WIP: add a stub IRC daemon named `kike'

As it is going to share a great lot of functionality with ZyklonB, I have
decided to extract the common parts into `common.c' and make the two subprojects
include this file.

The Single Compile Unit concept has proven valuable (sub-second compile times,
dead code warnings, almost no need for function declarations, whole-program
optimizations), and the sources aren't that long so far anyway.

I am probably going to add CMake support later but so far it's not a priority.
This project is meant to be portable and freely relocatable (ie. no hardcoded
paths if I can avoid it).

1 files changed, 68 insertions, 1605 deletions

diff --git a/src/zyklonb.c b/src/zyklonb.c
index a182d17..69c41c1 100644
--- a/src/zyklonb.c
+++ b/src/zyklonb.c
@@ -18,1464 +18,10 @@
  *
  */
 
-#define _POSIX_C_SOURCE 199309L
-#define _XOPEN_SOURCE 500
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <errno.h>
-#include <string.h>
-#include <stdarg.h>
-#include <stdint.h>
-#include <stdbool.h>
-#include <ctype.h>
-
-#include <unistd.h>
-#include <sys/wait.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <poll.h>
-#include <signal.h>
-#include <strings.h>
-#include <regex.h>
-#include <libgen.h>
-
-#include <sys/socket.h>
-#include <netinet/in.h>
-#include <netdb.h>
-
-#ifndef NI_MAXHOST
-#define NI_MAXHOST 1025
-#endif // ! NI_MAXHOST
-
-#include <getopt.h>
-#include <openssl/ssl.h>
-#include <openssl/err.h>
-#include "siphash.h"
-
 #define PROGRAM_NAME "ZyklonB"
 #define PROGRAM_VERSION "alpha"
 
