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authorAaron Griffin <aaron@archlinux.org>2007-02-12 04:45:21 +0000
committerAaron Griffin <aaron@archlinux.org>2007-02-12 04:45:21 +0000
commitdfb1f1e23730c1d4e8aa5c041ed758063c81c692 (patch)
treeb56ef8e6e60cf353f487fed505e7f6e4cb83e95e /README
parent9803ec306691a51db820a7f14fc240eae4c910e8 (diff)
* Updated the README file
* Removed the handle->needles param. It's not needed not that alpm_list_t is public
Diffstat (limited to 'README')
-rw-r--r--README192
1 files changed, 75 insertions, 117 deletions
diff --git a/README b/README
index 2d0f307f..9b804f77 100644
--- a/README
+++ b/README
@@ -15,7 +15,7 @@ only accessible in read-only mode, through some clearly defined functions.
In addition to "alpm.h", the interfaces of "alpm_list.h" have also been made
available to the frontend. It is not a requirement for the frontend to use
these list functions; however, it prevents frontends from having to reimplement
-possibly useful functions.
+a list data structure.
Several structures and functions have been renamed compared to pacman 2.9 code.
This was done at first for the sake of naming scheme consistency, and then
@@ -25,53 +25,68 @@ same name declared in both spaces. To avoid such conflicts, internal function
names have been prepended with "_alpm_".
In a general manner, public library functions are named "alpm_<type>_<action>"
-(examples: alpm_trans_commit(), alpm_lib_release(), alpm_pkg_getinfo(), ...).
+(examples: alpm_trans_commit(), alpm_release(), alpm_pkg_getinfo(), ...).
Internal (and thus private) functions should be named "_alpm_XXX" for instance
(examples: _alpm_needbackup(), _alpm_runscriplet(), ...). Functions defined and
used inside a single file should be defined as "static".
-NOTE: The below descriptions may be severely outdated. Yes it needs updating,
-but it may be better done by doxygen comments and generated documentation.
-[HANDLE] (see handle.c)
+[Initialization]
-The "handle" object is the heart of the library. It is a global
-structure available from almost all other objects (althought some very
-low level objects should not be aware of the handle object, like chained
-list, package or groups structures.
+alpm_init() is used to initialize library internals and to create
+a transparent handle object. Before its call, the library can't be used.
-There is only one instance, created by the frontend upon
-"alpm_lib_init()" call, and destroyed upon "alpm_lib_release()" call.
+alpm_lib_release() just does the opposite (memory used by the library, and the
+handle is freed). After its call, the library is no longer available.
-alpm_lib_init() is used to initialize library internals and to create
-the handle object (handle != NULL).
-Before its call, the library can't be used.
-alpm_lib_release() just does the opposite (memory used by the library is
-freed, and handle is set to NULL).
-After its call, the library is no more available.
-The aim of the handle is to provide a central placeholder for essential
-library parameters (filesystem root, pointers to database objects,
-configuration parameters, ...)
+[Options]
-The handle also allows to register a log callback usable by the frontend
-to catch all sort of notifications from the library.
-The frontend can choose the level of verbosity (i.e. the mask), or can
-simply choose to not use the log callback.
-A friendly frontend should care at least for WARNING and ERROR
-notifications.
-Other notifications can safely be ignored and are mainly available for
-troubleshooting purpose.
+In the future, the library will not use any configuration file. It will be up
+to the front end to The handle holds a
+number of configuration options instead (IGNOREPKG, SYSLOG usage,
+log file name, registered databases, ...).
+
+All of the following options have a alpm_option_get_* and alpm_option_set_*
+function for getting and setting the value. The cannot be set before the
+library is initialized.
+
+* logcb: The callback function for "log" operations.
+* dlcb: The callback function for download progress.
+* logmask: The logging mask for which level of output is sent to the logcb.
+* root: The root directory on which pacman operates (Default: /)
+* dbpath: The base path to pacman's databases (Default: var/lib/pacman)
+* cachedir: The base path to pacman's download cache (Default: var/cache/pacman)
+* logfile: The base path to pacman's log file (Default: var/log/pacman.log)
+* usesyslog: Log to syslog instead of `logfile` for file-base logging.
