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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 18:35:28 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 18:35:28 +0000 |
commit | ea314d2f45c40a006c0104157013ab4b857f665f (patch) | |
tree | 3ef2971cb3675c318b8d9effd987854ad3f6d3e8 /man/dpkg-shlibdeps.pod | |
parent | Initial commit. (diff) | |
download | dpkg-ea314d2f45c40a006c0104157013ab4b857f665f.tar.xz dpkg-ea314d2f45c40a006c0104157013ab4b857f665f.zip |
Adding upstream version 1.22.4.upstream/1.22.4
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | man/dpkg-shlibdeps.pod | 510 |
1 files changed, 510 insertions, 0 deletions
diff --git a/man/dpkg-shlibdeps.pod b/man/dpkg-shlibdeps.pod new file mode 100644 index 0000000..0988775 --- /dev/null +++ b/man/dpkg-shlibdeps.pod @@ -0,0 +1,510 @@ +# dpkg manual page - dpkg-deb(1) +# +# Copyright © 1995-1996 Ian Jackson <ijackson@chiark.greenend.org.uk> +# Copyright © 2000 Wichert Akkerman <wakkerma@debian.org> +# Copyright © 2006 Frank Lichtenheld <djpig@debian.org> +# Copyright © 2007-2011 Raphaël Hertzog <hertzog@debian.org> +# Copyright © 2011-2013, 2015 Guillem Jover <guillem@debian.org> +# +# This is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2 of the License, or +# (at your option) any later version. +# +# This is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <https://www.gnu.org/licenses/>. + +=encoding utf8 + +=head1 NAME + +dpkg-shlibdeps - generate shared library substvar dependencies + +=head1 SYNOPSIS + +B<dpkg-shlibdeps> +[I<option>...] [B<-e>] I<executable> [I<option>...] + +=head1 DESCRIPTION + +B<dpkg-shlibdeps> +calculates shared library dependencies for executables named in its +arguments. +The dependencies are added to the substitution +variables file +B<debian/substvars> +as variable names +B<shlibs:>I<dependency-field> +where +I<dependency-field> +is a dependency field name. +Any other variables starting with +B<shlibs:> +are removed from the file. + +B<dpkg-shlibdeps> +has two possible sources of information to generate dependency +information. +Either +I<symbols> +files or +I<shlibs> +files. +For each binary that +B<dpkg-shlibdeps> +analyzes, it finds out the list of libraries that it's linked with. +Then, for each library, it looks up either the +I<symbols> +file, or the +I<shlibs> +file (if the former doesn't exist or if debian/shlibs.local contains +the relevant dependency). +Both files are supposed to be provided +by the library package and should thus be available as +%ADMINDIR%/info/I<package>.I<symbols> +or %ADMINDIR%/info/I<package>.I<shlibs>. +The package name is +identified in two steps: find the library file on the system (looking in +the same directories that B<ld.so> would use), then use +B<dpkg -S> I<library-file> +to lookup the package providing the library. + +=head2 Symbols files + +Symbols files contain finer-grained dependency information by providing +the minimum dependency for each symbol that the library exports. +The +script tries to find a symbols file associated to a library package +in the following places (first match is used): + +=over + +=item debian/*/DEBIAN/symbols + +Shared library information generated by the current build process that also invoked +B<dpkg-shlibdeps>. +They are generated by +L<dpkg-gensymbols(1)>. +They are only used if the library is found in a package's build tree. +The +symbols file in that build tree takes precedence over symbols files from +other binary packages. + +=item %PKGCONFDIR%/symbols/I<package>.symbols.I<arch> + +=item %PKGCONFDIR%/symbols/I<package>.symbols + +Per-system overriding shared library dependency information. +I<arch> is the architecture of the current system (obtained by +B<dpkg-architecture -qDEB_HOST_ARCH>). + +=item Output from “B<dpkg-query --control-path> I<package> symbols” + +Package-provided shared library dependency information. +Unless overridden by B<--admindir>, those files are located in +%ADMINDIR%. + +=back + +While scanning the symbols used by all binaries, +B<dpkg-shlibdeps> +remembers the (biggest) minimal version needed for each library. +At the end +of the process, it is able to write out the minimal dependency for every +library used (provided that the information of the I<symbols> files are +accurate). + +As a safe-guard measure, a symbols file can provide a +B<Build-Depends-Package> meta-information field and +B<dpkg-shlibdeps> +will extract the minimal version required by the corresponding package in +the B<Build-Depends> field and use this version if it's higher than the +minimal version computed by scanning symbols. + +=head2 Shlibs files + +Shlibs files associate directly a library to a dependency (without looking +at the symbols). +It's thus often stronger than really needed but very safe +and easy to handle. + +The dependencies for a library are looked up in several places. +The first +file providing information for the library of interest is used: + +=over + +=item debian/shlibs.local + +Package-local overriding shared library dependency information. + +=item %PKGCONFDIR%/shlibs.override + +Per-system overriding shared library dependency information. + +=item debian/*/DEBIAN/shlibs + +Shared library information generated by the current build process that also invoked +B<dpkg-shlibdeps>. +They are only used if the library is found in a package's build tree. +The +shlibs file in that build tree takes precedence over shlibs files from +other binary packages. + +=item Output from “B<dpkg-query --control-path> I<package> shlibs” + +Package-provided shared library dependency information. +Unless overridden by B<--admindir>, those files are located in +%ADMINDIR%. + +=item %PKGCONFDIR%/shlibs.default + +Per-system default shared library dependency information. + +=back + +The extracted dependencies are then directly used (except if they are +filtered out because they have been identified as duplicate, or as weaker +than another dependency). + +=head1 OPTIONS + +B<dpkg-shlibdeps> +interprets non-option arguments as executable names, just as if they'd +been supplied as +B<-e>I<executable>. + +=over + +=item B<-e>I<executable> + +Include dependencies appropriate for the shared libraries required by +I<executable>. +This option can be used multiple times. + +=item B<-l>I<directory> + +Prepend +I<directory> +to the list of directories to search for private shared libraries +(since dpkg 1.17.0). +This option can be used multiple times. + +B<Note>: Use this option instead of setting B<LD_LIBRARY_PATH>, +as that environment variable is used to control the run-time linker +and abusing it to set the shared library paths at build-time can be +problematic when cross-compiling for example. + +=item B<-d>I<dependency-field> + +Add dependencies to be added to the control file dependency field +I<dependency-field>. +(The dependencies for this field are placed in the variable +B<shlibs:>I<dependency-field>.) + +The +B<-d>I<dependency-field> +option takes effect for all executables after the option, until the +next +B<-d>I<dependency-field>. +The default +I<dependency-field> +is +B<Depends>. + +If the same dependency entry (or set of alternatives) appears in more +than one of the recognized dependency field names +B<Pre-Depends>, B<Depends>, B<Recommends>, B<Enhances> or B<Suggests> +then +B<dpkg-shlibdeps> +will automatically remove the dependency from all fields except the +one representing the most important dependencies. + +=item B<-p>I<varname-prefix> + +Start substitution variables with +I<varname-prefix>B<:> +instead of +B<shlibs:>. +Likewise, any existing substitution variables starting with +I<varname-prefix>B<:> +(rather than +B<shlibs:>) +are removed from the substitution variables file. + +=item B<-O>[I<filename>] + +Print substitution variable settings to standard output (or I<filename> +if specified, since dpkg 1.17.2), rather than being added to the +substitution variables file +(B<debian/substvars> +by default). + +=item B<-t>I<type> + +Prefer shared library dependency information tagged for the given +package type. +If no tagged information is available, falls back to untagged information. +The default package type is B<deb>. +Shared library dependency +information is tagged for a given type by prefixing it with the name of the +type, a colon, and whitespace. + +=item B<-L>I<local-shlibs-file> + +Read overriding shared library dependency information from +I<local-shlibs-file> +instead of +B<debian/shlibs.local>. + +=item B<-T>I<substvars-file> + +Write substitution variables in +I<substvars-file>; +the default is +B<debian/substvars>. + +=item B<-v> + +Enable verbose mode (since dpkg 1.14.8). +Numerous messages are displayed to explain what +B<dpkg-shlibdeps> +does. + +=item B<-x>I<package> + +Exclude the package from the generated dependencies (since dpkg 1.14.8). +This is useful to +avoid self-dependencies for packages which provide ELF binaries +(executables or library plugins) using a library contained in the same +package. +This option can be used multiple times to exclude several +packages. + +=item B<-S>I<package-build-dir> + +Look into I<package-build-dir> first when trying to find a library +(since dpkg 1.14.15). +This is +useful when the source package builds multiple flavors of the same library +and you want to ensure that you get the dependency from a given binary +package. +You can use this option multiple times: directories will be +tried in the same order before directories of other binary packages. + +=item B<-I>I<package-build-dir> + +Ignore I<package-build-dir> when looking for shlibs, symbols, and shared +library files (since dpkg 1.18.5). +You can use this option multiple times. + +=item B<--ignore-missing-info> + +Do not fail if dependency information can't be found for a shared library +(since dpkg 1.14.8). +Usage of this option is discouraged, all libraries should provide +dependency information (either with shlibs files, or with symbols files) +even if they are not yet used by other packages. + +=item B<--warnings=>I<value> + +I<value> is a bit field defining the set of warnings that +can be emitted by B<dpkg-shlibdeps> (since dpkg 1.14.17). +Bit 0 (value=1) enables the warning “symbol I<sym> used by I<binary> +found in none of the libraries”, bit 1 (value=2) enables the warning +“package could avoid a useless dependency” and bit 2 (value=4) enables +the warning “I<binary> should not be linked against I<library>”. +The default I<value> is 3: the first two warnings are active by +default, the last one is not. +Set I<value> to 7 if you want all +warnings to be active. + +=item B<--admindir=>I<dir> + +Change the location of the B<dpkg> database (since dpkg 1.14.0). +The default location is I<%ADMINDIR%>. + +=item B<-?>, B<--help> + +Show the usage message and exit. + +=item B<--version> + +Show the version and exit. + +=back + +=head1 ENVIRONMENT + +=over + +=item B<DPKG_COLORS> + +Sets the color mode (since dpkg 1.18.5). +The currently accepted values are: B<auto> (default), B<always> and +B<never>. + +=item B<DPKG_NLS> + +If set, it will be used to decide whether to activate Native Language Support, +also known as internationalization (or i18n) support (since dpkg 1.19.0). +The accepted values are: B<0> and B<1> (default). + +=back + +=head1 DIAGNOSTICS + +=head2 Warnings + +Since +B<dpkg-shlibdeps> +analyzes the set of symbols used by each binary of the generated package, +it is able to emit warnings in several cases. +They inform you of things that can be improved in the package. +In most cases, those improvements concern the upstream sources directly. +By order of decreasing importance, +here are the various warnings that you can encounter: + +=over + +=item B<symbol> I<sym> B<used by> I<binary> B<found in none of the libraries.> + +The indicated symbol has not been found in the libraries linked with the +binary. +The I<binary> is most likely a library and it needs to be linked +with an additional library during the build process (option +B<-l>I<library> of the linker). + +=item I<binary> B<contains an unresolvable reference to symbol> I<sym>B<: it's probably a plugin> + +The indicated symbol has not been found in the libraries linked with the +binary. +The I<binary> is most likely a plugin and the symbol is probably provided +by the program that loads this plugin. +In theory a +plugin doesn't have any SONAME but this binary does have one and as such +it could not be clearly identified as such. +However the fact that the +binary is stored in a non-public directory is a strong indication +that's it's not a normal shared library. +If the binary is really a plugin, then disregard this warning. +But there's always the possibility +that it's a real library and that programs linking to it are using an +RPATH so that the dynamic loader finds it. +In that case, the library is +broken and needs to be fixed. + +=item B<package could avoid a useless dependency if> I<binary> B<was not linked against> I<library> B<(it uses none of the library's symbols)> + +None of the I<binaries> that are linked with I<library> use