shared/api: Add ParseFileHeaders helper

Signed-off-by: Stéphane Graber <stgraber@stgraber.org>

shared/api/headers.go

@@ -0,0 +1,55 @@
+package api
+
+import (
+	"fmt"
+	"net/http"
+	"os"
+	"strconv"
+)
+
+// ParseFileHeaders extracts the file ownership, type, mode and operation type from HTTP headers.
+func ParseFileHeaders(headers http.Header) (int64, int64, int, string, string) {
+	getHeader := func(key string) string {
+		value := headers.Get(fmt.Sprintf("X-Incus-%s", key))
+		if value == "" {
+			// Legacy support.
+			value = headers.Get(fmt.Sprintf("X-LXD-%s", key))
+		}
+
+		return value
+	}
+
+	uid, err := strconv.ParseInt(getHeader("uid"), 10, 64)
+	if err != nil {
+		uid = -1
+	}
+
+	gid, err := strconv.ParseInt(getHeader("gid"), 10, 64)
+	if err != nil {
+		gid = -1
+	}
+
+	mode, err := strconv.Atoi(getHeader("mode"))
+	if err != nil {
+		mode = -1
+	} else {
+		rawMode, err := strconv.ParseInt(getHeader("mode"), 0, 0)
+		if err == nil {
+			mode = int(os.FileMode(rawMode) & os.ModePerm)
+		}
+	}
+
+	fileType := getHeader("type")
+	if fileType == "" {
+		// Default is standard file.
+		fileType = "file"
+	}
+
+	writeMode := getHeader("write")
+	if writeMode == "" {
+		// Default is to override the content.
+		writeMode = "overwrite"
+	}
+
+	return uid, gid, mode, fileType, writeMode
+}