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|
librefetch(8) -- downloads or creates a liberated source tarball
================================================================
## SYNOPSIS
`librefetch` [<OPTIONS>] <SOURCE-URL> [<OUTPUT-FILE>]<br>
`librefetch` `-`[`g`|`S`|`M`|`h`]
## DESCRIPTION
`librefetch` is a program to streamline creation of custom source
tarballs for `PKGBUILD(5)` files.
If a URL mentioned in the <source> array in a `PKGBUILD` is in a
location that Parabola uploads "custom" source tarballs to (or
configured locations), and no file is at that URL, librefetch will
automatically create it for you.
This works because a post-install script for the package configures
`librefetch` as the download agent for `https://` URLs in
`makepkg.conf`; allowing it to jump in and create a file if need be.
Because of this, it is almost never necessary to call `librefetch`
manually.
The post-install script also configures `librefetch` as the download
agent for `libre://` URLs, for compatibility with `PKGBUILD` files
that used a previous version of librefetch.
There are 6 modes:
* `download`: Download the tarball from the configured mirror.
* `create`: Create the tarball from a `PKGBUILD`/`SRCBUILD`.
* `checksums`: Generate integrity checks for source files.
* `srcbuild`: Print the effective build script.
* `makepkg`: Generate and print the location of the effective makepkg
script.
* `help`: Print `librefetch` usage information.
The normal mode of operation is `download` mode. If `download` mode
fails, it may choose to try `create` mode.
## OPTIONS
* `-C`: Force `create` mode (don't download)
* `-D`: Force `download` mode (don't create)
* `-p` <file>: Use an alternate build script for `create` mode
(instead of `PKGBUILD`). If an `SRCBUILD` file exists in the same
directory, it is used instead.
* `-g` | `--geninteg`: Use `checksums` mode: Generate integrity
checks for source files.
* `-S` | `--srcbuild`: Use `srcbuild` mode: print the effective build
script.
* `-M` | `--makepkg`: Use `makepkg` mode: generate and print the
location of the effective makepkg script.
* `-h` | `--help`: Use `help` mode: Show usage information.
Other options, if they are documented in `makepkg -h`, are passed to
the modified copy of makepkg created during `create` mode.
## DOWNLOAD MODE
If <SOURCE-URL> begins with the string `libre://`, it is replaced with
the first value in <MIRRORS>, as configured in `librefetch.conf(5)`;
this is for compatibility with `PKGBUILD` files that used a previous
version of librefetch.
It uses <DOWNLOADER>, as configured in `librefetch.conf` to attempt to
download the source tarball from that URL. If that fails, and
following conditions are met, it proceeds to `create` mode:
* The `-D` flag has not been specified to inhibit `create` mode.
* The <SOURCE-URL> begins with one of the values in <MIRRORS>.
The latter requirement allows librefetch to be used as a generic
HTTP(S) download agent, that can automatically create files from
whitelisted locations.
## CREATE MODE
The principle of `create` mode is that a special `PKGBUILD(5)` (called
`SRCBUILD(5)`) installs source files to <$pkgdir>, and the resulting
"package" is then used as a source tarball. The `SRCBUILD` exists in
the same directory as the `PKGBUILD`. It can be created manually, or
generated on-the-fly from the `PKGBUILD`. Extra steps are taken to
ensure that as long as the same directory contents go in, an identical
tarball will come out--the checksum of the file should not change
based on when it is built or who builds it.
The `SRCBUILD` is either created, or sanitized if it already exists.
If the output filename does not end with `.sig` or `.sig.part`, then
the `SRCBUILD` is fed to a modified version of `makepkg(8)`. If the
output filename does end with `.sig` or `.sig.part`, then it uses GPG
to create a signature. If the file it is trying to sign does not
exist yet, librefetch recurses on itself to create it.
The reason `makepkg` must be modified is that we need the resulting
tarball to be deterministic (as well as not containing package
metadata).
When this documentation speaks of a file being modified, it is a
temporary copy of the file that is modified, your original file will
remain intact.
