File 2421-file-allow-open-2-to-work-on-directories.patch of Package erlang
From bd3f4f05bb6dafdedbae5671ee50c769a3560021 Mon Sep 17 00:00:00 2001
From: Andre Nathan <andre@digirati.com.br>
Date: Thu, 18 Apr 2019 17:45:04 -0300
Subject: [PATCH] file: allow open/2 to work on directories
This is useful mainly to ensure that a new file has been persisted
to disk by calling file:sync/1 or file:datasync/1 on file's parent
directory.
---
erts/emulator/nifs/common/prim_file_nif.c | 3 ++
erts/emulator/nifs/common/prim_file_nif.h | 2 ++
erts/emulator/nifs/unix/unix_prim_file.c | 49 ++++++++++++++++++-------------
erts/emulator/nifs/win32/win_prim_file.c | 30 ++++++++++++++++---
lib/kernel/doc/src/file.xml | 10 +++++--
lib/kernel/src/file.erl | 4 +--
lib/kernel/test/file_SUITE.erl | 11 +++++++
7 files changed, 80 insertions(+), 29 deletions(-)
diff --git a/erts/emulator/nifs/common/prim_file_nif.c b/erts/emulator/nifs/common/prim_file_nif.c
index 3df04e42e2..9e9a14844e 100644
--- a/erts/emulator/nifs/common/prim_file_nif.c
+++ b/erts/emulator/nifs/common/prim_file_nif.c
@@ -231,6 +231,7 @@ static int load(ErlNifEnv *env, void** priv_data, ERL_NIF_TERM prim_file_pid)
am_append = enif_make_atom(env, "append");
am_sync = enif_make_atom(env, "sync");
am_skip_type_check = enif_make_atom(env, "skip_type_check");
+ am_directory = enif_make_atom(env, "directory");
am_read_write = enif_make_atom(env, "read_write");
am_none = enif_make_atom(env, "none");
@@ -447,6 +448,8 @@ static enum efile_modes_t efile_translate_modelist(ErlNifEnv *env, ERL_NIF_TERM
modes |= EFILE_MODE_SYNC;
} else if(enif_is_identical(head, am_skip_type_check)) {
modes |= EFILE_MODE_SKIP_TYPE_CHECK;
+ } else if (enif_is_identical(head, am_directory)) {
+ modes |= EFILE_MODE_DIRECTORY;
} else {
/* Modes like 'raw', 'ram', 'delayed_writes' etc are handled
* further up the chain. */
diff --git a/erts/emulator/nifs/common/prim_file_nif.h b/erts/emulator/nifs/common/prim_file_nif.h
index b2e30c59dd..020714a03b 100644
--- a/erts/emulator/nifs/common/prim_file_nif.h
+++ b/erts/emulator/nifs/common/prim_file_nif.h
@@ -30,6 +30,8 @@ enum efile_modes_t {
EFILE_MODE_SKIP_TYPE_CHECK = (1 << 5), /* Special for device files on Unix. */
EFILE_MODE_NO_TRUNCATE = (1 << 6), /* Special for reopening on VxWorks. */
+ EFILE_MODE_DIRECTORY = (1 << 7),
+
EFILE_MODE_READ_WRITE = EFILE_MODE_READ | EFILE_MODE_WRITE
};
diff --git a/erts/emulator/nifs/unix/unix_prim_file.c b/erts/emulator/nifs/unix/unix_prim_file.c
index 169b193993..20021b9358 100644
--- a/erts/emulator/nifs/unix/unix_prim_file.c
+++ b/erts/emulator/nifs/unix/unix_prim_file.c
@@ -107,7 +107,7 @@ ERL_NIF_TERM efile_get_handle(ErlNifEnv *env, efile_data_t *d) {
return result;
}
-static int open_file_type_check(const efile_path_t *path, int fd) {
+static int open_file_is_dir(const efile_path_t *path, int fd) {
struct stat file_info;
int error;
@@ -119,27 +119,14 @@ static int open_file_type_check(const efile_path_t *path, int fd) {
(void)path;
#endif
- if(error < 0) {
- /* If we failed to stat assume success and let the next call handle the
- * error. The old driver checked whether the file was to be used
- * immediately in a read within the call, but the new implementation
- * never does that. */
- return 1;
- }
-
- /* Allow everything that isn't a directory, and error out on the next call
- * if it's unsupported. */
- if(S_ISDIR(file_info.st_mode)) {
- return 0;
- }
-
- return 1;
+ /* Assume not a directory on error. */
+ return error == 0 && S_ISDIR(file_info.st_mode);
}
posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
ErlNifResourceType *nif_type, efile_data_t **d) {
- int flags, fd;
+ int mode, flags, fd;
flags = 0;
@@ -174,18 +161,38 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
#endif
}
+ if(modes & EFILE_MODE_DIRECTORY) {
+ mode = DIR_MODE;
+#ifdef O_DIRECTORY
+ flags |= O_DIRECTORY;
+#endif
+ } else {