-extern char **environ;
-
-#if defined __GNUC__
-#define ATTRIBUTE_PRINTF(x, y) __attribute__ ((format (printf, x, y)))
-#else // ! __GNUC__
-#define ATTRIBUTE_PRINTF(x, y)
-#endif // ! __GNUC__
-
-#if defined __GNUC__ && __GNUC__ >= 4
-#define ATTRIBUTE_SENTINEL __attribute__ ((sentinel))
-#else // ! __GNUC__ || __GNUC__ < 4
-#define ATTRIBUTE_SENTINEL
-#endif // ! __GNUC__ || __GNUC__ < 4
-
-#define N_ELEMENTS(a) (sizeof (a) / sizeof ((a)[0]))
-
-#define BLOCK_START  do {
-#define BLOCK_END    } while (0)
-
-// --- Utilities ---------------------------------------------------------------
-
-static void
-print_message (FILE *stream, const char *type, const char *fmt, ...)
-	ATTRIBUTE_PRINTF (3, 4);
-
-static void
-print_message (FILE *stream, const char *type, const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start (ap, fmt);
-	fprintf (stream, "%s ", type);
-	vfprintf (stream, fmt, ap);
-	fputs ("\n", stream);
-	va_end (ap);
-}
-
-#define print_fatal(...)    print_message (stderr, "fatal:",   __VA_ARGS__)
-#define print_error(...)    print_message (stderr, "error:",   __VA_ARGS__)
-#define print_warning(...)  print_message (stderr, "warning:", __VA_ARGS__)
-#define print_status(...)   print_message (stdout, "--",       __VA_ARGS__)
-
-// --- Debugging and assertions ------------------------------------------------
-
-// We should check everything that may possibly fail with at least a soft
-// assertion, so that any causes for problems don't slip us by silently.
-//
-// `g_soft_asserts_are_deadly' may be useful while running inside a debugger.
-
-static bool g_debug_mode;               ///< Debug messages are printed
-static bool g_soft_asserts_are_deadly;  ///< soft_assert() aborts as well
-
-#define print_debug(...)                                                       \
-	BLOCK_START                                                                \
-		if (g_debug_mode)                                                      \
-			print_message (stderr, "debug:", __VA_ARGS__);                     \
-	BLOCK_END
-
-static void
-assertion_failure_handler (bool is_fatal, const char *file, int line,
-	const char *function, const char *condition)
-{
-	if (is_fatal)
-	{
-		print_fatal ("assertion failed [%s:%d in function %s]: %s",
-			file, line, function, condition);
-		abort ();
-	}
-	else
-		print_debug ("assertion failed [%s:%d in function %s]: %s",
-			file, line, function, condition);
-}
-
-#define soft_assert(condition)                                                 \
-	((condition) ? true :                                                      \
-		(assertion_failure_handler (g_soft_asserts_are_deadly,                 \
-		__FILE__, __LINE__, __func__, #condition), false))
-
-#define hard_assert(condition)                                                 \
-	((condition) ? (void) 0 :                                                  \
-		assertion_failure_handler (true,                                       \
-		__FILE__, __LINE__, __func__, #condition))
-
-// --- Safe memory management --------------------------------------------------
-
-// When a memory allocation fails and we need the memory, we're usually pretty
-// much fucked.  Use the non-prefixed versions when there's a legitimate
-// worry that an unrealistic amount of memory may be requested for allocation.
-
-// XXX: it's not a good idea to use print_message() as it may want to allocate
-//   further memory for printf() and the output streams.  That may fail.
-
-static void *
-xmalloc (size_t n)
-{
-	void *p = malloc (n);
-	if (!p)
-	{
-		print_fatal ("malloc: %s", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-	return p;
-}
-
-static void *
-xcalloc (size_t n, size_t m)
-{
-	void *p = calloc (n, m);
-	if (!p && n && m)
-	{
-		print_fatal ("calloc: %s", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-	return p;
-}
-
-static void *
-xrealloc (void *o, size_t n)
-{
-	void *p = realloc (o, n);
-	if (!p && n)
-	{
-		print_fatal ("realloc: %s", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-	return p;
-}
-
-static void *
-xreallocarray (void *o, size_t n, size_t m)
-{
-	if (m && n > SIZE_MAX / m)
-	{
-		errno = ENOMEM;
-		print_fatal ("reallocarray: %s", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-	return xrealloc (o, n * m);
-}
-
-static char *
-xstrdup (const char *s)
-{
-	return strcpy (xmalloc (strlen (s) + 1), s);
-}
-
-static char *
-xstrndup (const char *s, size_t n)
-{
-	size_t size = strlen (s);
-	if (n > size)
-		n = size;
-
-	char *copy = xmalloc (n + 1);
-	memcpy (copy, s, n);
-	copy[n] = '\0';
-	return copy;
-}
-
-// --- Double-linked list helpers ----------------------------------------------
-
-// The links of the list need to have the members `prev' and `next'.
-
-#define LIST_PREPEND(head, link)                                               \
-	BLOCK_START                                                                \
-		(link)->prev = NULL;                                                   \
-		(link)->next = (head);                                                 \
-		if ((link)->next)                                                      \
-			(link)->next->prev = (link);                                       \
-		(head) = (link);                                                       \
-	BLOCK_END
-
-#define LIST_UNLINK(head, link)                                                \
-	BLOCK_START                                                                \
-		if ((link)->prev)                                                      \
-			(link)->prev->next = (link)->next;                                 \
-		else                                                                   \
-			(head) = (link)->next;                                             \
-		if ((link)->next)                                                      \
-			(link)->next->prev = (link)->prev;                                 \
-	BLOCK_END
-
-// --- Dynamically allocated string array --------------------------------------
-
-struct str_vector
-{
-	char **vector;
-	size_t len;
-	size_t alloc;
-};
-
-static void
-str_vector_init (struct str_vector *self)
-{
-	self->alloc = 4;
-	self->len = 0;
-	self->vector = xcalloc (sizeof *self->vector, self->alloc);
-}
-
-static void
-str_vector_free (struct str_vector *self)
-{
-	unsigned i;
-	for (i = 0; i < self->len; i++)
-		free (self->vector[i]);
-
-	free (self->vector);
-	self->vector = NULL;
-}
-
-static void
-str_vector_add_owned (struct str_vector *self, char *s)
-{
-	self->vector[self->len] = s;
-	if (++self->len >= self->alloc)
-		self->vector = xreallocarray (self->vector,
-			sizeof *self->vector, (self->alloc <<= 1));
-	self->vector[self->len] = NULL;
-}
-
-static void
-str_vector_add (struct str_vector *self, const char *s)
-{
-	str_vector_add_owned (self, xstrdup (s));
-}
-
-static void
-str_vector_add_args (struct str_vector *self, const char *s, ...)
-	ATTRIBUTE_SENTINEL;
-
-static void
-str_vector_add_args (struct str_vector *self, const char *s, ...)
-{
-	va_list ap;
