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| -rw-r--r-- | include/unistd.h | 105 |
1 files changed, 105 insertions, 0 deletions
diff --git a/include/unistd.h b/include/unistd.h new file mode 100644 index 0000000..cbc6b2d --- /dev/null +++ b/include/unistd.h @@ -0,0 +1,105 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef _UNISTD_H +#define _UNISTD_H +#include <slibc/version.h> + + +#include <slibc/features.h> + + + +#define __NEED_ptrdiff_t +#include <bits/types.h> + + +/** + * Set the high end of the calling process's + * data segment. + * + * The high end is defined as the last byte + * in the segment plus 1. + * + * Using `brk` is highly discouraged. `malloc`, + * `calloc` and `free`, and its related functions, + * fall be used instead as they are much more + * conformable. Use of `brk` can couse errors + * when using `malloc`, `free`, &c. Thus, `brk` + * shall (bascially) only be used if you are + * writting an alterantive malloc-implementation. + * + * `brk` was marked LEGACY in SUSv2, and it + * was removed from the POSIX standard in revision + * POSIX.1-2001. It is however fundamental in + * implementing a fast `malloc`-implementation. + * + * @param address The process's new high end of its data segment. + * If lower than the current low end, nothing will + * happen and the function will return with a success + * status. + * @return Zero on succes, -1 on error. On error, `errno` + * is set to indicate the error. + * + * @throws ENOMEM The process can allocate the requested amount + * of memory. Either the process store limit would + * have been exceeded, RAM and swap memory would + * have been exhausted, or the request would cause + * the data segment to overlap another segment. + */ +int brk(void*) /* TODO implement brk */ + __GCC_ONLY(__attribute__((warn_unused_result))); + +/** + * Set and get the current high end of the calling + * process's data segment. + * + * There is some documents that state that the new, + * rather than the previous, high end is returned. + * Additionally, some documentions do not document + * possible failure. Thus only `sbrk(0)` is guaranteed + * to be portable. The return type differs between + * implementations; common return types are `int`, + * `ssize_t`, `ptrdiff_t`, `ptrdiff_t`, `intptr_t`, + * and `void*`. Note that `int` is + * microarchitecture-portable. + * + * `sbrk` was marked LEGACY in SUSv2, and it + * was removed from the POSIX standard in revision + * POSIX.1-2001. It is however fundamental in + * implementing a fast `malloc`-implementation. + * + * @param delta The incremant of the size of the data segment, + * zero means that the high end shall not be moved + * (thus the current high end is returned,) a + * positive value will cause the segment to grow, + * a negative value will cause the segment to shrink. + * @return The previous high end. `(void*)-1` is returned on error. + * + * @throws ENOMEM The process can allocate the requested amount + * of memory. Either the process store limit would + * have been exceeded, RAM and swap memory would + * have been exhausted, or the request would cause + * the data segment to overlap another segment. + */ +void* sbrk(ptrdiff_t) /* TODO implement sbrk */ + __GCC_ONLY(__attribute__((warn_unused_result))); + + + +#endif + |