Simplify, do not install examples or info manual, and change license3.1.7

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 0 insertions, 1197 deletions

diff --git a/src/bus.c b/src/bus.c
deleted file mode 100644
index e9dd789..0000000
--- a/src/bus.c
+++ /dev/null
@@ -1,1197 +0,0 @@
-/**
- * MIT/X Consortium License
- * 
- * Copyright © 2015  Mattias Andrée <maandree@member.fsf.org>
- * 
- * Permission is hereby granted, free of charge, to any person obtaining a
- * copy of this software and associated documentation files (the "Software"),
- * to deal in the Software without restriction, including without limitation
- * the rights to use, copy, modify, merge, publish, distribute, sublicense,
- * and/or sell copies of the Software, and to permit persons to whom the
- * Software is furnished to do so, subject to the following conditions:
- * 
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- * 
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
- * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
- * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
- * DEALINGS IN THE SOFTWARE.
- */
-#define _XOPEN_SOURCE 700
-#define _GNU_SOURCE
-#include "bus.h"
-
-#include <stdlib.h>
-#include <stdio.h>
-#include <time.h>
-#include <errno.h>
-#include <string.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <time.h>
-
-#include <sys/ipc.h>
-#include <sys/sem.h>
-#include <sys/shm.h>
-
-
-
-#ifdef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_EVEN_HARDER
-# ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-#  define BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-# endif
-#endif
-#ifdef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-# ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-#  define BUS_SEMAPHORES_ARE_SYNCHRONOUS
-# endif
-#endif
-
-
-
-/**
- * Semaphore used to signal `bus_write` that `bus_read` is ready
- */
-#define S  0
-
-/**
- * Semaphore for making `bus_write` wait while `bus_read` is reseting `S`
- */
-#define W  1
-
-/**
- * Binary semaphore for making `bus_write` exclusively locked
- */
-#define X  2
-
-/**
- * Semaphore used to cue `bus_read` that it may read the shared memory
- */
-#define Q  3
-
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_EVEN_HARDER
-/**
- * Semaphore used to notify `bus_read` that it may restore `S`
- */
-#define N  4
-
-/**
- * The number of semaphores in the semaphore array
- */
-#define BUS_SEMAPHORES  5
-#else
-#define BUS_SEMAPHORES  4
-#endif
-
-/**
- * The default permission mits of the bus
- */
-#define DEFAULT_MODE  0600
-
-
-
-/**
- * Decrease the value of a semaphore by 1
- * 
- * @param   bus:const bus_t *  The bus
- * @param   semaphore:int      The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int          `SEM_UNDO` if the action should be undone when the program exits,
- *                             `IPC_NOWAIT` if the action should fail if it would block
- * @return  :int               0 on success, -1 on error
- */
-#define acquire_semaphore(bus, semaphore, flags) \
-	semaphore_op(bus, semaphore, -1, flags)
-
-/**
- * Increase the value of a semaphore by 1
- * 
- * @param   bus:const bus_t *  The bus
- * @param   semaphore:int      The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int          `SEM_UNDO` if the action should be undone when the program exits
- * @return  :int               0 on success, -1 on error
- */
-#define release_semaphore(bus, semaphore, flags) \
-	semaphore_op(bus, semaphore, +1, flags)
-
-/**
- * Wait for the value of a semaphore to become 0
- * 
- * @param   bus:const bus_t *  The bus
- * @param   semaphore:int      The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int          `IPC_NOWAIT` if the action should fail if it would block
- * @return  :int               0 on success, -1 on error
- */
-#define zero_semaphore(bus, semaphore, flags) \
-	semaphore_op(bus, semaphore, 0, flags)
-
-/**
- * Decrease the value of a semaphore by 1
- * 
- * @param   bus:const bus_t *                The bus
- * @param   semaphore:int                    The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int                        `SEM_UNDO` if the action should be undone when the program exits,
