TMP/missing.out" 2>"$TMP/missing.err"; then
  echo "missing transitive dependency unexpectedly loaded" >&2
  exit 1
fi
grep -q "cannot resolve DT_NEEDED 'libb.so.1'" "$TMP/missing.err"
mv "$TMP/lib/libb.so.1.save" "$TMP/lib/libb.so.1"

# The resolved filename is not trusted: its internal SONAME must be the exact
# DT_NEEDED identity requested by the dependent object.
cat > "$TMP/wrong.s" <<'EOS'
.global afoo
.text
afoo:
        RET
EOS
"$CPU_AS" -o "$TMP/wrong.o" "$TMP/wrong.s"
"$CPU_LD" --shared --soname=libwrong.so.9 \
  -o "$TMP/lib/libwrong.so.9.0.0" "$TMP/wrong.o"
rm "$TMP/lib/liba.so.1"
ln -s libwrong.so.9.0.0 "$TMP/lib/liba.so.1"
if "$CPU_RUN" --library-path="$TMP/lib" "$TMP/main" \
     >"$TMP/mismatch.out" 2>"$TMP/mismatch.err"; then
  echo "SONAME mismatch unexpectedly loaded" >&2
  exit 1
fi
grep -q "DT_NEEDED 'liba.so.1' resolved to SONAME 'libwrong.so.9'" \
  "$TMP/mismatch.err"
rm "$TMP/lib/liba.so.1"
ln -s liba.so.1.0.0 "$TMP/lib/liba.so.1"

# Dependency cycles are legal graph edges.  Registration by SONAME before
# recursive descent prevents A -> B -> A from recursing or loading twice.
cat > "$TMP/cycle-main.s" <<'EOS'
.global _life
.extern cycle_a
.text
_start_life:
        LDI     r64@0x00000, 40
        CALL    cycle_a
        MOV     r64@0x00018, r64@0x00000
        LDI     r32@0x00030, 0
        EXIT    r32@0x00030
EOS
cat > "$TMP/cycle-a.s" <<'EOS'
.global cycle_a
.text
cycle_a:
        LDI     r64@0x00008, 4
        IADD    r64@0x00000, r64@0x00000, r64@0x00008
        RET
EOS
cat > "$TMP/cycle-b.s" <<'EOS'
.global cycle_b
.text
cycle_b:
        RET
EOS
"$CPU_AS" -o "$TMP/cycle-main.o" "$TMP/cycle-main.s"
"$CPU_AS" -o "$TMP/cycle-a.o" "$TMP/cycle-a.s"
"$CPU_AS" -o "$TMP/cycle-b.o" "$TMP/cycle-b.s"

# Bootstrap one side of the cycle, build B -> A, then rebuild A -> B.
"$CPU_LD" --shared --soname=libcyclea.so.1 \
  -o "$TMP/lib/libcyclea.so.1.0.0" "$TMP/cycle-a.o"
ln -s libcyclea.so.1.0.0 "$TMP/lib/libcyclea.so.1"
ln -s libcyclea.so.1 "$TMP/lib/libcyclea.so"
"$CPU_LD" --shared --soname=libcycleb.so.1 \
  -L"$TMP/lib" -lcyclea \
  -o "$TMP/lib/libcycleb.so.1.0.0" "$TMP/cycle-b.o"
ln -s libcycleb.so.1.0.0 "$TMP/lib/libcycleb.so.1"
ln -s libcycleb.so.1 "$TMP/lib/libcycleb.so"
"$CPU_LD" --shared --soname=libcyclea.so.1 \
  -L"$TMP/lib" -lcycleb \
  -o "$TMP/lib/libcyclea.so.1.0.0" "$TMP/cycle-a.o"
"$CPU_LD" --dynamic --stack-size=4096 --no-heap \
  -L"$TMP/lib" -lcyclea -o "$TMP/cycle-main" "$TMP/cycle-main.o"
[ "`"$CPU_RUN" --library-path="$TMP/lib" \
        --int-reg=r64@0x00018 "$TMP/cycle-main"`" = 44 ]

# Explicit preload remains the override mechanism.  An ABI-v3 preload with the
# same SONAME satisfies the normal dependency and keeps the established
# explicit-preload priority.
cat > "$TMP/direct-main.s" <<'EOS'
.global _life
.extern foo
.text
_start_life:
        LDI     r64@0x00000, 40
        CALL    foo
        MOV     r64@0x00018, r64@0x00000
        LDI     r32@0x00030, 0
        EXIT    r32@0x00030
EOS
cat > "$TMP/foo.s" <<'EOS'
.global foo
.text
foo:
        LDI     r64@0x00008, 2
        IADD    r64@0x00000, r64@0x00000, r64@0x00008
        RET
EOS
cat > "$TMP/override.s" <<'EOS'
.global foo
.text
foo:
        LDI     r64@0x00008, 3
        IADD    r64@0x00000, r64@0x00000, r64@0x00008
        RET
EOS
"$CPU_AS" -o "$TMP/direct-main.o" "$TMP/direct-main.s"
"$CPU_AS" -o "$TMP/foo.o" "$TMP/foo.s"
"$CPU_AS" -o "$TMP/override.o" "$TMP/override.s"
"$CPU_LD" --shared --soname=libfoo.so.1 \
  -o "$TMP/lib/libfoo.so.1.0.0" "$TMP/foo.o"
ln -s libfoo.so.1.0.0 "$TMP/lib/libfoo.so.1"
ln -s libfoo.so.1 "$TMP/lib/libfoo.so"
"$CPU_LD" --shared --soname=libfoo.so.1 \
  -o "$TMP/override.so" "$TMP/override.o"
"$CPU_LD" --dynamic --stack-size=4096 --no-heap \
  -L"$TMP/lib" -lfoo -o "$TMP/direct-main" "$TMP/direct-main.o"
[ "`"$CPU_RUN" --library-path="$TMP/lib" \
        --int-reg=r64@0x00018 "$TMP/direct-main"`" = 42 ]
[ "`"$CPU_RUN" --library-path="$TMP/lib" \
        --ldpreload="$TMP/override.so" \
        --int-reg=r64@0x00018 "$TMP/direct-main"`" = 43 ]

exit 0