Allow case-insensitive filename globbing; add nocaseglob

- Add a FoldCase flag to the expand.Config struct, which is used to
  configure how expand.Fields behaves.
- Similarly, add a FoldCase Mode to pattern.Regexp. Setting the flag
  adds (?i) to the front of the generated regular expression.
- Use the former to set the latter when calling expand.Fields.
- Use all of the above to implement the "nocaseglob" shopt.

Rationale: I use expand.Fields to do filename expansion, for which I'd
like to do case-insensitive matching. E.g. I'd like "c*" to match both
"cmd" and "CHANGELOG.md"

expand/expand.go

@@ -68,6 +68,10 @@ type Config struct {
  // "**".
  GlobStar bool
 
+ // NoCaseGlob corresponds to the shell option that causes case-insensitive
+ // pattern matching in pathname expansion.
+ NoCaseGlob bool
+
  // NullGlob corresponds to the shell option that allows globbing
  // patterns which match nothing to result in zero fields.
  NullGlob bool
@@ -946,7 +950,11 @@ func (cfg *Config) glob(base, pat string) ([]string, error) {
  }
  continue
  }
- expr, err := pattern.Regexp(part, pattern.Filenames|pattern.EntireString)
+ mode := pattern.Filenames | pattern.EntireString
+ if cfg.NoCaseGlob {
+ mode |= pattern.NoGlobCase
+ }
+ expr, err := pattern.Regexp(part, mode)
  if err != nil {
  return nil, err
  }

expand/expand_test.go

@@ -4,6 +4,7 @@
 package expand
 
 import (
+ "io/fs"
  "os"
  "reflect"
  "strings"
@@ -90,3 +91,52 @@ func TestFieldsIdempotency(t *testing.T) {
  }
  }
 }
+
+func Test_glob(t *testing.T) {
+ cfg := &Config{
+ ReadDir2: func(string) ([]fs.DirEntry, error) {
+ return []fs.DirEntry{
+ &mockFileInfo{name: "a"},
+ &mockFileInfo{name: "ab"},
+ &mockFileInfo{name: "A"},
+ &mockFileInfo{name: "AB"},
+ }, nil
+ },
+ }
+
+ tests := []struct {
+ noCaseGlob bool
+ pat string
+ want []string
+ }{
+ {false, "a*", []string{"a", "ab"}},
+ {false, "A*", []string{"A", "AB"}},
+ {false, "*b", []string{"ab"}},
+ {false, "b*", nil},
+ {true, "a*", []string{"a", "ab", "A", "AB"}},
+ {true, "A*", []string{"a", "ab", "A", "AB"}},
+ {true, "*b", []string{"ab", "AB"}},
+ {true, "b*", nil},
+ }
+ for _, tc := range tests {
+ cfg.NoCaseGlob = tc.noCaseGlob
+ got, err := cfg.glob("/", tc.pat)
+ if err != nil {
+ t.Fatalf("did not want error, got %v", err)
+ }
+ if !reflect.DeepEqual(got, tc.want) {
+ t.Fatalf("wanted %q, got %q", tc.want, got)
+ }
+ }
+}
+
+type mockFileInfo struct {
+ name string
+ typ fs.FileMode
+ fs.DirEntry // Stub out everything but Name() & Type()
+}
+
+var _ fs.DirEntry = (*mockFileInfo)(nil)
+
+func (fi *mockFileInfo) Name() string { return fi.name }
+func (fi *mockFileInfo) Type() fs.FileMode { return fi.typ }

interp/api.go

@@ -493,6 +493,11 @@ var bashOptsTable = [...]bashOpt{
  defaultState: false,
  supported: true,
  },
+ {
+ name: "nocaseglob",
+ defaultState: false,
+ supported: true,
+ },
  {
  name: "nullglob",
  defaultState: false,
@@ -565,7 +570,6 @@ var bashOptsTable = [...]bashOpt{
  {name: "login_shell"},
  {name: "mailwarn"},
  {name: "no_empty_cmd_completion"},
- {name: "nocaseglob"},
  {name: "nocasematch"},
  {
  name: "progcomp",
@@ -589,6 +593,7 @@ var bashOptsTable = [...]bashOpt{
 // know which option we're after at compile time. First come the shell options,
 // then the bash options.
 const (
+ // These correspond to indexes in shellOptsTable
  optAllExport = iota
  optErrExit
  optNoExec
@@ -597,8 +602,11 @@ const (
  optXTrace
  optPipeFail
 
+ // These correspond to indexes (offset by the above seven items) of
+ // supported options in bashOptsTable
  optExpandAliases
  optGlobStar
+ optNoCaseGlob
  optNullGlob
 )
 

interp/interp_test.go

@@ -2139,6 +2139,24 @@ done <<< 2`,
  "shopt -s foo",
  "shopt: invalid option name \"foo\"\nexit status 1 #JUSTERR",
  },
+ {
+ // Beware that macOS file systems are by default case-preserving but
+ // case-insensitive, so e.g. "touch x X" creates only one file.
+ "touch a ab Ac Ad; shopt -u nocaseglob; echo a*",
+ "a ab\n",
+ },
+ {
+ "touch a ab Ac Ad; shopt -s nocaseglob; echo a*",
+ "Ac Ad a ab\n",
+ },
+ {
+ "touch a ab abB Ac Ad; shopt -u nocaseglob; echo *b",
+ "ab\n",
+ },
+ {
+ "touch a ab abB Ac Ad; shopt -s nocaseglob; echo *b",
+ "ab abB\n",
+ },
 
  // IFS
  {`echo -n "$IFS"`, " \t\n"},

interp/runner.go

@@ -163,6 +163,7 @@ func (r *Runner) updateExpandOpts() {
  }
  }
  r.ecfg.GlobStar = r.opts[optGlobStar]
+ r.ecfg.NoCaseGlob = r.opts[optNoCaseGlob]
  r.ecfg.NullGlob = r.opts[optNullGlob]
  r.ecfg.NoUnset = r.opts[optNoUnset]
 }

pattern/pattern.go

@@ -34,6 +34,7 @@ const (
  Filenames // "*" and "?" don't match slashes; only "**" does
  Braces // support "{a,b}" and "{1..4}"
  EntireString // match the entire string using ^$ delimiters
+ NoGlobCase // Do case-insensitive match (that is, use (?i) in the regexp)
 )
 
 var numRange = regexp.MustCompile(`^([+-]?\d+)\.\.([+-]?\d+)}`)
@@ -68,6 +69,9 @@ noopLoop:
  // Enable matching `\n` with the `.` metacharacter as globs match `\n`
  buf.WriteString("(?s)")
  dotMeta := false
+ if mode&NoGlobCase != 0 {
+ buf.WriteString("(?i)")
+ }
  if mode&EntireString != 0 {
  buf.WriteString("^")
  }
@@ -242,7 +246,7 @@ writeLoop:
  if mode&EntireString != 0 {
  buf.WriteString("$")
  }
- // No `.` metacharacters were used, so don't return the flag.
+ // No `.` metacharacters were used, so don't return the (?s) flag.
  if !dotMeta {
  return string(buf.Bytes()[4:]), nil
  }