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mconsole_user.c

/*
 * Copyright (C) 2001 Lennert Buytenhek (buytenh@gnu.org)
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <sys/un.h>
#include "kern_constants.h"
#include "mconsole.h"
#include "user.h"

static struct mconsole_command commands[] = {
      /*
       * With uts namespaces, uts information becomes process-specific, so
       * we need a process context.  If we try handling this in interrupt
       * context, we may hit an exiting process without a valid uts
       * namespace.
       */
      { "version", mconsole_version, MCONSOLE_PROC },
      { "halt", mconsole_halt, MCONSOLE_PROC },
      { "reboot", mconsole_reboot, MCONSOLE_PROC },
      { "config", mconsole_config, MCONSOLE_PROC },
      { "remove", mconsole_remove, MCONSOLE_PROC },
      { "sysrq", mconsole_sysrq, MCONSOLE_INTR },
      { "help", mconsole_help, MCONSOLE_INTR },
      { "cad", mconsole_cad, MCONSOLE_INTR },
      { "stop", mconsole_stop, MCONSOLE_PROC },
      { "go", mconsole_go, MCONSOLE_INTR },
      { "log", mconsole_log, MCONSOLE_INTR },
      { "proc", mconsole_proc, MCONSOLE_PROC },
      { "stack", mconsole_stack, MCONSOLE_INTR },
};

/* Initialized in mconsole_init, which is an initcall */
char mconsole_socket_name[256];

static int mconsole_reply_v0(struct mc_request *req, char *reply)
{
      struct iovec iov;
      struct msghdr msg;

      iov.iov_base = reply;
      iov.iov_len = strlen(reply);

      msg.msg_name = &(req->origin);
      msg.msg_namelen = req->originlen;
      msg.msg_iov = &iov;
      msg.msg_iovlen = 1;
      msg.msg_control = NULL;
      msg.msg_controllen = 0;
      msg.msg_flags = 0;

      return sendmsg(req->originating_fd, &msg, 0);
}

static struct mconsole_command *mconsole_parse(struct mc_request *req)
{
      struct mconsole_command *cmd;
      int i;

      for (i = 0; i < ARRAY_SIZE(commands); i++) {
            cmd = &commands[i];
            if (!strncmp(req->request.data, cmd->command,
                      strlen(cmd->command))) {
                  return cmd;
            }
      }
      return NULL;
}

#define MIN(a,b) ((a)<(b) ? (a):(b))

#define STRINGX(x) #x
#define STRING(x) STRINGX(x)

int mconsole_get_request(int fd, struct mc_request *req)
{
      int len;

      req->originlen = sizeof(req->origin);
      req->len = recvfrom(fd, &req->request, sizeof(req->request), 0,
                      (struct sockaddr *) req->origin, &req->originlen);
      if (req->len < 0)
            return 0;

      req->originating_fd = fd;

      if (req->request.magic != MCONSOLE_MAGIC) {
            /* Unversioned request */
            len = MIN(sizeof(req->request.data) - 1,
                    strlen((char *) &req->request));
            memmove(req->request.data, &req->request, len);
            req->request.data[len] = '\0';

            req->request.magic = MCONSOLE_MAGIC;
            req->request.version = 0;
            req->request.len = len;

            mconsole_reply_v0(req, "ERR Version 0 mconsole clients are "
                          "not supported by this driver");
            return 0;
      }

      if (req->request.len >= MCONSOLE_MAX_DATA) {
            mconsole_reply(req, "Request too large", 1, 0);
            return 0;
      }
      if (req->request.version != MCONSOLE_VERSION) {
            mconsole_reply(req, "This driver only supports version "
                         STRING(MCONSOLE_VERSION) " clients", 1, 0);
      }

      req->request.data[req->request.len] = '\0';
      req->cmd = mconsole_parse(req);
      if (req->cmd == NULL) {
            mconsole_reply(req, "Unknown command", 1, 0);
            return 0;
      }

      return 1;
}

int mconsole_reply_len(struct mc_request *req, const char *str, int total,
                   int err, int more)
{
      /*
       * XXX This is a stack consumption problem.  It'd be nice to
       * make it global and serialize access to it, but there are a
       * ton of callers to this function.
       */
      struct mconsole_reply reply;
      int len, n;

      do {
            reply.err = err;

            /* err can only be true on the first packet */
            err = 0;

            len = MIN(total, MCONSOLE_MAX_DATA - 1);

            if (len == total) reply.more = more;
            else reply.more = 1;

            memcpy(reply.data, str, len);
            reply.data[len] = '\0';
            total -= len;
            str += len;
            reply.len = len + 1;

            len = sizeof(reply) + reply.len - sizeof(reply.data);

            n = sendto(req->originating_fd, &reply, len, 0,
                     (struct sockaddr *) req->origin, req->originlen);

            if (n < 0)
                  return -errno;
      } while (total > 0);
      return 0;
}

int mconsole_reply(struct mc_request *req, const char *str, int err, int more)
{
      return mconsole_reply_len(req, str, strlen(str), err, more);
}


int mconsole_unlink_socket(void)
{
      unlink(mconsole_socket_name);
      return 0;
}

static int notify_sock = -1;

int mconsole_notify(char *sock_name, int type, const void *data, int len)
{
      struct sockaddr_un target;
      struct mconsole_notify packet;
      int n, err = 0;

      lock_notify();
      if (notify_sock < 0) {
            notify_sock = socket(PF_UNIX, SOCK_DGRAM, 0);
            if (notify_sock < 0) {
                  err = -errno;
                  printk(UM_KERN_ERR "mconsole_notify - socket failed, "
                         "errno = %d\n", errno);
            }
      }
      unlock_notify();

      if (err)
            return err;

      target.sun_family = AF_UNIX;
      strcpy(target.sun_path, sock_name);

      packet.magic = MCONSOLE_MAGIC;
      packet.version = MCONSOLE_VERSION;
      packet.type = type;
      len = (len > sizeof(packet.data)) ? sizeof(packet.data) : len;
      packet.len = len;
      memcpy(packet.data, data, len);

      err = 0;
      len = sizeof(packet) + packet.len - sizeof(packet.data);
      n = sendto(notify_sock, &packet, len, 0, (struct sockaddr *) &target,
               sizeof(target));
      if (n < 0) {
            err = -errno;
            printk(UM_KERN_ERR "mconsole_notify - sendto failed, "
                   "errno = %d\n", errno);
      }
      return err;
}

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