f67ad9c061
This ensures that docstring comments are wrapped to 80 chars. ffrank seemed to be making this mistake far too often, and it's a silly thing to look for manually. As it turns out, I've made it too, as have many others. Now we have a test that checks for most cases. There are still a few stray cases that aren't checked automatically, but this can be improved upon if someone is motivated to do so. Before anyone complains about the 80 character limit: this only checks docstring comments, not source code length or inline source code comments. There's no excuse for having docstrings that are badly reflowed or over 80 chars, particularly if you have an automated test.
312 lines
8.2 KiB
Go
312 lines
8.2 KiB
Go
// Mgmt
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// Copyright (C) 2013-2020+ James Shubin and the project contributors
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// Written by James Shubin <james@shubin.ca> and the project contributors
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package util
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import (
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"fmt"
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"os"
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"strings"
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)
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// Constant bytes for the who (u, g, or o) and the what (r, w, x, s, or t).
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const (
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ModeUser uint32 = 64
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ModeGroup uint32 = 8
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ModeOther uint32 = 1
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ModeRead uint32 = 4
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ModeWrite uint32 = 2
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ModeExec uint32 = 1
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ModeSetU uint32 = 4
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ModeSetG uint32 = 2
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ModeSticky uint32 = 1
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)
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// modeIsValidWho checks that only the characters 'u', 'g', 'o' are in the who
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// string. It expects that 'a' was expanded to "ugo" already and will return
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// false if not.
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func modeIsValidWho(who string) bool {
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for _, w := range []string{"u", "g", "o"} {
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who = strings.Replace(who, w, "", -1) // TODO: use ReplaceAll in 1.12
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}
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return len(who) == 0
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}
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// modeIsValidWhat checks that only the valid mode characters are in the what
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// string ('r', 'w', 'x', 's', 't').
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func modeIsValidWhat(what string) bool {
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for _, w := range []string{"r", "w", "x", "s", "t"} {
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what = strings.Replace(what, w, "", -1) // TODO: use ReplaceAll in 1.12
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}
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return len(what) == 0
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}
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// modeAssigned executes an assigment symbolic mode string (u=r). It clears out
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// any bits for every subject in who and then assigns the specified modes in
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// what.
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func modeAssigned(who, what string, from os.FileMode) (os.FileMode, error) {
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// Clear out any users defined in 'who'.
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for _, w := range who {
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switch w {
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case 'u':
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from = from &^ os.FileMode(448) // 111000000 in bytes
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from = from &^ os.ModeSetuid
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case 'g':
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from = from &^ os.FileMode(56) // 111000 in bytes
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from = from &^ os.ModeSetgid
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case 'o':
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from = from &^ os.FileMode(7) // 111 in bytes
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}
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}
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for _, c := range what {
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switch c {
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case 'r':
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m := modeValueFrom(who, ModeRead)
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if from&m == 0 {
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from = from | m
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}
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case 'w':
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m := modeValueFrom(who, ModeWrite)
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if from&m == 0 {
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from = from | m
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}
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case 'x':
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m := modeValueFrom(who, ModeExec)
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if from&m == 0 {
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from = from | m
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}
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case 's':
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for _, w := range who {
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switch w {
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case 'u':
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from = from | os.ModeSetuid
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case 'g':
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from = from | os.ModeSetgid
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}
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}
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case 't':
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from = from | os.ModeSticky
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default:
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return os.FileMode(0), fmt.Errorf("invalid character %q", c)
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}
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}
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return from, nil
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}
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// modeAdded executes an addition symbolic mode string (u+x) and will add the
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// bits requested in what if not present.
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func modeAdded(who, what string, from os.FileMode) (os.FileMode, error) {
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for _, c := range what {
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switch c {
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case 'r':
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m := modeValueFrom(who, ModeRead)
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if from&m == 0 {
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from = from | m
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}
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case 'w':
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m := modeValueFrom(who, ModeWrite)
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if from&m == 0 {
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from = from | m
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}
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case 'x':
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m := modeValueFrom(who, ModeExec)
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if from&m == 0 {
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from = from | m
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}
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case 's':
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for _, w := range who {
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switch w {
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case 'u':
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from = from | os.ModeSetuid
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case 'g':
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from = from | os.ModeSetgid
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}
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}
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case 't':
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from = from | os.ModeSticky
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default:
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return os.FileMode(0), fmt.Errorf("invalid character %q", c)
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}
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}
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return from, nil
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}
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// modeSubtracted executes an subtraction symbolic mode string (u+x) and will
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// removethe bits requested in what if present.
