Próximo: Caminhos de pesquisa, Anterior: Fases de construção, Acima: Interface de programação [Conteúdo][Índice]
As soon as you start writing non-trivial package definitions
(veja Definindo pacotes) or other build actions (veja Expressões-G),
you will likely start looking for helpers for “shell-like”
actions—creating directories, copying and deleting files recursively,
manipulating build phases, and so on. The (guix build utils) module
provides such utility procedures.
Most build systems load (guix build utils) (veja Sistemas de compilação).
Thus, when writing custom build phases for your package definitions, you can
usually assume those procedures are in scope.
When writing G-expressions, you can import (guix build utils) on the
“build side” using with-imported-modules and then put it in scope
with the use-modules form (veja Using Guile Modules em GNU
Guile Reference Manual):
(with-imported-modules '((guix build utils)) ;import it
(computed-file "empty-tree"
#~(begin
;; Put it in scope.
(use-modules (guix build utils))
;; Happily use its 'mkdir-p' procedure.
(mkdir-p (string-append #$output "/a/b/c")))))
The remainder of this section is the reference for most of the utility
procedures provided by (guix build utils).
This section documents procedures that deal with store file names.
Return the directory name of the store.
Return true if file is in the store.
Strip the /gnu/store and hash from file, a store file name.
The result is typically a "package-version" string.
Given name, a package name like "foo-0.9.1b", return two
values: "foo" and "0.9.1b". When the version part is
unavailable, name and #f are returned. The first hyphen
followed by a digit is considered to introduce the version part.
The procedures below deal with files and file types.
Return #t if dir exists and is a directory.
Return #t if file exists and is executable.
Return #t if file is a symbolic link (aka. a “symlink”).
Return #t if file is, respectively, an ELF file, an ar
archive (such as a .a static library), or a gzip file.
If file is a gzip file, reset its embedded timestamp (as with
gzip --no-name) and return true. Otherwise return #f.
When keep-mtime? is true, preserve file’s modification time.
The following procedures and macros help create, modify, and delete files.
They provide functionality comparable to common shell utilities such as
mkdir -p, cp -r, rm -r, and sed.
They complement Guile’s extensive, but low-level, file system interface
(veja POSIX em GNU Guile Reference Manual).
Run body with directory as the process’s current directory.
Essentially, this macro changes the current directory to directory
before evaluating body, using chdir (veja Processes em GNU Guile Reference Manual). It changes back to the initial directory when
the dynamic extent of body is left, be it via normal procedure
return or via a non-local exit such as an exception.
Create directory dir and all its ancestors.
Create directory if it does not exist and copy file in there under the same name.
Make file writable for its owner.
copy-file] [#:keep-mtime? #f] [#:keep-permissions? #t] [#:select? (const
#t)] Copy source directory to destination. Follow symlinks if
follow-symlinks? is true; otherwise, just preserve them. Call
copy-file to copy regular files. Call select?, taking two
arguments, file and stat, for each entry in source, where
file is the entry’s absolute file name and stat is the result of
lstat (or stat if follow-symlinks? is true); exclude
entries for which select? does not return true. When
keep-mtime? is true, keep the modification time of the files in
source on those of destination. When keep-permissions? is
true, preserve file permissions. Write verbose output to the log
port.
Delete dir recursively, like rm -rf, without following
symlinks. Don’t follow mount points either, unless follow-mounts? is
true. Report but ignore errors.
file by the string returned by body. body is evaluated with each match-var bound to the corresponding positional regexp sub-expression. For example:
(substitute* file
(("hello")
"good morning\n")
(("foo([a-z]+)bar(.*)$" all letters end)
(string-append "baz" letters end)))
Here, anytime a line of file contains hello, it is replaced by
good morning. Anytime a line of file matches the second
regexp, all is bound to the complete match, letters is bound
to the first sub-expression, and end is bound to the last one.
When one of the match-var is _, no variable is bound to the
corresponding match substring.
Alternatively, file may be a list of file names, in which case they are all subject to the substitutions.