- *                                           `IPC_NOWAIT` if the action should fail if it would block
- * @param   timeout:const struct timespec *  The amount of time to wait before failing
- * @return  :int                             0 on success, -1 on error
- */
-#define acquire_semaphore_timed(bus, semaphore, flags, timeout) \
-	semaphore_op_timed(bus, semaphore, -1, flags, timeout)
-
-/**
- * Increase the value of a semaphore by 1
- * 
- * @param   bus:const bus_t *                The bus
- * @param   semaphore:int                    The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int                        `SEM_UNDO` if the action should be undone when the program exits
- * @param   timeout:const struct timespec *  The amount of time to wait before failing
- * @return  :int                             0 on success, -1 on error
- */
-#define release_semaphore_timed(bus, semaphore, flags, timeout) \
-	semaphore_op_timed(bus, semaphore, +1, flags, timeout)
-
-/**
- * Wait for the value of a semaphore to become 0
- * 
- * @param   bus:const bus_t *                The bus
- * @param   semaphore:int                    The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   flags:int                        `IPC_NOWAIT` if the action should fail if it would block
- * @param   timeout:const struct timespec *  The amount of time to wait before failing
- * @return  :int                             0 on success, -1 on error
- */
-#define zero_semaphore_timed(bus, semaphore, flags, timeout) \
-	semaphore_op_timed(bus, semaphore, 0, flags, timeout)
-
-/**
- * Open the semaphore array
- * 
- * @param   bus:const bus_t *  The bus
- * @return  :int               0 on success, -1 on error
- */
-#define open_semaphores(bus) \
-	(((bus)->sem_id = semget((bus)->key_sem, BUS_SEMAPHORES, 0)) == -1 ? -1 : 0)
-
-/**
- * Write a message to the shared memory
- * 
- * @param   bus:const bus_t *  The bus
- * @param   msg:const char *   The message
- * @return  :int               0 on success, -1 on error
- */
-#define write_shared_memory(bus, msg) \
-	(memcpy((bus)->message, msg, (strlen(msg) + 1) * sizeof(char)))
-
-
-/**
- * Set `delta` to the convertion of `timeout` from absolute to relative time,
- * measured in the clock whose ID is specified by `clockid`
- * 
- * @scope  timeout:struct timespec          Output variable for relative time
- * @scope  timeout:const struct timespec *  The absolute time
- * @scope  clockid:clockid_t                The clock time is measured
- */
-#define DELTA \
-	do { \
-		if (absolute_time_to_delta_time(&delta, timeout, clockid) < 0)  goto fail; \
-		else if ((delta.tv_sec < 0) || (delta.tv_nsec < 0))  { errno = EAGAIN; goto fail; } \
-	} while (0)
-
-
-/**
- * If `flags & (bus_flag)`, this macro evalutes to `sys_flag`,
- * otherwise this macro evalutes to 0.
- */
-#define F(bus_flag, sys_flag)  \
-	((flags & (bus_flag)) ? sys_flag : 0)
-
-
-
-/**
- * Statement wrapper that goes to `fail` on failure
- */
-#define t(inst) \
-	if ((inst) == -1)  goto fail
-
-
-
-#ifdef _SEM_SEMUN_UNDEFINED
-union semun {
-	int val;
-	struct semid_ds *buf;
-	unsigned short *array;
-};
-#endif
-
-
-
-/**
- * Create a semaphore array for the bus
- * 
- * @param   bus  Bus information to fill with the key of the created semaphore array
- * @return       0 on success, -1 on error
- */
-static int
-create_semaphores(bus_t *bus)
-{
-	int id = -1, rint, saved_errno;
-	double r;
-	union semun values;
-
-	values.array = NULL;
-
-	/* Create semaphore array. */
-	for (;;) {
-		rint = rand();
-		r = (double)rint;
-		r /= (double)RAND_MAX + 1;
-		r *= (1 << (8 * sizeof(key_t) - 2)) - 1;
-		bus->key_sem = (key_t)r + 1;
-		if (bus->key_sem == IPC_PRIVATE)
-			continue;
-		id = semget(bus->key_sem, BUS_SEMAPHORES, IPC_CREAT | IPC_EXCL | DEFAULT_MODE);
-		if (id != -1)
-			break;
-		if ((errno != EEXIST) && (errno != EINTR))
-			goto fail;
-	}
-
-	/* Initialise the array. */
-	values.array = calloc((size_t)BUS_SEMAPHORES, sizeof(unsigned short));
-	if (!values.array)
-		goto fail;
-	values.array[X] = 1;
-	if (semctl(id, 0, SETALL, values.array) == -1)
-		goto fail;
-	free(values.array);
-	values.array = NULL;
-
-	return 0;
-
-fail:
-	saved_errno = errno;
-	if (id != -1)
