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-rw-r--r--tools/go_marshal/gomarshal/generator.go4
-rw-r--r--tools/go_marshal/gomarshal/generator_interfaces.go1
-rw-r--r--tools/go_marshal/gomarshal/generator_interfaces_struct.go23
-rw-r--r--tools/go_marshal/gomarshal/util.go154
4 files changed, 141 insertions, 41 deletions
diff --git a/tools/go_marshal/gomarshal/generator.go b/tools/go_marshal/gomarshal/generator.go
index 935a36b25..43e668b63 100644
--- a/tools/go_marshal/gomarshal/generator.go
+++ b/tools/go_marshal/gomarshal/generator.go
@@ -326,7 +326,7 @@ func (g *Generator) collectImports(a *ast.File, f *token.FileSet) map[string]imp
// Make sure we have an import that doesn't use any local names that
// would conflict with identifiers in the generated code.
- if len(i.name) == 1 {
+ if len(i.name) == 1 && i.name != "_" {
abortAt(f.Position(spec.Pos()), fmt.Sprintf("Import has a single character local name '%s'; this may conflict with code generated by go_marshal, use a multi-character import alias", i.name))
}
if _, ok := badIdentsMap[i.name]; ok {
@@ -421,7 +421,7 @@ func (g *Generator) Run() error {
// the list of imports we need to copy to the generated code.
for name, _ := range impl.is {
if !g.imports.markUsed(name) {
- panic(fmt.Sprintf("Generated code for '%s' referenced a non-existent import with local name '%s'", impl.typeName(), name))
+ panic(fmt.Sprintf("Generated code for '%s' referenced a non-existent import with local name '%s'. Either go-marshal needs to add an import to the generated file, or a package in an input source file has a package name differ from the final component of its path, which go-marshal doesn't know how to detect; use an import alias to work around this limitation.", impl.typeName(), name))
}
}
ts = append(ts, g.generateOneTestSuite(t))
diff --git a/tools/go_marshal/gomarshal/generator_interfaces.go b/tools/go_marshal/gomarshal/generator_interfaces.go
index 8812c6878..8f1c27145 100644
--- a/tools/go_marshal/gomarshal/generator_interfaces.go
+++ b/tools/go_marshal/gomarshal/generator_interfaces.go
@@ -72,7 +72,6 @@ func (g *interfaceGenerator) recordUsedMarshallable(m string) {
func (g *interfaceGenerator) recordUsedImport(i string) {
g.is[i] = struct{}{}
-
}
func (g *interfaceGenerator) recordPotentiallyNonPackedField(fieldName string) {
diff --git a/tools/go_marshal/gomarshal/generator_interfaces_struct.go b/tools/go_marshal/gomarshal/generator_interfaces_struct.go
index bd57eae0e..e837f58db 100644
--- a/tools/go_marshal/gomarshal/generator_interfaces_struct.go
+++ b/tools/go_marshal/gomarshal/generator_interfaces_struct.go
@@ -152,7 +152,7 @@ func (g *interfaceGenerator) emitMarshallableForStruct(st *ast.StructType) {
g.shift("dst", len)
} else {
// We can't use shiftDynamic here because we don't have
- // an instance of the dynamic type we can referece here
+ // an instance of the dynamic type we can reference here
// (since the version in this struct is anonymous). Use
// a typed nil pointer to call SizeBytes() instead.
g.emit("dst = dst[(*%s)(nil).SizeBytes():]\n", t.Name)
@@ -162,6 +162,11 @@ func (g *interfaceGenerator) emitMarshallableForStruct(st *ast.StructType) {
g.marshalScalar(g.fieldAccessor(n), t.Name, "dst")
},
selector: func(n, tX, tSel *ast.Ident) {
+ if n.Name == "_" {
+ g.emit("// Padding: dst[:sizeof(%s)] ~= %s(0)\n", tX.Name, tSel.Name)
+ g.emit("dst = dst[(*%s.%s)(nil).SizeBytes():]\n", tX.Name, tSel.Name)
+ return
+ }
g.marshalScalar(g.fieldAccessor(n), fmt.Sprintf("%s.%s", tX.Name, tSel.Name), "dst")
},
array: func(n, t *ast.Ident, size int) {
@@ -199,11 +204,11 @@ func (g *interfaceGenerator) emitMarshallableForStruct(st *ast.StructType) {
if len, dynamic := g.scalarSize(t); !dynamic {
g.shift("src", len)
} else {
- // We can't use shiftDynamic here because we don't have
- // an instance of the dynamic type we can reference here
- // (since the version in this struct is anonymous). Use
- // a typed nil pointer to call SizeBytes() instead.