+ mode = FILE_MODE;
+ }
+
do {
- fd = open((const char*)path->data, flags, FILE_MODE);
+ fd = open((const char*)path->data, flags, mode);
} while(fd == -1 && errno == EINTR);
if(fd != -1) {
efile_unix_t *u;
- if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) && !open_file_type_check(path, fd)) {
+#ifndef O_DIRECTORY
+ /* On platforms without O_DIRECTORY support, ensure that using the
+ * directory flag to open a file fails. */
+ if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) &&
+ (modes & EFILE_MODE_DIRECTORY) && !open_file_is_dir(path, fd)) {
close(fd);
+ return ENOTDIR;
+ }
+#endif
- /* This is blatantly incorrect, but we're documented as returning
- * this for everything that isn't a file. */
+ /* open() works on directories without the O_DIRECTORY flag but for
+ * consistency across platforms we require that the user has requested
+ * directory mode. */
+ if(!(modes & EFILE_MODE_SKIP_TYPE_CHECK) &&
+ !(modes & EFILE_MODE_DIRECTORY) && open_file_is_dir(path, fd)) {
+ close(fd);
return EISDIR;
}
diff --git a/erts/emulator/nifs/win32/win_prim_file.c b/erts/emulator/nifs/win32/win_prim_file.c
index e7d3924240..13306104c0 100644
--- a/erts/emulator/nifs/win32/win_prim_file.c
+++ b/erts/emulator/nifs/win32/win_prim_file.c
@@ -269,6 +269,17 @@ static int normalize_path_result(ErlNifBinary *path) {
return enif_realloc_binary(path, length * sizeof(WCHAR));
}
+/* @brief Checks whether all the given attributes are set on the object at the
+ * given handle. Note that it assumes false on errors. */
+static int handle_has_file_attributes(HANDLE handle, DWORD mask) {
+ BY_HANDLE_FILE_INFORMATION native_file_info;
+ if(!GetFileInformationByHandle(handle, &native_file_info)) {
+ return 0;
+ }
+
+ return !!((native_file_info.dwFileAttributes & mask) == mask);
+}
+
/** @brief Checks whether all the given attributes are set on the object at the
* given path. Note that it assumes false on errors. */
static int has_file_attributes(const efile_path_t *path, DWORD mask) {
@@ -412,10 +423,15 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
ASSERT_PATH_FORMAT(path);
+ attributes = 0;
access_flags = 0;
open_mode = 0;
- if(modes & EFILE_MODE_READ && !(modes & EFILE_MODE_WRITE)) {
+ if(modes & EFILE_MODE_DIRECTORY) {
+ attributes = FILE_FLAG_BACKUP_SEMANTICS;
+ access_flags = GENERIC_READ;
+ open_mode = OPEN_EXISTING;
+ } else if(modes & EFILE_MODE_READ && !(modes & EFILE_MODE_WRITE)) {
access_flags = GENERIC_READ;
open_mode = OPEN_EXISTING;
} else if(modes & EFILE_MODE_WRITE && !(modes & EFILE_MODE_READ)) {
@@ -438,9 +454,9 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
}
if(modes & EFILE_MODE_SYNC) {
- attributes = FILE_FLAG_WRITE_THROUGH;
+ attributes |= FILE_FLAG_WRITE_THROUGH;
} else {
- attributes = FILE_ATTRIBUTE_NORMAL;
+ attributes |= FILE_ATTRIBUTE_NORMAL;
}
handle = CreateFileW((WCHAR*)path->data, access_flags,
@@ -449,6 +465,12 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
if(handle != INVALID_HANDLE_VALUE) {
efile_win_t *w;
+ /* Directory mode specified, but path is not a directory. */
+ if((modes & EFILE_MODE_DIRECTORY) && !handle_has_file_attributes(handle, FILE_ATTRIBUTE_DIRECTORY)) {
+ CloseHandle(handle);
+ return ENOTDIR;
+ }
+
w = (efile_win_t*)enif_alloc_resource(nif_type, sizeof(efile_win_t));
w->handle = handle;
@@ -461,7 +483,7 @@ posix_errno_t efile_open(const efile_path_t *path, enum efile_modes_t modes,
/* Rewrite all failures on directories to EISDIR to match the old
* driver. */
- if(has_file_attributes(path, FILE_ATTRIBUTE_DIRECTORY)) {
+ if(!(modes & EFILE_MODE_DIRECTORY) && has_file_attributes(path, FILE_ATTRIBUTE_DIRECTORY)) {
return EISDIR;
}
diff --git a/lib/kernel/doc/src/file.xml b/lib/kernel/doc/src/file.xml
index fc25e83d40..b3e8149cc2 100644
--- a/lib/kernel/doc/src/file.xml
+++ b/lib/kernel/doc/src/file.xml
@@ -939,6 +939,10 @@ f.txt: {person, "kalle", 25}.
