lib/libdpv/util.c

   1 /*-
   2  * Copyright (c) 2013-2014 Devin Teske <dteske@FreeBSD.org>
   3  * 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  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  */
  26
  27 #include <sys/cdefs.h>
  28 __FBSDID("$FreeBSD$");
  29
  30 #include <err.h>
  31 #include <limits.h>
  32 #include <spawn.h>
  33 #include <stdio.h>
  34 #include <stdlib.h>
  35 #include <unistd.h>
  36
  37 #include "util.h"
  38
  39 extern char **environ;
  40 static char cmdbuf[CMDBUFMAX]   = "";
  41 static char shellcmd[PATH_MAX]  = PATH_SHELL;
  42 static char *shellcmd_argv[6]   = {
  43         shellcmd,
  44         __DECONST(char *, "-c"),
  45         cmdbuf,
  46         __DECONST(char *, "--"),
  47         shellcmd,
  48         NULL,
  49 };
  50
  51 /*
  52  * Spawn a sh(1) command. Writes the resulting process ID to the pid_t pointed
  53  * at by `pid'. Returns a file descriptor (int) suitable for writing data to
  54  * the spawned command (data written to file descriptor is seen as standard-in
  55  * by the spawned sh(1) command). Returns `-1' if unable to spawn command.
  56  *
  57  * If cmd contains a single "%s" sequence, replace it with label if non-NULL.
  58  */
  59 int
  60 shell_spawn_pipecmd(const char *cmd, const char *label, pid_t *pid)
  61 {
  62         int error;
  63         int len;
  64         posix_spawn_file_actions_t action;
  65 #if SHELL_SPAWN_DEBUG
  66         unsigned int i;
  67 #endif
  68         int stdin_pipe[2] = { -1, -1 };
  69
  70         /* Populate argument array */
  71         if (label != NULL && fmtcheck(cmd, "%s") == cmd)
  72                 len = snprintf(cmdbuf, CMDBUFMAX, cmd, label);
  73         else
  74                 len = snprintf(cmdbuf, CMDBUFMAX, "%s", cmd);
  75         if (len >= CMDBUFMAX) {
  76                 warnx("%s:%d:%s: cmdbuf[%u] too small to hold cmd argument",
  77                     __FILE__, __LINE__, __func__, CMDBUFMAX);
  78                 return (-1);
  79         }
  80
  81         /* Open a pipe to communicate with [X]dialog(1) */
  82         if (pipe(stdin_pipe) < 0)
  83                 err(EXIT_FAILURE, "%s: pipe(2)", __func__);
  84
  85         /* Fork sh(1) process */
  86 #if SHELL_SPAWN_DEBUG
  87         fprintf(stderr, "%s: spawning `", __func__);
  88         for (i = 0; shellcmd_argv[i] != NULL; i++) {
  89                 if (i == 0)
  90                         fprintf(stderr, "%s", shellcmd_argv[i]);
  91                 else if (i == 2)
  92                         fprintf(stderr, " '%s'", shellcmd_argv[i]);
  93                 else
  94                         fprintf(stderr, " %s", shellcmd_argv[i]);
  95         }
  96         fprintf(stderr, "'\n");
  97 #endif
  98         posix_spawn_file_actions_init(&action);
  99         posix_spawn_file_actions_adddup2(&action, stdin_pipe[0], STDIN_FILENO);
 100         posix_spawn_file_actions_addclose(&action, stdin_pipe[1]);
 101         error = posix_spawnp(pid, shellcmd, &action,
 102             (const posix_spawnattr_t *)NULL, shellcmd_argv, environ);
 103         if (error != 0)
 104                 err(EXIT_FAILURE, "%s: posix_spawnp(3)", __func__);
 105
 106         return stdin_pipe[1];
 107 }