+* upgradedelay: The time span to wait before listing a package as an upgrade (Default: 0)
+* xfercommand: The command to use for downloading instead of pacman's internal
+ downloading functionality.
+* nopassiveftp: Do not use passive FTP commands for ftp connections.
+* chomp: No way, easter eggs are secret!
+* usecolor: Unimplemented, but for the future. You can assume what it means.
+
+The following options also have a `alpm_option_add_*` function, as the values
+are list structures (NOTE: The add functions are NOT plural, as they're in
+english: alpm_option_get_noupgrades -> alpm_option_add_noupgrade).
+
+* noupgrades: Files which will never be touched by pacman (extracted as .pacnew)
+* noextracts: Files which will never be extracted at all (no .pacnew file)
+* ignorepkgs: Packages to ignore when upgrading.
+* holdpkgs: Packages which must be upgraded before continuing.
-Last, but not least, the handle holds a _unique_ transaction object.
+The following options are read-only, having ONLY alpm_option_get_* functions:
+* localdb: A pmdb_t structure for the local (installed) database
+* syncdbs: A list of pmdb_t structures to which pacman can sync from.
-[TRANSACTION] (see trans.c, and also alpm.c)
+
+[Transactions]
The transaction sturcture permits easy manipulations of several packages
at a time (i.e. adding, upgrade and removal operations).
-A transaction can be initiatied with a type (ADD, UPGRADE or REMOVE),
+A transaction can be initiated with a type (ADD, UPGRADE or REMOVE),
and some flags (NODEPS, FORCE, CASCADE, ...).
Note: there can only be one type at a time: a transaction is either
@@ -91,97 +106,60 @@ These targets represent the list of packages to be handled.
Then, a transaction needs to be prepared (alpm_trans_prepare()). It
means that the various targets added, will be inspected and challenged
-against the set of alreayd installed packages (dependency checkings,
+against the set of already installed packages (dependency checkings,
Last, a callback is associated with each transaction. During the
transaction resolution, each time a new step is started or done (i.e
-dependency or conflict checkings, package adding or removal, ...), the
+dependency or conflict checking, package adding or removal, ...), the
callback is called, allowing the frontend to be aware of the progress of
the resolution. Can be useful to implement a progress bar.
-[CONFIGURATION/OPTIONS] (see handle.c)
-
-The library does not use any configuration file. The handle holds a
-number of configuration options instead (IGNOREPKG, SYSLOG usage,
-log file name, registered databases, ...).
-It is up to the frontend to set the options of the library.
-Options can be manipulated using calls to
-alpm_set_option()/alpm_get_option().
-
-Note: the file system root is a special option which can only be defined
-when calling alpm_lib_init(). It can't be modified afterwards.
-
-
-[CACHE] (see cache.c)
-
-Compared to pacman 2.9, there is now one cache object connected to each
-database object.
-There are both a package and a group cache.
-The cache is loaded only on demand (i.e the cache is loaded the first
-time data from it should be used).
+[Package Cache]
-Note: the cache of a database is always updated by the library after
+libalpm maintains two caches for each DB. One is a general package cache, the
+other is a group cache (for package groups). These caches are loaded on demand,
+and freed when the libary is.
+It is important to note tha, as a general rule, package structures should NOT be
+freed manually, as they SHOULD be part of the cache.
+The cache of a database is always updated by the library after
an operation changing the database content (adding and/or removal of
-packages).
-Beware frontends ;)
+packages). Beware frontends ;)
-[PACKAGE] (see package.c, and also db.c)
+[Package]
-The package structure is using three new fields, namely: origin, data,
-infolevel.
-The purpose of these fields is to know some extra info about data stored
-in package structures.
+The package structure maintains all information for a package. In general,
+packages should never be freed from front-ends, as they should always be part of
+the package cache.
-For instance, where is the package coming from (i.e origin)?
-Was it loaded from a file or loaded from the cache?
-If it's coming from a file, then the field data holds the full path and
-name of the file, and infolevel is set to the highest possible value
-(all package fields are reputed to be known).
