* bug#34069: rename-file on fifos hangs if cross device
2019-01-14 13:03 bug#34069: dired-do-rename on fifos hangs if cross device 積丹尼 Dan Jacobson
2020-08-31 10:26 ` Stefan Kangas
@ 2022-12-18 21:06 ` Paul Eggert
1 sibling, 0 replies; 4+ messages in thread
From: Paul Eggert @ 2022-12-18 21:06 UTC (permalink / raw)
To: Lars Ingebrigtsen
Cc: 34069, Stefan Kangas, 積丹尼 Dan Jacobson
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In reviewing that patch I discovered that there's a similar bug in
copy-file, and that there's some opportunity to simplify and robustify
the rename-file code. I installed the attached patches on master to do that.
[-- Attachment #2: 0001-Don-t-hang-when-copying-FIFOs.patch --]
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From ab3cfa4a17663cf479f286149a2289974dd67240 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 18 Dec 2022 11:45:06 -0800
Subject: [PATCH 1/2] =?UTF-8?q?Don=E2=80=99t=20hang=20when=20copying=20FIF?=
=?UTF-8?q?Os?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
* src/fileio.c (Fcopy_file): Open the input file with O_NONBLOCK.
This prevents a hang if the input file is a FIFO.
If it’s a regular file O_NONBLOCK has no effect;
otherwise the file is soon rejected anyway.
---
src/fileio.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/src/fileio.c b/src/fileio.c
index 92335b639c..a50f8d67c1 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -2219,7 +2219,7 @@ DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6,
report_file_error ("Copying permissions to", newname);
}
#else /* not WINDOWSNT */
- ifd = emacs_open (SSDATA (encoded_file), O_RDONLY, 0);
+ ifd = emacs_open (SSDATA (encoded_file), O_RDONLY | O_NONBLOCK, 0);
if (ifd < 0)
report_file_error ("Opening input file", file);
--
2.38.1
[-- Attachment #3: 0002-Improve-rename-file-fix-bug-34069.patch --]
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From 79e1bff2694444a27036b08e8fa2a6619b40dc2a Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 18 Dec 2022 12:57:57 -0800
Subject: [PATCH 2/2] Improve rename-file fix (bug#34069)
* src/fileio.c (Frename_file): No need for a special case to
rename a fifo, since we already tried and failed to rename it.
Also improve symlink handling, in that if readlink fails report an
error rather than trying to treat the link as a regular file.
---
src/fileio.c | 35 ++++++++++++-----------------------
1 file changed, 12 insertions(+), 23 deletions(-)
diff --git a/src/fileio.c b/src/fileio.c
index a50f8d67c1..789f3d509e 100644
--- a/src/fileio.c
+++ b/src/fileio.c
@@ -134,6 +134,7 @@ #define DRIVE_LETTER(x) c_tolower (x)
is added here. */
static Lisp_Object Vwrite_region_annotation_buffers;
+static Lisp_Object emacs_readlinkat (int, char const *);
static Lisp_Object file_name_directory (Lisp_Object);
static bool a_write (int, Lisp_Object, ptrdiff_t, ptrdiff_t,
Lisp_Object *, struct coding_system *);
@@ -2710,31 +2711,19 @@ DEFUN ("rename-file", Frename_file, Srename_file, 2, 3,
}
if (dirp)
call4 (Qcopy_directory, file, newname, Qt, Qnil);
- else
- {
- Lisp_Object symlink_target
- = (S_ISLNK (file_st.st_mode)
- ? check_emacs_readlinkat (AT_FDCWD, file, SSDATA (encoded_file))
- : Qnil);
- if (!NILP (symlink_target))
- Fmake_symbolic_link (symlink_target, newname, ok_if_already_exists);
- else if (S_ISFIFO (file_st.st_mode))
- {
- /* If it's a FIFO, calling `copy-file' will hang if it's a
- inter-file system move, so do it here. (It will signal
- an error in that case, but it won't hang in any case.) */
- if (!NILP (ok_if_already_exists))
- barf_or_query_if_file_exists (newname, false,
- "rename to it",
- FIXNUMP (ok_if_already_exists),
- false);
- if (rename (SSDATA (encoded_file), SSDATA (encoded_newname)) != 0)
- report_file_errno ("Renaming", list2 (file, newname), errno);
- return Qnil;
- }
+ else if (S_ISREG (file_st.st_mode))
+ Fcopy_file (file, newname, ok_if_already_exists, Qt, Qt, Qt);
+ else if (S_ISLNK (file_st.st_mode))
+ {
+ Lisp_Object target = emacs_readlinkat (AT_FDCWD,
+ SSDATA (encoded_file));
+ if (!NILP (target))
+ Fmake_symbolic_link (target, newname, ok_if_already_exists);
else
- Fcopy_file (file, newname, ok_if_already_exists, Qt, Qt, Qt);
+ report_file_error ("Renaming", list2 (file, newname));
}
+ else
+ report_file_errno ("Renaming", list2 (file, newname), rename_errno);
specpdl_ref count = SPECPDL_INDEX ();
specbind (Qdelete_by_moving_to_trash, Qnil);
--
2.38.1
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