pkg/compiler: add glob type

* all: add new typename dirname

The current way to check files under sysfs or proc is:
- define a string to represent each file
- open the file
- pass the fd to write / read / close

The issues above are:
- Need to know what file present on target device
- Need to write openat for each file

With dirname added, which will open one file
in the directory randomly and then pass the fd to
write/read/close.

* all: use typename glob to match filename

Fixes #481

3 files changed, 32 insertions, 2 deletions

diff --git a/pkg/compiler/testdata/all.txt b/pkg/compiler/testdata/all.txt
index 17b7c838d..b1adf2321 100644
--- a/pkg/compiler/testdata/all.txt
+++ b/pkg/compiler/testdata/all.txt
@@ -252,6 +252,9 @@ foo_templ9(a ptr[in, templ_base3[int64]])
 foo_templ10(a ptr[in, templ_base4[int8]])
 foo_templ11(a ptr[in, templ_base5[42, int8]])
 
+foo_glob0(a ptr[in, glob["/sys/"]])
+foo_glob1(a ptr[in, glob["/sys/**/*"]])
+
 # Structs.
 
 s0 {
diff --git a/pkg/compiler/testdata/errors.txt b/pkg/compiler/testdata/errors.txt
index d3658d239..670cc0193 100644
--- a/pkg/compiler/testdata/errors.txt
+++ b/pkg/compiler/testdata/errors.txt
@@ -334,6 +334,11 @@ foo$210(a ptr[in, templ11[0, 1, int8]])		### template templ11 needs 2 arguments
 foo$211(a ptr[in, templ9])			### template templ9 needs 1 arguments instead of 0
 foo$212(a ptr[in, templ11[1]])			### template templ11 needs 2 arguments instead of 1
 
+foo$glob001(a ptr[in, glob[1]])			### unexpected int 1, string arg must be a string literal or string flags
+foo$glob002(a ptr[in, glob])			### glob only accepts 1 arg, provided 0
+foo$glob003(a ptr[in, glob["/sys", 5]])		### glob only accepts 1 arg, provided 2
+foo$glob004(a ptr[in, glob["/sys", 5, 2]])	### wrong number of arguments for type glob, expect [literal or flags], [size], [opt]
+
 # fmt
 
 foo$fmt0(a ptr[in, fmt])			### wrong number of arguments for type fmt, expect format, value
@@ -355,4 +360,4 @@ struct$perfielddir {
 	f4	int32	(in, inout)	### arg/field has multiple direction attributes
 	f5	int32	(out, inout)	### arg/field has multiple direction attributes
 	f6	int32	(in, out, inout)	### arg/field has multiple direction attributes
-}
\ No newline at end of file
+}
diff --git a/pkg/compiler/types.go b/pkg/compiler/types.go
index 038a05f24..d62c8fd48 100644
--- a/pkg/compiler/types.go
+++ b/pkg/compiler/types.go
@@ -598,10 +598,11 @@ func genTextType(t *ast.Type) prog.TextKind {
 
 const (
 	stringnoz = "stringnoz"
+	glob      = "glob"
 )
 
 var typeString = &typeDesc{
-	Names:        []string{"string", stringnoz},
+	Names:        []string{"string", glob, stringnoz},
 	CanBeTypedef: true,
 	OptArgs:      2,
 	Args: []namedArg{
@@ -612,6 +613,15 @@ var typeString = &typeDesc{
 		if t.Ident == stringnoz && len(args) > 1 {
 			comp.error(args[0].Pos, "fixed-size string can't be non-zero-terminated")
 		}
+		if t.Ident == glob {
+			pos := t.Pos
+			if len(args) > 0 {
+				pos = args[0].Pos
+			}
+			if len(args) != 1 {
+				comp.error(pos, "glob only accepts 1 arg, provided %v", len(args))
+			}
+		}
 	},
 	CheckConsts: func(comp *compiler, t *ast.Type, args []*ast.Type, base prog.IntTypeCommon) {
 		if len(args) > 1 {
@@ -626,6 +636,9 @@ var typeString = &typeDesc{
 		}
 	},
 	Varlen: func(comp *compiler, t *ast.Type, args []*ast.Type) bool {
+		if t.Ident == glob {
+			return true
+		}
 		return comp.stringSize(t, args) == varlenString
 	},
 	ZeroSize: func(comp *compiler, t *ast.Type, args []*ast.Type) bool {
@@ -645,6 +658,15 @@ var typeString = &typeDesc{
 				NoZ:        t.Ident == stringnoz,
 			}
 		}
+		if len(args) > 0 && t.Ident == glob {
+			base.TypeSize = 0
+			return &prog.BufferType{
+				TypeCommon: base.TypeCommon,
+				Kind:       prog.BufferGlob,
+				SubKind:    args[0].String,
+				NoZ:        false,
+			}
+		}
 		subkind := ""
 		if len(args) > 0 && args[0].Ident != "" {
 			subkind = args[0].Ident