-		semctl(id, 0, IPC_RMID);
-	free(values.array);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Create a shared memory for the bus
- * 
- * @param   bus  Bus information to fill with the key of the created shared memory
- * @return       0 on success, -1 on error
- */
-static int
-create_shared_memory(bus_t *bus)
-{
-	int id = -1, rint, saved_errno;
-	double r;
-	struct shmid_ds _info;
-
-	/* Create shared memory. */
-	for (;;) {
-		rint = rand();
-		r = (double)rint;
-		r /= (double)RAND_MAX + 1;
-		r *= (1 << (8 * sizeof(key_t) - 2)) - 1;
-		bus->key_shm = (key_t)r + 1;
-		if (bus->key_shm == IPC_PRIVATE)
-			continue;
-		id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, IPC_CREAT | IPC_EXCL | DEFAULT_MODE);
-		if (id != -1)
-			break;
-		if ((errno != EEXIST) && (errno != EINTR))
-			goto fail;
-	}
-
-	return 0;
-
-fail:
-	saved_errno = errno;
-	if (id != -1)
-		shmctl(id, IPC_RMID, &_info);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Remove the semaphore array for the bus
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-static int
-remove_semaphores(const bus_t *bus)
-{
-	int id = semget(bus->key_sem, BUS_SEMAPHORES, 0);
-	return ((id == -1) || (semctl(id, 0, IPC_RMID) == -1)) ? -1 : 0;
-}
-
-
-/**
- * Remove the shared memory for the bus
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-static int
-remove_shared_memory(const bus_t *bus)
-{
-	struct shmid_ds _info;
-	int id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, 0);
-	return ((id == -1) || (shmctl(id, IPC_RMID, &_info) == -1)) ? -1 : 0;
-}
-
-
-/**
- * Increase or decrease the value of a semaphore, or wait the it to become 0
- * 
- * @param   bus        Bus information
- * @param   semaphore  The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   delta      The adjustment to make to the semaphore's value, 0 to wait for it to become 0
- * @param   flags      `SEM_UNDO` if the action should be undone when the program exits
- * @return             0 on success, -1 on error
- */
-static int
-semaphore_op(const bus_t *bus, int semaphore, int delta, int flags)
-{
-	struct sembuf op;
-	op.sem_num = (unsigned short)semaphore;
-	op.sem_op = (short)delta;
-	op.sem_flg = (short)flags;
-	return semop(bus->sem_id, &op, (size_t)1);
-}
-
-
-/**
- * Increase or decrease the value of a semaphore, or wait the it to become 0
- * 
- * @param   bus        Bus information
- * @param   semaphore  The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   delta      The adjustment to make to the semaphore's value, 0 to wait for it to become 0
- * @param   flags      `SEM_UNDO` if the action should be undone when the program exits
- * @param   timeout    The amount of time to wait before failing
- * @return             0 on success, -1 on error
- */
-static int
-semaphore_op_timed(const bus_t *bus, int semaphore, int delta, int flags, const struct timespec *timeout)
-{
-	struct sembuf op;
-	op.sem_num = (unsigned short)semaphore;
-	op.sem_op = (short)delta;
-	op.sem_flg = (short)flags;
-	return semtimedop(bus->sem_id, &op, (size_t)1, timeout);
-}
-
-
-/**
- * Set the value of a semaphore
- * 
- * @param   bus        Bus information
- * @param   semaphore  The index of the semaphore, `S`, `W`, `X` or `Q`
- * @param   value      The new value of the semaphore
- * @return             0 on success, -1 on error
- */
-static int
-write_semaphore(const bus_t *bus, unsigned semaphore, int value)
-{
-	union semun semval;
-	semval.val = value;
-	return semctl(bus->sem_id, (unsigned short)semaphore, SETVAL, semval);
-}
-
-
-/**
- * Open the shared memory for the bus
- * 
- * @param   bus    Bus information
- * @param   flags  `BUS_RDONLY`, `BUS_WRONLY` or `BUS_RDWR`
- * @return         0 on success, -1 on error
- */
-static int
-open_shared_memory(bus_t *bus, int flags)
-{
-	int id;
-	void *address;
-	t(id = shmget(bus->key_shm, (size_t)BUS_MEMORY_SIZE, 0));
-	address = shmat(id, NULL, (flags & BUS_RDONLY) ? SHM_RDONLY : 0);
-	if ((address == (void *)-1) || !address)
-		goto fail;
-	bus->message = (char *)address;
-	return 0;
-fail:
-	return -1;
-}
-
-
-/**
- * Close the shared memory for the bus
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-static int
-close_shared_memory(bus_t *bus)
-{
