symbols_map: don't error on bad elf files
There are cc_binary_prebuilt modules in the tree that are shell
scripts, and attempting to extract an elf ID from them results
in an error. Ignore too short files and files missing the elf
magic header the same way we do for elf files without an elf ID.
Bug: 218888599
Test: Test_elfIdentifierFromReaderAt_BadElfFile
Change-Id: If7117925ca2371a8ee61ba3616372f6e9b0fab0e
diff --git a/cmd/symbols_map/elf_test.go b/cmd/symbols_map/elf_test.go
index e616228..b96ea59 100644
--- a/cmd/symbols_map/elf_test.go
+++ b/cmd/symbols_map/elf_test.go
@@ -16,11 +16,46 @@
import (
"bytes"
+ "debug/elf"
"encoding/binary"
"reflect"
"testing"
)
+func Test_elfIdentifierFromReaderAt_BadElfFile(t *testing.T) {
+ tests := []struct {
+ name string
+ contents string
+ }{
+ {
+ name: "empty",
+ contents: "",
+ },
+ {
+ name: "text",
+ contents: "#!/bin/bash\necho foobar",
+ },
+ {
+ name: "empty elf",
+ contents: emptyElfFile(),
+ },
+ }
+
+ for _, tt := range tests {
+ t.Run(tt.name, func(t *testing.T) {
+ buf := bytes.NewReader([]byte(tt.contents))
+ _, err := elfIdentifierFromReaderAt(buf, "<>", false)
+ if err == nil {
+ t.Errorf("expected error reading bad elf file without allowMissing")
+ }
+ _, err = elfIdentifierFromReaderAt(buf, "<>", true)
+ if err != nil {
+ t.Errorf("expected no error reading bad elf file with allowMissing, got %q", err.Error())
+ }
+ })
+ }
+}
+
func Test_readNote(t *testing.T) {
note := []byte{
0x04, 0x00, 0x00, 0x00,
@@ -43,3 +78,36 @@
t.Errorf("incorrect return, want %#v got %#v", expectedDescs, descs)
}
}
+
+// emptyElfFile returns an elf file header with no program headers or sections.
+func emptyElfFile() string {
+ ident := [elf.EI_NIDENT]byte{}
+ identBuf := bytes.NewBuffer(ident[0:0:elf.EI_NIDENT])
+ binary.Write(identBuf, binary.LittleEndian, []byte("\x7fELF"))
+ binary.Write(identBuf, binary.LittleEndian, elf.ELFCLASS64)
+ binary.Write(identBuf, binary.LittleEndian, elf.ELFDATA2LSB)
+ binary.Write(identBuf, binary.LittleEndian, elf.EV_CURRENT)
+ binary.Write(identBuf, binary.LittleEndian, elf.ELFOSABI_LINUX)
+ binary.Write(identBuf, binary.LittleEndian, make([]byte, 8))
+
+ header := elf.Header64{
+ Ident: ident,
+ Type: uint16(elf.ET_EXEC),
+ Machine: uint16(elf.EM_X86_64),
+ Version: uint32(elf.EV_CURRENT),
+ Entry: 0,
+ Phoff: uint64(binary.Size(elf.Header64{})),
+ Shoff: uint64(binary.Size(elf.Header64{})),
+ Flags: 0,
+ Ehsize: uint16(binary.Size(elf.Header64{})),
+ Phentsize: 0x38,
+ Phnum: 0,
+ Shentsize: 0x40,
+ Shnum: 0,
+ Shstrndx: 0,
+ }
+
+ buf := &bytes.Buffer{}
+ binary.Write(buf, binary.LittleEndian, header)
+ return buf.String()
+}