-
-	va_start (ap, s);
-	while (s)
-	{
-		str_vector_add (self, s);
-		s = va_arg (ap, const char *);
-	}
-	va_end (ap);
-}
-
-static void
-str_vector_add_vector (struct str_vector *self, char **vector)
-{
-	while (*vector)
-		str_vector_add (self, *vector++);
-}
-
-static void
-str_vector_remove (struct str_vector *self, size_t i)
-{
-	hard_assert (i < self->len);
-	free (self->vector[i]);
-	memmove (self->vector + i, self->vector + i + 1,
-		(self->len-- - i) * sizeof *self->vector);
-}
-
-// --- Dynamically allocated strings -------------------------------------------
-
-// Basically a string builder to abstract away manual memory management.
-
-struct str
-{
-	char *str;                          ///< String data, null terminated
-	size_t alloc;                       ///< How many bytes are allocated
-	size_t len;                         ///< How long the string actually is
-};
-
-/// We don't care about allocations that are way too large for the content, as
-/// long as the allocation is below the given threshold.  (Trivial heuristics.)
-#define STR_SHRINK_THRESHOLD (1 << 20)
-
-static void
-str_init (struct str *self)
-{
-	self->alloc = 16;
-	self->len = 0;
-	self->str = strcpy (xmalloc (self->alloc), "");
-}
-
-static void
-str_free (struct str *self)
-{
-	free (self->str);
-	self->str = NULL;
-	self->alloc = 0;
-	self->len = 0;
-}
-
-static void
-str_reset (struct str *self)
-{
-	str_free (self);
-	str_init (self);
-}
-
-static char *
-str_steal (struct str *self)
-{
-	char *str = self->str;
-	self->str = NULL;
-	str_free (self);
-	return str;
-}
-
-static void
-str_ensure_space (struct str *self, size_t n)
-{
-	// We allocate at least one more byte for the terminating null character
-	size_t new_alloc = self->alloc;
-	while (new_alloc <= self->len + n)
-		new_alloc <<= 1;
-	if (new_alloc != self->alloc)
-		self->str = xrealloc (self->str, (self->alloc = new_alloc));
-}
-
-static void
-str_append_data (struct str *self, const char *data, size_t n)
-{
-	str_ensure_space (self, n);
-	memcpy (self->str + self->len, data, n);
-	self->len += n;
-	self->str[self->len] = '\0';
-}
-
-static void
-str_append_c (struct str *self, char c)
-{
-	str_append_data (self, &c, 1);
-}
-
-static void
-str_append (struct str *self, const char *s)
-{
-	str_append_data (self, s, strlen (s));
-}
-
-static void
-str_append_str (struct str *self, const struct str *another)
-{
-	str_append_data (self, another->str, another->len);
-}
-
-static int
-str_append_vprintf (struct str *self, const char *fmt, va_list va)
-{
-	va_list ap;
-	int size;
-
-	va_copy (ap, va);
-	size = vsnprintf (NULL, 0, fmt, ap);
-	va_end (ap);
-
-	if (size < 0)
-		return -1;
-
-	va_copy (ap, va);
-	str_ensure_space (self, size);
-	size = vsnprintf (self->str + self->len, self->alloc - self->len, fmt, ap);
-	va_end (ap);
-
-	if (size > 0)
-		self->len += size;
-
-	return size;
-}
-
-static int
-str_append_printf (struct str *self, const char *fmt, ...)
-	ATTRIBUTE_PRINTF (2, 3);
-
-static int
-str_append_printf (struct str *self, const char *fmt, ...)
-{
-	va_list ap;
-
-	va_start (ap, fmt);
-	int size = str_append_vprintf (self, fmt, ap);
-	va_end (ap);
-	return size;
-}
-
-static void
-str_remove_slice (struct str *self, size_t start, size_t length)
-{
-	size_t end = start + length;
-	hard_assert (end <= self->len);
-	memmove (self->str + start, self->str + end, self->len - end);
-	self->str[self->len -= length] = '\0';
-
-	// Shrink the string if the allocation becomes way too large
-	if (self->alloc >= STR_SHRINK_THRESHOLD && self->len < (self->alloc >> 2))
-		self->str = xrealloc (self->str, self->alloc >>= 2);
-}
-
-// --- Errors ------------------------------------------------------------------
-
-// Error reporting utilities.  Inspired by GError, only much simpler.
-
-struct error
-{
-	size_t domain;                      ///< The domain of the error
-	int id;                             ///< The concrete error ID
-	char *message;                      ///< Textual description of the event
-};
-
-static size_t
-error_resolve_domain (size_t *tag)
-{
-	// This method is fairly sensitive to the order in which resolution
-	// requests come in, does not provide a good way of decoding the number
-	// back to a meaningful identifier, and may not play all too well with
-	// dynamic libraries when a module is e.g. statically linked into multiple
-	// libraries, but it's fast, simple, and more than enough for our purposes.
-	static size_t domain_counter;
-
-	if (!*tag)
-		*tag = ++domain_counter;
-	return *tag;
-}
-
-static void
-error_set (struct error **e, size_t domain, int id,
-	const char *message, ...) ATTRIBUTE_PRINTF (4, 5);
-
-static void
-error_set (struct error **e, size_t domain, int id,
-	const char *message, ...)
-{
-	if (!e)
-		return;
-
-	va_list ap;
-	va_start (ap, message);
-	int size = snprintf (NULL, 0, message, ap);
-	va_end (ap);
-
-	hard_assert (size >= 0);
-
-	struct error *tmp = xmalloc (sizeof *tmp);
-	tmp->domain = domain;
-	tmp->id = id;
-	tmp->message = xmalloc (size + 1);
-
-	va_start (ap, message);
-	size = snprintf (tmp->message, size + 1, message, ap);
-	va_end (ap);
-
-	hard_assert (size >= 0);
-
-	soft_assert (*e == NULL);
-	*e = tmp;
-}
-
-static void
-error_free (struct error *e)
-{
-	free (e->message);
-	free (e);
-}
-
-static void
-error_propagate (struct error **destination, struct error *source)
-{
-	if (!destination)
-	{
-		error_free (source);
-		return;
-	}
-
-	soft_assert (*destination == NULL);
-	*destination = source;
-}
-
-// --- String hash map ---------------------------------------------------------
-
-// The most basic <string, managed pointer> map (or associative array).
-
-struct str_map_link
-{
-	struct str_map_link *next;          ///< The next link in a chain
-	struct str_map_link *prev;          ///< The previous link in a chain
-
-	void *data;                         ///< Payload
-	size_t key_length;                  ///< Length of the key without '\0'
-	char key[];                         ///< The key for this link
-};
-
-struct str_map
-{
-	struct str_map_link **map;          ///< The hash table data itself
-	size_t alloc;                       ///< Number of allocated entries
-	size_t len;                         ///< Number of entries in the table
-	void (*free) (void *);              ///< Callback to destruct the payload
-};
-
-#define STR_MAP_MIN_ALLOC 16
-
-typedef void (*str_map_free_func) (void *);
-
-static void
-str_map_init (struct str_map *self)
-{
-	self->alloc = STR_MAP_MIN_ALLOC;
-	self->len = 0;
-	self->free = NULL;
-	self->map = xcalloc (self->alloc, sizeof *self->map);
-}
-
-static void
-str_map_free (struct str_map *self)
-{
-	struct str_map_link **iter, **end = self->map + self->alloc;
-	struct str_map_link *link, *tmp;
-
-	for (iter = self->map; iter < end; iter++)
-		for (link = *iter; link; link = tmp)
-		{
-			tmp = link->next;
-			if (self->free)
-				self->free (link->data);
-			free (link);
-		}
-
-	free (self->map);
-	self->map = NULL;
-}
-
-static uint64_t
