Everest Linux

1 - Introduction

libglacier is the backend library for Glacier. It simplifies many functions and allows users to extend Glacier's functionality.

2 - Installation

In order to install libglacier, the following libraries must be installed:

libcolor
libconfig

Once these libraries are installed, clone the libglacier repository:

$ git clone https://git.everestlinux.org/EverestLinux/libglacier

Enter the repository and edit the make configuration file:

$ cd libglacier

$ ${EDITOR} config.mk

CAUTION

Before proceeding with ANY other step, make sure you define PREFIX in config.mk.

By default this variable is not defined. Results will be unexpected if the library is compiled without PREFIX defined.

Build the library:

$ make lib

NOTE

libglacier is provided as a static library only.

If you wish to compile a shared library instead, you must edit the Makefile

3 - Using libglacier in a program

To use libglacier in a program, include the relevant header files:

CODE: Including libglacier header files

#include <glacier_config.h>

#include <glacier_data.h>

#include <glacier_log.h>

#include <glacier_pkgops.h>

#include <glacier_runtime.h>

To compile libglacier into your program, add the following compile flag:

-lconfig

4 - Configuration Functions

libglacier supplies functions for parsing and getting values from libconfig-syntax configuration files. While only three are present, more are planned for the future.

4.1 init_config

init_config initializes the libconfig library, and allows configuration files to be parsed.

No parameters are accepted by init_config.

CODE: init_config used in a program

#include <glacier_config.h>

int

main()

{

init_config();

}

init_config returns 0 on success, and 1 on failure.

4.2 die_config

die_config unloads the libconfig library. You should always run this when you're finished with libconfig in order to free memory.

No parameters are accepted by die_config.

CODE: die_config used in a program

#include <glacier_config.h>

int

main()

{

die_config();

}

die_config returns 0 on success, and 1 on failure.

4.3 load_all_from_config

load_all_from_config loads all expected settings from /etc/glacier.cfg.

No parameters are accepted by load_all_from_config.

CODE: load_all_from_config used in a program

#include <glacier_config.h>

int

main()

{

init_config();

}

5 - Data structure functions

Since Glacier is a package manager, libglacier provides functions for creating and handling dependency trees.

5.1 create_node

create_node creates a node for a dependency tree.

create_node accepts the following parameters:

char *data (the name of the node to create)

CODE: create_node used in a program

#include <glacier_data.h>

int

main()

{

struct node package = create_node("Package");

}

5.2 add_child

add_child adds a specified child node to a parent node.

add_child accepts the following parameters:

struct node *parent (the parent node which the child will be added to)
struct node *child (the child node which will be added to the parent node)

CODE: add_child used in a program

#include <glacier_data.h>

int

main()

{

struct node pack = create_node("pack");

struct node dep1 = create_node("dep1");

add_child(pack, dep1);

}

5.3 print_tree

print_tree prints a dependency tree specified at its root node.

print_tree accepts the following parameters:

struct node *root (the root node of the tree to print
int level (the number of levels to descend)

CODE: print_tree used in a program

#include <glacier_data.h>

int

main()

{

struct node pack = create_node("pack");

struct node dep1 = create_node("dep1");

add_child(pack, dep1);

print_tree(pack, 0);

}

6 - Logging Functions

The logging functions libglacier provides are designed to allow a uniform style of output.

The following logging functions are included:

infolog
warnlog
errlog
successlog

These four functions accept the following parameters:

char MSG (the message to output

NOTE:

Logging functions do not require a newline character ('\n'), they will automatically place one after the message.

CODE: Logging functions used in a program

#include <glacier_log.h>

int

main()

{

infolog("This is an info message");

warnlog("This is a warning message");

errlog("This is an error message");

successlog("This is a success message");

}

7 - Package Operation Functions

This section describes the numerous functions related to operations on packages.

7.1 mkworkspace

mkworkspace creates a Glacier workspace at /tmp/glacier-workspace.

mkworkspace accepts no parameters.

mkworkspace returns the following values:

0 on success
2 on library error

CODE: mkworkspace used in a program

#include <glacier_pkgops.h>

int

main()

{

mkworkspace();

}

7.2 prepare_pkg

prepare_pkg copies a package archive from the local package database to the workspace, and untars it.

prepare_pkg accepts the following parameters:

char PACKAGE[] (the package file to prepare)

prepare_pkg returns the following values:

0 on success
1 on package does not exist, or error untarring

CODE: prepare_pkg used in a program

#include <glacier_pkgops.h>

int

main()

{

prepare_pkg("/glacier/localdb/epkgs-x86_64-musl/foo.tar");

}

CAUTION:

This example presented is not the best. Instead of manually specifying the package directory, you should be calling the system profile.

7.3 run_make_task

run_make_task runs a specified make task in a package's current working directory.

run_make_task accepts the following parameters:

char TASK[] (the make task to run

run_make_task returns the following values:

0 on success
1 on failure

CODE: run_make_task used in a program

#include <glacier_pkgops.h>

int

main()

{

prepare_pkg("/glacier/localdb/epkgs-x86_64-musl/foo.tar");

run_make_task("installpkg");

}

8 - Runtime Functions

The functions described here are used for various runtime checks.

8.1 runtime_exists

runtime_exists checks if necessary runtime files exist and are in their correct locations.

runtime_exists accepts no parameters.

runtime_exists returns no values.

CODE: runtime_exists used in a program

#include <glacier_runtime.h>

int

main()

{

runtime_exists();

}

8.2