5b9fea01ee
Revamp the build system to be more inline with other Prometheus exporters. Notably add Darwin and Windows build targets, and add support for releases using tar files.
83 lines
1.7 KiB
Go
83 lines
1.7 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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This file contains the code to check for suspicious shifts.
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*/
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package main
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import (
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"go/ast"
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"go/constant"
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"go/token"
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"go/types"
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)
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func init() {
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register("shift",
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"check for useless shifts",
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checkShift,
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binaryExpr, assignStmt)
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}
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func checkShift(f *File, node ast.Node) {
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switch node := node.(type) {
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case *ast.BinaryExpr:
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if node.Op == token.SHL || node.Op == token.SHR {
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checkLongShift(f, node, node.X, node.Y)
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}
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case *ast.AssignStmt:
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if len(node.Lhs) != 1 || len(node.Rhs) != 1 {
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return
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}
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if node.Tok == token.SHL_ASSIGN || node.Tok == token.SHR_ASSIGN {
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checkLongShift(f, node, node.Lhs[0], node.Rhs[0])
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}
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}
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}
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// checkLongShift checks if shift or shift-assign operations shift by more than
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// the length of the underlying variable.
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func checkLongShift(f *File, node ast.Node, x, y ast.Expr) {
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v := f.pkg.types[y].Value
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if v == nil {
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return
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}
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amt, ok := constant.Int64Val(v)
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if !ok {
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return
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}
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t := f.pkg.types[x].Type
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if t == nil {
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return
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}
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b, ok := t.Underlying().(*types.Basic)
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if !ok {
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return
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}
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var size int64
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var msg string
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switch b.Kind() {
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case types.Uint8, types.Int8:
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size = 8
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case types.Uint16, types.Int16:
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size = 16
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case types.Uint32, types.Int32:
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size = 32
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case types.Uint64, types.Int64:
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size = 64
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case types.Int, types.Uint, types.Uintptr:
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// These types may be as small as 32 bits, but no smaller.
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size = 32
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msg = "might be "
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default:
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return
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}
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if amt >= size {
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ident := f.gofmt(x)
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f.Badf(node.Pos(), "%s %stoo small for shift of %d", ident, msg, amt)
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}
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}
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