-	t(shmdt(bus->message));
-	bus->message = NULL;
-	return 0;
-fail:
-	return -1;
-}
-
-
-/**
- * Get a random ASCII letter or digit
- * 
- * @return  A random ASCII letter or digit
- */
-static char
-randomchar(void)
-{
-	int rint = rand();
-	double r = (double)rint;
-	r /= (double)RAND_MAX + 1;
-	r *= 10 + 26 + 26;
-	return "0123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM"[(int)r];
-}
-
-
-/**
- * Basically, this is `mkdir -p -m $mode $pathname`
- * 
- * @param   pathname  The pathname of the directory to create if missing
- * @param   mode      The permission bits of any created directory
- * @return            0 on sucess, -1 on error
- */
-static int
-mkdirs(char *pathname, mode_t mode)
-{
-	size_t i, n = strlen(pathname);
-	char c;
-	for (i = 0; i < n; i++)
-		if (pathname[i] != '/')
-			break;
-	for (; i < n; i++) {
-		if (pathname[i] == '/') {
-			c = pathname[i];
-			if (access(pathname, F_OK))
-				if (mkdir(pathname, mode) < 0)
-					return -1;
-			pathname[i] = c;
-			break;
-		}
-	}
-	if (access(pathname, F_OK))
-		if (mkdir(pathname, mode) < 0)
-			return -1;
-	return 0;
-}
-
-
-/**
- * Convert an absolute time to a relative time
- * 
- * @param   delta     Output parameter for the relative time
- * @param   absolute  The absolute time
- * @param   clockid   The ID of the clock the time is measured in
- * @return            0 on success, -1 on error
- */
-static int
-absolute_time_to_delta_time(struct timespec *delta, const struct timespec *absolute, clockid_t clockid)
-{
-	if (clock_gettime(clockid, delta) < 0)
-		return -1;
-
-	delta->tv_sec  = absolute->tv_sec  - delta->tv_sec;
-	delta->tv_nsec = absolute->tv_nsec - delta->tv_nsec;
-
-	if (delta->tv_nsec < 0L) {
-		delta->tv_nsec += 1000000000L;
-		delta->tv_sec -= 1;
-	}
-	if (delta->tv_nsec >= 1000000000L) {
-		delta->tv_nsec -= 1000000000L;
-		delta->tv_sec += 1;
-	}
-
-	return 0;
-}
-
-
-
-/**
- * Create a new bus
- * 
- * @param   file      The pathname of the bus, `NULL` to create a random one
- * @param   flags     `BUS_EXCL` (if `file` is not `NULL`) to fail if the file
- *                    already exists, otherwise if the file exists, nothing
- *                    will happen;
- *                    `BUS_INTR` to fail if interrupted
- * @param   out_file  Output parameter for the pathname of the bus
- * @return            0 on success, -1 on error
- */
-int
-bus_create(const char *restrict file, int flags, char **restrict out_file)
-{
-	int fd = -1, saved_errno;
-	bus_t bus;
-	char buf[1 + 2 * (3 * sizeof(ssize_t) + 2)];
-	size_t ptr, len;
-	ssize_t wrote;
-	char *genfile = NULL;
-	const char *env;
-
-	if (out_file)
-		*out_file = NULL;
-
-	bus.sem_id = -1;
-	bus.key_sem = -1;
-	bus.key_shm = -1;
-	bus.message = NULL;
-	bus.first_poll = 0;
-
-	srand((unsigned int)time(NULL) + (unsigned int)rand());
-
-	if (file) {
-		fd = open(file, O_WRONLY | O_CREAT | O_EXCL, DEFAULT_MODE);
-		if (fd == -1) {
-			if ((errno != EEXIST) || (flags & BUS_EXCL))
-				return -1;
-			goto done;
-		}
-	} else {
-		env = getenv("XDG_RUNTIME_DIR");
-		if (!env || !*env)
-			env = "/run";
-		genfile = malloc((strlen(env) + 6 + 7 + 30) * sizeof(char));
-		if (!genfile)
-			goto fail;
-		if (out_file)
-			*out_file = genfile;
-		sprintf(genfile, "%s/bus", env);
-		t(mkdirs(genfile, 0755));
-		sprintf(genfile, "%s/bus/random.", env);
-		len = strlen(genfile);
-		genfile[len + 30] = '\0';
-	retry:
-		for (ptr = 0; ptr < 30; ptr++)
-			genfile[len + ptr] = randomchar();
-		fd = open(genfile, O_WRONLY | O_CREAT | O_EXCL, DEFAULT_MODE);
-		if (fd == -1) {
-			if (errno == EEXIST)
-				goto retry;
-			return -1;
-		}
-	}
-
-	t(create_semaphores(&bus));
-	t(create_shared_memory(&bus));
-
-	sprintf(buf, "%zi\n%zi\n", (ssize_t)(bus.key_sem), (ssize_t)(bus.key_shm));
-	for (len = strlen(buf), ptr = 0; ptr < len;) {
-		wrote = write(fd, buf + ptr, len - ptr);
-		if (wrote < 0) {
-			if ((errno != EINTR) || (flags & BUS_INTR))
-				goto fail;
-		} else {
-			ptr += (size_t)wrote;
-		}
-	}
-	close(fd);
-
-done:
-	if (out_file && !*out_file) {
-		len = strlen(file) + 1;
-		*out_file = malloc(len * sizeof(char));
-		memcpy(*out_file, file, len * sizeof(char));
-	} else if (!out_file) {
-		free(genfile);
-	}