Be careful about using $ to match the end of a line; by itself it
won’t match the terminating newline of a line. For example, to match a
whole line ending with a backslash, one needs a regex like
"(.*)\\\\\n$".
This section documents procedures to search and filter files.
Return a predicate that returns true when passed a file name whose base name matches regexp.
lexicographically sorted list of files under dir for which pred
returns true. pred is passed two arguments: the absolute file name,
and its stat buffer; the default predicate always returns true. pred
can also be a regular expression, in which case it is equivalent to
(file-name-predicate pred). stat is used to obtain file
information; using lstat means that symlinks are not followed. If
directories? is true, then directories will also be included. If
fail-on-error? is true, raise an exception upon error.
Here are a few examples where we assume that the current directory is the root of the Guix source tree:
;; List all the regular files in the current directory. (find-files ".") ⇒ ("./.dir-locals.el" "./.gitignore" …) ;; List all the .scm files under gnu/services. (find-files "gnu/services" "\\.scm$") ⇒ ("gnu/services/admin.scm" "gnu/services/audio.scm" …) ;; List ar files in the current directory. (find-files "." (lambda (file stat) (ar-file? file))) ⇒ ("./libformat.a" "./libstore.a" …)
Return the complete file name for program as found in $PATH, or
#f if program could not be found.
Return the complete file name for name as found in inputs;
search-input-file searches for a regular file and
search-input-directory searches for a directory. If name could
not be found, an exception is raised.
Here, inputs must be an association list like inputs and
native-inputs as available to build phases (veja Fases de construção).
Here is a (simplified) example of how search-input-file is used in a
build phase of the wireguard-tools package:
(add-after 'install 'wrap-wg-quick
(lambda* (#:key inputs outputs #:allow-other-keys)
(let ((coreutils (string-append (assoc-ref inputs "coreutils")
"/bin")))
(wrap-program (search-input-file outputs "bin/wg-quick")
#:sh (search-input-file inputs "bin/bash")
`("PATH" ":" prefix ,(list coreutils))))))
You’ll find handy procedures to spawn processes in this module, essentially
convenient wrappers around Guile’s system* (veja system* em GNU Guile Reference Manual).
Invoke program with the given args. Raise an
&invoke-error exception if the exit code is non-zero; otherwise
return #t.
The advantage compared to system* is that you do not need to check
the return value. This reduces boilerplate in shell-script-like snippets
for instance in package build phases.
Return true if c is an &invoke-error condition.
Access specific fields of c, an &invoke-error condition.
Report to port (by default the current error port) about c, an
&invoke-error condition, in a human-friendly way.
Typical usage would look like this:
(use-modules (srfi srfi-34) ;for 'guard' (guix build utils)) (guard (c ((invoke-error? c) (report-invoke-error c))) (invoke "date" "--imaginary-option")) -| command "date" "--imaginary-option" failed with status 1
Invoke program with args and capture program’s standard
output and standard error. If program succeeds, print nothing and
return the unspecified value; otherwise, raise a &message error
condition that includes the status code and the output of program.
Here’s an example:
(use-modules (srfi srfi-34) ;for 'guard' (srfi srfi-35) ;for 'message-condition?' (guix build utils)) (guard (c ((message-condition? c) (display (condition-message c)))) (invoke/quiet "date") ;all is fine (invoke/quiet "date" "--imaginary-option")) -| 'date --imaginary-option' exited with status 1; output follows: date: unrecognized option '--imaginary-option' Try 'date --help' for more information.
The (guix build utils) also contains tools to manipulate build phases
as used by build systems (veja Sistemas de compilação). Build phases are
represented as association lists or “alists” (veja Association Lists em GNU Guile Reference Manual) where each key is a symbol naming the
phase and the associated value is a procedure (veja Fases de construção).
Guile core and the (srfi srfi-1) module both provide tools to
manipulate alists. The (guix build utils) module complements those
with tools written with build phases in mind.