-Otherwise, if the package comes from a database, data is a pointer to
-the database structure hosting the package, and infolevel is set
-according to the db_read() infolevel parameter (it is possible using
-db_read() to only read a part of the package datas).
+The 'origin' data member indicates whether the package is from a file
+(i.e. -U operations) or from the package cache. In the case of a file, all data
+members available are present in the structure. Packages indicated as being
+from the cache have data members filled on demand. For this reason, the
+alpm_pkg_get_* functions will load the data from the DB as needed.
-Indeed, to reduce database access, all packages data requested by the
-frontend are comming from the cache. As a consequence, the library needs
-to know exactly the level of information about packages it holds, and
-then decide if more data needs to be fetched from the database.
-In file alpm.c, have a look at alpm_pkg_getinfo() function to get an
-overview.
-
-
-[ERRORS] (error.c)
+[Errors]
The library provides a global variable pm_errno.
It aims at being to the library what errno is for C system calls.
Almost all public library functions are returning an integer value: 0
-indicating success, whereas -1 would indicate a failure.
+indicating success, -1 indicating a failure.
If -1 is returned, the variable pm_errno is set to a meaningful value
-(not always yet, but it should improve ;).
Wise frontends should always care for these returned values.
Note: the helper function alpm_strerror() can also be used to translate
the error code into a more friendly sentence.
-[LIST] (see list.c, and especially list wrappers in alpm.c)
+[List - alpm_list_t]
+The alpm_list_t structure is a doubly-linked list for use with the libalpm
+routines. This type is provided publicly so that frontends are free to use it
+if they have no native list type (C++, glib, python, etc all have list types).
+See the proper man pages for alpm_list_t references.
-It is a double chained list structure, use only for the internal needs
-of the library.
-A frontend should be free to use its own data structures to manipulate
-packages.
-For instance, consider a graphical frontend using the gtk toolkit (and
-as a consequence the glib library). The frontend will make use of the
-glib chained lists or trees.
-As a consequence, the library only provides a simple and very small
-interface to retrieve pointers to its internal data (see functions
-alpm_list_first(), alpm_list_next() and alpm_list_getdata()), giving to
-the frontend the responsibility to copy and store the data retrieved
-from the library in its own data structures.
PACMAN frontend overview & internals
@@ -189,7 +167,7 @@ PACMAN frontend overview & internals
Here are some words about the frontend responsibilities.
The library can operate only a small set of well defined operations and
-dumy operations.
+dummy operations.
High level features are left to the frontend ;)
@@ -212,7 +190,7 @@ remove.c and sync.c).
[CONFIGURATION] (see conf.c)
The frontend is using a configuration file, usually "/etc/pacman.conf".
-Part of these options are only usefull for the frontend only (mainly,
+Part of these options are only useful for the frontend only (mainly,
the download stuffs, and some options like HOLDPKG).
The rest is used to configure the library.
@@ -224,28 +202,8 @@ Nothing new here, excepted some reorganization.
The file pacman.c has been divided into several smaller files, namely
add.c, remove.c, sync.c and query.c, to hold the big parts: pacman_add,
pacman_remove, pacman_sync.
-These 3 functions have been splitted too to ease the code reading.
-
-
-[DONWLOAD] (see download.c)
-
-The library is not providing download facilities. As a consequence, it
-is up the the frontend to retrieve packages from Arch Linux servers.
-To do so, pacman is linked against an improved version of libftp
-supporting both http and ftp donwloads.
-As a consequence, the frontend is repsonsible for the directory
-/var/cache/pacman/pkgs.
-One can consider that this cache is a facility provided by pacman.
-
-Note: other frontends have to download packages by themselves too,
-although the cache directory can be shared by several frontends.
-
-
-[LIST] (see list.c)
-Single chained list.
-A minimalistic chained list implementation to store options from the
-configuration file, and targets passed to pacman on the command line.
+These 3 functions have been split to ease the code reading.
LIMITATIONS/BEHAVIOR CHANGES COMPARED TO PACMAN 2.9