-	return 0;
-
-fail:
-	saved_errno = errno;
-	if (bus.key_sem)
-		remove_semaphores(&bus);
-	if (bus.key_shm)
-		remove_shared_memory(&bus);
-	if (fd == -1)
-		close(fd);
-	if (out_file)
-		*out_file = NULL;
-	free(genfile);
-	unlink(file);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Remove a bus
- * 
- * @param   file  The pathname of the bus
- * @return        0 on success, -1 on error
- */
-int
-bus_unlink(const char *file)
-{
-	int r = 0, saved_errno = 0;
-	bus_t bus;
-	t(bus_open(&bus, file, -1));
-
-	r |= remove_semaphores(&bus);
-	if (r && !saved_errno)
-		saved_errno = errno;
-
-	r |= remove_shared_memory(&bus);
-	if (r && !saved_errno)
-		saved_errno = errno;
-
-	r |= unlink(file);
-	if (r && !saved_errno)
-		saved_errno = errno;
-
-	errno = saved_errno;
-	return r;
-fail:
-	return -1;
-}
-
-
-/**
- * Open an existing bus
- * 
- * @param   bus    Bus information to fill
- * @param   file   The filename of the bus
- * @param   flags  `BUS_RDONLY`, `BUS_WRONLY` or `BUS_RDWR`
- *                 any negative value is used internally
- *                 for telling the function to not actually
- *                 opening the bus, but just to parse the file
- * @return         0 on success, -1 on error
- */
-int
-bus_open(bus_t *restrict bus, const char *restrict file, int flags)
-{
-	int saved_errno;
-	char *line = NULL;
-	size_t len = 0;
-	FILE *f;
-
-	bus->sem_id = -1;
-	bus->key_sem = -1;
-	bus->key_shm = -1;
-	bus->message = NULL;
-
-	f = fopen(file, "r");
-
-	t(getline(&line, &len, f));
-	t(bus->key_sem = (key_t)atoll(line));
-	free(line), line = NULL, len = 0;
-
-	t(getline(&line, &len, f));
-	t(bus->key_shm = (key_t)atoll(line));
-	free(line), line = NULL;
-
-	fclose(f);
-
-	if (flags >= 0) {
-		t(open_semaphores(bus));
-		t(open_shared_memory(bus, flags));
-	}
-	return 0;
-fail:
-	saved_errno = errno;
-	free(line);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Close a bus
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-int
-bus_close(bus_t *bus)
-{
-	bus->sem_id = -1;
-	if (bus->message)
-		t(close_shared_memory(bus));
-	bus->message = NULL;
-	return 0;
-
-fail:
-	return -1;
-}
-
-
-/**
- * Broadcast a message on a bus
- * 
- * @param   bus      Bus information
- * @param   message  The message to write, may not be longer than
- *                   `BUS_MEMORY_SIZE` including the NUL-termination
- * @param   flags    `BUS_NOWAIT` if this function shall fail if
- *                   another process is currently running this
- *                   procedure
- * @return           0 on success, -1 on error
- */
-int
-bus_write(const bus_t *bus, const char *message, int flags)
-{
-	int saved_errno;
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	int state = 0;
-#endif
-	if (acquire_semaphore(bus, X, SEM_UNDO | F(BUS_NOWAIT, IPC_NOWAIT)) == -1)
-		return -1;
-	t(zero_semaphore(bus, W, 0));
-	write_shared_memory(bus, message);
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	t(release_semaphore(bus, N, SEM_UNDO));  state++;
-#endif
-	t(write_semaphore(bus, Q, 0));
-	t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	t(acquire_semaphore(bus, N, SEM_UNDO));  state--;
-#endif
-	t(release_semaphore(bus, X, SEM_UNDO));
-	return 0;
-
-fail:
-	saved_errno = errno;
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	if (state > 0)
-		acquire_semaphore(bus, N, SEM_UNDO);
-#endif
-	release_semaphore(bus, X, SEM_UNDO);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Broadcast a message on a bus
- * 
- * @param   bus      Bus information
- * @param   message  The message to write, may not be longer than
- *                   `BUS_MEMORY_SIZE` including the NUL-termination
- * @param   timeout  The time the operation shall fail with errno set
- *                   to `EAGAIN` if not completed
- * @param   clockid  The ID of the clock the `timeout` is measured with,
- *                   it most be a predictable clock
- * @return           0 on success, -1 on error
- */
-int bus_write_timed(const bus_t *bus, const char *message,
-		    const struct timespec *timeout, clockid_t clockid)
-{
-	int saved_errno;
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	int state = 0;
-#endif
-	struct timespec delta;
-	if (!timeout)