Modify phases sequentially as per each clause, which may have one of the following forms:
(delete old-phase-name) (replace old-phase-name new-phase) (add-before old-phase-name new-phase-name new-phase) (add-after old-phase-name new-phase-name new-phase)
Where every phase-name above is an expression evaluating to a symbol, and new-phase an expression evaluating to a procedure.
The example below is taken from the definition of the grep package.
It adds a phase to run after the install phase, called
fix-egrep-and-fgrep. That phase is a procedure (lambda* is
for anonymous procedures) that takes a #:outputs keyword argument and
ignores extra keyword arguments (veja Optional Arguments em GNU
Guile Reference Manual, for more on lambda* and optional and keyword
arguments.) The phase uses substitute* to modify the installed
egrep and fgrep scripts so that they refer to grep by
its absolute file name:
(modify-phases %standard-phases
(add-after 'install 'fix-egrep-and-fgrep
;; Patch 'egrep' and 'fgrep' to execute 'grep' via its
;; absolute file name instead of searching for it in $PATH.
(lambda* (#:key outputs #:allow-other-keys)
(let* ((out (assoc-ref outputs "out"))
(bin (string-append out "/bin")))
(substitute* (list (string-append bin "/egrep")
(string-append bin "/fgrep"))
(("^exec grep")
(string-append "exec " bin "/grep")))))))
In the example below, phases are modified in two ways: the standard
configure phase is deleted, presumably because the package does not
have a configure script or anything similar, and the default
install phase is replaced by one that manually copies the executable
files to be installed:
(modify-phases %standard-phases
(delete 'configure) ;no 'configure' script
(replace 'install
(lambda* (#:key outputs #:allow-other-keys)
;; The package's Makefile doesn't provide an "install"
;; rule so do it by ourselves.
(let ((bin (string-append (assoc-ref outputs "out")
"/bin")))
(install-file "footswitch" bin)
(install-file "scythe" bin)))))
It is not unusual for a command to require certain environment variables to be set for proper functioning, typically search paths (veja Caminhos de pesquisa). Failing to do that, the command might fail to find files or other commands it relies on, or it might pick the “wrong” ones—depending on the environment in which it runs. Examples include:
PATH;
GUILE_LOAD_PATH
and GUILE_LOAD_COMPILED_PATH;
QT_PLUGIN_PATH.
For a package writer, the goal is to make sure commands always work the same
rather than depend on some external settings. One way to achieve that is to
wrap commands in a thin script that sets those environment variables,
thereby ensuring that those run-time dependencies are always found. The
wrapper would be used to set PATH, GUILE_LOAD_PATH, or
QT_PLUGIN_PATH in the examples above.
To ease that task, the (guix build utils) module provides a couple of
helpers to wrap commands.
Make a wrapper for program. variables should look like this:
'(variable delimiter position list-of-directories)
where delimiter is optional. : will be used if delimiter
is not given.
For example, this call:
(wrap-program "foo"
'("PATH" ":" = ("/gnu/.../bar/bin"))
'("CERT_PATH" suffix ("/gnu/.../baz/certs"
"/qux/certs")))
will copy foo to .foo-real and create the file foo with the following contents:
#!location/of/bin/bash
export PATH="/gnu/.../bar/bin"
export CERT_PATH="$CERT_PATH${CERT_PATH:+:}/gnu/.../baz/certs:/qux/certs"
exec -a $0 location/of/.foo-real "$@"
If program has previously been wrapped by wrap-program, the
wrapper is extended with definitions for variables. If it is not,
sh will be used as the interpreter.
Wrap the script program such that variables are set first. The
format of variables is the same as in the wrap-program
procedure. This procedure differs from wrap-program in that it does
not create a separate shell script. Instead, program is modified
directly by prepending a Guile script, which is interpreted as a comment in
the script’s language.
Special encoding comments as supported by Python are recreated on the second line.
Note that this procedure can only be used once per file as Guile scripts are not supported.
Próximo: Caminhos de pesquisa, Anterior: Fases de construção, Acima: Interface de programação [Conteúdo][Índice]