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Subject: |
Atomic (fast) install |
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Date: |
Thu, 25 Mar 2021 12:24:13 +0200 |
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User-agent: |
Evolution 3.41.1 |
Hello,
I use automake with libtool . The latter has “fast install” option.
My config.status contains:
enable_fast_install='yes'
fast_install=$enable_fast_install
During “make install” it prints:
/bin/sh ./libtool --mode=install /usr/bin/install -c
lib/libcyrus_min.la lib/libcyrus.la imap/libcyrus_imap.la
sieve/libcyrus_sieve.la '/usr/local/lib'
libtool: install: /usr/bin/install -c lib/.libs/libcyrus_min.so.0.0.0
/usr/local/lib/libcyrus_min.so.0.0.0
libtool: install: (cd /usr/local/lib && { ln -s -f
libcyrus_min.so.0.0.0 libcyrus_min.so.0 || { rm -f libcyrus_min.so.0 &&
ln -s libcyrus_min.so.0.0.0 libcyrus_min.so.0; }; })
libtool: install: (cd /usr/local/lib && { ln -s -f
libcyrus_min.so.0.0.0 libcyrus_min.so || { rm -f libcyrus_min.so && ln
-s libcyrus_min.so.0.0.0 libcyrus_min.so; }; })
libtool: install: /usr/bin/install -c lib/.libs/libcyrus_min.lai
/usr/local/lib/libcyrus_min.la
libtool: install: /usr/bin/install -c lib/.libs/libcyrus.so.0.0.0
/usr/local/lib/libcyrus.so.0.0.0
libtool: install: (cd /usr/local/lib && { ln -s -f libcyrus.so.0.0.0
libcyrus.so.0 || { rm -f libcyrus.so.0 && ln -s libcyrus.so.0.0.0
libcyrus.so.0; }; })
libtool: install: (cd /usr/local/lib && { ln -s -f libcyrus.so.0.0.0
libcyrus.so || { rm -f libcyrus.so && ln -s libcyrus.so.0.0.0
libcyrus.so; }; })
libtool: install: /usr/bin/install -c lib/.libs/libcyrus.lai
/usr/local/lib/libcyrus.la
libtool: warning: relinking 'imap/libcyrus_imap.la'
for some shared libraries, but it does not print it for all shared
libraries. It does not print it for libcyrus_min.so or libcyrus.so
Moreover (Auto)make install calls:
/bin/sh ./libtool --mode=install /usr/bin/install -c imap/httpd
'/usr/local/libexec'
which triggers these syscalls:
[pid 346601] stat("/usr/local/libexec/httpd", {st_mode=S_IFREG|0755,
st_size=3362912, ...}) = 0
[pid 346601] newfstatat(AT_FDCWD, "imap/.libs/httpd",
{st_mode=S_IFREG|0755, st_size=3362912, ...}, 0) = 0
[pid 346601] newfstatat(AT_FDCWD, "/usr/local/libexec/httpd",
{st_mode=S_IFREG|0755, st_size=3362912, ...}, AT_SYMLINK_NOFOLLOW) = 0
[pid 346601] unlink("/usr/local/libexec/httpd") = 0
[pid 346601] openat(AT_FDCWD, "imap/.libs/httpd", O_RDONLY) = 3
[pid 346601] fstat(3, {st_mode=S_IFREG|0755, st_size=3362912, ...}) = 0
[pid 346601] openat(AT_FDCWD, "/usr/local/libexec/httpd",
O_WRONLY|O_CREAT|O_EXCL, 0600) = 4
[pid 346601] fstat(4, {st_mode=S_IFREG|0600, st_size=0, ...}) = 0
[pid 346601] ioctl(4, BTRFS_IOC_CLONE or FICLONE, 3) = -1 EOPNOTSUPP
(Operation not supported)
[pid 346601] fadvise64(3, 0, 0, POSIX_FADV_SEQUENTIAL) = 0
[pid 346601] mmap(NULL, 139264, PROT_READ|PROT_WRITE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fb61f408000
[pid 346601] read(3,
"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\2\0>\0\1\0\0\0\260\343A\0\0\0\0\0"...,
131072) = 131072
[pid 346601] write(4,
"\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\2\0>\0\1\0\0\0\260\343A\0\0\0\0\0"...,
131072) = 131072
[pid 346601] read(3,
"\377H\211\302H\213\205h\372\377\377\211\331H\211\306H\307\307\4\252\35
3\212\350t\0\6\0H\213E\340"..., 131072) = 131072
[pid 346601] write(4,
"\377H\211\302H\213\205h\372\377\377\211\331H\211\306H\307\307\4\252\35
3\212\350t\0\6\0H\213E\340"..., 131072) = 131072
...
[pid 346601] chmod("/usr/local/libexec/httpd", 0755) = 0
[pid 346601] lstat("/usr/local/libexec/httpd", {st_mode=S_IFREG|0755,
st_size=3362912, ...}) = 0
That said, the installation is not atomic. The bytes destination file
is replaced byte by byte, rather than writing the result to a temporary
file and then calling rename(2), thus ensuring that the file is always
executable.
Cyrus IMAP is a server, consisting of several executable files
(daemons). When an executable file notices, that its timestamp has
changed, the daemon terminates and is then started again (from the new
executable). The problem is, that during this process, there is a
timegap, where the process-file has newer timestamp, but is not
executable yet, as `install` currently moves data to it.
As far the install executable is concerned, I raised the atomicity to
coreutils at debbugs.gnu.org/cgi/bugreport.cgi?bug=47380 .
• Please adjust Automake on “make install” to do (per default or with
an option) atomic install of files, even when libtool is involved: the
file is moved to a temporary destination first, and then rename(2)d, or
the source is moved to the destination, disappearing from the source,
or something like this.
• Why does “fast install” relink some libraries, but others not?
• Since ./libtool starts with
#! /bin/sh
do not call
/bin/sh ./libtool --mode=install /usr/bin/install -c imap/httpd
'/usr/local/libexec'
but
./libtool --mode=install /usr/bin/install -c imap/httpd
'/usr/local/libexec'
Greetings
Дилян
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--- Begin Message ---
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Subject: |
Re: bug#47381: Atomic (fast) install |
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Date: |
Fri, 26 Mar 2021 16:39:06 -0600 |
Thanks for the reports, but:
1) Automake can only run whatever install program has been specified by
the user. It does not seem possible (or sensible) to me to guarantee
atomic installs at the automake level. (This behavior by cyrus imap also
seems undesirable to me, but whatever.)
2) I have never heard of "fast install" before, and have barely ever
touched libtool in general. You'll need to ask the libtool maintainers.
3) I have seen explicit invocation of "/bin/sh <script>" in other
contexts. I'm not sure why (noexec filesystems are all I can think of),
but I don't see a need to change it, either. If it's causing an actual
problem, feel free to report that.
Sorry this is not a very helpful reply, but it's what I've got.
--best, karl.
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