= Standard API =

This document serves as an overview of HelenOS standard user space API implemented in ''HelenOS C library'' and the relation of this API to common standards such as "C Standard Library" (as defined by various ISO C standards, such as C99) and ''C POSIX Library'' standards.

{{{#!box type=note
'''General note:''' The primary aim of ''HelenOS C library'' is not to be 100% compatible with the standards. For both many fundamental reasons (HelenOS is not a unix-like operating system) and practical reasons (our subjective dislike of some aspects of the standards, security issues, etc.) the ''HelenOS C library'' follows the standards very loosely. Many functions are not implemented because lack of current need or simple because lack of manpower and many functions closely resemble their standard-compliant counterparts, but behave very slightly differently. In an increasing number of cases, a part of the legacy standard-compliant interfaces is replaced by HelenOS native ones.
}}}

== Native Interfaces ==

  * [wiki:FilesystemAPITutorial]
  * [wiki:NetworkAPITutorial]
  * [wiki:StringAPI]

== Legacy Interfaces ==

=== dirent.h ===

|| '''Function''' || '''Based on'''         || '''Std Compliant''' ||
|| closedir       || POSIX-1.2001           || mostly              ||
|| opendir        || POSIX-1-2001           || mostly              ||
|| readdir        || POSIX-1.2001           || mostly              ||
|| rewinddir      || POSIX-1.2001           || mostly              ||

=== stdio.h ====

|| '''Function''' || '''Based on'''         || '''Std Compliant''' ||
|| clearerr       || POSIX-1.2001, C89, C99 || mostly              ||
|| fclose         || POSIX-1.2001, C89, C99 || mostly              ||
|| fdopen         || POSIX-1.2001           || mostly              ||
|| feof           || POSIX-1.2001, C89, C99 || mostly              ||
|| ferror         || POSIX-1.2001, C89, C99 || mostly              ||
|| fflush         || POSIX-1.2001, C89, C99 || mostly              ||
|| fgetc          || POSIX-1.2001, C89, C99 || mostly              ||
|| fgets          || POSIX-1.2001, C89, C99 || mostly              ||
|| fileno         || POSIX-1.2001           || mostly              ||
|| fopen          || POSIX-1.2001, C89, C99 || mostly              ||
|| fputc          || POSIX-1.2001, C89, C99 || mostly              ||
|| fputs          || POSIX-1.2001, C89, C99 || mostly              ||
|| fprintf        || POSIX-1.2001, C89, C99 || mostly              ||
|| fread          || POSIX-1.2001, C89, C99 || mostly              ||
|| freopen        || POSIX-1.2001, C89, C99 || mostly              ||
|| fseek          || POSIX-1.2001, C89, C99 || mostly              ||
|| ftell          || POSIX-1.2001, C89, C99 || mostly              ||
|| fwrite         || POSIX-1.2001, C89, C99 || mostly              ||
|| rewind         || POSIX-1.2001, C89, C99 || mostly              ||
|| setvbuf        || C89, C99               || mostly              ||
|| setbuf         || C89, C99               || mostly              ||
|| vfprintf       || POSIX-1.2001, C89, C99 || mostly              ||
|| ungetc         || POSIX-1.2001, C89, C99 || mostly              ||

=== unistd.h ===

Implemented functions (items marked wit D have been removed in the development version):

|| '''Function''' || '''Based on'''         || '''Std Compliant''' || '''Note'''                                          ||
|| sleep          || POSIX.1-2001           || mostly              ||                                                     ||
|| usleep         || POSIX.1-2001           || mostly              || obsoleted and replaced by nanosleep in POSIX.1-2008 ||