## SRCBUILD GENERATION
As explained in the `CREATE MODE` section, in `create` mode, this
program generates an `SRCBUILD` file. For debugging purposes, this
file can be printed instead of executed with `srcbuild` mode.
### PRE-EXISTING SRCBUILD
The use of `SRCBUILD` files pre-dates `librefetch`. By convention,
they set <PKGDEST> and <PKGEXT> in `package()` in order to modify the
behavior of `makepkg`. Because a modified version of `makepkg` is
used, this interferes with the correct behavior. To compensate for
this, lines containing "`PKGDEST=`" or "`PKGEXT=`" are deleted from
the `SRCBUILD`.
The general idea is that `build()` makes any modifications to the
source, then `package()` copies it from <$srcdir> to <$pkgdir>.
### SRCBUILD FROM PKGBUILD
Possibly more elegant than having a separate `SRCBUILD` file is having
an `mksource()` function in the main `PKGBUILD`. This results in less
boilerplate and fewer files to edit.
Note that this only happens if a file named `SRCBUILD` doesn't already
exist; when migrating a package from a manually created `SRCBUILD` to
this method, the `SRCBUILD` must be deleted (or renamed) for this to
work.
The dynamically created `SRCBUILD` is created by copying `PKGBUILD` to
a temporary file, then re-setting variables and re-defining functions.
Following is a table of the translations.
Variables
source = mksource
noextract = mknoextract
*sums = mk*sums (md5, sha1, sha224, sha256, sha384, sha512)
depends = <empty>
checkdepends = <empty>
makedepends = mkdepends
*_$CARCH = <unset>
Functions
prepare() { :; }
build() { mksource; }
check() { :; }
package() { cp -a "$srcdir"/*/ "$pkgdir/"; }
The `mksource()` function does not need to be defined. If it isn't
defined, then no transformations will be made to the source between it
being extracted to <$srcdir> and copied to <$pkgdir>.
In summary:
* Set <mksource=()> and <mkmd5sums=()> to act as <source=()> and
<md5sums=()>, respectively.
* Declare a `mksource()` function to make modifications to the
source, if necessary.
Other changes:
* <pkgname> is set to <pkgbase>, or the first element of the
<pkgname> array (the effect is that split packaging is turned
off).
* <options=()> is set have `makepkg` avoid making changes to
<$pkgdir>. The exact change is:
options=(!strip docs libtool staticlibs emptydirs !zipman purge !upx)
* <PURGE_TARGETS=()> has VCS directories added to it:
PURGE_TARGETS=(.bzr/ .cvs/ .git/ .hg/ .svn/ .makepkg/)
### MAKEPKG MODIFICATIONS
The following modifications are made to makepkg:
* Allow us to manipulate the output file (<$pkg_file>)
* Do not include metadata in the output file (<${comp_files[@]}>)
* Force 'ustar' tar format, don't allow it to upgrade to 'pax' to
store extended file attributes.
* Don't symlink the resulting file into the current directory.
* <PURGE_TARGETS> interprets an item as a directory if it ends with a
slash ("/").
* Timestamps in <$pkgdir> are reset to the date specified in
<SOURCE_DATE_EPOCH>[1], or "1990-01-01 0:0:0 +0" if it's not set, so
that the resulting tarball will be the same, regardless of when it
was created.
* Sort the files included in the tarball; normally the order of files
in a tarball is essentially random (even if it tends to be the same
when re-created on the same machine).
* append `-libre` to <$srcdir>
* append `-libre` to <$pkgbasedir> (which becomes <$pkgdir>)
* Don't check if the package has already been built.
For debugging purposes, this modified makepkg can be printed instead
of executed with `makepkg` mode. Before it is run in create mode,
`PKGEXT`, `PKGDEST`, and `pkg_file` are set as environment variables.
## CONFIGURATION
See `librefetch.conf(5)` for details on configuring librefetch using
the `librefetch.conf` file.
## SEE ALSO
librefetch.conf(5), makepkg(8), PKGBUILD(5), SRCBUILD(5)
## NOTES
1. <SOURCE_DATE_EPOCH> specification for build systems
https://reproducible-builds.org/specs/source-date-epoch/
|
