Fix for rust and swift coverages (#6517)

* coverage: introduces llvm-cov-rel

Cf https://github.com/google/oss-fuzz/issues/6268

Latest clang-14 and clang-13 used by rust or swift have a slightly
different profraw file format

llvm-cov-rel is tool that will update the profraw file produced
by clang-13 to one readable by clang-14 llvm-cov tools

* Suricata as a rust project

* rust coverage: remaps every rust subdirectory in fuzz

So that projects not using default fuzz_targets subdir
get the good remap, and hence the good coverage report

3 files changed, 188 insertions, 1 deletions

diff --git a/infra/base-images/base-builder/cargo b/infra/base-images/base-builder/cargo
index d83e1d2e..c60c7611 100755
--- a/infra/base-images/base-builder/cargo
+++ b/infra/base-images/base-builder/cargo
@@ -35,7 +35,11 @@ then
     # go into fuzz directory if not already the case
     cd fuzz || true
     fuzz_src_abspath=`pwd`
-    export RUSTFLAGS="$RUSTFLAGS --remap-path-prefix fuzz_targets=$fuzz_src_abspath/fuzz_targets"
+    # Default directory is fuzz_targets, but some projects like image-rs use fuzzers.
+    while read i; do
+        export RUSTFLAGS="$RUSTFLAGS --remap-path-prefix $i=$fuzz_src_abspath/$i"
+        # Bash while syntax so that we modify RUSTFLAGS in main shell instead of a subshell.
+    done <<< "$(ls */*.rs | cut -d/ -f1 | uniq)"
     # we do not want to trigger debug assertions and stops
     export RUSTFLAGS="$RUSTFLAGS -C debug-assertions=no"
     # do not optimize with --release, leading to Malformed instrumentation profile data
diff --git a/infra/base-images/base-runner/coverage b/infra/base-images/base-runner/coverage
index 54154212..40c31e07 100755
--- a/infra/base-images/base-runner/coverage
+++ b/infra/base-images/base-runner/coverage
@@ -99,6 +99,9 @@ function run_fuzz_target {
     return 0
   fi
 
+  # If necessary translate to latest profraw version.
+  llvm-cov-rel $OUT/$target $profraw_file_mask tmp.profraw
+  mv tmp.profraw $profraw_file_mask
   llvm-profdata merge -j=1 -sparse $profraw_file_mask -o $profdata_file
 