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func modeSubtracted(who, what string, from os.FileMode) (os.FileMode, error) {
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for _, c := range what {
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switch c {
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case 'r':
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m := modeValueFrom(who, ModeRead)
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if from&m != 0 {
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from = from &^ m
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}
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case 'w':
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m := modeValueFrom(who, ModeWrite)
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if from&m != 0 {
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from = from &^ m
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}
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case 'x':
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m := modeValueFrom(who, ModeExec)
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if from&m != 0 {
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from = from &^ m
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}
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case 's':
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for _, w := range who {
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switch w {
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case 'u':
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if from&os.ModeSetuid != 0 {
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from = from &^ os.ModeSetuid
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}
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case 'g':
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if from&os.ModeSetgid != 0 {
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from = from &^ os.ModeSetgid
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}
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}
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}
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case 't':
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if from&os.ModeSticky != 0 {
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from = from | os.ModeSticky
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}
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default:
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return os.FileMode(0), fmt.Errorf("invalid character %q", c)
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}
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}
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return from, nil
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}
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// modeValueFrom will return the bits requested for the mode in the correct
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// possitions for the specified subjects in who.
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func modeValueFrom(who string, modeType uint32) os.FileMode {
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i := uint32(0)
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for _, w := range who {
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switch w {
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case 'u':
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i += ModeUser * uint32(modeType)
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case 'g':
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i += ModeGroup * uint32(modeType)
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case 'o':
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i += ModeOther * uint32(modeType)
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}
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}
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return os.FileMode(i)
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}
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// ParseSymbolicModes parses a slice of symbolic mode strings. By default it
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// will only accept the assignment input (=), but if allowAssign is true, then
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// all symbolic mode strings (=, +, -) can be used as well.
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//
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// Symbolic mode is expected to be a string of who (user, group, other) then the
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// operation (=, +, -) then the change (read, write, execute, setuid, setgid,
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// sticky).
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//
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// Eg: ug=rw
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//
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// If you repeat yourself in the slice (eg. u=rw,u=w) ParseSymbolicModes will
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// fail with an error.
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func ParseSymbolicModes(modes []string, from os.FileMode, allowAssign bool) (os.FileMode, error) {
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symModes := make([]struct {
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mode, who, what string
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parse func(who, what string, from os.FileMode) (os.FileMode, error)
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}, len(modes))
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for i, mode := range modes {
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symModes[i].mode = mode
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// If string contains '=' and no '+/-' it is safe to guess it is
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// an assign.
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if strings.Contains(mode, "=") && !strings.ContainsAny(mode, "+-") {
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m := strings.Split(mode, "=")
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if len(m) != 2 {
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return os.FileMode(0), fmt.Errorf("only a single %q is allowed but found %d", "=", len(m))
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}
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symModes[i].who = m[0]
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symModes[i].what = m[1]
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symModes[i].parse = modeAssigned
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continue
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} else if strings.Contains(mode, "+") && !strings.ContainsAny(mode, "=-") && allowAssign {
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m := strings.Split(mode, "+")
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if len(m) != 2 {
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return os.FileMode(0), fmt.Errorf("only a single %q is allowed but found %d", "+", len(m))
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}
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symModes[i].who = m[0]
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symModes[i].what = m[1]
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symModes[i].parse = modeAdded
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continue
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} else if strings.Contains(mode, "-") && !strings.ContainsAny(mode, "=+") && allowAssign {
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m := strings.Split(mode, "-")
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if len(m) != 2 {
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return os.FileMode(0), fmt.Errorf("only a single %q is allowed but found %d", "-", len(m))
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}
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symModes[i].who = m[0]
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symModes[i].what = m[1]
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symModes[i].parse = modeSubtracted
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continue
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}
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return os.FileMode(0), fmt.Errorf("%s is not a valid a symbolic mode", symModes[i].mode)
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}
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// Validate input and verify the slice of symbolic modes does not
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// contain redundancy.
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seen := make(map[rune]struct{}) // validate that subjects are not duplicated
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for i := range symModes {
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if strings.ContainsRune(symModes[i].who, 'a') || symModes[i].who == "" {
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// If 'a' or empty who (implicit 'a') is called and
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// there are more symbolic modes in the slice then it
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// must be a repetition.
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if len(symModes) > 1 {
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return os.FileMode(0), fmt.Errorf("subject was repeated: each subject (u,g,o) is only accepted once")
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}
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symModes[i].who = "ugo"
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}
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if !modeIsValidWhat(symModes[i].what) || !modeIsValidWho(symModes[i].who) {
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return os.FileMode(0), fmt.Errorf("unexpected character assignment in %s", symModes[i].mode)
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}
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for _, w := range symModes[i].who {
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if _, ok := seen[w]; ok {
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return os.FileMode(0), fmt.Errorf("subject was repeated: only define each subject (u,g,o) once")
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}
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seen[w] = struct{}{}
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}
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}
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// Parse each symbolic mode accumulatively onto the file mode.
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for _, m := range symModes {
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var err error
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from, err = m.parse(m.who, m.what, from)
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if err != nil {
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return os.FileMode(0), err
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}
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}
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return from, nil
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}
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