Difference between revisions of "Portage API"

Revision as of 23:39, October 1, 2015

This page is the beginning of the missing documentation on the Portage Python API.

Introduction

Portage has always had a Python API; however, this API does not appear to be documented at all. This page represents an initial effort to document the API that is available for querying packages, etc.

Portage DBAPI

The API that exists in Portage to query this is called the DBAPI. The "porttree" is the nickname used to describe the Portage tree, which is typically stored in /usr/portage. In these examples, we will use Portage's python DBAPI to query the porttree using the interactive python interpreter.

w520 drobbins # python
Python 3.3.5 (default, Sep 21 2015, 23:01:43) 
[GCC 4.9.3] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> portage.root
'/'
>>> import portage
>>> p = portage.db[portage.root]["porttree"].dbapi
>>>

p now contains a reference to the DBAPI associated with the Portage tree associated with the system installed at portage.root, which is typically /usr/portage. We can now perform various queries using this variable.

>>> p.cp_list("sys-apps/portage")
['sys-apps/portage-2.3.6-r9', 'sys-apps/portage-2.3.8']

Above, cp_list takes what is called a "catpkg", which is a reference to a particular ebuild in a repository in "category/packagename" format. We can also get lists of specific available packages, using other functions:

>>> p.match("sys-apps/portage")
['sys-apps/portage-2.3.6-r9', 'sys-apps/portage-2.3.8']
>>> p.match("=sys-apps/portage-2*")
['sys-apps/portage-2.3.6-r9', 'sys-apps/portage-2.3.8']

While at first the match() method looks no different than the cp_list() method, you can see that it accepts any valid dependency atom, which is any individual dependency reference to a particular package. The match() method is actually a shortcut for the more sophisticated xmatch() method -- it matches all visible (non-masked) packages that satisfy the dependency.

Using xmatch(), more sophisticated matching can be performed:

>>> p.xmatch("match-visible", "=sys-apps/portage-2*")
['sys-apps/portage-2.3.6-r9', 'sys-apps/portage-2.3.8']

As you can see, xmatch() with the "match_visible" gives us the identical results as match(). In fact, match() is a shortcut for this particular xmatch() call. However, xmatch() has other matching methods, detailed below:

match mode	Description	Return Type
`bestmatch-visible`	Find the best (highest) visible (unmasked) match for the dependency.	single string
`match-all`	Find all matches, masked or unmasked.	list of strings
`match-visible`	Find all visible (unmasked) matches for the dependency.	list of strings
`minimum-all`	Find the lowest match for the dependency, ignoring masks.	single string
`minimum-visible`	Find the lowest match for the dependency, respecting masks.	single string

Querying Package Metadata

Portage is designed to extract and cache a certain set of data from each ebuild, called metadata, and this metadata is queryable and used for dependency calculations, fetching sources, etc. Querying of metadata for a particular ebuild can be performed using the aux_get() DBAPI method:

>>> p.aux_get("sys-apps/portage-2.3.8", ["EAPI", "SRC_URI"])
['5-progress', 'https://www.github.com/funtoo/portage-funtoo/tarball/funtoo-2.3.8 -> portage-funtoo-2.3.8.tar.gz']

The parameters of the aux_get() method are, first, the name of a package in "catpkg-v" format, which is a reference to a specific version of a package in "category/packagename-version(-revision)" format. The second argument is a list or tuple of metadata to return. A list is returned containing the queried metadata in the order specified in the first argument. If necessary, Portage will evaluate the contents of the ebuild to extract and cache this metadata. For porttrees, the following metadata is available (and this may vary by EAPI):

Metadata	Description
`DEFINED_PHASES`	String containing all phases (see Ebuild Functions) defined in the ebuild, delimited by spaces.
`DEPEND`	Build dependencies
`EAPI`	Ebuild API version
`HDEPEND`	Host Build Dependencies (EAPI 5-hdepend only)
`INHERITED`	A complete list of eclasses used by this ebuild, directly or indirectly (via eclasses inheriting other eclasses)
`IUSE`	`IUSE` variable from ebuild
`KEYWORDS`	`KEYWORDS` (masking) setting
`LICENSE`	`LICENSE` variable from ebuild
`PDEPEND`	`PDEPEND` variable from ebuild
`PROPERTIES`	`PROPERTIES` variable from ebuild
`PROVIDE`	`PROVIDE` variable from ebuild
`RDEPEND`	Runtime dependencies
`REQUIRED_USE`	`REQUIRED_USE` variable from ebuild
`repository`	Repository name ("gentoo" in main Gentoo or Funtoo Portage tree)
`RESTRICT`	`RESTRICT` variable from ebuild
`SLOT`	`SLOT` variable from ebuild

Manipulating and Comparing Package Strings

Portage's API contains a number of functions that are used to manipulate and split Portage's various types of package strings, and these functions are defined in /usr/lib/python3.3/site-packages/portage/version.py. Here is a list of the various functions available:

Function name	Description	Example	Result
`catpkgsplit(cpv_string)`	Takes a complete catpkg-version string, and splits into category, package name, package version, package revision. Will return `None` if argument string is invalid -- such as missing a version, or category.	portage.catpkgsplit("foo-bar/oni-1.0-r1")	('foo-bar', 'oni', '1.0', 'r1')
`catsplit(catpkg_string)`	Takes a string in catpkg or catpkg-version format, and splits into category and "other" part (list of length 2) at the initial "/" separator. Equivalent to `string.split(catpkg_string, "/", maxsplit=1)`. No validation of the package or package-version part is performed.	portage.catsplit("foo-bar/oni-1.0-r1") portage.catsplit("foo-bar/oni-2asdfz00")	['foo-bar', 'oni-1.0'] ['foo-bar', 'oni-2asdfz00']
`pkgsplit(pv_or_cpv_string)`	Takes a complete catpkg-version string or a pkg-version string, and splits into catpkg (or package, if pkg-version specified), package version, package revision. Will return `None` if argument string is invalid -- such as missing a version, or category.	portage.pkgsplit("foo-bar/oni-1.0-r1") portage.pkgsplit("oni-1.0-r1")	('foo-bar/oni', '1.0', 'r1') ('oni', '1.0', 'r1')
`ververify(version_string)`	Takes a version string (can include revision,) and uses regexes to determine if it is valid and supporte by Portage. Returns True or False.	portage.ververify("1.0-r1")	True
`vercmp(version_string_1, version_string_2)`	Compares two version strings and determines which string is greater. If first string is a higher version, then a positive number is returned. If the second string is a higher version, a negative number is returned. If the versions are considered to be equal, then zero is returned.	portage.vercmp("1.0-r1", "1.0-r2")	-1
`pkgcmp(pkgsplit_1, pkgsplit_2)`	Compares two packages in `pkgsplit()` format. If first package is a higher version, then a positive number is returned. If the second package is a higher version, a negative number is returned. If the versions are considered to be equal, then zero is returned. Note that the package or catpkg atoms used for each pkgsplit call must match exactly, or the packages will be considered to be different and uncomparable and `None` will be returned.	pkgcmp(pkgsplit("oni-1.0-r1"), pkgsplit("oni-1.0-r2")) pkgcmp(pkgsplit("oni-1.0-r1"), pkgsplit("boni-1.0-r2"))	-1 None

@@ Line 88: / Line 88: @@
 {{TableEnd}}
-== Manipulating Package Strings ==
+== Manipulating and Comparing Package Strings ==
 Portage's API contains a number of functions that are used to manipulate and split Portage's various types of package strings, and these functions are defined in {{f|/usr/lib/python3.3/site-packages/portage/version.py}}. Here is a list of the various functions available: