cmd/go/internal/work: support pkgconf 1.4 and later

Fixes #23373

Fix interfacing with latest(1.4+) pkgconf versions, as they have change the
output format, by extending parsing function splitPkgConfigOutput to accommodate
more possible fragment escaping formats. Function is based on pkgconfigs own
implementation at
https://github.com/pkgconf/pkgconf/blob/master/libpkgconf/argvsplit.c. Along
with this change test case TestSplitPkgConfigOutput have been expanded. Thanks
to ignatenko for help on test cases and insights in to the pkgconfig.

Change-Id: I55301bb564b07128d5564ec1454dd247f84a95c3
Reviewed-on: https://go-review.googlesource.com/86541
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/internal/work/build_test.go

@@ -42,15 +42,60 @@ func TestSplitPkgConfigOutput(t *testing.T) {
 	}{
 		{[]byte(`-r:foo -L/usr/white\ space/lib -lfoo\ bar -lbar\ baz`), []string{"-r:foo", "-L/usr/white space/lib", "-lfoo bar", "-lbar baz"}},
 		{[]byte(`-lextra\ fun\ arg\\`), []string{`-lextra fun arg\`}},
-		{[]byte(`broken flag\`), []string{"broken", "flag"}},
 		{[]byte("\textra     whitespace\r\n"), []string{"extra", "whitespace"}},
 		{[]byte("     \r\n      "), nil},
+		{[]byte(`"-r:foo" "-L/usr/white space/lib" "-lfoo bar" "-lbar baz"`), []string{"-r:foo", "-L/usr/white space/lib", "-lfoo bar", "-lbar baz"}},
+		{[]byte(`"-lextra fun arg\\"`), []string{`-lextra fun arg\`}},
+		{[]byte(`"     \r\n\      "`), []string{`     \r\n\      `}},
+		{[]byte(`""`), nil},
+		{[]byte(``), nil},
+		{[]byte(`"\\"`), []string{`\`}},
+		{[]byte(`"\x"`), []string{`\x`}},
+		{[]byte(`"\\x"`), []string{`\x`}},
+		{[]byte(`'\\'`), []string{`\`}},
+		{[]byte(`'\x'`), []string{`\x`}},
+		{[]byte(`"\\x"`), []string{`\x`}},
+		{[]byte(`-fPIC -I/test/include/foo -DQUOTED='"/test/share/doc"'`), []string{"-fPIC", "-I/test/include/foo", `-DQUOTED="/test/share/doc"`}},
+		{[]byte(`-fPIC -I/test/include/foo -DQUOTED="/test/share/doc"`), []string{"-fPIC", "-I/test/include/foo", "-DQUOTED=/test/share/doc"}},
+		{[]byte(`-fPIC -I/test/include/foo -DQUOTED=\"/test/share/doc\"`), []string{"-fPIC", "-I/test/include/foo", `-DQUOTED="/test/share/doc"`}},
+		{[]byte(`-fPIC -I/test/include/foo -DQUOTED='/test/share/doc'`), []string{"-fPIC", "-I/test/include/foo", "-DQUOTED=/test/share/doc"}},
+		{[]byte(`-DQUOTED='/te\st/share/d\oc'`), []string{`-DQUOTED=/te\st/share/d\oc`}},
+		{[]byte(`-Dhello=10 -Dworld=+32 -DDEFINED_FROM_PKG_CONFIG=hello\ world`), []string{"-Dhello=10", "-Dworld=+32", "-DDEFINED_FROM_PKG_CONFIG=hello world"}},
+		{[]byte(`"broken\"" \\\a "a"`), []string{"broken\"", "\\a", "a"}},
 	} {
-		got := splitPkgConfigOutput(test.in)
+		got, err := splitPkgConfigOutput(test.in)
+		if err != nil {
+			t.Errorf("splitPkgConfigOutput on %v failed with error %v", test.in, err)
+			continue
+		}
+		if !reflect.DeepEqual(got, test.want) {
+			t.Errorf("splitPkgConfigOutput(%v) = %v; want %v", test.in, got, test.want)
+		}
+	}
+
+	for _, test := range []struct {
+		in   []byte
+		want []string
+	}{
+		// broken quotation
+		{[]byte(`"     \r\n      `), nil},
+		{[]byte(`"-r:foo" "-L/usr/white space/lib "-lfoo bar" "-lbar baz"`), nil},
+		{[]byte(`"-lextra fun arg\\`), nil},
+		// broken char escaping
+		{[]byte(`broken flag\`), nil},
+		{[]byte(`extra broken flag \`), nil},
+		{[]byte(`\`), nil},
+		{[]byte(`"broken\"" "extra" \`), nil},
+	} {
+		got, err := splitPkgConfigOutput(test.in)
+		if err == nil {
+			t.Errorf("splitPkgConfigOutput(%v) = %v; haven't failed with error as expected.", test.in, got)
+		}
 		if !reflect.DeepEqual(got, test.want) {
 			t.Errorf("splitPkgConfigOutput(%v) = %v; want %v", test.in, got, test.want)
 		}
 	}
+
 }
 