- g.emit("src = src[(*%s)(nil).SizeBytes():]\n", t.Name)
+ // We don't have an instance of the dynamic type we can
+ // reference here (since the version in this struct is
+ // anonymous). Use a typed nil pointer to call
+ // SizeBytes() instead.
+ g.shiftDynamic("src", fmt.Sprintf("(*%s)(nil)", t.Name))
g.recordPotentiallyNonPackedField(fmt.Sprintf("(*%s)(nil)", t.Name))
}
return
@@ -211,6 +216,12 @@ func (g *interfaceGenerator) emitMarshallableForStruct(st *ast.StructType) {
g.unmarshalScalar(g.fieldAccessor(n), t.Name, "src")
},
selector: func(n, tX, tSel *ast.Ident) {
+ if n.Name == "_" {
+ g.emit("// Padding: %s ~= src[:sizeof(%s.%s)]\n", g.fieldAccessor(n), tX.Name, tSel.Name)
+ g.emit("src = src[(*%s.%s)(nil).SizeBytes():]\n", tX.Name, tSel.Name)
+ g.recordPotentiallyNonPackedField(fmt.Sprintf("(*%s.%s)(nil)", tX.Name, tSel.Name))
+ return
+ }
g.unmarshalScalar(g.fieldAccessor(n), fmt.Sprintf("%s.%s", tX.Name, tSel.Name), "src")
},
array: func(n, t *ast.Ident, size int) {
diff --git a/tools/go_marshal/gomarshal/util.go b/tools/go_marshal/gomarshal/util.go
index 4cb22dd2d..96025ff39 100644
--- a/tools/go_marshal/gomarshal/util.go
+++ b/tools/go_marshal/gomarshal/util.go
@@ -285,6 +285,11 @@ type importStmt struct {
aliased bool
// Indicates whether this import was referenced by generated code.
used bool
+ // AST node and file set representing the import statement, if any. These
+ // are only non-nil if the import statement originates from an input source
+ // file.
+ spec *ast.ImportSpec
+ fset *token.FileSet
}
func newImport(p string) *importStmt {
@@ -310,14 +315,27 @@ func newImportFromSpec(spec *ast.ImportSpec, f *token.FileSet) *importStmt {
name: name,
path: p,
aliased: spec.Name != nil,
+ spec: spec,
+ fset: f,
}
}
+// String implements fmt.Stringer.String. This generates a string for the import
+// statement appropriate for writing directly to generated code.
func (i *importStmt) String() string {
if i.aliased {
- return fmt.Sprintf("%s \"%s\"", i.name, i.path)
+ return fmt.Sprintf("%s %q", i.name, i.path)
}
- return fmt.Sprintf("\"%s\"", i.path)
+ return fmt.Sprintf("%q", i.path)
+}
+
+// debugString returns a debug string representing an import statement. This
+// representation is not valid golang code and is used for debugging output.
+func (i *importStmt) debugString() string {
+ if i.spec != nil && i.fset != nil {
+ return fmt.Sprintf("%s: %s", i.fset.Position(i.spec.Path.Pos()), i)
+ }
+ return fmt.Sprintf("(go-marshal import): %s", i)
}
func (i *importStmt) markUsed() {
@@ -329,43 +347,78 @@ func (i *importStmt) equivalent(other *importStmt) bool {
}
// importTable represents a collection of importStmts.
+//
+// An importTable may contain multiple import statements referencing the same
+// local name. All import statements aliasing to the same local name are
+// technically ambiguous, as if such an import name is used in the generated
+// code, it's not clear which import statement it refers to. We ignore any
+// potential collisions until actually writing the import table to the generated
+// source file. See importTable.write.
+//
+// Given the following import statements across all the files comprising a
+// package marshalled:
+//
+// "sync"
+// "pkg/sync"
+// "pkg/sentry/kernel"
+// ktime "pkg/sentry/kernel/time"
+//
+// An importTable representing them would look like this:
+//
+// importTable {
+// is: map[string][]*importStmt {
+// "sync": []*importStmt{
+// importStmt{name:"sync", path:"sync", aliased:false}
+// importStmt{name:"sync", path:"pkg/sync", aliased:false}
+// },
+// "kernel": []*importStmt{importStmt{
+// name: "kernel",
+// path: "pkg/sentry/kernel",
+// aliased: false
+// }},
+// "ktime": []*importStmt{importStmt{
+// name: "ktime",
+// path: "pkg/sentry/kernel/time",
+// aliased: true,
+// }},
+// }
+// }
+//
+// Note that the local name "sync" is assigned to two different import
+// statements. This is possible if the import statements are from different
+// source files in the same package.
