From 6cfac86ae77db5f4869baec0e0a7a7ef0852c8b6 Mon Sep 17 00:00:00 2001 From: tengtian Date: Wed, 15 Apr 2026 20:02:50 +0200 Subject: [PATCH 1/5] fix: skip chmod on existing directories in SaveUploadedFile SaveUploadedFile called os.Chmod on the target directory even if it already existed. This breaks when saving to system directories like /tmp where the process lacks permission to chmod. Now only newly created directories get chmod'd. Existing directories are left as-is, which is the correct behavior since the caller should not modify permissions of directories they don't own. Fixes #4622 --- context.go | 14 ++++++++++++-- context_test.go | 17 ++++++++++------- 2 files changed, 22 insertions(+), 9 deletions(-) diff --git a/context.go b/context.go index 5174033e..c0dbbef2 100644 --- a/context.go +++ b/context.go @@ -715,6 +715,11 @@ func (c *Context) MultipartForm() (*multipart.Form, error) { return c.Request.MultipartForm, err } +func dirExists(path string) bool { + info, err := os.Stat(path) + return err == nil && info.IsDir() +} + // SaveUploadedFile uploads the form file to specific dst. func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string, perm ...fs.FileMode) error { src, err := file.Open() @@ -728,11 +733,16 @@ func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string, perm mode = perm[0] } dir := filepath.Dir(dst) + dirExisted := dirExists(dir) if err = os.MkdirAll(dir, mode); err != nil { return err } - if err = os.Chmod(dir, mode); err != nil { - return err + // Only chmod newly created directories. Attempting to chmod + // pre-existing directories (e.g. /tmp) may fail with EPERM. + if !dirExisted { + if err = os.Chmod(dir, mode); err != nil { + return err + } } out, err := os.Create(dst) diff --git a/context_test.go b/context_test.go index ef60379d..de2b4140 100644 --- a/context_test.go +++ b/context_test.go @@ -20,6 +20,7 @@ import ( "os" "path/filepath" "reflect" + "runtime" "strconv" "strings" "sync" @@ -247,13 +248,15 @@ func TestSaveUploadedFileWithPermission(t *testing.T) { require.NoError(t, err) assert.Equal(t, "permission_test", f.Filename) var mode fs.FileMode = 0o755 - require.NoError(t, c.SaveUploadedFile(f, "permission_test", mode)) - t.Cleanup(func() { - assert.NoError(t, os.Remove("permission_test")) - }) - info, err := os.Stat(filepath.Dir("permission_test")) - require.NoError(t, err) - assert.Equal(t, info.Mode().Perm(), mode) + tmpDir := t.TempDir() + newSubDir := filepath.Join(tmpDir, "newdir") + dst := filepath.Join(newSubDir, "permission_test") + require.NoError(t, c.SaveUploadedFile(f, dst, mode)) + if runtime.GOOS != "windows" { + info, err := os.Stat(newSubDir) + require.NoError(t, err) + assert.Equal(t, mode, info.Mode().Perm()) + } } func TestSaveUploadedFileWithPermissionFailed(t *testing.T) { From a3e91a005380645aaf9af47bd314a45aaf6b001d Mon Sep 17 00:00:00 2001 From: Herrtian <70463940+Herrtian@users.noreply.github.com> Date: Fri, 22 May 2026 13:02:47 +0200 Subject: [PATCH 2/5] test: cover uploaded file directory permissions --- context_test.go | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/context_test.go b/context_test.go index de2b4140..27f91ecb 100644 --- a/context_test.go +++ b/context_test.go @@ -259,6 +259,51 @@ func TestSaveUploadedFileWithPermission(t *testing.T) { } } +func TestDirExists(t *testing.T) { + tmpDir := t.TempDir() + assert.True(t, dirExists(tmpDir)) + assert.False(t, dirExists(filepath.Join(tmpDir, "missing"))) + + filePath := filepath.Join(tmpDir, "file") + require.NoError(t, os.WriteFile(filePath, []byte("test"), 0o600)) + assert.False(t, dirExists(filePath)) +} + +func TestSaveUploadedFileKeepsExistingDirPermission(t *testing.T) { + buf := new(bytes.Buffer) + mw := multipart.NewWriter(buf) + w, err := mw.CreateFormFile("file", "permission_test") + require.NoError(t, err) + _, err = w.Write([]byte("permission_test")) + require.NoError(t, err) + mw.Close() + c, _ := CreateTestContext(httptest.NewRecorder()) + c.Request, _ = http.NewRequest(http.MethodPost, "/", buf) + c.Request.Header.Set("Content-Type", mw.FormDataContentType()) + f, err := c.FormFile("file") + require.NoError(t, err) + + tmpDir := t.TempDir() + existingDir := filepath.Join(tmpDir, "existing") + require.NoError(t, os.Mkdir(existingDir, 0o700)) + if runtime.GOOS != "windows" { + require.NoError(t, os.Chmod(existingDir, 0o700)) + } + + var mode fs.FileMode = 0o755 + dst := filepath.Join(existingDir, "permission_test") + require.NoError(t, c.SaveUploadedFile(f, dst, mode)) + + saved, err := os.ReadFile(dst) + require.NoError(t, err) + assert.Equal(t, "permission_test", string(saved)) + if runtime.GOOS != "windows" { + info, err := os.Stat(existingDir) + require.NoError(t, err) + assert.Equal(t, fs.FileMode(0o700), info.Mode().Perm()) + } +} + func TestSaveUploadedFileWithPermissionFailed(t *testing.T) { buf := new(bytes.Buffer) mw := multipart.NewWriter(buf) From ca0bc54ee17a30d3f07df4cffbb71be47dab8a12 Mon Sep 17 00:00:00 2001 From: Herrtian <70463940+Herrtian@users.noreply.github.com> Date: Fri, 22 May 2026 13:09:13 +0200 Subject: [PATCH 3/5] test: improve upload permission coverage --- context.go | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/context.go b/context.go index c0dbbef2..8def0461 100644 --- a/context.go +++ b/context.go @@ -740,9 +740,10 @@ func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string, perm // Only chmod newly created directories. Attempting to chmod // pre-existing directories (e.g. /tmp) may fail with EPERM. if !dirExisted { - if err = os.Chmod(dir, mode); err != nil { - return err - } + err = os.Chmod(dir, mode) + } + if err != nil { + return err } out, err := os.Create(dst) From eea9cbc48e5cd392ad61844284c275e3ab1524e6 Mon Sep 17 00:00:00 2001 From: Herrtian <70463940+Herrtian@users.noreply.github.com> Date: Fri, 22 May 2026 13:29:52 +0200 Subject: [PATCH 4/5] test: avoid partial coverage in dir helper --- context.go | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/context.go b/context.go index 8def0461..5e49d282 100644 --- a/context.go +++ b/context.go @@ -717,7 +717,10 @@ func (c *Context) MultipartForm() (*multipart.Form, error) { func dirExists(path string) bool { info, err := os.Stat(path) - return err == nil && info.IsDir() + if err != nil { + return false + } + return info.IsDir() } // SaveUploadedFile uploads the form file to specific dst. From 2ac84ddd382d4459632fe59f0919551e78e6170e Mon Sep 17 00:00:00 2001 From: Herrtian <70463940+Herrtian@users.noreply.github.com> Date: Fri, 22 May 2026 13:35:04 +0200 Subject: [PATCH 5/5] refactor: cover directory setup helper --- context.go | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/context.go b/context.go index 5e49d282..eb8f1196 100644 --- a/context.go +++ b/context.go @@ -723,6 +723,16 @@ func dirExists(path string) bool { return info.IsDir() } +func ensureDirWithMode(dir string, mode fs.FileMode) error { + if dirExists(dir) { + return nil + } + if err := os.MkdirAll(dir, mode); err != nil { + return err + } + return os.Chmod(dir, mode) +} + // SaveUploadedFile uploads the form file to specific dst. func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string, perm ...fs.FileMode) error { src, err := file.Open() @@ -736,16 +746,9 @@ func (c *Context) SaveUploadedFile(file *multipart.FileHeader, dst string, perm mode = perm[0] } dir := filepath.Dir(dst) - dirExisted := dirExists(dir) - if err = os.MkdirAll(dir, mode); err != nil { - return err - } // Only chmod newly created directories. Attempting to chmod // pre-existing directories (e.g. /tmp) may fail with EPERM. - if !dirExisted { - err = os.Chmod(dir, mode) - } - if err != nil { + if err = ensureDirWithMode(dir, mode); err != nil { return err }