support for POSIX <c>O_SYNC</c> or equivalent, use of the <c>sync</c>
flag causes <c>open</c> to return <c>{error, enotsup}</c>.</p>
</item>
+ <tag><c>directory</c></tag>
+ <item>
+ <p>Allows <c>open</c> to work on directories.</p>
+ </item>
</taglist>
<p>Returns:</p>
<taglist>
@@ -985,8 +989,10 @@ f.txt: {person, "kalle", 25}.
</item>
<tag><c>enotdir</c></tag>
<item>
- <p>A component of the filename is not a directory. On some
- platforms, <c>enoent</c> is returned instead.</p>
+ <p>A component of the filename is not a directory, or the
+ filename itself is not a directory if <c>directory</c>
+ mode was specified. On some platforms, <c>enoent</c> is
+ returned instead.</p>
</item>
<tag><c>enospc</c></tag>
<item>
diff --git a/lib/kernel/src/file.erl b/lib/kernel/src/file.erl
index 1d4e37196c..a0616da670 100644
--- a/lib/kernel/src/file.erl
+++ b/lib/kernel/src/file.erl
@@ -460,7 +460,7 @@ raw_write_file_info(Name, #file_info{} = Info) ->
-spec open(File, Modes) -> {ok, IoDevice} | {error, Reason} when
File :: Filename | iodata(),
Filename :: name_all(),
- Modes :: [mode() | ram],
+ Modes :: [mode() | ram | directory],
IoDevice :: io_device(),
Reason :: posix() | badarg | system_limit.
@@ -1143,7 +1143,7 @@ path_script(Path, File, Bs) ->
{ok, IoDevice, FullName} | {error, Reason} when
Path :: [Dir :: name_all()],
Filename :: name_all(),
- Modes :: [mode()],
+ Modes :: [mode() | directory],
IoDevice :: io_device(),
FullName :: filename_all(),
Reason :: posix() | badarg | system_limit.
diff --git a/lib/kernel/test/file_SUITE.erl b/lib/kernel/test/file_SUITE.erl
index 3bc8e6e828..21aaefa654 100644
--- a/lib/kernel/test/file_SUITE.erl
+++ b/lib/kernel/test/file_SUITE.erl
@@ -989,6 +989,14 @@ new_modes(Config) when is_list(Config) ->
ok
end,
+ % open directory
+ {ok, Fd9} = ?FILE_MODULE:open(NewDir, [directory]),
+ ok = ?FILE_MODULE:close(Fd9),
+
+ % open raw directory
+ {ok, Fd10} = ?FILE_MODULE:open(NewDir, [raw, directory]),
+ ok = ?FILE_MODULE:close(Fd10),
+
[] = flush(),
ok.
@@ -1238,6 +1246,9 @@ open_errors(Config) when is_list(Config) ->
{error, E4} = ?FILE_MODULE:open(DataDirSlash, [write]),
{eisdir,eisdir,eisdir,eisdir} = {E1,E2,E3,E4},
+ Real = filename:join(DataDir, "realmen.html"),
+ {error, enotdir} = ?FILE_MODULE:open(Real, [directory]),
+
{'EXIT', {badarg, _}} = (catch ?FILE_MODULE:open("foo", [raw, ram])),
[] = flush(),
ok.
--
2.16.4
