+++ /dev/null
-/*
- * Copyright (C) 2013-2015 David Herrmann <dh.herrmann@gmail.com>
- *
- * kdbus is free software; you can redistribute it and/or modify it under
- * the terms of the GNU Lesser General Public License as published by the
- * Free Software Foundation; either version 2.1 of the License, or (at
- * your option) any later version.
- */
-
-/*
- * Example: Workers
- * This program computes prime-numbers based on the sieve of Eratosthenes. The
- * master sets up a shared memory region and spawns workers which clear out the
- * non-primes. The master reacts to keyboard input and to client-requests to
- * control what each worker does. Note that this is in no way meant as efficient
- * way to compute primes. It should only serve as example how a master/worker
- * concept can be implemented with kdbus used as control messages.
- *
- * The main process is called the 'master'. It creates a new, private bus which
- * will be used between the master and its workers to communicate. The master
- * then spawns a fixed number of workers. Whenever a worker dies (detected via
- * SIGCHLD), the master spawns a new worker. When done, the master waits for all
- * workers to exit, prints a status report and exits itself.
- *
- * The master process does *not* keep track of its workers. Instead, this
- * example implements a PULL model. That is, the master acquires a well-known
- * name on the bus which each worker uses to request tasks from the master. If
- * there are no more tasks, the master will return an empty task-list, which
- * casues a worker to exit immediately.
- *
- * As tasks can be computationally expensive, we support cancellation. Whenever
- * the master process is interrupted, it will drop its well-known name on the
- * bus. This causes kdbus to broadcast a name-change notification. The workers
- * check for broadcast messages regularly and will exit if they receive one.
- *
- * This example exists of 4 objects:
- * * master: The master object contains the context of the master process. This
- * process manages the prime-context, spawns workers and assigns
- * prime-ranges to each worker to compute.
- * The master itself does not do any prime-computations itself.
- * * child: The child object contains the context of a worker. It inherits the
- * prime context from its parent (the master) and then creates a new
- * bus context to request prime-ranges to compute.
- * * prime: The "prime" object is used to abstract how we compute primes. When
- * allocated, it prepares a memory region to hold 1 bit for each
- * natural number up to a fixed maximum ('MAX_PRIMES').
- * The memory region is backed by a memfd which we share between
- * processes. Each worker now gets assigned a range of natural
- * numbers which it clears multiples of off the memory region. The
- * master process is responsible of distributing all natural numbers
- * up to the fixed maximum to its workers.
- * * bus: The bus object is an abstraction of the kdbus API. It is pretty
- * straightfoward and only manages the connection-fd plus the
- * memory-mapped pool in a single object.
- *
- * This example is in reversed order, which should make it easier to read
- * top-down, but requires some forward-declarations. Just ignore those.
- */
-
-#include <ctype.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <linux/memfd.h>
-#include <signal.h>
-#include <stdbool.h>
-#include <stddef.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/poll.h>
-#include <sys/signalfd.h>
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <sys/wait.h>
-#include <time.h>
-#include <unistd.h>
-#include "kdbus-api.h"
-
-/* FORWARD DECLARATIONS */
-
-#define POOL_SIZE (16 * 1024 * 1024)
-#define MAX_PRIMES (2UL << 24)
-#define WORKER_COUNT (16)
-#define PRIME_STEPS (65536 * 4)
-
-static const char *arg_busname = "example-workers";
-static const char *arg_modname = "kdbus";
-static const char *arg_master = "org.freedesktop.master";
-
-static int err_assert(int r_errno, const char *msg, const char *func, int line,
- const char *file)
-{
- r_errno = (r_errno != 0) ? -abs(r_errno) : -EFAULT;
- if (r_errno < 0) {
- errno = -r_errno;
- fprintf(stderr, "ERR: %s: %m (%s:%d in %s)\n",
- msg, func, line, file);
- }
- return r_errno;
-}
-
-#define err_r(_r, _msg) err_assert((_r), (_msg), __func__, __LINE__, __FILE__)
-#define err(_msg) err_r(errno, (_msg))
-
-struct prime;
-struct bus;
-struct master;
-struct child;
-
-struct prime {
- int fd;
- uint8_t *area;
- size_t max;
- size_t done;
- size_t status;
-};
-
-static int prime_new(struct prime **out);
-static void prime_free(struct prime *p);
-static bool prime_done(struct prime *p);
-static void prime_consume(struct prime *p, size_t amount);
-static int prime_run(struct prime *p, struct bus *cancel, size_t number);
-static void prime_print(struct prime *p);
-
-struct bus {
- int fd;
- uint8_t *pool;
-};
-
-static int bus_open_connection(struct bus **out, uid_t uid, const char *name,
- uint64_t recv_flags);
-static void bus_close_connection(struct bus *b);
-static void bus_poool_free_slice(struct bus *b, uint64_t offset);
-static int bus_acquire_name(struct bus *b, const char *name);
-static int bus_install_name_loss_match(struct bus *b, const char *name);
-static int bus_poll(struct bus *b);
-static int bus_make(uid_t uid, const char *name);
-
-struct master {
- size_t n_workers;
- size_t max_workers;
-
- int signal_fd;
- int control_fd;
-
- struct prime *prime;
- struct bus *bus;
-};
-
-static int master_new(struct master **out);
-static void master_free(struct master *m);
-static int master_run(struct master *m);
-static int master_poll(struct master *m);
-static int master_handle_stdin(struct master *m);
-static int master_handle_signal(struct master *m);
-static int master_handle_bus(struct master *m);
-static int master_reply(struct master *m, const struct kdbus_msg *msg);
-static int master_waitpid(struct master *m);
-static int master_spawn(struct master *m);
-
-struct child {
- struct bus *bus;
- struct prime *prime;
-};
-
-static int child_new(struct child **out, struct prime *p);
-static void child_free(struct child *c);
-static int child_run(struct child *c);
-
-/* END OF FORWARD DECLARATIONS */
-
-/*
- * This is the main entrypoint of this example. It is pretty straightforward. We
- * create a master object, run the computation, print a status report and then
- * exit. Nothing particularly interesting here, so lets look into the master
- * object...