+//
+// Since go-marshal generates a single output file per package regardless of the
+// number of input files, if "sync" is referenced by any generated code, it's
+// unclear which import statement "sync" refers to. While it's theoretically
+// possible to resolve this by assigning a unique local alias to each instance
+// of the sync package, go-marshal currently aborts when it encounters such an
+// ambiguity.
+//
+// TODO(b/151478251): importTable considers the final component of an import
+// path to be the package name, but this is only a convention. The actual
+// package name is determined by the package statement in the source files for
+// the package.
type importTable struct {
// Map of imports and whether they should be copied to the output.
- is map[string]*importStmt
+ is map[string][]*importStmt
}
func newImportTable() *importTable {
return &importTable{
- is: make(map[string]*importStmt),
+ is: make(map[string][]*importStmt),
}
}
-// Merges import statements from other into i. Collisions in import statements
-// result in a panic.
+// Merges import statements from other into i.
func (i *importTable) merge(other *importTable) {
- for name, im := range other.is {
- dup, ok := i.is[name]
- if ok {
- // When merging two imports, if either are marked used, the merged entry
- // should also be marked used.
- im.used = im.used || dup.used
-
- if !dup.equivalent(im) {
- panic(fmt.Sprintf("Found colliding import statements: ours: %+v, other's: %+v", dup, im))
- }
- }
- i.is[name] = im
+ for name, ims := range other.is {
+ i.is[name] = append(i.is[name], ims...)
}
}
func (i *importTable) addStmt(s *importStmt) *importStmt {
- if old, ok := i.is[s.name]; ok && !old.equivalent(s) {
- // We could theoretically handle the collision by assigning a local name
- // to one of the imports. However, this is a non-trivial transformation.
- // Given that collisions should be rare, simply panic on collision.
- panic(fmt.Sprintf("Import collision: old: %s as %v; new: %v as %v", old.path, old.name, s.path, s.name))
- }
- i.is[s.name] = s
+ i.is[s.name] = append(i.is[s.name], s)
return s
}
@@ -381,16 +434,20 @@ func (i *importTable) addFromSpec(spec *ast.ImportSpec, f *token.FileSet) *impor
// Marks the import named n as used. If no such import is in the table, returns
// false.
func (i *importTable) markUsed(n string) bool {
- if n, ok := i.is[n]; ok {
- n.markUsed()
+ if ns, ok := i.is[n]; ok {
+ for _, n := range ns {
+ n.markUsed()
+ }
return true
}
return false
}
func (i *importTable) clear() {
- for _, i := range i.is {
- i.used = false
+ for _, is := range i.is {
+ for _, i := range is {
+ i.used = false
+ }
}
}
@@ -401,9 +458,42 @@ func (i *importTable) write(out io.Writer) error {
}
imports := make([]string, 0, len(i.is))
- for _, i := range i.is {
- if i.used {
- imports = append(imports, i.String())
+ for name, is := range i.is {
+ var lastUsed *importStmt
+ var ambiguous bool
+
+ for _, i := range is {
+ if i.used {
+ if lastUsed != nil {
+ if !i.equivalent(lastUsed) {
+ ambiguous = true
+ }
+ }
+ lastUsed = i
+ }
+ }
+
+ if ambiguous {
+ // We have two or more import statements across the different source
+ // files that share a local name, and at least one of these imports
+ // are used by the generated code. This ambiguity can't be resolved
+ // by go-marshal and requires the user intervention. Dump a list of
+ // the colliding import statements and let the user modify the input
+ // files as appropriate.
+ var b strings.Builder
+ fmt.Fprintf(&b, "The imported name %q is used by one of the types marked for marshalling, and which import statement the code refers to is ambiguous. Perhaps give the imports unique local names?\n\n", name)
+ fmt.Fprintf(&b, "The following %d import statements are ambiguous for the local name %q:\n", len(is), name)
+ // Note: len(is) is guaranteed to be 1 or greater or ambiguous can't
+ // be true. Therefore the slicing below is safe.
+ for _, i := range is[:len(is)-1] {
+ fmt.Fprintf(&b, " %v\n", i.debugString())
+ }
+ fmt.Fprintf(&b, " %v", is[len(is)-1].debugString())
+ panic(b.String())
+ }
+
+ if lastUsed != nil {
+ imports = append(imports, lastUsed.String())
}
}
sort.Strings(imports)
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-03 00:26:24 +0000