-		return bus_write(bus, message, 0);
-
-	DELTA;
-	if (acquire_semaphore_timed(bus, X, SEM_UNDO, &delta) == -1)
-		return -1;
-	DELTA;
-	t(zero_semaphore_timed(bus, W, 0, &delta));
-	write_shared_memory(bus, message);
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	t(release_semaphore(bus, N, SEM_UNDO));  state++;
-#endif
-	t(write_semaphore(bus, Q, 0));
-	t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	t(acquire_semaphore(bus, N, SEM_UNDO));  state--;
-#endif
-	t(release_semaphore(bus, X, SEM_UNDO));
-	return 0;
-
-fail:
-	saved_errno = errno;
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS
-	if (state > 0)
-		acquire_semaphore(bus, N, SEM_UNDO);
-#endif
-	release_semaphore(bus, X, SEM_UNDO);
-	errno = saved_errno;
-	return -1;
-}
-
-
-/**
- * Listen (in a loop, forever) for new message on a bus
- * 
- * @param   bus        Bus information
- * @param   callback   Function to call when a message is received, the
- *                     input parameters will be the read message and
- *                     `user_data` from `bus_read`'s parameter with the
- *                     same name. The message must have been parsed or
- *                     copied when `callback` returns as it may be over
- *                     overridden after that time. `callback` should
- *                     return either of the the values:
- *                       *  0:  stop listening
- *                       *  1:  continue listening
- *                       * -1:  an error has occurred
- *                     However, the function [`bus_read`] will invoke
- *                     `callback` with `message` set to `NULL`one time
- *                     directly after it has started listening on the
- *                     bus. This is to the the program now it can safely
- *                     continue with any action that requires that the
- *                     programs is listening on the bus.
- * @param   user_data  Parameter passed to `callback`
- * @return             0 on success, -1 on error
- */
-int
-bus_read(const bus_t *restrict bus, int (*callback)(const char *message, void *user_data), void *user_data)
-{
-	int r, state = 0, saved_errno;
-	if (release_semaphore(bus, S, SEM_UNDO) == -1)
-		return -1;
-	t(r = callback(NULL, user_data));
-	if (!r)  goto done;
-	for (;;) {
-		t(release_semaphore(bus, Q, 0));
-		t(zero_semaphore(bus, Q, 0));
-		t(r = callback(bus->message, user_data));
-		if (!r)  goto done;
-		t(release_semaphore(bus, W, SEM_UNDO));  state++;
-		t(acquire_semaphore(bus, S, SEM_UNDO));  state++;
-		t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-		t(zero_semaphore(bus, N, 0));
-#endif
-		t(release_semaphore(bus, S, SEM_UNDO));  state--;
-		t(acquire_semaphore(bus, W, SEM_UNDO));  state--;
-	}
-
-fail:
-	saved_errno = errno;
-	if (state > 1)
-		release_semaphore(bus, S, SEM_UNDO);
-	if (state > 0)
-		acquire_semaphore(bus, W, SEM_UNDO);
-	acquire_semaphore(bus, S, SEM_UNDO);
-	errno = saved_errno;
-	return -1;
-
-done:
-	t(acquire_semaphore(bus, S, SEM_UNDO));
-	return 0;
-}
-
-
-/**
- * Listen (in a loop, forever) for new message on a bus
- * 
- * @param   bus        Bus information
- * @param   callback   Function to call when a message is received, the
- *                     input parameters will be the read message and
- *                     `user_data` from `bus_read`'s parameter with the
- *                     same name. The message must have been parsed or
- *                     copied when `callback` returns as it may be over
- *                     overridden after that time. `callback` should
- *                     return either of the the values:
- *                       *  0:  stop listening
- *                       *  1:  continue listening
- *                       * -1:  an error has occurred
- *                     However, the function [`bus_read`] will invoke
- *                     `callback` with `message` set to `NULL`one time
- *                     directly after it has started listening on the
- *                     bus. This is to the the program now it can safely
- *                     continue with any action that requires that the
- *                     programs is listening on the bus.
