external/ibm-public/postfix/dist/src/util/exec_command.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      exec_command 3
   6 /* SUMMARY
   7 /*      execute command
   8 /* SYNOPSIS
   9 /*      #include <exec_command.h>
  10 /*
  11 /*      NORETURN exec_command(command)
  12 /*      const char *command;
  13 /* DESCRIPTION
  14 /*      \fIexec_command\fR() replaces the current process by an instance
  15 /*      of \fIcommand\fR. This routine uses a simple heuristic to avoid
  16 /*      the overhead of running a command shell interpreter.
  17 /* DIAGNOSTICS
  18 /*      This routine never returns. All errors are fatal.
  19 /* LICENSE
  20 /* .ad
  21 /* .fi
  22 /*      The Secure Mailer license must be distributed with this software.
  23 /* AUTHOR(S)
  24 /*      Wietse Venema
  25 /*      IBM T.J. Watson Research
  26 /*      P.O. Box 704
  27 /*      Yorktown Heights, NY 10598, USA
  28 /*--*/
  29
  30 /* System library. */
  31
  32 #include <sys_defs.h>
  33 #include <unistd.h>
  34 #include <string.h>
  35 #ifdef USE_PATHS_H
  36 #include <paths.h>
  37 #endif
  38 #include <errno.h>
  39 #include <string.h>
  40
  41 /* Utility library. */
  42
  43 #include <msg.h>
  44 #include <argv.h>
  45 #include <exec_command.h>
  46
  47 /* Application-specific. */
  48
  49 #define SPACE_TAB       " \t"
  50
  51 /* exec_command - exec command */
  52
  53 NORETURN exec_command(const char *command)
  54 {
  55     ARGV   *argv;
  56
  57     /*
  58      * Character filter. In this particular case, we allow space and tab in
  59      * addition to the regular character set.
  60      */
  61     static char ok_chars[] = "1234567890!@%-_=+:,./\
  62 abcdefghijklmnopqrstuvwxyz\
  63 ABCDEFGHIJKLMNOPQRSTUVWXYZ" SPACE_TAB;
  64
  65     /*
  66      * See if this command contains any shell magic characters.
  67      */
  68     if (command[strspn(command, ok_chars)] == 0) {
  69
  70         /*
  71          * No shell meta characters found, so we can try to avoid the overhead
  72          * of running a shell. Just split the command on whitespace and exec
  73          * the result directly.
  74          */
  75         argv = argv_split(command, SPACE_TAB);
  76         (void) execvp(argv->argv[0], argv->argv);
  77
  78         /*
  79          * Auch. Perhaps they're using some shell built-in command.
  80          */
  81         if (errno != ENOENT || strchr(argv->argv[0], '/') != 0)
  82             msg_fatal("execvp %s: %m", argv->argv[0]);
  83
  84         /*
  85          * Not really necessary, but...
  86          */
  87         argv_free(argv);
  88     }
  89
  90     /*
  91      * Pass the command to a shell.
  92      */
  93     (void) execl(_PATH_BSHELL, "sh", "-c", command, (char *) 0);
  94     msg_fatal("execl %s: %m", _PATH_BSHELL);
  95 }
  96
  97 #ifdef TEST
  98
  99  /*
 100   * Yet another proof-of-concept test program.
 101   */
 102 #include <vstream.h>
 103 #include <msg_vstream.h>
 104
 105 int     main(int argc, char **argv)
 106 {
 107     msg_vstream_init(argv[0], VSTREAM_ERR);
 108     if (argc != 2)
 109         msg_fatal("usage: %s 'command'", argv[0]);
 110     exec_command(argv[1]);
 111 }
 112
 113 #endif