[pacman-dev] multiple extraction from package

[Andrew Fyfe]

Dan McGee wrote:
> On 7/9/07, Xavier <shiningxc at gmail.com> wrote:
>> The last commit made me remind of a little issue I wanted to bring a few hours ago,
>> thanks Dan :)
>>
>> grep "\.INSTALL" lib/libalpm/*.c
>> lib/libalpm/add.c:        } else if(strcmp(entryname, ".INSTALL") == 0) {
>> lib/libalpm/package.c:    } else if(strcmp(entry_name,  ".INSTALL") == 0) {
>> lib/libalpm/trans.c:    _alpm_unpack(installfn,tmpdir, ".INSTALL");
>> lib/libalpm/trans.c:    snprintf(scriptfn, PATH_MAX, "%s/.INSTALL", tmpdir);
>>
>> The archive is read 3 times, in 3 different places.
>> In particular, the .INSTALL file is checked for existence in package.c , for
>> knowing the package has a scriptlet.
>> In trans.c , the .INSTALL file is extracted to /tmp/ for running the
>> preinstall scriptlet.
>> And in add.c , the .INSTALL file is extracted to $dbpath/local , which is by
>> the way causing some issues :
>> http://www.archlinux.org/pipermail/pacman-dev/2007-July/008693.html
>>
>> I wonder if it wouldn't be possible to read the archive just in one place,
>> and extracting files just once.
>> Or well, I don't know what is the best way, extracting files to /tmp/ and
>> then moving them around (like for backup files), or extracting them several
>> times from the archive (like .INSTALL) , or maybe keeping the special dot files
>> from the archive in memory or something.
>>
>> Well, it's not that important, but it's related to the issue in the link
>> above, that I would like to fix, so I just wanted to know if everyone was happy
>> with the current way pacman reads/extracts files from the archive.
> 
> The biggest problem- this isn't exactly easy to clean up.
> 
> If we could knock this down to two times, that would be much better,
> that is for sure. However, I'm not sure how to do this easily without
> doing a lot of changes to libalpm. Of course, these changes are
> probably needed bigtime.
> 
> -Dan
> 
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I would leave this for post-3.1

But back to the point, I think we need a temporary directory 
(mkdtemp(/tmp/XXXXXXX)) where we put install and changelog before we 
commit a package to the database. Looking at this from the point of view 
of a normal db I would never enter the install file before I've actual 
created a valid entry for the package (the desc file).

Andrew