- * @param   user_data  Parameter passed to `callback`
- * @param   timeout    The time the operation shall fail with errno set
- *                     to `EAGAIN` if not completed, note that the callback
- *                     function may or may not have been called
- * @param   clockid    The ID of the clock the `timeout` is measured with,
- *                     it most be a predictable clock
- * @return             0 on success, -1 on error
- */
-int bus_read_timed(const bus_t *restrict bus, int (*callback)(const char *message, void *user_data),
-                   void *user_data, const struct timespec *timeout, clockid_t clockid)
-{
-	int r, state = 0, saved_errno;
-	struct timespec delta;
-	if (!timeout)
-		return bus_read(bus, callback, user_data);
-
-	DELTA;
-	if (release_semaphore_timed(bus, S, SEM_UNDO, &delta) == -1)
-		return -1;
-	t(r = callback(NULL, user_data));
-	if (!r)  goto done;
-	for (;;) {
-		DELTA;
-		t(release_semaphore_timed(bus, Q, 0, &delta));
-		DELTA;
-		t(zero_semaphore_timed(bus, Q, 0, &delta));
-		t(r = callback(bus->message, user_data));
-		if (!r)  goto done;
-		t(release_semaphore(bus, W, SEM_UNDO));  state++;
-		t(acquire_semaphore(bus, S, SEM_UNDO));  state++;
-		t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-		t(zero_semaphore(bus, N, 0));
-#endif
-		t(release_semaphore(bus, S, SEM_UNDO));  state--;
-		t(acquire_semaphore(bus, W, SEM_UNDO));  state--;
-	}
-
-fail:
-	saved_errno = errno;
-	if (state > 1)
-		release_semaphore(bus, S, SEM_UNDO);
-	if (state > 0)
-		acquire_semaphore(bus, W, SEM_UNDO);
-	acquire_semaphore(bus, S, SEM_UNDO);
-	errno = saved_errno;
-	return -1;
-
-done:
-	t(acquire_semaphore(bus, S, SEM_UNDO));
-	return 0;
-}
-
-
-/**
- * Announce that the thread is listening on the bus.
- * This is required so the will does not miss any
- * messages due to race conditions. Additionally,
- * not calling this function will cause the bus the
- * misbehave, is `bus_poll` is written to expect
- * this function to have been called.
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-int
-bus_poll_start(bus_t *bus)
-{
-	bus->first_poll = 1;
-	t(release_semaphore(bus, S, SEM_UNDO));
-	t(release_semaphore(bus, Q, 0));
-	return 0;
-
-fail:
-	return -1;
-}
-
-
-/**
- * Announce that the thread has stopped listening on the bus.
- * This is required so that the thread does not cause others
- * to wait indefinitely.
- * 
- * @param   bus  Bus information
- * @return       0 on success, -1 on error
- */
-int
-bus_poll_stop(const bus_t *bus)
-{
-	return acquire_semaphore(bus, S, SEM_UNDO | IPC_NOWAIT);
-}
-
-
-/**
- * Wait for a message to be broadcasted on the bus.
- * The caller should make a copy of the received message,
- * without freeing the original copy, and parse it in a
- * separate thread. When the new thread has started be
- * started, the caller of this function should then
- * either call `bus_poll` again or `bus_poll_stop`.
- * 
- * @param   bus    Bus information
- * @param   flags  `BUS_NOWAIT` if the bus should fail and set `errno` to
- *                 `EAGAIN` if there isn't already a message available on the bus
- * @return         The received message, `NULL` on error
- */
-const char *
-bus_poll(bus_t *bus, int flags)
-{
-	int state = 0, saved_errno;
-	if (!bus->first_poll) {
-		t(release_semaphore(bus, W, SEM_UNDO));  state++;
-		t(acquire_semaphore(bus, S, SEM_UNDO));  state++;
-		t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-		t(zero_semaphore(bus, N, 0));
-#endif
-		t(release_semaphore(bus, S, SEM_UNDO));  state--;
-		t(acquire_semaphore(bus, W, SEM_UNDO));  state--;
-		t(release_semaphore(bus, Q, 0));
-	} else {
-		bus->first_poll = 0;
-	}
-	state--;
-	t(zero_semaphore(bus, Q, F(BUS_NOWAIT, IPC_NOWAIT)));
-	return bus->message;
-
-fail:
-	saved_errno = errno;
-	if (state > 1)
-		release_semaphore(bus, S, SEM_UNDO);
-	if (state > 0)
-		acquire_semaphore(bus, W, SEM_UNDO);
-	if (state < 0)
-		bus->first_poll = 1;
-	errno = saved_errno;
-	return NULL;
-}
-
-
-/**
- * Wait for a message to be broadcasted on the bus.
- * The caller should make a copy of the received message,
- * without freeing the original copy, and parse it in a
- * separate thread. When the new thread has started be
- * started, the caller of this function should then
- * either call `bus_poll_timed` again or `bus_poll_stop`.