 func TestSharedLibName(t *testing.T) {

src/cmd/go/internal/work/exec.go

@@ -900,36 +900,64 @@ func (b *Builder) PkgconfigCmd() string {
 }
 
 // splitPkgConfigOutput parses the pkg-config output into a slice of
-// flags. pkg-config always uses \ to escape special characters.
-func splitPkgConfigOutput(out []byte) []string {
+// flags. This implements the algorithm from pkgconf/libpkgconf/argvsplit.c.
+func splitPkgConfigOutput(out []byte) ([]string, error) {
 	if len(out) == 0 {
-		return nil
+		return nil, nil
 	}
 	var flags []string
-	flag := make([]byte, len(out))
-	r, w := 0, 0
-	for r < len(out) {
-		switch out[r] {
-		case ' ', '\t', '\r', '\n':
-			if w > 0 {
-				flags = append(flags, string(flag[:w]))
+	flag := make([]byte, 0, len(out))
+	escaped := false
+	quote := byte(0)
+
+	for _, c := range out {
+		if escaped {
+			if quote != 0 {
+				switch c {
+				case '$', '`', '"', '\\':
+				default:
+					flag = append(flag, '\\')
+				}
+				flag = append(flag, c)
+			} else {
+				flag = append(flag, c)
 			}
-			w = 0
-		case '\\':
-			r++
-			fallthrough
-		default:
-			if r < len(out) {
-				flag[w] = out[r]
-				w++
+			escaped = false
+		} else if quote != 0 {
+			if c == quote {
+				quote = 0
+			} else {
+				switch c {
+				case '\\':
+					escaped = true
+				default:
+					flag = append(flag, c)
+				}
 			}
+		} else if strings.IndexByte(" \t\n\v\f\r", c) < 0 {
+			switch c {
+			case '\\':
+				escaped = true
+			case '\'', '"':
+				quote = c
+			default:
+				flag = append(flag, c)
+			}
+		} else if len(flag) != 0 {
+			flags = append(flags, string(flag))
+			flag = flag[:0]
 		}
-		r++
 	}
-	if w > 0 {
-		flags = append(flags, string(flag[:w]))
+	if escaped {
+		return nil, errors.New("broken character escaping in pkgconf output ")
+	}
+	if quote != 0 {
+		return nil, errors.New("unterminated quoted string in pkgconf output ")
+	} else if len(flag) != 0 {
+		flags = append(flags, string(flag))
 	}
-	return flags
+
+	return flags, nil
 }
 
 // Calls pkg-config if needed and returns the cflags/ldflags needed to build the package.
@@ -961,7 +989,10 @@ func (b *Builder) getPkgConfigFlags(p *load.Package) (cflags, ldflags []string,
 			return nil, nil, errPrintedOutput
 		}
 		if len(out) > 0 {
-			cflags = splitPkgConfigOutput(out)
+			cflags, err = splitPkgConfigOutput(out)
+			if err != nil {
+				return nil, nil, err
+			}
 			if err := checkCompilerFlags("CFLAGS", "pkg-config --cflags", cflags); err != nil {
 				return nil, nil, err
 			}