Inter-package conflicts require the presence of two or more packages in a particular configuration, and thus tend to be harder to detect and localize than conventional (intra-package) defects. Hundreds of such inter-package conflicts go undetected by the normal testing and distribution process until they are later reported by a user. The reason for this is that current meta-data is not fine-grained and accurate enough to cover all common types of conflicts. A case study of inter-package conflicts in Debian has shown that with more detailed package meta-data, at least one third of all package conflicts could be prevented relatively easily, while another one third could be found by targeted testing of packages that share common resources or characteristics. This paper reports the case study and proposes ideas to detect inter-package conflicts in the future.
An advantage of self-contained software bundles is the ease of testing and deployment, as system-specific configurations and libraries have only limited impact on the software bundle. However, statically linking all libraries used by a bundle requires much disk space. If many applications include the same statically-linked libraries, these libraries are duplicated within the same system. Deduplication addresses this problem @cite_8 @cite_16 . Memory and storage deduplication merge same-contents chunks on block level, and reduce the consumptions of physical memory. By sharing identical chunks of storage, logical-level redundancies caused by static linking are resolved on the physical level.
@cite_16 @cite_8
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Current OSes include many logical sharing techniques (shared library, symbolic link, etc.) on memory and storage. Unfortunately they cause security and management problems which come from the dynamic management of logical sharing; e.g., search path replacement attack, GOT (Global Offset Table) overwrite attack, Dependency Hell, etc. This paper proposes that self-contained binaries eliminate the problems caused by logical sharing. The memory and storage overheads caused by self-contained binaries are mitigated by physical sharing (memory and disk deduplication). The effect of deduplication was investigated on the KVM virtual machine with KSM (Kernel Samepage Merging) and LBCAS (Loopback Content Addressable Storage). Static linking has many advantages over dynamic linking. It is simple to understand, implement, and use. It ensures that an executable is self-contained and does not depend on a particular set of libraries during execution. As a consequence, the user executes exactly the same executable image as was tested by the developer, diminishing the risk that the user's environment will affect correct behavior. The major disadvantages of static linking are increases in the memory required to run an executable, network bandwidth to transfer it, and disk space to store it. In this paper we describe the SLINKY system that uses digest-based sharing to combine the simplicity of static linking with the space savings of dynamic linking: although SLINKY executables are completely self-contained, minimal performance and disk-space penalties are incurred if two executables use the same library. We have developed a SLINKY prototype that consists of tools for adding digests to executables, a slight modification of the Linux kernel to use those digests to share code pages, and tools for transferring files between machines based on digests of their contents. Results show that our prototype has no measurable performance decrease relative to dynamic linking, a comparable memory footprint, a 20 storage space increase, and a 34 increase in the network bandwidth required to transfer the packages. We believe that SLINKY obviates many of the justifications for dynamic linking, making static linking a superior technology for software organization and distribution.