core: Implement FastAbs to avoid repeated os.Getwd calls (#6687)

* core: Implement FastAbs to avoid repeated os.Getwd calls

* Lint

* Rename files

10 files changed, 90 insertions, 16 deletions

diff --git a/caddyconfig/caddyfile/parse.go b/caddyconfig/caddyfile/parse.go
index e19b3b97d..d04a1ac46 100644
--- a/caddyconfig/caddyfile/parse.go
+++ b/caddyconfig/caddyfile/parse.go
@@ -423,7 +423,7 @@ func (p *parser) doImport(nesting int) error {
 		// make path relative to the file of the _token_ being processed rather
 		// than current working directory (issue #867) and then use glob to get
 		// list of matching filenames
-		absFile, err := filepath.Abs(p.Dispenser.File())
+		absFile, err := caddy.FastAbs(p.Dispenser.File())
 		if err != nil {
 			return p.Errf("Failed to get absolute path of file: %s: %v", p.Dispenser.File(), err)
 		}
@@ -622,7 +622,7 @@ func (p *parser) doSingleImport(importFile string) ([]Token, error) {
 
 	// Tack the file path onto these tokens so errors show the imported file's name
 	// (we use full, absolute path to avoid bugs: issue #1892)
-	filename, err := filepath.Abs(importFile)
+	filename, err := caddy.FastAbs(importFile)
 	if err != nil {
 		return nil, p.Errf("Failed to get absolute path of file: %s: %v", importFile, err)
 	}
diff --git a/filepath.go b/filepath.go
new file mode 100644
index 000000000..ae9d54051
--- /dev/null
+++ b/filepath.go
@@ -0,0 +1,37 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//go:build !windows
+
+package caddy
+
+import (
+	"os"
+	"path/filepath"
+)
+
+// FastAbs is an optimized version of filepath.Abs for Unix systems,
+// since we don't expect the working directory to ever change once
+// Caddy is running. Avoid the os.Getwd() syscall overhead.
+func FastAbs(path string) (string, error) {
+	if filepath.IsAbs(path) {
+		return filepath.Clean(path), nil
+	}
+	if wderr != nil {
+		return "", wderr
+	}
+	return filepath.Join(wd, path), nil
+}
+
+var wd, wderr = os.Getwd()
diff --git a/filepath_windows.go b/filepath_windows.go
new file mode 100644
index 000000000..4e46b0445
--- /dev/null
+++ b/filepath_windows.go
@@ -0,0 +1,25 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package caddy
+
+import (
+	"path/filepath"
+)
+
+// FastAbs can't be optimized on Windows because the
+// syscall.FullPath function takes an input.
+func FastAbs(path string) (string, error) {
+	return filepath.Abs(path)
+}
diff --git a/filesystem.go b/filesystem.go
index 9785f57d4..d6679e90b 100644
--- a/filesystem.go
+++ b/filesystem.go
@@ -1,3 +1,17 @@
+// Copyright 2015 Matthew Holt and The Caddy Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
 package caddy
 
 import "io/fs"
diff --git a/listen.go b/listen.go
index f5c2086a6..1a7051bbf 100644
--- a/listen.go
+++ b/listen.go
@@ -30,7 +30,7 @@ import (
 	"go.uber.org/zap"
 )
 
-func reuseUnixSocket(network, addr string) (any, error) {
+func reuseUnixSocket(_, _ string) (any, error) {
 	return nil, nil
 }
 
diff --git a/modules/caddyhttp/fileserver/staticfiles.go b/modules/caddyhttp/fileserver/staticfiles.go
index 4ae69b647..2b0caecfc 100644
--- a/modules/caddyhttp/fileserver/staticfiles.go
+++ b/modules/caddyhttp/fileserver/staticfiles.go
@@ -204,7 +204,7 @@ func (fsrv *FileServer) Provision(ctx caddy.Context) error {
 	// absolute paths before the server starts for very slight performance improvement
 	for i, h := range fsrv.Hide {
 		if !strings.Contains(h, "{") && strings.Contains(h, separator) {
-			if abs, err := filepath.Abs(h); err == nil {
+			if abs, err := caddy.FastAbs(h); err == nil {
 				fsrv.Hide[i] = abs
 			}
 		}
@@ -636,7 +636,7 @@ func (fsrv *FileServer) transformHidePaths(repl *caddy.Replacer) []string {
 	for i := range fsrv.Hide {
 		hide[i] = repl.ReplaceAll(fsrv.Hide[i], "")
 		if strings.Contains(hide[i], separator) {
-			abs, err := filepath.Abs(hide[i])
+			abs, err := caddy.FastAbs(hide[i])
 			if err == nil {
 				hide[i] = abs
 			}
@@ -655,7 +655,7 @@ func fileHidden(filename string, hide []string) bool {
 	}
 
