--- Begin Message ---
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Subject: |
24.3; copy-file fails on chmod when copying to FAT filesystem |
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Date: |
Fri, 13 Dec 2013 23:51:20 +0400 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux) |
Please describe exactly what actions triggered the bug, and
the precise symptoms of the bug. If you can, give a recipe
starting from `emacs -Q':
Having org on ext4 filesystem with 0664 permission on org/work.org, and
c1 on FAT filesystem with file permissions 0075 (in fact, SD card on
Android system, so such strange permissions) I do
M-: copy-file("org/work.org" "c1/work.org" t)
and get an error
Debugger entered--Lisp error: (file-error "Doing chmod" "operation not
permitted" $
copy-file("org/work.org" "c1/work.org" t)
eval((copy-file "org/work.org" "c1/work.org" t) nil)
eval-expression((copy-file "org/work.org" "c1/work.org" t) nil)
call-interactively(eval-expression nil nil)
That's right, it cannot do a chmod, but it cannot do it there at all, so
there is no sense to fail here.
The problem does not exist in GNU Emacs 23.4.1
(arm-unknown-linux-gnueabihf) of 2013-07-01 on henze, modified by Debian
In GNU Emacs 24.3.1 (arm-unknown-linux-gnueabihf)
of 2013-10-01 on hummel, modified by Debian
Configured using:
`configure '--build' 'arm-linux-gnueabihf' '--build'
'arm-linux-gnueabihf' '--prefix=/usr' '--sharedstatedir=/var/lib'
'--libexecdir=/usr/lib' '--localstatedir=/var/lib'
'--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes'
'--enable-locallisppath=/etc/emacs24:/etc/emacs:/usr/local/share/emacs/24.3/site-l\
isp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/24.3/site-lisp:/usr/share/em\
acs/site-lisp'
'--with-crt-dir=/usr/lib/arm-linux-gnueabihf' '--with-x=no'
'--without-gconf' '--without-gsettings'
'build_alias=arm-linux-gnueabihf' 'CFLAGS=-g -O2 -fstack-protector
--param=ssp-buffer-size=4 -Wformat -Werror=format-security -Wall'
'LDFLAGS=-Wl,-z,relro' 'CPPFLAGS=-D_FORTIFY_SOURCE=2''
Important settings:
value of $LC_MESSAGES: C
value of $LANG: en_US.UTF-8
locale-coding-system: utf-8-unix
default enable-multibyte-characters: t
Major mode: Fundamental
Recent input:
ESC : ( c o p y - f i l e
SPC " o r g / e m a c s . DEL DEL DEL DEL DEL DEL w
o r k . o r g " SPC " c 1 / w o r k . o r g " ) RET
C-]
--- End Message ---
--- Begin Message ---
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Subject: |
Re: 24.3; copy-file fails on chmod when copying to FAT filesystem |
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Date: |
Sun, 29 Dec 2013 10:31:33 -0800 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 |
Artem Chuprina wrote:
PE> I expect this setup will cause problems with other applications,
PE> not just Emacs. GNU tar would be one example.
You are wrong again.
Well, as Andreas mentioned, I was right about cp, so the
"again" in your remark is incorrect; but you are correct about
'tar'; it uses a trick in which it sets the umask to 0 to
avoid the need for fchmod.
Still, many programs don't use that trick, and you'll run
into problems with these programs. GNU cpio would be one
example; if you do something like "find . -print | cpio -pdmuv .../dest",
where "dest" is in that file system, cpio will report an error
because it can't change the permission of the file that it creates.
In reviewing the email in this bug report it appears that we do
have a real problem here, and that a "real" solution will probably
require redesigning the API significantly so that there's a
copy-file variant that doesn't throw errors, or something like that.
Right now we're just trying to fix bugs, though, so I installed
the more-conservative change, where copy-file doesn't try to fchmod
an existing file -- this causes copy-file to act more like plain 'cp'
and I expect it's what more copy-file users would expect anyway.
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