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package managers

14 Feb 2010

i’ve been into package managers for some time and i always wondered why developers have to define dependencies manually and not supported by a program using ‘a syscall interface monitoring all OPEN calls’ in combination to something like ldd for the built binary.

the idea is pretty simple:

  1. first** try to compile the program you want to packet**. if all compiles then you probably have installed all required libraries on the system. (i assume PATH and LD_LIBRARY_PATH wasn’t altered).
  2. next create a package as an  ebuild for instance. the ‘configure’ and ‘make’ step can be called by ‘emerge’. emerge could then monitor everything, as
  3. on ‘build time’ of the package ********** all OPEN syscalls are monitored** and every single file which is opened (which in theory belongs to a different installed ‘known’ package) is checked for the owner package. a group of packages which the ‘build step’ belongs to is acquired, and
  4. finally after the source has successfully compiled the binary is processed by ‘ldd’ which usually looks like:

    # ldd which htop linux-vdso.so.1 =>  (0x00007fffce0a7000) libncursesw.so.5 => /lib/libncursesw.so.5 (0x00007f305f907000) libm.so.6 => /lib/libm.so.6 (0x00007f305f684000) libc.so.6 => /lib/libc.so.6 (0x00007f305f328000) libdl.so.2 => /lib/libdl.so.2 (0x00007f305f124000) /lib64/ld-linux-x86-64.so.2 (0x00007f305fb64000) now every library the binary depends on is expected to be from a specific package (again - which in theory belongs to a different installed ‘known’ package)
  5. finally all this automatically detected dependencies are reported to the package maintainer and one probably could also check the existing dependencies for the package to see if they match.
  6. another important point would be if a package, NO read: if a upstream package is removing support for something which requires an external library, does include a dependency which is not used anymore it could be dropped automatically as well.

i did not test if that would actually work but i can’t think of any issue why it should not.

i’ve had some other ideas as well, if you are curious you can read the article in my wiki [1]. if you want to contribute please don’t use the comment field, just write me an email or ask me for a wiki account and you can change it directly.

my goal is to evaluate a mixture of the concept of ebuilds - everything built from source - with having binary packages combined to a p2p network in both hosting ‘already compiled packages’ as well as a distributed compile farm. currently it’s a mixture of german and english but i might fix that soon. another important goal is to merge package management at some yet unknown point to remove redundant work and to have a common package manager for all linux distribution as well as all other distributaions as mac os x and windows.

spoken in analogies: the same process for building a cross platform package manager is ‘cmake’ for cross platform build system generation which was (or currently is) replacing  ‘autotools’.