chore: Refactor Sample Code to Separate Files

Split the code in `source.go` to individual sample files, one per rule.
This will help contributors submit samples for new rules, or
improvements to existing rules. The cgo sample was all that was left
after refactoring, which resulted in its own sample file.

Sample code was also formatted to have some level of consistency.
Each sample go "file" attempts to keep the formatting of `gofmt`, and
each code sample is in its own section in the sample file.

Signed-off-by: Adam Kaplan <adam@adambkaplan.com>

testutils/g305_samples.go

@@ -0,0 +1,178 @@
+package testutils
+
+import "github.com/securego/gosec/v2"
+
+var (
+	// SampleCodeG305 - File path traversal when extracting zip/tar archives
+	SampleCodeG305 = []CodeSample{
+		{[]string{`
+package unzip
+
+import (
+	"archive/zip"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func unzip(archive, target string) error {
+	reader, err := zip.OpenReader(archive)
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(target, 0750); err != nil {
+		return err
+	}
+
+	for _, file := range reader.File {
+		path := filepath.Join(target, file.Name)
+		if file.FileInfo().IsDir() {
+			os.MkdirAll(path, file.Mode()) //#nosec
+			continue
+		}
+
+		fileReader, err := file.Open()
+		if err != nil {
+			return err
+		}
+		defer fileReader.Close()
+
+		targetFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
+		if err != nil {
+			return err
+		}
+		defer targetFile.Close()
+
+		if _, err := io.Copy(targetFile, fileReader); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+`}, 1, gosec.NewConfig()},
+		{[]string{`
+package unzip
+
+import (
+	"archive/zip"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+func unzip(archive, target string) error {
+	reader, err := zip.OpenReader(archive)
+	if err != nil {
+		return err
+	}
+
+	if err := os.MkdirAll(target, 0750); err != nil {
+		return err
+	}
+
+	for _, file := range reader.File {
+                archiveFile := file.Name
+		path := filepath.Join(target, archiveFile)
+		if file.FileInfo().IsDir() {
+			os.MkdirAll(path, file.Mode()) //#nosec
+			continue
+		}
+
+		fileReader, err := file.Open()
+		if err != nil {
+			return err
+		}
+		defer fileReader.Close()
+
+		targetFile, err := os.OpenFile(path, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())
+		if err != nil {
+			return err
+		}
+		defer targetFile.Close()
+
+		if _, err := io.Copy(targetFile, fileReader); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+`}, 1, gosec.NewConfig()},
+		{[]string{`
+package zip
+
+import (
+    "archive/zip"
+    "io"
+    "os"
+    "path"
+)
+
+func extractFile(f *zip.File, destPath string) error {
+    filePath := path.Join(destPath, f.Name)
+    os.MkdirAll(path.Dir(filePath), os.ModePerm)
+
+    rc, err := f.Open()
+    if err != nil {
+        return err
+    }
+    defer rc.Close()
+
+    fw, err := os.Create(filePath)
+    if err != nil {
+        return err
+    }
+    defer fw.Close()
+
+    if _, err = io.Copy(fw, rc); err != nil {
+        return err
+    }
+
+    if f.FileInfo().Mode()&os.ModeSymlink != 0 {
+        return nil
+    }
+
+    if err = os.Chtimes(filePath, f.ModTime(), f.ModTime()); err != nil {
+        return err
+    }
+    return os.Chmod(filePath, f.FileInfo().Mode())
+}
+`}, 1, gosec.NewConfig()},
+		{[]string{`
+package tz
+
+import (
+    "archive/tar"
+    "io"
+    "os"
+    "path"
+)
+
+func extractFile(f *tar.Header, tr *tar.Reader, destPath string) error {
+    filePath := path.Join(destPath, f.Name)
+    os.MkdirAll(path.Dir(filePath), os.ModePerm)
+
+    fw, err := os.Create(filePath)
+    if err != nil {
+        return err
+    }
+    defer fw.Close()
+
+    if _, err = io.Copy(fw, tr); err != nil {
+        return err
+    }
+
+    if f.FileInfo().Mode()&os.ModeSymlink != 0 {
+        return nil
+    }
+
+    if err = os.Chtimes(filePath, f.FileInfo().ModTime(), f.FileInfo().ModTime()); err != nil {
+        return err
+    }
+    return os.Chmod(filePath, f.FileInfo().Mode())
+}
+`}, 1, gosec.NewConfig()},
+	}
+)