   # Delete unnecessary and (potentially) large .profraw files.
diff --git a/infra/base-images/base-runner/gocoverage/llvm-cov-rel/llvm-profraw-relative.go b/infra/base-images/base-runner/gocoverage/llvm-cov-rel/llvm-profraw-relative.go
new file mode 100644
index 00000000..91556c7c
--- /dev/null
+++ b/infra/base-images/base-runner/gocoverage/llvm-cov-rel/llvm-profraw-relative.go
@@ -0,0 +1,180 @@
+package main
+
+import (
+	"debug/elf"
+	"encoding/binary"
+	"flag"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+)
+
+type ProfrawHeaderVersion7 struct {
+	ProfrawHeaderGeneric
+	BinaryIdsSize              uint64
+	DataSize                   uint64
+	PaddingBytesBeforeCounters uint64
+	CountersSize               uint64
+	PaddingBytesAfterCounters  uint64
+	NamesSize                  uint64
+	CountersDelta              uint64
+	NamesDelta                 uint64
+	ValueKindLast              uint64
+}
+
+type ProfrawHeaderGeneric struct {
+	Magic   uint64
+	Version uint64
+}
+
+type ProfrawData struct {
+	NameRef         uint64
+	FuncHash        uint64
+	CounterPtr      uint64
+	FunctionPointer uint64
+	Values          uint64
+	NumCounters     uint32
+	NumValueSites   []uint16
+}
+
+const PROFRAW_HEADER_GENERIC_LEN = 16
+const PROFRAW_HEADER_7_LEN = 88
+
+func parseProfrawHeaderGeneric(data []byte) (ProfrawHeaderGeneric, error) {
+	r := ProfrawHeaderGeneric{}
+	if len(data) < PROFRAW_HEADER_GENERIC_LEN {
+		return r, io.EOF
+	}
+	r.Magic = binary.LittleEndian.Uint64(data[:8])
+	r.Version = binary.LittleEndian.Uint64(data[8:16])
+	if r.Magic != 0xff6c70726f667281 {
+		return r, fmt.Errorf("Invalid magic %x", r.Magic)
+	}
+	return r, nil
+}
+
+func relativizeAddress(data []byte, offset int, databegin uint64, sectPrfCnts uint64, sectPrfData uint64) {
+	value := binary.LittleEndian.Uint64(data[offset : offset+8])
+	if value >= sectPrfCnts && value < sectPrfData {
+		// If the value is an address in the right section,
+		// Make it relative.
+		value = value - databegin
+		binary.LittleEndian.PutUint64(data[offset:offset+8], value)
+	}
+
+}
+
+func profrawDataLen(ipvklast uint64) int {
+	return 44 + 2*(int(ipvklast)+1)
+}
+
+func relativizeProfraw(data []byte, sectPrfCnts uint64, sectPrfData uint64) (error, []byte) {
+	h := ProfrawHeaderVersion7{}
+	var err error
+	h.ProfrawHeaderGeneric, err = parseProfrawHeaderGeneric(data)
+	if err != nil {
+		return err, data
+	}
+	if h.Version == 5 {
+		// Upgrade from 5 to 7 by adding a zero binaryids in the header.
+		binary.LittleEndian.PutUint64(data[8:16], 7)
+		h.Version = 7
+		data2 := make([]byte, len(data)+8)
+		copy(data2, data[0:16])
+		copy(data2[24:], data[16:])
+		data = data2
+	}
+	if h.Version < 7 {
+		return fmt.Errorf("Invalid version for profraw file: %v", h.Version), data
+	}
+	// At one point clang-14 will update to 8, and more work will be needed.
+	if len(data) < PROFRAW_HEADER_7_LEN {
+		return io.EOF, data
+	}
+	h.BinaryIdsSize = binary.LittleEndian.Uint64(data[16:24])
+	h.DataSize = binary.LittleEndian.Uint64(data[24:32])
+	h.PaddingBytesBeforeCounters = binary.LittleEndian.Uint64(data[32:40])
+	h.CountersSize = binary.LittleEndian.Uint64(data[40:48])
+	h.PaddingBytesAfterCounters = binary.LittleEndian.Uint64(data[48:56])
+	h.NamesSize = binary.LittleEndian.Uint64(data[56:64])
+	h.CountersDelta = binary.LittleEndian.Uint64(data[64:72])
+	h.NamesDelta = binary.LittleEndian.Uint64(data[72:80])
+	h.ValueKindLast = binary.LittleEndian.Uint64(data[80:88])
+
+	if h.CountersDelta != sectPrfCnts-sectPrfData {
+		// Rust linking adds an offset ? not seen in readelf.
+		sectPrfData = h.CountersDelta - sectPrfCnts + sectPrfData
+		sectPrfCnts = h.CountersDelta
+	}
+	dataref := sectPrfData
+	relativizeAddress(data, 64, dataref, sectPrfCnts, sectPrfData)
+
+	offset := PROFRAW_HEADER_7_LEN + int(h.BinaryIdsSize)
+	for i := uint64(0); i < h.DataSize; i++ {
+		if len(data) < offset+profrawDataLen(h.ValueKindLast) {
+			return io.EOF, data
+		}
+		d := ProfrawData{}
+		d.NameRef = binary.LittleEndian.Uint64(data[offset : offset+8])
+		d.FuncHash = binary.LittleEndian.Uint64(data[offset+8 : offset+16])
+		d.CounterPtr = binary.LittleEndian.Uint64(data[offset+16 : offset+24])
+		d.FunctionPointer = binary.LittleEndian.Uint64(data[offset+24 : offset+32])
+		d.Values = binary.LittleEndian.Uint64(data[offset+32 : offset+40])
+		d.NumCounters = binary.LittleEndian.Uint32(data[offset+40 : offset+44])
+		d.NumValueSites = make([]uint16, h.ValueKindLast+1)
+		for j := 0; j <= int(h.ValueKindLast); j++ {
+			d.NumValueSites[j] = binary.LittleEndian.Uint16(data[offset+44+2*j : offset+46+2*j])
+		}
+
+		relativizeAddress(data, offset+16, dataref, sectPrfCnts, sectPrfData)
+		// We need this because of CountersDelta -= sizeof(*SrcData); in __llvm_profile_merge_from_buffer.
+		dataref += uint64(profrawDataLen(h.ValueKindLast))
+
+		offset += profrawDataLen(h.ValueKindLast)
+	}
+	return nil, data
+}
+
+func main() {
+	flag.Parse()
+
+	if len(flag.Args()) != 3 {
+		log.Fatalf("needs exactly three arguments : binary, profraw, output")
+	}
+
+	// First find llvm profile sections addresses in the elf.
+	f, err := elf.Open(flag.Args()[0])
+	if err != nil {
+		log.Fatalf("failed to read elf: %v", err)
+	}
+	sectPrfCnts := uint64(0)
+	sectPrfData := uint64(0)
+	for i := range f.Sections {
+		if f.Sections[i].Name == "__llvm_prf_cnts" {
+			sectPrfCnts = f.Sections[i].Addr
+		} else if f.Sections[i].Name == "__llvm_prf_data" {
+			sectPrfData = f.Sections[i].Addr
+			// Maybe rather sectPrfCntsEnd as f.Sections[i].Addr + f.Sections[i].Size for __llvm_prf_cnts.
+		}
+	}
+	if sectPrfCnts == 0 || sectPrfData == 0 {
+		log.Fatalf("Elf has not __llvm_prf_cnts and __llvm_prf_data sections")
+	}
+
+	// Process profraw file.
+	data, err := ioutil.ReadFile(flag.Args()[1])
+	if err != nil {
+		log.Fatalf("failed to read file: %v", err)
+	}
+	err, data = relativizeProfraw(data, sectPrfCnts, sectPrfData)
+	if err != nil {
+		log.Fatalf("failed to process file: %v", err)
+	}
+
+	// Write output file.
+	err = ioutil.WriteFile(flag.Args()[2], data, 0644)
+	if err != nil {
+		log.Fatalf("failed to write file: %v", err)
+	}
+}