 	// all path comparisons use the complete absolute path if possible
-	filenameAbs, err := filepath.Abs(filename)
+	filenameAbs, err := caddy.FastAbs(filename)
 	if err == nil {
 		filename = filenameAbs
 	}
diff --git a/modules/caddyhttp/reverseproxy/fastcgi/fastcgi.go b/modules/caddyhttp/reverseproxy/fastcgi/fastcgi.go
index 3985465ba..d451dd380 100644
--- a/modules/caddyhttp/reverseproxy/fastcgi/fastcgi.go
+++ b/modules/caddyhttp/reverseproxy/fastcgi/fastcgi.go
@@ -228,7 +228,7 @@ func (t Transport) buildEnv(r *http.Request) (envVars, error) {
 	ip = strings.Replace(ip, "]", "", 1)
 
 	// make sure file root is absolute
-	root, err := filepath.Abs(repl.ReplaceAll(t.Root, "."))
+	root, err := caddy.FastAbs(repl.ReplaceAll(t.Root, "."))
 	if err != nil {
 		return nil, err
 	}
diff --git a/modules/caddyhttp/reverseproxy/reverseproxy.go b/modules/caddyhttp/reverseproxy/reverseproxy.go
index 8dd3ba1b6..30d9af101 100644
--- a/modules/caddyhttp/reverseproxy/reverseproxy.go
+++ b/modules/caddyhttp/reverseproxy/reverseproxy.go
@@ -549,7 +549,7 @@ func (h *Handler) proxyLoopIteration(r *http.Request, origReq *http.Request, w h
 	// ding the health status of the upstream (an error can still
 	// occur after the roundtrip if, for example, a response handler
 	// after the roundtrip returns an error)
-	if succ, ok := proxyErr.(roundtripSucceeded); ok {
+	if succ, ok := proxyErr.(roundtripSucceededError); ok {
 		return true, succ.error
 	}
 
@@ -953,10 +953,10 @@ func (h *Handler) reverseProxy(rw http.ResponseWriter, req *http.Request, origRe
 			res.Body.Close()
 		}
 
-		// wrap any route error in roundtripSucceeded so caller knows that
+		// wrap any route error in roundtripSucceededError so caller knows that
 		// the roundtrip was successful and to not retry
 		if routeErr != nil {
-			return roundtripSucceeded{routeErr}
+			return roundtripSucceededError{routeErr}
 		}
 
 		// we're done handling the response, and we don't want to
@@ -1433,9 +1433,9 @@ type TLSTransport interface {
 	EnableTLS(base *TLSConfig) error
 }
 
-// roundtripSucceeded is an error type that is returned if the
+// roundtripSucceededError is an error type that is returned if the
 // roundtrip succeeded, but an error occurred after-the-fact.
-type roundtripSucceeded struct{ error }
+type roundtripSucceededError struct{ error }
 
 // bodyReadCloser is a reader that, upon closing, will return
 // its buffer to the pool and close the underlying body reader.
diff --git a/modules/caddytls/connpolicy.go b/modules/caddytls/connpolicy.go
index 46afc6693..9332cf2ed 100644
--- a/modules/caddytls/connpolicy.go
+++ b/modules/caddytls/connpolicy.go
@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"io"
 	"os"
-	"path/filepath"
 	"strings"
 
 	"github.com/mholt/acmez/v2"
@@ -358,7 +357,7 @@ func (p *ConnectionPolicy) buildStandardTLSConfig(ctx caddy.Context) error {
 		if err != nil {
 			return err
 		}
-		filename, err = filepath.Abs(filename)
+		filename, err = caddy.FastAbs(filename)
 		if err != nil {
 			return err
 		}
diff --git a/modules/logging/filewriter.go b/modules/logging/filewriter.go
index 44c0feb67..62d500dca 100644
--- a/modules/logging/filewriter.go
+++ b/modules/logging/filewriter.go
@@ -20,7 +20,6 @@ import (
 	"io"
 	"math"
 	"os"
-	"path/filepath"
 	"strconv"
 
 	"github.com/dustin/go-humanize"
@@ -133,7 +132,7 @@ func (fw *FileWriter) Provision(ctx caddy.Context) error {
 }
 
 func (fw FileWriter) String() string {
-	fpath, err := filepath.Abs(fw.Filename)
+	fpath, err := caddy.FastAbs(fw.Filename)
 	if err == nil {
 		return fpath
 	}