-str_map_hash (const char *s, size_t len)
-{
-	static unsigned char key[16] = "SipHash 2-4 key!";
-	return siphash (key, (const void *) s, len);
-}
-
-static uint64_t
-str_map_pos (struct str_map *self, const char *s)
-{
-	size_t mask = self->alloc - 1;
-	return str_map_hash (s, strlen (s)) & mask;
-}
-
-static uint64_t
-str_map_link_hash (struct str_map_link *self)
-{
-	return str_map_hash (self->key, self->key_length);
-}
-
-static void
-str_map_resize (struct str_map *self, size_t new_size)
-{
-	struct str_map_link **old_map = self->map;
-	size_t i, old_size = self->alloc;
-
-	// Only powers of two, so that we don't need to compute the modulo
-	hard_assert ((new_size & (new_size - 1)) == 0);
-	size_t mask = new_size - 1;
-
-	self->alloc = new_size;
-	self->map = xcalloc (self->alloc, sizeof *self->map);
-	for (i = 0; i < old_size; i++)
-	{
-		struct str_map_link *iter = old_map[i], *next_iter;
-		while (iter)
-		{
-			next_iter = iter->next;
-			uint64_t pos = str_map_link_hash (iter) & mask;
-			LIST_PREPEND (self->map[pos], iter);
-			iter = next_iter;
-		}
-	}
-
-	free (old_map);
-}
-
-static void
-str_map_set (struct str_map *self, const char *key, void *value)
-{
-	uint64_t pos = str_map_pos (self, key);
-	struct str_map_link *iter = self->map[pos];
-	for (; iter; iter = iter->next)
-	{
-		if (strcmp (key, iter->key))
-			continue;
-
-		// Storing the same data doesn't destroy it
-		if (self->free && value != iter->data)
-			self->free (iter->data);
-
-		if (value)
-		{
-			iter->data = value;
-			return;
-		}
-
-		LIST_UNLINK (self->map[pos], iter);
-		free (iter);
-		self->len--;
-
-		// The array should be at least 1/4 full
-		if (self->alloc >= (STR_MAP_MIN_ALLOC << 2)
-		 && self->len < (self->alloc >> 2))
-			str_map_resize (self, self->alloc >> 2);
-		return;
-	}
-
-	if (!value)
-		return;
-
-	if (self->len >= self->alloc)
-	{
-		str_map_resize (self, self->alloc << 1);
-		pos = str_map_pos (self, key);
-	}
-
-	// Link in a new element for the given <key, value> pair
-	size_t key_length = strlen (key);
-	struct str_map_link *link = xmalloc (sizeof *link + key_length + 1);
-	link->data = value;
-	link->key_length = key_length;
-	memcpy (link->key, key, key_length + 1);
-
-	LIST_PREPEND (self->map[pos], link);
-	self->len++;
-}
-
-static void *
-str_map_find (struct str_map *self, const char *key)
-{
-	struct str_map_link *iter = self->map[str_map_pos (self, key)];
-	for (; iter; iter = iter->next)
-		if (!strcmp (key, (char *) iter + sizeof *iter))
-			return iter->data;
-	return NULL;
-}
-
-// --- File descriptor utilities -----------------------------------------------
-
-static void
-set_cloexec (int fd)
-{
-	soft_assert (fcntl (fd, F_SETFD, fcntl (fd, F_GETFD) | FD_CLOEXEC) != -1);
-}
-
-static bool
-set_blocking (int fd, bool blocking)
-{
-	int flags = fcntl (fd, F_GETFL);
-	hard_assert (flags != -1);
-
-	bool prev = !(flags & O_NONBLOCK);
-	if (blocking)
-		flags &= ~O_NONBLOCK;
-	else
-		flags |=  O_NONBLOCK;
-
-	hard_assert (fcntl (fd, F_SETFL, flags) != -1);
-	return prev;
-}
-
-static void
-xclose (int fd)
-{
-	while (close (fd) == -1)
-		if (!soft_assert (errno == EINTR))
-			break;
-}
-
-// --- Polling -----------------------------------------------------------------
-
-// Basically the poor man's GMainLoop/libev/libuv.  It might make some sense
-// to instead use those tested and proven libraries but we don't need much
-// and it's interesting to implement.
-
-// At the moment the FD's are stored in an unsorted array.  This is not ideal
-// complexity-wise but I don't think I have much of a choice with poll(),
-// and neither with epoll for that matter.
-//
-//                         unsorted array       sorted array
-//           search             O(n)       O(log n) [O(log log n)]
-//           insert by fd       O(n)                O(n)
-//           delete by fd       O(n)                O(n)
-//
-// Insertion in the unsorted array can be reduced to O(1) if I maintain a
-// bitmap of present FD's but that's still not a huge win.
-//
-// I don't expect this to be much of an issue, as there are typically not going
-// to be that many FD's to watch, and the linear approach is cache-friendly.
-
-typedef void (*poller_dispatcher_func) (const struct pollfd *, void *);
-
-#define POLLER_MIN_ALLOC 16
-
-#ifdef __linux__
-
-// I don't really need this, I've basically implemented this just because I can.
-
-#include <sys/epoll.h>
-
-struct poller_info
-{
-	int fd;                             ///< Our file descriptor
-	uint32_t events;                    ///< The events we registered
-	poller_dispatcher_func dispatcher;  ///< Event dispatcher
-	void *user_data;                    ///< User data
-};
-
-struct poller
-{
-	int epoll_fd;                       ///< The epoll FD
-	struct poller_info **info;          ///< Information associated with each FD
-	struct epoll_event *revents;        ///< Output array for epoll_wait()
-	size_t len;                         ///< Number of polled descriptors
-	size_t alloc;                       ///< Number of entries allocated
-
-	/// Index of the element in `revents' that's currently being dispatched,
-	/// or -1 if we're not dispatching at the moment.
-	int dispatch_iterator;
-
-	/// The total number of entries stored in `revents' by epoll_wait().
-	int dispatch_total;
-};
-
-static void
-poller_init (struct poller *self)
-{
-	self->epoll_fd = epoll_create (POLLER_MIN_ALLOC);
-	hard_assert (self->epoll_fd != -1);
-	set_cloexec (self->epoll_fd);
-
-	self->len = 0;
-	self->alloc = POLLER_MIN_ALLOC;
-	self->info = xcalloc (self->alloc, sizeof *self->info);
-	self->revents = xcalloc (self->alloc, sizeof *self->revents);
-
-	self->dispatch_iterator = -1;
-	self->dispatch_total = 0;
-}
-
-static void
-poller_free (struct poller *self)
-{
-	for (size_t i = 0; i < self->len; i++)
-	{
-		struct poller_info *info = self->info[i];
-		hard_assert (epoll_ctl (self->epoll_fd,
-			EPOLL_CTL_DEL, info->fd, (void *) "") != -1);
-		free (info);
-	}
-
-	xclose (self->epoll_fd);
-	free (self->info);
-	free (self->revents);
-}
-
-static ssize_t
-poller_find_by_fd (struct poller *self, int fd)
-{
-	for (size_t i = 0; i < self->len; i++)
-		if (self->info[i]->fd == fd)
-			return i;
-	return -1;
-}
-
-static void
-poller_ensure_space (struct poller *self)
-{
-	if (self->len < self->alloc)
-		return;
-
-	self->alloc <<= 1;
-	self->revents = xreallocarray
-		(self->revents, sizeof *self->revents, self->alloc);
-	self->info = xreallocarray
-		(self->info, sizeof *self->info, self->alloc);
-}
-
-static int
-poller_epoll_to_poll_events (int events)
-{
-	int result = 0;
-	if (events & EPOLLIN)   result |= POLLIN;
-	if (events & EPOLLOUT)  result |= POLLOUT;
-	if (events & EPOLLERR)  result |= POLLERR;
-	if (events & EPOLLHUP)  result |= POLLHUP;
-	if (events & EPOLLPRI)  result |= POLLPRI;
-	return result;
-}
-
-static uint32_t
-poller_poll_to_epoll_events (uint32_t events)
-{
-	uint32_t result = 0;
-	if (events & POLLIN)   result |= EPOLLIN;
-	if (events & POLLOUT)  result |= EPOLLOUT;
