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/**
* mds — A micro-display server
* Copyright © 2014 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 MDS_LIBMDSSERVER_MACROS_H
#define MDS_LIBMDSSERVER_MACROS_H
/*
#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#include <string.h>
*/
/**
* Wrapper for `snprintf` that allows you to forget about the buffer size
*
* @param buffer:char[] The buffer, must be of the type `char[]` and not `char*`
* @param format:char* The format
* @param ... The arguments
*/
#define xsnprintf(buffer, format, ...) \
snprintf(buffer, sizeof(buffer) / sizeof(char), format, __VA_ARGS__)
/**
* Wrapper for `fprintf` that prints to `stderr` with
* the program name prefixed and new line suffixed
*
* @param format:char* The format
*/
#define eprint(format) \
fprintf(stderr, "%s: " format "\n", *argv)
/**
* Wrapper for `fprintf` that prints to `stderr` with
* the program name prefixed and new line suffixed
*
* @param format:char* The format
* @param ... The arguments
*/
#define eprintf(format, ...) \
fprintf(stderr, "%s: " format "\n", *argv, __VA_ARGS__)
/**
* Wrapper for `pthread_mutex_lock` and `pthread_mutex_unlock`
*
* @param mutex:pthread_mutex_t The mutex
* @param instructions The instructions to run while the mutex is locked
*/
#define with_mutex(mutex, instructions) \
pthread_mutex_lock(&(mutex)); \
instructions \
pthread_mutex_unlock(&(mutex))
/**
* Return the maximum value of two values
*
* @param a One of the values
* @param b The other one of the values
* @return The maximum value
*/
#define max(a, b) \
(a < b ? b : a)
/**
* Return the minimum value of two values
*
* @param a One of the values
* @param b The other one of the values
* @return The minimum value
*/
#define min(a, b) \
(a < b ? a : b)
/**
* Cast a buffer to another type and get the slot for an element
*
* @param buffer:char* The buffer
* @param type The data type of the elements for the data type to cast the buffer to
* @param index:size_t The index of the element to address
* @return [type] A slot that can be set or get
*/
#define buf_cast(buffer, type, index) \
((type*)(buffer))[index]
/**
* Set the value of an element a buffer that is being cast
*
* @param buffer:char* The buffer
* @param type The data type of the elements for the data type to cast the buffer to
* @param index:size_t The index of the element to address
* @param variable:type The new value of the element
* @return :variable The new value of the element
*/
#define buf_set(buffer, type, index, variable) \
((type*)(buffer))[index] = (variable)
/**
* Get the value of an element a buffer that is being cast
*
* @param buffer:char* The buffer
* @param type The data type of the elements for the data type to cast the buffer to
* @param index:size_t The index of the element to address
* @param variable:type Slot to set with the value of the element
* @return :variable The value of the element
*/
#define buf_get(buffer, type, index, variable) \
variable = ((type*)(buffer))[index]
/**
* Increase the pointer of a buffer
*
* @param buffer:char* The buffer
* @param type A data type
* @param count The number elements of the data type `type` to increase the pointer with
*/
#define buf_next(buffer, type, count) \
buffer += (count) * sizeof(type) / sizeof(char)
/**
* Decrease the pointer of a buffer
*
* @param buffer:char* The buffer
* @param type A data type
* @param count The number elements of the data type `type` to decrease the pointer with
*/
#define buf_prev(buffer, type, count) \
buffer -= (count) * sizeof(type) / sizeof(char)
/**
* This macro combines `buf_set` with `buf_next`, it sets
* element zero and increase the pointer by one element
*
* @param buffer:char* The buffer
* @param type The data type of the elements for the data type to cast the buffer to
* @param variable:type The new value of the element
* @return :variable The new value of the element
*/
#define buf_set_next(buffer, type, variable) \
buf_set(buffer, type, 0, variable); \
buf_next(buffer, type, 1)
/**
* This macro combines `buf_set` with `buf_next`, it sets
* element zero and increase the pointer by one element
*
* @param buffer:char* The buffer
* @param type The data type of the elements for the data type to cast the buffer to
* @param variable:type Slot to set with the value of the element
* @return :variable The value of the element
*/
#define buf_get_next(buffer, type, variable) \
buf_get(buffer, type, 0, variable); \
buf_next(buffer, type, 1)
/**
* Check whether two strings are equal
*
* @param a:char* One of the strings
* @param b:char* The other of the strings
* @return :int Whether the strings are equal
*/
#define strequals(a, b) \
(strcmp(a, b) == 0)
/**
* Check whether a string starts with another string
*
* @param haystack:char* The string to inspect
* @param needle:char* The string `haystack` should start with
* @return :int Whether `haystack` starts with `needle`
*/
#define startswith(haystack, needle) \
(strstr(haystack, needle) == haystack)
/**
* Set effective user and the effective group to the
* real user and the real group, respectively. If the
* group cannot be set, the user till not be set either.
*
* @return :int Non-zero on error
*/
#define drop_privileges() \
((getegid() == getgid() ? 0 : setegid(getgid())) || \
(geteuid() == getuid() ? 0 : seteuid(getuid())))
#endif
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