- * 
- * @param   bus      Bus information
- * @param   timeout  The time the operation shall fail with errno set
- *                   to `EAGAIN` if not completed
- * @param   clockid  The ID of the clock the `timeout` is measured with,
- *                   it most be a predictable clock
- * @return           The received message, `NULL` on error
- */
-const char *bus_poll_timed(bus_t *bus, const struct timespec *timeout, clockid_t clockid)
-{
-	int state = 0, saved_errno;
-	struct timespec delta;
-	if (!timeout)
-		return bus_poll(bus, 0);
-
-	if (!bus->first_poll) {
-		t(release_semaphore(bus, W, SEM_UNDO));  state++;
-		t(acquire_semaphore(bus, S, SEM_UNDO));  state++;
-		t(zero_semaphore(bus, S, 0));
-#ifndef BUS_SEMAPHORES_ARE_SYNCHRONOUS_ME_HARDER
-		t(zero_semaphore(bus, N, 0));
-#endif
-		t(release_semaphore(bus, S, SEM_UNDO));  state--;
-		t(acquire_semaphore(bus, W, SEM_UNDO));  state--;
-		t(release_semaphore(bus, Q, 0));
-	} else {
-		bus->first_poll = 0;
-	}
-	state--;
-	DELTA;
-	t(zero_semaphore_timed(bus, Q, 0, &delta));
-	return bus->message;
-
-fail:
-	saved_errno = errno;
-	if (state > 1)
-		release_semaphore(bus, S, SEM_UNDO);
-	if (state > 0)
-		acquire_semaphore(bus, W, SEM_UNDO);
-	if (state < 0)
-		bus->first_poll = 1;
-	errno = saved_errno;
-	return NULL;
-}
-
-
-/**
- * Change the ownership of a bus
- * 
- * `stat(2)` can be used of the bus's associated file to get the bus's ownership
- * 
- * @param   file   The pathname of the bus
- * @param   owner  The user ID of the bus's new owner
- * @param   group  The group ID of the bus's new group
- * @return         0 on success, -1 on error
- */
-int
-bus_chown(const char *file, uid_t owner, gid_t group)
-{
-	bus_t bus;
-	struct semid_ds sem_stat;
-	struct shmid_ds shm_stat;
-	int shm_id;
-
-	t(bus_open(&bus, file, -1));
-	t(chown(file, owner, group));
-
-	/* chown sem */
-	t(open_semaphores(&bus));
-	t(semctl(bus.sem_id, 0, IPC_STAT, &sem_stat));
-	sem_stat.sem_perm.uid = owner;
-	sem_stat.sem_perm.gid = group;
-	t(semctl(bus.sem_id, 0, IPC_SET, &sem_stat));
-
-	/* chown shm */
-	t(shm_id = shmget(bus.key_shm, (size_t)BUS_MEMORY_SIZE, 0));
-	t(shmctl(shm_id, IPC_STAT, &shm_stat));
-	shm_stat.shm_perm.uid = owner;
-	shm_stat.shm_perm.gid = group;
-	t(shmctl(shm_id, IPC_SET, &shm_stat));
-
-	return 0;
-fail:
-	return -1;
-}
-
-
-/**
- * Change the permissions for a bus
- * 
- * `stat(2)` can be used of the bus's associated file to get the bus's permissions
- * 
- * @param   file  The pathname of the bus
- * @param   mode  The permissions of the bus, any permission for a user implies
- *                full permissions for that user, except only the owner may
- *                edit the bus's associated file
- * @return        0 on success, -1 on error
- */
-int
-bus_chmod(const char *file, mode_t mode)
-{
-	bus_t bus;
-	mode_t fmode;
-	struct semid_ds sem_stat;
-	struct shmid_ds shm_stat;
-	int shm_id;
-
-	mode = (mode & S_IRWXU) ? (mode | S_IRWXU) : (mode & (mode_t)~S_IRWXU);
-	mode = (mode & S_IRWXG) ? (mode | S_IRWXG) : (mode & (mode_t)~S_IRWXG);
-	mode = (mode & S_IRWXO) ? (mode | S_IRWXO) : (mode & (mode_t)~S_IRWXO);
-	mode &= (S_IWUSR | S_IWGRP | S_IWOTH | S_IRUSR | S_IRGRP | S_IROTH);
-	fmode = mode & (mode_t)~(S_IWGRP | S_IWOTH);
-
-	t(bus_open(&bus, file, -1));
-	t(chmod(file, fmode));
-
-	/* chmod sem */
-	t(open_semaphores(&bus));
-	t(semctl(bus.sem_id, 0, IPC_STAT, &sem_stat));
-	sem_stat.sem_perm.mode = (unsigned short)mode;
-	t(semctl(bus.sem_id, 0, IPC_SET, &sem_stat));
-
-	/* chmod shm */
-	t(shm_id = shmget(bus.key_shm, (size_t)BUS_MEMORY_SIZE, 0));
-	t(shmctl(shm_id, IPC_STAT, &shm_stat));
-	shm_stat.shm_perm.mode = (unsigned short)mode;
-	t(shmctl(shm_id, IPC_SET, &shm_stat));
-
-	return 0;
-fail:
-	return -1;
-}
-