any of the +symbols provided by the library. +By fixing all the binaries, you would avoid +the dependency associated to this library (unless the same dependency is +also generated by another library that is really used). + +=item B<package could avoid a useless dependency if> I<binaries> B<were not linked against> I<library> B<(they use none of the library's symbols)> + +Exactly the same as the above warning, but for multiple binaries. + +=item I<binary> B<should not be linked against> I<library> B<(it uses none of the library's symbols)> + +The I<binary> is linked to a library that it doesn't need. +It's not a +problem but some small performance improvements in binary load time can be +obtained by not linking this library to this binary. +This warning checks +the same information as the previous one but does it for each binary +instead of doing the check globally on all binaries analyzed. + +=back + +=head2 Errors + +B<dpkg-shlibdeps> +will fail if it can't find a public library used by a binary or if this +library has no associated dependency information (either shlibs file or +symbols file). +A public library has a SONAME and is versioned (libsomething.so.I<X>). +A private library (like a plugin) should not +have a SONAME and doesn't need to be versioned. + +=over + +=item B<couldn't find library> I<library-soname> B<needed by> I<binary> B<(its RPATH is '>I<rpath>B<')> + +The I<binary> uses a library called I<library-soname> but +B<dpkg-shlibdeps> +has been unable to find the library. +B<dpkg-shlibdeps> +creates a list of directories to check as following: directories listed in +the RPATH of the binary, directories added by the B<-l> option, directories +listed in the B<LD_LIBRARY_PATH> environment variable, cross multiarch +directories (ex. /lib/arm64-linux-gnu, /usr/lib/arm64-linux-gnu), standard +public directories (/lib, /usr/lib), directories listed in /etc/ld.so.conf, +and obsolete multilib directories (/lib32, /usr/lib32, /lib64, /usr/lib64). +Then it checks those directories in the package's build tree +of the binary being analyzed, in the packages' build trees indicated with +the B<-S> command-line option, in other packages' build trees that contains +a DEBIAN/shlibs or DEBIAN/symbols file and finally in the root directory. +If the library is not found in any of those directories, then you get this +error. + +If the library not found is in a private directory of the same package, +then you want to add the directory with B<-l>. +If it's in another +binary package being built, you want to make sure that the shlibs/symbols +file of this package is already created and that B<-l> +contains the appropriate directory if it also is in a private directory. + +=item B<no dependency information found for> I<library-file> B<(used by> I<binary>B<).> + +The library needed by I<binary> has been found by +B<dpkg-shlibdeps> +in I<library-file> but +B<dpkg-shlibdeps> +has been unable to find any dependency information for that library. +To +find out the dependency, it has tried to map the library to a Debian +package with the help of +B<dpkg -S> I<library-file>. +Then it checked the corresponding shlibs and symbols files in +%ADMINDIR%/info/, and in the various package's build trees +(debian/*/DEBIAN/). + +This failure can be caused by a bad or missing shlibs or symbols file +in the package of the library. +It might also happen if the library is +built within the same source package and if the shlibs files has not yet +been created (in which case you must fix debian/rules to create +the shlibs before calling B<dpkg-shlibdeps>). +Bad RPATH can also +lead to the library being found under a non-canonical name (example: +/usr/lib/openoffice.org/../lib/libssl.so.0.9.8 instead of +/usr/lib/libssl.so.0.9.8) that's not associated to any package, +B<dpkg-shlibdeps> +tries to work around this by trying to fallback on a canonical name (using +L<realpath(3)>) +but it might not always work. +It's always best to clean up the RPATH +of the binary to avoid problems. + +Calling +B<dpkg-shlibdeps> +in verbose mode (B<-v>) will provide much more information about where it +tried to find the dependency information. +This might be useful if you +don't understand why it's giving you this error. + +=back + +=head1 SEE ALSO + +L<deb-substvars(5)>, +L<deb-shlibs(5)>, +L<deb-symbols(5)>, +L<dpkg-gensymbols(1)>. |