-	if (events & POLLERR)  result |= EPOLLERR;
-	if (events & POLLHUP)  result |= EPOLLHUP;
-	if (events & POLLPRI)  result |= EPOLLPRI;
-	return result;
-}
-
-static void
-poller_set (struct poller *self, int fd, short int events,
-	poller_dispatcher_func dispatcher, void *data)
-{
-	ssize_t index = poller_find_by_fd (self, fd);
-	bool modifying = true;
-	if (index == -1)
-	{
-		poller_ensure_space (self);
-		self->info[index = self->len++] = xcalloc (1, sizeof **self->info);
-		modifying = false;
-	}
-
-	struct poller_info *info = self->info[index];
-	info->fd = fd;
-	info->dispatcher = dispatcher;
-	info->user_data = data;
-
-	struct epoll_event event;
-	event.events = poller_poll_to_epoll_events (events);
-	event.data.ptr = info;
-	hard_assert (epoll_ctl (self->epoll_fd,
-		modifying ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &event) != -1);
-}
-
-static void
-poller_remove_from_dispatch (struct poller *self,
-	const struct poller_info *info)
-{
-	if (self->dispatch_iterator == -1)
-		return;
-
-	int i;
-	for (i = self->dispatch_iterator; i < self->dispatch_total; i++)
-		if (self->revents[i].data.ptr == info)
-			break;
-	if (i == self->dispatch_total)
-		return;
-
-	if (i != --self->dispatch_total)
-		self->revents[i] = self->revents[self->dispatch_total];
-
-	// We've removed the element we're currently processing; go back one entry
-	// so that we don't skip the one we might have replaced it with.
-	if (i == self->dispatch_iterator)
-		self->dispatch_iterator--;
-}
-
-static void
-poller_remove_at_index (struct poller *self, size_t index)
-{
-	hard_assert (index < self->len);
-	struct poller_info *info = self->info[index];
-
-	poller_remove_from_dispatch (self, info);
-	hard_assert (epoll_ctl (self->epoll_fd,
-		EPOLL_CTL_DEL, info->fd, (void *) "") != -1);
-
-	free (info);
-	if (index != --self->len)
-		self->info[index] = self->info[self->len];
-}
-
-static void
-poller_run (struct poller *self)
-{
-	// Not reentrant
-	hard_assert (self->dispatch_iterator == -1);
-
-	int n_fds;
-	do
-		n_fds = epoll_wait (self->epoll_fd, self->revents, self->len, -1);
-	while (n_fds == -1 && errno == EINTR);
-
-	if (n_fds == -1)
-	{
-		print_fatal ("%s: %s", "epoll", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-
-	for (int i = 0; i < n_fds; i++)
-	{
-		struct epoll_event *revents = self->revents + i;
-		struct poller_info *info = revents->data.ptr;
-
-		struct pollfd pfd;
-		pfd.fd = info->fd;
-		pfd.revents = poller_epoll_to_poll_events (revents->events);
-		pfd.events = poller_epoll_to_poll_events (info->events);
-
-		self->dispatch_iterator = i;
-		self->dispatch_total = n_fds;
-
-		info->dispatcher (&pfd, info->user_data);
-
-		i = self->dispatch_iterator;
-		n_fds = self->dispatch_total;
-	}
-
-	self->dispatch_iterator = -1;
-	self->dispatch_total = 0;
-}
-
-#else  // !__linux__
-
-struct poller_info
-{
-	poller_dispatcher_func dispatcher;  ///< Event dispatcher
-	void *user_data;                    ///< User data
-};
-
-struct poller
-{
-	struct pollfd *fds;                 ///< Polled descriptors
-	struct poller_info *fds_info;       ///< Additional information for each FD
-	size_t len;                         ///< Number of polled descriptors
-	size_t alloc;                       ///< Number of entries allocated
-
-	int dispatch_index;                 ///< The currently dispatched FD or -1
-};
-
-static void
-poller_init (struct poller *self)
-{
-	self->alloc = POLLER_MIN_ALLOC;
-	self->len = 0;
-	self->fds = xcalloc (self->alloc, sizeof *self->fds);
-	self->fds_info = xcalloc (self->alloc, sizeof *self->fds_info);
-	self->dispatch_index = -1;
-}
-
-static void
-poller_free (struct poller *self)
-{
-	free (self->fds);
-	free (self->fds_info);
-}
-
-static ssize_t
-poller_find_by_fd (struct poller *self, int fd)
-{
-	for (size_t i = 0; i < self->len; i++)
-		if (self->fds[i].fd == fd)
-			return i;
-	return -1;
-}
-
-static void
-poller_ensure_space (struct poller *self)
-{
-	if (self->len < self->alloc)
-		return;
-
-	self->alloc <<= 1;
-	self->fds = xreallocarray (self->fds, sizeof *self->fds, self->alloc);
-	self->fds_info = xreallocarray
-		(self->fds_info, sizeof *self->fds_info, self->alloc);
-}
-
-static void
-poller_set (struct poller *self, int fd, short int events,
-	poller_dispatcher_func dispatcher, void *data)
-{
-	ssize_t index = poller_find_by_fd (self, fd);
-	if (index == -1)
-	{
-		poller_ensure_space (self);
-		index = self->len++;
-	}
-
-	struct pollfd *new_entry = self->fds + index;
-	memset (new_entry, 0, sizeof *new_entry);
-	new_entry->fd = fd;
-	new_entry->events = events;
-
-	self->fds_info[self->len] = (struct poller_info) { dispatcher, data };
-}
-
-static void
-poller_remove_at_index (struct poller *self, size_t index)
-{
-	hard_assert (index < self->len);
-	if (index == --self->len)
-		return;
-
-	// Make sure that we don't disrupt the dispatch loop; kind of crude
-	if ((int) index < self->dispatch_index)
-	{
-		memmove (self->fds + index, self->fds + index + 1,
-			(self->len - index) * sizeof *self->fds);
-		memmove (self->fds_info + index, self->fds_info + index + 1,
-			(self->len - index) * sizeof *self->fds_info);
-	}
-	else
-	{
-		self->fds[index]      = self->fds[self->len];
-		self->fds_info[index] = self->fds_info[self->len];
-	}
-
-	if ((int) index <= self->dispatch_index)
-		self->dispatch_index--;
-}
-
-static void
-poller_run (struct poller *self)
-{
-	// Not reentrant
-	hard_assert (self->dispatch_index == -1);
-
-	int result;
-	do
-		result = poll (self->fds, self->len, -1);
-	while (result == -1 && errno == EINTR);
-
-	if (result == -1)
-	{
-		print_fatal ("%s: %s", "poll", strerror (errno));
-		exit (EXIT_FAILURE);
-	}
-
-	for (int i = 0; i < (int) self->len; i++)
-	{
-		struct pollfd pfd = self->fds[i];
-		if (!pfd.revents)
-			continue;
-
-		struct poller_info *info = self->fds_info + i;
-		self->dispatch_index = i;
-		info->dispatcher (&pfd, info->user_data);
-		i = self->dispatch_index;
-	}
-
-	self->dispatch_index = -1;
-}
-
-#endif  // !__linux__
-
-// --- Utilities ---------------------------------------------------------------
-
-static void
-split_str_ignore_empty (const char *s, char delimiter, struct str_vector *out)
-{
-	const char *begin = s, *end;
-
-	while ((end = strchr (begin, delimiter)))
-	{
-		if (begin != end)
-			str_vector_add_owned (out, xstrndup (begin, end - begin));
-		begin = ++end;
-	}
-
-	if (*begin)
-		str_vector_add (out, begin);
-}
-
-static char *
-strip_str_in_place (char *s, const char *stripped_chars)
-{
-	char *end = s + strlen (s);
-	while (end > s && strchr (stripped_chars, end[-1]))
-		*--end = '\0';
-
-	char *start = s + strspn (s, stripped_chars);
-	if (start > s)
-		memmove (s, start, end - start + 1);
-	return s;
-}
-
-static bool
-str_append_env_path (struct str *output, const char *var, bool only_absolute)
-{
-	const char *value = getenv (var);
-
-	if (!value || (only_absolute && *value != '/'))
-		return false;
-
-	str_append (output, value);
-	return true;
-}
-
-static void
-get_xdg_home_dir (struct str *output, const char *var, const char *def)
-{
-	str_reset (output);
-	if (!str_append_env_path (output, var, true))
-	{
-		str_append_env_path (output, "HOME", false);
-		str_append_c (output, '/');
-		str_append (output, def);
-	}
-}
-
-static size_t io_error_domain_tag;
-#define IO_ERROR (error_resolve_domain (&io_error_domain_tag))
-
-enum
-{
-	IO_ERROR_FAILED
-};
-
-static bool
-ensure_directory_existence (const char *path, struct error **e)
-{
-	struct stat st;
-
-	if (stat (path, &st))
-	{
-		if (mkdir (path, S_IRWXU | S_IRWXG | S_IRWXO))
-		{
-			error_set (e, IO_ERROR, IO_ERROR_FAILED,
-				"cannot create directory `%s': %s",
-				path, strerror (errno));
-			return false;
-		}
-	}
-	else if (!S_ISDIR (st.st_mode))
-	{
-		error_set (e, IO_ERROR, IO_ERROR_FAILED,
-			"cannot create directory `%s': %s",
-			path, "file exists but is not a directory");
-		return false;
-	}
-	return true;
-}
-
-static bool
-mkdir_with_parents (char *path, struct error **e)
-{
-	char *p = path;
-
-	// XXX: This is prone to the TOCTTOU problem.  The solution would be to
-	//   rewrite the function using the {mkdir,fstat}at() functions from
-	//   POSIX.1-2008, ideally returning a file descriptor to the open
-	//   directory, with the current code as a fallback.  Or to use chdir().
-	while ((p = strchr (p + 1, '/')))
-	{
-		*p = '\0';
-		bool success = ensure_directory_existence (path, e);
-		*p = '/';
-
-		if (!success)
-			return false;
-	}
-
-	return ensure_directory_existence (path, e);
-}
-
-static bool
-set_boolean_if_valid (bool *out, const char *s)
-{
-	if      (!strcasecmp (s, "yes"))    *out = true;
-	else if (!strcasecmp (s, "no"))     *out = false;
-	else if (!strcasecmp (s, "on"))     *out = true;
-	else if (!strcasecmp (s, "off"))    *out = false;
-	else if (!strcasecmp (s, "true"))   *out = true;
-	else if (!strcasecmp (s, "false"))  *out = false;
-	else return false;
-
-	return true;
-}
-
-static void
-regerror_to_str (int code, const regex_t *preg, struct str *out)
-{
-	size_t required = regerror (code, preg, NULL, 0);
-	str_ensure_space (out, required);
-	out->len += regerror (code, preg,
-		out->str + out->len, out->alloc - out->len) - 1;
-}
-
-static size_t regex_error_domain_tag;
-#define REGEX_ERROR (error_resolve_domain (&regex_error_domain_tag))
-
-enum
-{
-	REGEX_ERROR_COMPILATION_FAILED
-};
-
-static bool
-regex_match (const char *regex, const char *s, struct error **e)
-{
-	regex_t re;
-	int err = regcomp (&re, regex, REG_EXTENDED | REG_NOSUB);
-	if (err)
-	{
-		struct str desc;
-
-		str_init (&desc);
-		regerror_to_str (err, &re, &desc);
-		error_set (e, REGEX_ERROR, REGEX_ERROR_COMPILATION_FAILED,
-			"failed to compile regular expression: %s", desc.str);
-		str_free (&desc);
-		return false;
-	}
-
-	bool result = regexec (&re, s, 0, NULL, 0) != REG_NOMATCH;
-	regfree (&re);
-	return result;
-}
-
-static bool
-read_line (FILE *fp, struct str *s)
-{
-	int c;
-	bool at_end = true;
-
-	str_reset (s);
-	while ((c = fgetc (fp)) != EOF)
-	{
-		at_end = false;
-		if (c == '\r')
-			continue;
-		if (c == '\n')
-			break;
-		str_append_c (s, c);
-	}
-
-	return !at_end;
-}
-
-// --- IRC utilities -----------------------------------------------------------
-
-struct irc_message
-{
-	char *prefix;
-	char *command;
-	struct str_vector params;
-};
-
-static void
-irc_parse_message (struct irc_message *msg, const char *line)
-{
-	msg->prefix = NULL;
-	msg->command = NULL;
-	str_vector_init (&msg->params);
-
-	// Prefix
-	if (*line == ':')
-	{
-		size_t prefix_len = strcspn (++line, " ");
-		msg->prefix = xstrndup (line, prefix_len);
-		line += prefix_len;
-	}
-
-	// Command name
-	{
-		while (*line == ' ')
-			line++;
-
-		size_t cmd_len = strcspn (line, " ");
-		msg->command = xstrndup (line, cmd_len);
-		line += cmd_len;
-	}
-
-	// Arguments
-	while (true)
-	{
-		while (*line == ' ')
-			line++;
-
-		if (*line == ':')
-		{
-			str_vector_add (&msg->params, ++line);
-			break;
-		}
-
-		size_t param_len = strcspn (line, " ");
-		if (!param_len)
-			break;
-
-		str_vector_add_owned (&msg->params, xstrndup (line, param_len));
-		line += param_len;
-	}
-}
-
-static void
-irc_free_message (struct irc_message *msg)
-{
-	free (msg->prefix);
-	free (msg->command);
-	str_vector_free (&msg->params);
-}
-
-static void
-irc_process_buffer (struct str *buf,
-	void (*callback)(const struct irc_message *, const char *, void *),
-	void *user_data)
-{
-	char *start = buf->str;
-	char *end = start + buf->len;
-
-	for (char *p = start; p + 1 < end; p++)
-	{
-		// Split the input on newlines
-		if (p[0] != '\r' || p[1] != '\n')
-			continue;
-
-		*p = 0;
-
-		struct irc_message msg;
-		irc_parse_message (&msg, start);
-		callback (&msg, start, user_data);
-		irc_free_message (&msg);
-
-		start = p + 2;
-	}
-
-	str_remove_slice (buf, 0, start - buf->str);
-}
-
-// --- Configuration -----------------------------------------------------------
-
-// The keys are stripped of surrounding whitespace, the values are not.
-
-static size_t config_error_domain_tag;
-#define CONFIG_ERROR (error_resolve_domain (&config_error_domain_tag))
-
-enum
-{
-	CONFIG_ERROR_MALFORMED
-};
-
-struct config_item
-{
-	const char *key;
-	const char *default_value;
-	const char *description;
-};
-
-static FILE *
-get_config_file (void)
-{
-	struct str_vector paths;
-	struct str config_home, file;
-	const char *xdg_config_dirs;
-	unsigned i;
-	FILE *fp = NULL;
-
-	str_vector_init (&paths);
-
-	str_init (&config_home);
-	get_xdg_home_dir (&config_home, "XDG_CONFIG_HOME", ".config");
-	str_vector_add (&paths, config_home.str);
-	str_free (&config_home);
-
-	if ((xdg_config_dirs = getenv ("XDG_CONFIG_DIRS")))
-		split_str_ignore_empty (xdg_config_dirs, ':', &paths);
-
-	str_init (&file);
-	for (i = 0; i < paths.len; i++)
-	{
-		// As per spec, relative paths are ignored
-		if (*paths.vector[i] != '/')
-			continue;
-
-		str_reset (&file);
-		str_append (&file, paths.vector[i]);
-		str_append (&file, "/" PROGRAM_NAME "/" PROGRAM_NAME ".conf");
-
-		if ((fp = fopen (file.str, "r")))
-			break;
-	}
-
-	str_free (&file);
-	str_vector_free (&paths);
-	return fp;
-}
-
-static bool
-read_config_file (struct str_map *config, struct error **e)
-{
-	struct str line;
-	FILE *fp = get_config_file ();
-	unsigned line_no = 0;
-	bool errors = false;
-
-	if (!fp)
-		return true;
-
-	str_init (&line);
-	for (line_no = 1; read_line (fp, &line); line_no++)
-	{
-		char *start = line.str;
-		if (*start == '#')
-			continue;
-
-		while (isspace (*start))
-			start++;
-
-		char *end = strchr (start, '=');
-		if (!end)
-		{
-			if (*start)
-			{
-				error_set (e, CONFIG_ERROR, CONFIG_ERROR_MALFORMED,
-					"line %u in config: %s", line_no, "malformed input");
-				errors = true;
-				break;
-			}
-		}
-		else
-		{
-			char *value = end + 1;
-			do
-				*end = '\0';
-			while (isspace (*--end));
-
-			str_map_set (config, start, xstrdup (value));
-		}
-	}
-
-	str_free (&line);
-	fclose (fp);
-
-	return !errors;
-}
+#include "common.c"
 
