feat(envd): add composite file upload API

packages/envd/internal/api/multipart.go

@@ -0,0 +1,214 @@
+package api
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"os"
+	"os/user"
+	"path/filepath"
+	"syscall"
+
+	"github.com/google/uuid"
+
+	"github.com/e2b-dev/infra/packages/envd/internal/execcontext"
+	"github.com/e2b-dev/infra/packages/envd/internal/logs"
+	"github.com/e2b-dev/infra/packages/envd/internal/permissions"
+)
+
+func (a *API) PostFilesCompose(w http.ResponseWriter, r *http.Request) {
+	defer r.Body.Close()
+
+	operationID := logs.AssignOperationID()
+
+	var req ComposeRequest
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		jsonError(w, http.StatusBadRequest, fmt.Errorf("invalid request body: %w", err))
+
+		return
+	}
+
+	if len(req.SourcePaths) == 0 {
+		jsonError(w, http.StatusBadRequest, fmt.Errorf("source_paths must not be empty"))
+
+		return
+	}
+
+	if req.Destination == "" {
+		jsonError(w, http.StatusBadRequest, fmt.Errorf("destination is required"))
+
+		return
+	}
+
+	username, err := execcontext.ResolveDefaultUsername(req.Username, a.defaults.User)
+	if err != nil {
+		a.logger.Error().Err(err).Str(string(logs.OperationIDKey), operationID).Msg("no user specified")
+		jsonError(w, http.StatusBadRequest, err)
+
+		return
+	}
+
+	u, err := user.Lookup(username)
+	if err != nil {
+		errMsg := fmt.Errorf("error looking up user '%s': %w", username, err)
+		a.logger.Error().Err(errMsg).Str(string(logs.OperationIDKey), operationID).Msg("user lookup failed")
+		jsonError(w, http.StatusUnauthorized, errMsg)
+
+		return
+	}
+
+	uid, gid, err := permissions.GetUserIdInts(u)
+	if err != nil {
+		errMsg := fmt.Errorf("error getting user ids: %w", err)
+		a.logger.Error().Err(errMsg).Str(string(logs.OperationIDKey), operationID).Msg("failed to get user ids")
+		jsonError(w, http.StatusInternalServerError, errMsg)
+
+		return
+	}
+
+	destPath, err := permissions.ExpandAndResolve(req.Destination, u, a.defaults.Workdir)
+	if err != nil {
+		errMsg := fmt.Errorf("error resolving destination path: %w", err)
+		a.logger.Error().Err(errMsg).Str(string(logs.OperationIDKey), operationID).Msg("path resolution failed")
+		jsonError(w, http.StatusBadRequest, errMsg)
+
+		return
+	}
+
+	resolvedSources := make([]string, len(req.SourcePaths))
+	for i, src := range req.SourcePaths {
+		resolved, err := permissions.ExpandAndResolve(src, u, a.defaults.Workdir)
+		if err != nil {
+			jsonError(w, http.StatusBadRequest, fmt.Errorf("error resolving source path %q: %w", src, err))
+
+			return
+		}
+
+		if resolved == destPath {
+			jsonError(w, http.StatusBadRequest, fmt.Errorf("source path %q cannot be the same as destination", src))
+
+			return
+		}
+
+		info, err := os.Stat(resolved)
+		if err != nil {
+			jsonError(w, http.StatusNotFound, fmt.Errorf("source file not found: %s", src))
+
+			return
+		}
+
+		if !info.Mode().IsRegular() {
+			jsonError(w, http.StatusBadRequest, fmt.Errorf("source path is not a regular file: %s", src))
+
+			return
+		}
+
+		resolvedSources[i] = resolved
+	}
+
+	err = permissions.EnsureDirs(filepath.Dir(destPath), uid, gid)
+	if err != nil {
+		jsonError(w, http.StatusInternalServerError, fmt.Errorf("error ensuring directories: %w", err))
+
+		return
+	}
+
+	// Write to a temporary file and rename on success to avoid destroying
+	// any pre-existing file at destPath if assembly fails midway.
+	tmpPath := destPath + ".e2b-compose." + uuid.New().String() + ".tmp"
+
+	destFile, err := os.OpenFile(tmpPath, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o666)
+	if err != nil {
+		if errors.Is(err, syscall.ENOSPC) {
+			jsonError(w, http.StatusInsufficientStorage, fmt.Errorf("not enough disk space available"))
+
+			return
+		}
+
+		jsonError(w, http.StatusInternalServerError, fmt.Errorf("error creating destination file: %w", err))
+
+		return
+	}
+
+	err = os.Chown(tmpPath, uid, gid)
+	if err != nil {
+		destFile.Close()
+		os.Remove(tmpPath)
+		jsonError(w, http.StatusInternalServerError, fmt.Errorf("error changing file ownership: %w", err))
+
+		return
+	}
+
+	var totalSize int64
+
+	for _, srcPath := range resolvedSources {
+		srcFile, err := os.Open(srcPath)
+		if err != nil {
+			destFile.Close()
+			os.Remove(tmpPath)
+			jsonError(w, http.StatusInternalServerError, fmt.Errorf("error opening source file %s: %w", srcPath, err))
+
+			return
+		}
+
+		// ReadFrom uses copy_file_range on Linux for zero-copy transfers
+		// between regular files — data moves kernel-side without touching
+		// userspace buffers.
+		n, err := destFile.ReadFrom(srcFile)
+		srcFile.Close()
+
+		if err != nil {
+			destFile.Close()
+			os.Remove(tmpPath)
+
+			if errors.Is(err, syscall.ENOSPC) {
+				jsonError(w, http.StatusInsufficientStorage, fmt.Errorf("not enough disk space available"))
+
+				return
+			}
+
+			jsonError(w, http.StatusInternalServerError, fmt.Errorf("error composing source %s: %w", srcPath, err))
+
+			return
+		}
+
+		totalSize += n
+	}
+
+	if err := destFile.Close(); err != nil {
+		os.Remove(tmpPath)
+		jsonError(w, http.StatusInternalServerError, fmt.Errorf("error closing destination file: %w", err))
+
+		return
+	}
+
+	if err := os.Rename(tmpPath, destPath); err != nil {
+		os.Remove(tmpPath)
+		jsonError(w, http.StatusInternalServerError, fmt.Errorf("error finalizing compose: %w", err))
+
+		return
+	}
+
+	for _, srcPath := range resolvedSources {
+		os.Remove(srcPath)
+	}
+
+	a.logger.Info().
+		Str(string(logs.OperationIDKey), operationID).
+		Str("path", destPath).
+		Int("sources", len(resolvedSources)).
+		Int64("size", totalSize).
+		Msg("File compose completed")
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+
+	if err := json.NewEncoder(w).Encode(EntryInfo{
+		Path: destPath,
+		Name: filepath.Base(destPath),
+		Type: File,
+	}); err != nil {
+		a.logger.Error().Err(err).Str(string(logs.OperationIDKey), operationID).Msg("failed to encode compose response")
+	}
+}