lib/roken/detach.c

   1 /*-
   2  * Copyright (c) 2015
   3  *      Cryptonector LLC.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Cryptonector LLC may not be used to endorse or promote products
  14  *    derived from this software without specific prior written
  15  *    permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 #include <config.h>
  31 #include <errno.h>
  32 #include <fcntl.h>
  33 #ifdef WIN32
  34 #include <io.h>
  35 #include <stdlib.h>
  36 #else
  37 #include <unistd.h>
  38 #endif
  39 #include "roken.h"
  40
  41 #ifdef WIN32
  42 #define dup2 _dup2
  43 #endif
  44
  45 static int pipefds[2] = {-1, -1};
  46
  47 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
  48 roken_detach_prep(int argc, char **argv, char *special_arg)
  49 {
  50     pid_t child;
  51     char buf[1];
  52     ssize_t bytes;
  53     int status;
  54
  55     pipefds[0] = -1;
  56     pipefds[1] = -1;
  57
  58 #ifdef WIN32
  59     if (_pipe(pipefds, 4, O_BINARY) == -1)
  60         err(1, "failed to setup to detach daemon (_pipe failed)");
  61 #else
  62     if (pipe(pipefds) == -1)
  63         err(1, "failed to setup to detach daemon (pipe failed)");
  64 #endif
  65
  66 #ifndef WIN32
  67     fflush(stdout);
  68     child = fork();
  69 #else
  70     {
  71         intptr_t child_handle;
  72         int write_side;
  73         size_t i;
  74         char *fildes;
  75         char **new_argv;
  76
  77         new_argv = calloc(argc + 2, sizeof(*new_argv));
  78         if (new_argv == NULL)
  79             err(1, "Out of memory");
  80
  81         write_side = _dup(pipefds[1]); /* The new fd will be inherited */
  82         if (write_side == -1)
  83             err(1, "Out of memory");
  84
  85         if (asprintf(&fildes, "%d", write_side) == -1 ||
  86             fildes == NULL)
  87             err(1, "failed to setup to detach daemon (_dup failed)");
  88
  89         new_argv[0] = argv[0];
  90         new_argv[1] = special_arg;
  91         new_argv[2] = fildes;
  92         for (i = 1; argv[i] != NULL; i++)
  93             new_argv[i + 1] = argv[i];
  94         new_argv[argc + 2] = NULL;
  95
  96         _flushall();
  97         child_handle = spawnvp(_P_NOWAIT, argv[0], new_argv);
  98         if (child_handle == -1)
  99           child = (pid_t)-1;
 100         else
 101           child = GetProcessId((HANDLE)child_handle);
 102     }
 103 #endif
 104     if (child == (pid_t)-1)
 105         err(1, "failed to setup to fork daemon (fork failed)");
 106
 107 #ifndef WIN32
 108     if (child == 0) {
 109         int fd;
 110
 111         (void) close(pipefds[0]);
 112         pipefds[0] = -1;
 113         /*
 114          * Keep stdout/stderr for now so output and errors prior to
 115          * detach_finish() can be seen by the user.
 116          */
 117         fd = open(_PATH_DEVNULL, O_RDWR, 0);
 118         if (fd == -1)
 119             err(1, "failed to open /dev/null");
 120         (void) dup2(fd, STDIN_FILENO);
 121         if (fd > STDERR_FILENO)
 122             (void) close(fd);
 123         return;
 124     }
 125 #endif
 126
 127     (void) close(pipefds[1]);
 128     pipefds[1] = -1;
 129     do {
 130         bytes = read(pipefds[0], buf, sizeof(buf));
 131     } while (bytes == -1 && errno == EINTR);
 132     if (bytes == -1) {
 133         /*
 134          * No need to wait for the process.  We've killed it.  If it
 135          * doesn't want to exit, we'd have to wait potentially forever,
 136          * but we want to indicate failure to the user as soon as
 137          * possible.  A wait with timeout would end the same way
 138          * (attempting to kill the process).
 139          */
 140         err(1, "failed to setup daemon child (read from child pipe)");
 141     }
 142     if (bytes == 0) {
 143         warnx("daemon child preparation failed, waiting for child");
 144         status = wait_for_process(child);
 145         if (SE_IS_ERROR(status) || SE_PROCSTATUS(status) != 0)
 146             errx(SE_PROCSTATUS(status),
 147                  "daemon child preparation failed (child exited)");
 148     }
 149     _exit(0);
 150 }
 151
 152 #ifdef WIN32
 153 #ifdef dup2
 154 #undef dup2
 155 #endif
 156 #define dup2 _dup2
 157 #endif
 158
 159 ROKEN_LIB_FUNCTION void ROKEN_LIB_CALL
 160 roken_detach_finish(const char *dir, int daemon_child_fd)
 161 {
 162     char buf[1] = "";
 163     ssize_t bytes;
 164     int fd;
 165
 166     if (pipefds[1] == -1 && daemon_child_fd != -1)
 167         pipefds[1] = daemon_child_fd;
 168     if (pipefds[0] != -1)
 169         (void) close(pipefds[0]);
 170     if (pipefds[1] == -1)
 171         return;
 172
 173 #ifdef HAVE_SETSID
 174     if (setsid() == -1)
 175         err(1, "failed to detach from tty");
 176 #endif
 177
 178 #ifndef WIN32
 179     /*
 180      * Hopefully we've written any pidfiles by now, if they had to be in
 181      * the current directory...
 182      *
 183      * The daemons do re-open logs and so on, therefore this chdir()
 184      * call needs to be optional for testing.
 185      */
 186     if (dir != NULL && chdir(dir) == -1)
 187         err(1, "failed to chdir to /");
 188 #endif
 189
 190     do {
 191         bytes = write(pipefds[1], buf, sizeof(buf));
 192     } while (bytes == -1 && errno == EINTR);
 193     if (bytes == -1)
 194         err(1, "failed to signal parent while detaching");
 195     (void) close(pipefds[1]);
 196     if (bytes != sizeof(buf))
 197         errx(1, "failed to signal parent while detaching");
 198
 199     fd = open(_PATH_DEVNULL, O_RDWR, 0);
 200     if (fd == -1)
 201         err(1, "failed to open /dev/null");
 202     /*
 203      * Maybe we should check that our output got written, if redirected
 204      * to a file.  File utils normally do this.
 205      */
 206     (void) dup2(fd, STDOUT_FILENO);
 207     (void) dup2(fd, STDERR_FILENO);
 208     if (fd > 2)
 209         (void) close(fd);
 210 }