- */
-int main(int argc, char **argv)
-{
- struct master *m = NULL;
- int r;
-
- r = master_new(&m);
- if (r < 0)
- goto out;
-
- r = master_run(m);
- if (r < 0)
- goto out;
-
- if (0)
- prime_print(m->prime);
-
-out:
- master_free(m);
- if (r < 0 && r != -EINTR)
- fprintf(stderr, "failed\n");
- else
- fprintf(stderr, "done\n");
- return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
-}
-
-/*
- * ...this will allocate a new master context. It keeps track of the current
- * number of children/workers that are running, manages a signalfd to track
- * SIGCHLD, and creates a private kdbus bus. Afterwards, it opens its connection
- * to the bus and acquires a well known-name (arg_master).
- */
-static int master_new(struct master **out)
-{
- struct master *m;
- sigset_t smask;
- int r;
-
- m = calloc(1, sizeof(*m));
- if (!m)
- return err("cannot allocate master");
-
- m->max_workers = WORKER_COUNT;
- m->signal_fd = -1;
- m->control_fd = -1;
-
- /* Block SIGINT and SIGCHLD signals */
- sigemptyset(&smask);
- sigaddset(&smask, SIGINT);
- sigaddset(&smask, SIGCHLD);
- sigprocmask(SIG_BLOCK, &smask, NULL);
-
- m->signal_fd = signalfd(-1, &smask, SFD_CLOEXEC);
- if (m->signal_fd < 0) {
- r = err("cannot create signalfd");
- goto error;
- }
-
- r = prime_new(&m->prime);
- if (r < 0)
- goto error;
-
- m->control_fd = bus_make(getuid(), arg_busname);
- if (m->control_fd < 0) {
- r = m->control_fd;
- goto error;
- }
-
- /*
- * Open a bus connection for the master, and require each received
- * message to have a metadata item of type KDBUS_ITEM_PIDS attached.
- * The current UID is needed to compute the name of the bus node to
- * connect to.
- */
- r = bus_open_connection(&m->bus, getuid(),
- arg_busname, KDBUS_ATTACH_PIDS);
- if (r < 0)
- goto error;
-
- /*
- * Acquire a well-known name on the bus, so children can address
- * messages to the master using KDBUS_DST_ID_NAME as destination-ID
- * of messages.
- */
- r = bus_acquire_name(m->bus, arg_master);
- if (r < 0)
- goto error;
-
- *out = m;
- return 0;
-
-error:
- master_free(m);
- return r;
-}
-
-/* pretty straightforward destructor of a master object */
-static void master_free(struct master *m)
-{
- if (!m)
- return;
-
- bus_close_connection(m->bus);
- if (m->control_fd >= 0)
- close(m->control_fd);
- prime_free(m->prime);
- if (m->signal_fd >= 0)
- close(m->signal_fd);
- free(m);
-}
-
-static int master_run(struct master *m)
-{
- int res, r = 0;
-
- while (!prime_done(m->prime)) {
- while (m->n_workers < m->max_workers) {
- r = master_spawn(m);
- if (r < 0)
- break;
- }
-
- r = master_poll(m);
- if (r < 0)
- break;
- }
-
- if (r < 0) {
- bus_close_connection(m->bus);
- m->bus = NULL;
- }
-
- while (m->n_workers > 0) {
- res = master_poll(m);
- if (res < 0) {
- if (m->bus) {
- bus_close_connection(m->bus);
- m->bus = NULL;
- }
- r = res;
- }
- }
-
- return r == -EINTR ? 0 : r;
-}
-
-static int master_poll(struct master *m)
-{
- struct pollfd fds[3] = {};
- int r = 0, n = 0;
-
- /*
- * Add stdin, the eventfd and the connection owner file descriptor to
- * the pollfd table, and handle incoming traffic on the latter in
- * master_handle_bus().
- */
- fds[n].fd = STDIN_FILENO;
- fds[n++].events = POLLIN;
- fds[n].fd = m->signal_fd;
- fds[n++].events = POLLIN;
- if (m->bus) {
- fds[n].fd = m->bus->fd;
- fds[n++].events = POLLIN;
- }
-
- r = poll(fds, n, -1);
- if (r < 0)
- return err("poll() failed");
-
- if (fds[0].revents & POLLIN)
- r = master_handle_stdin(m);
- else if (fds[0].revents)
- r = err("ERR/HUP on stdin");
- if (r < 0)
- return r;
-
- if (fds[1].revents & POLLIN)
- r = master_handle_signal(m);
- else if (fds[1].revents)
- r = err("ERR/HUP on signalfd");
- if (r < 0)
- return r;
-
- if (fds[2].revents & POLLIN)
- r = master_handle_bus(m);
- else if (fds[2].revents)
- r = err("ERR/HUP on bus");
-
- return r;
-}
-
-static int master_handle_stdin(struct master *m)
-{
- char buf[128];
- ssize_t l;
- int r = 0;
-
- l = read(STDIN_FILENO, buf, sizeof(buf));
- if (l < 0)
- return err("cannot read stdin");
- if (l == 0)
- return err_r(-EINVAL, "EOF on stdin");
-
- while (l-- > 0) {
- switch (buf[l]) {
- case 'q':
- /* quit */
- r = -EINTR;
- break;
- case '\n':
- case ' ':
- /* ignore */
- break;
- default:
- if (isgraph(buf[l]))
- fprintf(stderr, "invalid input '%c'\n", buf[l]);
- else
- fprintf(stderr, "invalid input 0x%x\n", buf[l]);
- break;
- }
- }
-
- return r;
-}
-
-static int master_handle_signal(struct master *m)
-{
- struct signalfd_siginfo val;
- ssize_t l;
-
- l = read(m->signal_fd, &val, sizeof(val));
- if (l < 0)
- return err("cannot read signalfd");
- if (l != sizeof(val))
- return err_r(-EINVAL, "invalid data from signalfd");
-
- switch (val.ssi_signo) {
- case SIGCHLD:
- return master_waitpid(m);
- case SIGINT:
- return err_r(-EINTR, "interrupted");
- default:
- return err_r(-EINVAL, "caught invalid signal");
- }
-}
-
-static int master_handle_bus(struct master *m)
-{
- struct kdbus_cmd_recv recv = { .size = sizeof(recv) };
- const struct kdbus_msg *msg = NULL;
- const struct kdbus_item *item;
- const struct kdbus_vec *vec = NULL;
- int r = 0;
-
- /*
- * To receive a message, the KDBUS_CMD_RECV ioctl is used.
- * It takes an argument of type 'struct kdbus_cmd_recv', which
- * will contain information on the received message when the call
- * returns. See kdbus.message(7).
- */
- r = kdbus_cmd_recv(m->bus->fd, &recv);
- /*
- * EAGAIN is returned when there is no message waiting on this
- * connection. This is not an error - simply bail out.
- */
- if (r == -EAGAIN)
- return 0;
- if (r < 0)
- return err_r(r, "cannot receive message");
-
- /*
- * Messages received by a connection are stored inside the connection's
- * pool, at an offset that has been returned in the 'recv' command
- * struct above. The value describes the relative offset from the
- * start address of the pool. A message is described with
- * 'struct kdbus_msg'. See kdbus.message(7).
- */
- msg = (void *)(m->bus->pool + recv.msg.offset);
-
- /*
- * A messages describes its actual payload in an array of items.
- * KDBUS_FOREACH() is a simple iterator that walks such an array.
- * struct kdbus_msg has a field to denote its total size, which is
- * needed to determine the number of items in the array.
- */
- KDBUS_FOREACH(item, msg->items,
- msg->size - offsetof(struct kdbus_msg, items)) {
- /*
- * An item of type PAYLOAD_OFF describes in-line memory
- * stored in the pool at a described offset. That offset is
- * relative to the start address of the message header.
- * This example program only expects one single item of that
- * type, remembers the struct kdbus_vec member of the item
- * when it sees it, and bails out if there is more than one
- * of them.
- */
- if (item->type == KDBUS_ITEM_PAYLOAD_OFF) {
- if (vec) {
- r = err_r(-EEXIST,
- "message with multiple vecs");
- break;
- }
- vec = &item->vec;
- if (vec->size != 1) {
- r = err_r(-EINVAL, "invalid message size");
- break;
- }
-
- /*
- * MEMFDs are transported as items of type PAYLOAD_MEMFD.
- * If such an item is attached, a new file descriptor was
- * installed into the task when KDBUS_CMD_RECV was called, and
- * its number is stored in item->memfd.fd.
- * Implementers *must* handle this item type and close the
- * file descriptor when no longer needed in order to prevent
- * file descriptor exhaustion. This example program just bails
- * out with an error in this case, as memfds are not expected
- * in this context.
- */
- } else if (item->type == KDBUS_ITEM_PAYLOAD_MEMFD) {
- r = err_r(-EINVAL, "message with memfd");
- break;
- }
- }
- if (r < 0)
- goto exit;
- if (!vec) {
- r = err_r(-EINVAL, "empty message");
- goto exit;
- }
-
- switch (*((const uint8_t *)msg + vec->offset)) {
- case 'r': {
- r = master_reply(m, msg);
- break;
- }
- default:
- r = err_r(-EINVAL, "invalid message type");
- break;
- }
-
-exit:
- /*
- * We are done with the memory slice that was given to us through
- * recv.msg.offset. Tell the kernel it can use it for other content
- * in the future. See kdbus.pool(7).
- */
- bus_poool_free_slice(m->bus, recv.msg.offset);
- return r;
-}
-
-static int master_reply(struct master *m, const struct kdbus_msg *msg)
-{
- struct kdbus_cmd_send cmd;
- struct kdbus_item *item;
- struct kdbus_msg *reply;
- size_t size, status, p[2];
- int r;
-
- /*
- * This functions sends a message over kdbus. To do this, it uses the
- * KDBUS_CMD_SEND ioctl, which takes a command struct argument of type
- * 'struct kdbus_cmd_send'. This struct stores a pointer to the actual
- * message to send. See kdbus.message(7).
- */
- p[0] = m->prime->done;
- p[1] = prime_done(m->prime) ? 0 : PRIME_STEPS;
-
- size = sizeof(*reply);
- size += KDBUS_ITEM_SIZE(sizeof(struct kdbus_vec));
-
- /* Prepare the message to send */
- reply = alloca(size);
- memset(reply, 0, size);
- reply->size = size;
-
- /* Each message has a cookie that can be used to send replies */
- reply->cookie = 1;
-
- /* The payload_type is arbitrary, but it must be non-zero */
- reply->payload_type = 0xdeadbeef;
-
- /*
- * We are sending a reply. Let the kernel know the cookie of the
- * message we are replying to.
- */
- reply->cookie_reply = msg->cookie;
-
- /*
- * Messages can either be directed to a well-known name (stored as
- * string) or to a unique name (stored as number). This example does
- * the latter. If the message would be directed to a well-known name
- * instead, the message's dst_id field would be set to
- * KDBUS_DST_ID_NAME, and the name would be attaches in an item of type
- * KDBUS_ITEM_DST_NAME. See below for an example, and also refer to
- * kdbus.message(7).
- */
- reply->dst_id = msg->src_id;
-
- /* Our message has exactly one item to store its payload */
- item = reply->items;
- item->type = KDBUS_ITEM_PAYLOAD_VEC;
- item->size = KDBUS_ITEM_HEADER_SIZE + sizeof(struct kdbus_vec);
- item->vec.address = (uintptr_t)p;
- item->vec.size = sizeof(p);
-
- /*
- * Now prepare the command struct, and reference the message we want
- * to send.
- */
- memset(&cmd, 0, sizeof(cmd));
- cmd.size = sizeof(cmd);
- cmd.msg_address = (uintptr_t)reply;
-
- /*
- * Finally, employ the command on the connection owner
- * file descriptor.
- */
- r = kdbus_cmd_send(m->bus->fd, &cmd);
- if (r < 0)
- return err_r(r, "cannot send reply");
-
- if (p[1]) {
- prime_consume(m->prime, p[1]);
- status = m->prime->done * 10000 / m->prime->max;
- if (status != m->prime->status) {
- m->prime->status = status;
- fprintf(stderr, "status: %7.3lf%%\n",
- (double)status / 100);
- }
- }
-
- return 0;
-}
-
-static int master_waitpid(struct master *m)
-{
- pid_t pid;
- int r;
-
- while ((pid = waitpid(-1, &r, WNOHANG)) > 0) {
- if (m->n_workers > 0)
- --m->n_workers;
- if (!WIFEXITED(r))
- r = err_r(-EINVAL, "child died unexpectedly");
- else if (WEXITSTATUS(r) != 0)
- r = err_r(-WEXITSTATUS(r), "child failed");
- }
-
- return r;
-}
-
-static int master_spawn(struct master *m)
-{
- struct child *c = NULL;
- struct prime *p = NULL;
- pid_t pid;
- int r;
-
- /* Spawn off one child and call child_run() inside it */
-
- pid = fork();
- if (pid < 0)
- return err("cannot fork");
- if (pid > 0) {
- /* parent */
- ++m->n_workers;
- return 0;
- }
-
- /* child */
-
- p = m->prime;
- m->prime = NULL;
- master_free(m);
-
- r = child_new(&c, p);
- if (r < 0)
- goto exit;
-
- r = child_run(c);
-
-exit:
- child_free(c);
- exit(abs(r));
-}
-
-static int child_new(struct child **out, struct prime *p)
-{
- struct child *c;
- int r;
-
- c = calloc(1, sizeof(*c));
- if (!c)
- return err("cannot allocate child");
-
- c->prime = p;
-
- /*
- * Open a connection to the bus and require each received message to
- * carry a list of the well-known names the sendind connection currently
- * owns. The current UID is needed in order to determine the name of the
- * bus node to connect to.
- */
- r = bus_open_connection(&c->bus, getuid(),
- arg_busname, KDBUS_ATTACH_NAMES);
- if (r < 0)
- goto error;
-
- /*
- * Install a kdbus match so the child's connection gets notified when
- * the master loses its well-known name.
- */
- r = bus_install_name_loss_match(c->bus, arg_master);
- if (r < 0)
- goto error;
-
- *out = c;
- return 0;
-
-error:
- child_free(c);
- return r;
-}
-
-static void child_free(struct child *c)
-{
- if (!c)
- return;
-
- bus_close_connection(c->bus);
- prime_free(c->prime);
- free(c);
-}
-
-static int child_run(struct child *c)
-{
- struct kdbus_cmd_send cmd;
- struct kdbus_item *item;
- struct kdbus_vec *vec = NULL;
- struct kdbus_msg *msg;
- struct timespec spec;
- size_t n, steps, size;
- int r = 0;
-
- /*
- * Let's send a message to the master and ask for work. To do this,
- * we use the KDBUS_CMD_SEND ioctl, which takes an argument of type
- * 'struct kdbus_cmd_send'. This struct stores a pointer to the actual
- * message to send. See kdbus.message(7).
- */
- size = sizeof(*msg);
- size += KDBUS_ITEM_SIZE(strlen(arg_master) + 1);
- size += KDBUS_ITEM_SIZE(sizeof(struct kdbus_vec));
-
- msg = alloca(size);
- memset(msg, 0, size);
- msg->size = size;
-
- /*
- * Tell the kernel that we expect a reply to this message. This means
- * that
- *
- * a) The remote peer will gain temporary permission to talk to us
- * even if it would not be allowed to normally.
- *
- * b) A timeout value is required.
- *
- * For asynchronous send commands, if no reply is received, we will
- * get a kernel notification with an item of type
- * KDBUS_ITEM_REPLY_TIMEOUT attached.
- *
- * For synchronous send commands (which this example does), the
- * ioctl will block until a reply is received or the timeout is
- * exceeded.
- */
- msg->flags = KDBUS_MSG_EXPECT_REPLY;
-
- /* Set our cookie. Replies must use this cookie to send their reply. */
- msg->cookie = 1;
-
- /* The payload_type is arbitrary, but it must be non-zero */
- msg->payload_type = 0xdeadbeef;
-
- /*
- * We are sending our message to the current owner of a well-known
- * name. This makes an item of type KDBUS_ITEM_DST_NAME mandatory.
- */
- msg->dst_id = KDBUS_DST_ID_NAME;
-
- /*
- * Set the reply timeout to 5 seconds. Timeouts are always set in
- * absolute timestamps, based con CLOCK_MONOTONIC. See kdbus.message(7).
- */
- clock_gettime(CLOCK_MONOTONIC_COARSE, &spec);
- msg->timeout_ns += (5 + spec.tv_sec) * 1000ULL * 1000ULL * 1000ULL;
- msg->timeout_ns += spec.tv_nsec;
-
- /*
- * Fill the appended items. First, set the well-known name of the
- * destination we want to talk to.
- */
- item = msg->items;
- item->type = KDBUS_ITEM_DST_NAME;
- item->size = KDBUS_ITEM_HEADER_SIZE + strlen(arg_master) + 1;
- strcpy(item->str, arg_master);
-
- /*
- * The 2nd item contains a vector to memory we want to send. It
- * can be content of any type. In our case, we're sending a one-byte
- * string only. The memory referenced by this item will be copied into
- * the pool of the receveiver connection, and does not need to be
- * valid after the command is employed.
- */
- item = KDBUS_ITEM_NEXT(item);
- item->type = KDBUS_ITEM_PAYLOAD_VEC;
- item->size = KDBUS_ITEM_HEADER_SIZE + sizeof(struct kdbus_vec);
- item->vec.address = (uintptr_t)"r";
- item->vec.size = 1;
-
- /* Set up the command struct and reference the message we prepared */
- memset(&cmd, 0, sizeof(cmd));
- cmd.size = sizeof(cmd);
- cmd.msg_address = (uintptr_t)msg;
-
- /*
- * The send commands knows a mode in which it will block until a
- * reply to a message is received. This example uses that mode.
- * The pool offset to the received reply will be stored in the command
- * struct after the send command returned. See below.
- */
- cmd.flags = KDBUS_SEND_SYNC_REPLY;
-
- /*
- * Finally, employ the command on the connection owner
- * file descriptor.
- */
- r = kdbus_cmd_send(c->bus->fd, &cmd);
- if (r == -ESRCH || r == -EPIPE || r == -ECONNRESET)
- return 0;
- if (r < 0)
- return err_r(r, "cannot send request to master");
-
- /*
- * The command was sent with the KDBUS_SEND_SYNC_REPLY flag set,
- * and returned successfully, which means that cmd.reply.offset now
- * points to a message inside our connection's pool where the reply
- * is found. This is equivalent to receiving the reply with
- * KDBUS_CMD_RECV, but it doesn't require waiting for the reply with
- * poll() and also saves the ioctl to receive the message.
- */
- msg = (void *)(c->bus->pool + cmd.reply.offset);
-
- /*
- * A messages describes its actual payload in an array of items.
- * KDBUS_FOREACH() is a simple iterator that walks such an array.
- * struct kdbus_msg has a field to denote its total size, which is
- * needed to determine the number of items in the array.
- */
- KDBUS_FOREACH(item, msg->items,
- msg->size - offsetof(struct kdbus_msg, items)) {
- /*
- * An item of type PAYLOAD_OFF describes in-line memory
- * stored in the pool at a described offset. That offset is
- * relative to the start address of the message header.
- * This example program only expects one single item of that
- * type, remembers the struct kdbus_vec member of the item
- * when it sees it, and bails out if there is more than one
- * of them.
- */
- if (item->type == KDBUS_ITEM_PAYLOAD_OFF) {
- if (vec) {
- r = err_r(-EEXIST,
- "message with multiple vecs");
- break;
- }
- vec = &item->vec;
- if (vec->size != 2 * sizeof(size_t)) {
- r = err_r(-EINVAL, "invalid message size");
- break;
- }
- /*
- * MEMFDs are transported as items of type PAYLOAD_MEMFD.
- * If such an item is attached, a new file descriptor was
- * installed into the task when KDBUS_CMD_RECV was called, and
- * its number is stored in item->memfd.fd.
- * Implementers *must* handle this item type close the
- * file descriptor when no longer needed in order to prevent
- * file descriptor exhaustion. This example program just bails
- * out with an error in this case, as memfds are not expected
- * in this context.
- */
- } else if (item->type == KDBUS_ITEM_PAYLOAD_MEMFD) {
- r = err_r(-EINVAL, "message with memfd");
- break;
- }
- }
- if (r < 0)
- goto exit;
- if (!vec) {
- r = err_r(-EINVAL, "empty message");
- goto exit;
- }
-
- n = ((size_t *)((const uint8_t *)msg + vec->offset))[0];
- steps = ((size_t *)((const uint8_t *)msg + vec->offset))[1];
-
- while (steps-- > 0) {
- ++n;
- r = prime_run(c->prime, c->bus, n);
- if (r < 0)
- break;
- r = bus_poll(c->bus);
- if (r != 0) {
- r = r < 0 ? r : -EINTR;
- break;
- }
- }
-
-exit:
- /*
- * We are done with the memory slice that was given to us through
- * cmd.reply.offset. Tell the kernel it can use it for other content
- * in the future. See kdbus.pool(7).
- */
- bus_poool_free_slice(c->bus, cmd.reply.offset);
- return r;
-}
-
-/*
- * Prime Computation
- *
- */
-
-static int prime_new(struct prime **out)
-{
- struct prime *p;
- int r;
-
- p = calloc(1, sizeof(*p));
- if (!p)
- return err("cannot allocate prime memory");
-
- p->fd = -1;
- p->area = MAP_FAILED;
- p->max = MAX_PRIMES;
-
- /*
- * Prepare and map a memfd to store the bit-fields for the number
- * ranges we want to perform the prime detection on.
- */
- p->fd = syscall(__NR_memfd_create, "prime-area", MFD_CLOEXEC);
- if (p->fd < 0) {
- r = err("cannot create memfd");
- goto error;
- }
-
- r = ftruncate(p->fd, p->max / 8 + 1);
- if (r < 0) {
- r = err("cannot ftruncate area");
- goto error;
- }
-
- p->area = mmap(NULL, p->max / 8 + 1, PROT_READ | PROT_WRITE,
- MAP_SHARED, p->fd, 0);
- if (p->area == MAP_FAILED) {
- r = err("cannot mmap memfd");
- goto error;
- }
-
- *out = p;
- return 0;
-
-error:
- prime_free(p);
- return r;
-}
-
-static void prime_free(struct prime *p)
-{
- if (!p)
- return;
-
- if (p->area != MAP_FAILED)
- munmap(p->area, p->max / 8 + 1);
- if (p->fd >= 0)
- close(p->fd);
- free(p);
-}
-
-static bool prime_done(struct prime *p)
-{
- return p->done >= p->max;
-}
-
-static void prime_consume(struct prime *p, size_t amount)
-{
- p->done += amount;
-}
-
-static int prime_run(struct prime *p, struct bus *cancel, size_t number)
-{
- size_t i, n = 0;
- int r;
-
- if (number < 2 || number > 65535)
- return 0;
-
- for (i = number * number;
- i < p->max && i > number;
- i += number) {
- p->area[i / 8] |= 1 << (i % 8);
-
- if (!(++n % (1 << 20))) {
- r = bus_poll(cancel);
- if (r != 0)
- return r < 0 ? r : -EINTR;
- }
- }
-
- return 0;
-}
-
-static void prime_print(struct prime *p)
-{
- size_t i, l = 0;
-
- fprintf(stderr, "PRIMES:");
- for (i = 0; i < p->max; ++i) {
- if (!(p->area[i / 8] & (1 << (i % 8))))
- fprintf(stderr, "%c%7zu", !(l++ % 16) ? '\n' : ' ', i);
- }
- fprintf(stderr, "\nEND\n");
-}
-
-static int bus_open_connection(struct bus **out, uid_t uid, const char *name,
- uint64_t recv_flags)
-{
- struct kdbus_cmd_hello hello;
- char path[128];
- struct bus *b;
- int r;
-
- /*
- * The 'bus' object is our representation of a kdbus connection which
- * stores two details: the connection owner file descriptor, and the
- * mmap()ed memory of its associated pool. See kdbus.connection(7) and
- * kdbus.pool(7).
- */
- b = calloc(1, sizeof(*b));
- if (!b)
- return err("cannot allocate bus memory");
-
- b->fd = -1;
- b->pool = MAP_FAILED;
-
- /* Compute the name of the bus node to connect to. */
- snprintf(path, sizeof(path), "/sys/fs/%s/%lu-%s/bus",
- arg_modname, (unsigned long)uid, name);
- b->fd = open(path, O_RDWR | O_CLOEXEC);
- if (b->fd < 0) {
- r = err("cannot open bus");
- goto error;
- }
-
- /*
- * To make a connection to the bus, the KDBUS_CMD_HELLO ioctl is used.
- * It takes an argument of type 'struct kdbus_cmd_hello'.
- */
- memset(&hello, 0, sizeof(hello));
- hello.size = sizeof(hello);
-
- /*
- * Specify a mask of metadata attach flags, describing metadata items
- * that this new connection allows to be sent.
- */
- hello.attach_flags_send = _KDBUS_ATTACH_ALL;
-
- /*
- * Specify a mask of metadata attach flags, describing metadata items
- * that this new connection wants to be receive along with each message.
- */
- hello.attach_flags_recv = recv_flags;
-
- /*
- * A connection may choose the size of its pool, but the number has to
- * comply with two rules: a) it must be greater than 0, and b) it must
- * be a mulitple of PAGE_SIZE. See kdbus.pool(7).
- */
- hello.pool_size = POOL_SIZE;
-
- /*
- * Now employ the command on the file descriptor opened above.
- * This command will turn the file descriptor into a connection-owner
- * file descriptor that controls the life-time of the connection; once
- * it's closed, the connection is shut down.
- */
- r = kdbus_cmd_hello(b->fd, &hello);
- if (r < 0) {
- err_r(r, "HELLO failed");
- goto error;
- }
-
- bus_poool_free_slice(b, hello.offset);
-
- /*
- * Map the pool of the connection. Its size has been set in the
- * command struct above. See kdbus.pool(7).
- */
- b->pool = mmap(NULL, POOL_SIZE, PROT_READ, MAP_SHARED, b->fd, 0);
- if (b->pool == MAP_FAILED) {
- r = err("cannot mmap pool");
- goto error;
- }
-
- *out = b;
- return 0;
-
-error:
- bus_close_connection(b);
- return r;
-}
-
-static void bus_close_connection(struct bus *b)
-{
- if (!b)
- return;
-
- /*
- * A bus connection is closed by simply calling close() on the
- * connection owner file descriptor. The unique name and all owned
- * well-known names of the conneciton will disappear.
- * See kdbus.connection(7).
- */
- if (b->pool != MAP_FAILED)
- munmap(b->pool, POOL_SIZE);
- if (b->fd >= 0)
- close(b->fd);
- free(b);
-}
-
-static void bus_poool_free_slice(struct bus *b, uint64_t offset)
-{
- struct kdbus_cmd_free cmd = {
- .size = sizeof(cmd),
- .offset = offset,
- };
- int r;
-
- /*
- * Once we're done with a piece of pool memory that was returned
- * by a command, we have to call the KDBUS_CMD_FREE ioctl on it so it
- * can be reused. The command takes an argument of type
- * 'struct kdbus_cmd_free', in which the pool offset of the slice to
- * free is stored. The ioctl is employed on the connection owner
- * file descriptor. See kdbus.pool(7),
- */
- r = kdbus_cmd_free(b->fd, &cmd);
- if (r < 0)
- err_r(r, "cannot free pool slice");
-}
-
-static int bus_acquire_name(struct bus *b, const char *name)
-{
- struct kdbus_item *item;
- struct kdbus_cmd *cmd;
- size_t size;
- int r;
-
- /*
- * This function acquires a well-known name on the bus through the
- * KDBUS_CMD_NAME_ACQUIRE ioctl. This ioctl takes an argument of type
- * 'struct kdbus_cmd', which is assembled below. See kdbus.name(7).
- */
- size = sizeof(*cmd);
- size += KDBUS_ITEM_SIZE(strlen(name) + 1);
-
- cmd = alloca(size);
- memset(cmd, 0, size);
- cmd->size = size;
-
- /*
- * The command requires an item of type KDBUS_ITEM_NAME, and its
- * content must be a valid bus name.
- */
- item = cmd->items;
- item->type = KDBUS_ITEM_NAME;
- item->size = KDBUS_ITEM_HEADER_SIZE + strlen(name) + 1;
- strcpy(item->str, name);
-
- /*
- * Employ the command on the connection owner file descriptor.
- */
- r = kdbus_cmd_name_acquire(b->fd, cmd);
- if (r < 0)
- return err_r(r, "cannot acquire name");
-
- return 0;
-}
-
-static int bus_install_name_loss_match(struct bus *b, const char *name)
-{
- struct kdbus_cmd_match *match;
- struct kdbus_item *item;
- size_t size;
- int r;
-
- /*
- * In order to install a match for signal messages, we have to
- * assemble a 'struct kdbus_cmd_match' and use it along with the
- * KDBUS_CMD_MATCH_ADD ioctl. See kdbus.match(7).
- */
- size = sizeof(*match);
- size += KDBUS_ITEM_SIZE(sizeof(item->name_change) + strlen(name) + 1);
-
- match = alloca(size);
- memset(match, 0, size);
- match->size = size;
-
- /*
- * A match is comprised of many 'rules', each of which describes a
- * mandatory detail of the message. All rules of a match must be
- * satified in order to make a message pass.
- */
- item = match->items;
-
- /*
- * In this case, we're interested in notifications that inform us
- * about a well-known name being removed from the bus.
- */
- item->type = KDBUS_ITEM_NAME_REMOVE;
- item->size = KDBUS_ITEM_HEADER_SIZE +
- sizeof(item->name_change) + strlen(name) + 1;
-
- /*
- * We could limit the match further and require a specific unique-ID
- * to be the new or the old owner of the name. In this case, however,
- * we don't, and allow 'any' id.
- */
- item->name_change.old_id.id = KDBUS_MATCH_ID_ANY;
- item->name_change.new_id.id = KDBUS_MATCH_ID_ANY;
-
- /* Copy in the well-known name we're interested in */
- strcpy(item->name_change.name, name);
-
- /*
- * Add the match through the KDBUS_CMD_MATCH_ADD ioctl, employed on
- * the connection owner fd.
- */
- r = kdbus_cmd_match_add(b->fd, match);
- if (r < 0)
- return err_r(r, "cannot add match");
-
- return 0;
-}
-
-static int bus_poll(struct bus *b)
-{
- struct pollfd fds[1] = {};
- int r;
-
- /*
- * A connection endpoint supports poll() and will wake-up the
- * task with POLLIN set once a message has arrived.
- */
- fds[0].fd = b->fd;
- fds[0].events = POLLIN;
- r = poll(fds, sizeof(fds) / sizeof(*fds), 0);
- if (r < 0)
- return err("cannot poll bus");
- return !!(fds[0].revents & POLLIN);
-}
-
-static int bus_make(uid_t uid, const char *name)
-{
- struct kdbus_item *item;
- struct kdbus_cmd *make;
- char path[128], busname[128];
- size_t size;
- int r, fd;
-
- /*
- * Compute the full path to the 'control' node. 'arg_modname' may be
- * set to a different value than 'kdbus' for development purposes.
- * The 'control' node is the primary entry point to kdbus that must be
- * used in order to create a bus. See kdbus(7) and kdbus.bus(7).
- */
- snprintf(path, sizeof(path), "/sys/fs/%s/control", arg_modname);
-
- /*
- * Compute the bus name. A valid bus name must always be prefixed with
- * the EUID of the currently running process in order to avoid name
- * conflicts. See kdbus.bus(7).
- */
- snprintf(busname, sizeof(busname), "%lu-%s", (unsigned long)uid, name);
-
- fd = open(path, O_RDWR | O_CLOEXEC);
- if (fd < 0)
- return err("cannot open control file");
-
- /*
- * The KDBUS_CMD_BUS_MAKE ioctl takes an argument of type
- * 'struct kdbus_cmd', and expects at least two items attached to
- * it: one to decribe the bloom parameters to be propagated to
- * connections of the bus, and the name of the bus that was computed
- * above. Assemble this struct now, and fill it with values.
- */
- size = sizeof(*make);
- size += KDBUS_ITEM_SIZE(sizeof(struct kdbus_bloom_parameter));
- size += KDBUS_ITEM_SIZE(strlen(busname) + 1);
-
- make = alloca(size);
- memset(make, 0, size);
- make->size = size;
-
- /*
- * Each item has a 'type' and 'size' field, and must be stored at an
- * 8-byte aligned address. The KDBUS_ITEM_NEXT macro is used to advance
- * the pointer. See kdbus.item(7) for more details.
- */
- item = make->items;
- item->type = KDBUS_ITEM_BLOOM_PARAMETER;
- item->size = KDBUS_ITEM_HEADER_SIZE + sizeof(item->bloom_parameter);
- item->bloom_parameter.size = 8;
- item->bloom_parameter.n_hash = 1;
-
- /* The name of the new bus is stored in the next item. */
- item = KDBUS_ITEM_NEXT(item);
- item->type = KDBUS_ITEM_MAKE_NAME;
- item->size = KDBUS_ITEM_HEADER_SIZE + strlen(busname) + 1;
- strcpy(item->str, busname);
-
- /*
- * Now create the bus via the KDBUS_CMD_BUS_MAKE ioctl and return the
- * fd that was used back to the caller of this function. This fd is now
- * called a 'bus owner file descriptor', and it controls the life-time
- * of the newly created bus; once the file descriptor is closed, the
- * bus goes away, and all connections are shut down. See kdbus.bus(7).
- */
- r = kdbus_cmd_bus_make(fd, make);
- if (r < 0) {
- err_r(r, "cannot make bus");
- close(fd);
- return r;
- }
-
- return fd;
-}
projects / platform / kernel / linux-exynos.git / commitdiff