 // --- Configuration (application-specific) ------------------------------------
 
@@ -1498,18 +44,9 @@ static struct config_item g_config_table[] =
 	{ "plugins",         NULL,              "The plugins to load on startup" },
 	{ "plugin_dir",      NULL,              "Where to search for plugins"    },
 	{ "recover",         "on",              "Whether to re-launch on crash"  },
-};
 
-static void
-load_config_defaults (struct str_map *config)
-{
-	for (size_t i = 0; i < N_ELEMENTS (g_config_table); i++)
-	{
-		const struct config_item *item = g_config_table + i;
-		if (item->default_value)
-			str_map_set (config, item->key, xstrdup (item->default_value));
-	}
-}
+	{ NULL,              NULL,              NULL                             }
+};
 
 // --- Application data --------------------------------------------------------
 
@@ -1598,51 +135,51 @@ struct bot_context
 };
 
 static void
-bot_context_init (struct bot_context *ctx)
+bot_context_init (struct bot_context *self)
 {
-	str_map_init (&ctx->config);
-	ctx->config.free = free;
-	load_config_defaults (&ctx->config);
+	str_map_init (&self->config);
+	self->config.free = free;
+	load_config_defaults (&self->config, g_config_table);
 
-	ctx->irc_fd = -1;
-	str_init (&ctx->read_buffer);
-	ctx->irc_ready = false;
+	self->irc_fd = -1;
+	str_init (&self->read_buffer);
+	self->irc_ready = false;
 
-	ctx->ssl = NULL;
-	ctx->ssl_ctx = NULL;
+	self->ssl = NULL;
+	self->ssl_ctx = NULL;
 
-	ctx->plugins = NULL;
-	str_map_init (&ctx->plugins_by_name);
+	self->plugins = NULL;
+	str_map_init (&self->plugins_by_name);
 
-	poller_init (&ctx->poller);
-	ctx->quitting = false;
-	ctx->polling = false;
+	poller_init (&self->poller);
+	self->quitting = false;
+	self->polling = false;
 }
 
 static void
-bot_context_free (struct bot_context *ctx)
+bot_context_free (struct bot_context *self)
 {
-	str_map_free (&ctx->config);
-	str_free (&ctx->read_buffer);
+	str_map_free (&self->config);
+	str_free (&self->read_buffer);
 
 	// TODO: terminate the plugins properly before this is called
 	struct plugin_data *link, *tmp;
-	for (link = ctx->plugins; link; link = tmp)
+	for (link = self->plugins; link; link = tmp)
 	{
 		tmp = link->next;
 		plugin_data_free (link);
 		free (link);
 	}
 
-	if (ctx->irc_fd != -1)
-		xclose (ctx->irc_fd);
-	if (ctx->ssl)
-		SSL_free (ctx->ssl);
-	if (ctx->ssl_ctx)
-		SSL_CTX_free (ctx->ssl_ctx);
+	if (self->irc_fd != -1)
+		xclose (self->irc_fd);
+	if (self->ssl)
+		SSL_free (self->ssl);
+	if (self->ssl_ctx)
+		SSL_CTX_free (self->ssl_ctx);
 
-	str_map_free (&ctx->plugins_by_name);
-	poller_free (&ctx->poller);
+	str_map_free (&self->plugins_by_name);
+	poller_free (&self->poller);
 }
 
 static void
@@ -1690,7 +227,8 @@ irc_send (struct bot_context *ctx, const char *format, ...)
 		fputs ("\"\n", stderr);
 	}
 
-	soft_assert (ctx->irc_fd != -1);
+	if (!soft_assert (ctx->irc_fd != -1))
+		return false;
 
 	va_start (ap, format);
 	struct str str;
@@ -2143,10 +681,8 @@ on_plugin_writable (const struct pollfd *fd, struct plugin_data *plugin)
 	struct str *buf = &plugin->write_buffer;
 	size_t written_total = 0;
 
-	// TODO: see "Advanced Programming in the UNIX Environment" Figure C.19;
-	//   check for any unexpected behaviour that might occur
-	if (fd->revents != POLLOUT)
-		print_debug ("poller fd %d: revents: %d", fd->fd, fd->revents);
+	if (fd->revents & ~(POLLOUT | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
 
 	while (written_total != buf->len)
 	{
@@ -2157,15 +693,18 @@ on_plugin_writable (const struct pollfd *fd, struct plugin_data *plugin)
 		{
 			if (errno == EAGAIN)
 				break;
+			if (errno == EINTR)
+				continue;
 
-			if (!soft_assert (errno == EINTR) && !plugin->is_zombie)
-			{
-				print_debug ("%s: %s", "recv", strerror (errno));
-				print_error ("failure on writing to plugin `%s',"
-					" therefore I'm unloading it", plugin->name);
-				plugin_zombify (plugin);
-				break;
-			}
+			soft_assert (errno == EPIPE);
+			// Zombies shouldn't get dispatched for writability
+			hard_assert (!plugin->is_zombie);
+
+			print_debug ("%s: %s", "write", strerror (errno));
+			print_error ("failure on writing to plugin `%s',"
+				" therefore I'm unloading it", plugin->name);
+			plugin_zombify (plugin);
+			break;
 		}
 
