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The current DSO dependency sorting tests are for a limited number of specific cases, including some from particular bug reports. Add tests that systematically cover all possible DAGs for an executable and the shared libraries it depends on, directly or indirectly, up to four objects (an executable and three shared libraries). (For this kind of DAG - ones with a single source vertex from which all others are reachable, and an ordering on the edges from each vertex - there are 57 DAGs on four vertices, 3399 on five vertices and 1026944 on six vertices; see https://arxiv.org/pdf/2303.14710 for more details on this enumeration. I've tested that the 3399 cases with five vertices do all pass if enabled.) These tests are replicating the sorting logic from the dynamic linker (thereby, for example, asserting that it doesn't accidentally change); I'm not claiming that the logic in the dynamic linker is in some abstract sense optimal. Note that these tests do illustrate how in some cases the two sorting algorithms produce different results for a DAG (I think all the existing tests for such differences are ones involving cycles, and the motivation for the new algorithm was also to improve the handling of cycles): tst-dso-ordering-all4-44: a->[bc];{}->[cba] output(glibc.rtld.dynamic_sort=1): c>b>a>{}<a<b<c output(glibc.rtld.dynamic_sort=2): b>c>a>{}<a<c<b They also illustrate that sometimes the sorting algorithms do not follow the order in which dependencies are listed in DT_NEEDED even though there is a valid topological sort that does follow that, which might be counterintuitive considering that the DT_NEEDED ordering is followed in the simplest cases: tst-dso-ordering-all4-56: {}->[abc] output: c>b>a>{}<a<b<c shows such a simple case following DT_NEEDED order for destructor execution (the reverse of it for constructor execution), but tst-dso-ordering-all4-41: a->[cb];{}->[cba] output: c>b>a>{}<a<b<c shows that c and b are in the opposite order to what might be expected from the simplest case, though there is no dependency requiring such an opposite order to be used. (I'm not asserting that either of those things is a problem, simply observing them as less obvious properties of the sorting algorithms shown up by these tests.) Tested for x86_64. |
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This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu and x86_64-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arc*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 loongarch64-*-linux-gnu Hardware floating point, LE only. m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu or1k-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv32-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.