 		// This may be equivalent to EAGAIN on some implementations
@@ -2301,10 +840,8 @@ plugin_process_message (const struct irc_message *msg,
 static void
 on_plugin_readable (const struct pollfd *fd, struct plugin_data *plugin)
 {
-	// TODO: see "Advanced Programming in the UNIX Environment" Figure C.19;
-	//   check for any unexpected behaviour that might occur
-	if (fd->revents != POLLIN)
-		print_debug ("poller fd %d: revents: %d", fd->fd, fd->revents);
+	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
 
 	// TODO: see if I can reuse irc_fill_read_buffer()
 	struct str *buf = &plugin->read_buffer;
@@ -2818,11 +1355,11 @@ start:
 		buf->alloc - buf->len - 1 /* null byte */);
 
 	const char *error_info = NULL;
-	switch (SSL_get_error (ctx->ssl, n_read))
+	switch (xssl_get_error (ctx->ssl, n_read, &error_info))
 	{
 	case SSL_ERROR_NONE:
 		buf->str[buf->len += n_read] = '\0';
-		return IRC_READ_AGAIN;
+		return IRC_READ_OK;
 	case SSL_ERROR_ZERO_RETURN:
 		return IRC_READ_EOF;
 	case SSL_ERROR_WANT_READ:
@@ -2835,28 +1372,12 @@ start:
 		soft_assert (poll (&pfd, 1, 0) > 0);
 		goto start;
 	}
-	case SSL_ERROR_SYSCALL:
-	{
-		int err;
-		if ((err = ERR_get_error ()))
-			error_info = ERR_error_string (err, NULL);
-		else if (n_read == 0)
-			return IRC_READ_EOF;
-		else
-		{
-			if (errno == EINTR)
-				goto start;
-			error_info = strerror (errno);
-		}
-		break;
-	}
-	case SSL_ERROR_SSL:
+	case XSSL_ERROR_TRY_AGAIN:
+		goto start;
 	default:
-		error_info = ERR_error_string (ERR_get_error (), NULL);
+		print_debug ("%s: %s: %s", __func__, "SSL_read", error_info);
+		return IRC_READ_ERROR;
 	}
-
-	print_debug ("%s: %s: %s", __func__, "SSL_read", error_info);
-	return IRC_READ_ERROR;
 }
 
 static enum irc_read_result
@@ -2975,8 +1496,8 @@ on_irc_disconnected (struct bot_context *ctx)
 static void
 on_irc_readable (const struct pollfd *fd, struct bot_context *ctx)
 {
-	if (fd->revents != POLLIN)
-		print_debug ("poller fd %d: revents: %d", fd->fd, fd->revents);
+	if (fd->revents & ~(POLLIN | POLLHUP | POLLERR))
+		print_debug ("fd %d: unexpected revents: %d", fd->fd, fd->revents);
 
 	(void) set_blocking (ctx->irc_fd, false);
 
@@ -3144,75 +1665,6 @@ on_signal_pipe_readable (const struct pollfd *fd, struct bot_context *ctx)
 }
 
 static void
-write_default_configuration (const char *filename)
-{
-	struct str path, base;
-	int status = EXIT_SUCCESS;
-
-	str_init (&path);
-	str_init (&base);
-
-	if (filename)
-	{
-		char *tmp = xstrdup (filename);
-		str_append (&path, dirname (tmp));
-		strcpy (tmp, filename);
-		str_append (&base, basename (tmp));
-		free (tmp);
-	}
-	else
-	{
-		get_xdg_home_dir (&path, "XDG_CONFIG_HOME", ".config");
-		str_append (&path, "/" PROGRAM_NAME);
-		str_append (&base, PROGRAM_NAME ".conf");
-	}
-
-	struct error *e = NULL;
-	if (!mkdir_with_parents (path.str, &e))
-	{
-		print_fatal ("%s", e->message);
-		status = EXIT_FAILURE;
-		goto out;
-	}
-
-	str_append_c (&path, '/');
-	str_append_str (&path, &base);
-
-	FILE *fp = fopen (path.str, "w");
-	if (!fp)
-	{
-		print_fatal ("could not open `%s' for writing: %s",
-			path.str, strerror (errno));
-		status = EXIT_FAILURE;
-		goto out;
-	}
-
-	errno = 0;
-	for (size_t i = 0; i < N_ELEMENTS (g_config_table); i++)
-	{
-		const struct config_item *item = g_config_table + i;
-		fprintf (fp, "# %s\n", item->description);
-		if (item->default_value)
-			fprintf (fp, "%s=%s\n", item->key, item->default_value);
-		else
-			fprintf (fp, "#%s=\n", item->key);
-	}
-	fclose (fp);
-	if (errno)
-	{
-		print_fatal ("writing to `%s' failed: %s", path.str, strerror (errno));
-		status = EXIT_FAILURE;
-		goto out;
-	}
-	print_status ("configuration written to `%s'", path.str);
-
-out:
-	str_free (&path);
-	str_free (&base);
-	exit (status);
-}
-
-static void
 print_usage (const char *program_name)
 {
 	fprintf (stderr,
@@ -3234,6 +1686,7 @@ main (int argc, char *argv[])
 	str_vector_init (&g_original_argv);
 	str_vector_add_vector (&g_original_argv, argv);
 
+	struct error *e = NULL;
 	static struct option opts[] =
 	{
 		{ "debug",             no_argument,       NULL, 'd' },
@@ -3263,8 +1716,18 @@ main (int argc, char *argv[])
 			printf (PROGRAM_NAME " " PROGRAM_VERSION "\n");
 			exit (EXIT_SUCCESS);
 		case 'w':
-			write_default_configuration (optarg);
-			abort ();
+		{
+			char *filename = write_default_config (optarg, g_config_table, &e);
+			if (!filename)
+			{
+				print_fatal ("%s", e->message);
+				error_free (e);
+				exit (EXIT_FAILURE);
+			}
+			print_status ("configuration written to `%s'", filename);
+			free (filename);
+			exit (EXIT_SUCCESS);
+		}
 		default:
 			print_fatal ("error in options");
 			exit (EXIT_FAILURE);
@@ -3277,12 +1740,12 @@ main (int argc, char *argv[])
 	SSL_library_init ();
 	atexit (EVP_cleanup);
 	SSL_load_error_strings ();
+	// XXX: ERR_load_BIO_strings()?  Anything else?
 	atexit (ERR_free_strings);
 
 	struct bot_context ctx;
 	bot_context_init (&ctx);
 
-	struct error *e = NULL;
 	if (!read_config_file (&ctx.config, &e))
 	{
 		print_fatal ("error loading configuration: %s", e->message);