include/wvsystem.h

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 1997-2002 Net Integration Technologies, Inc.
   4  */
   5 #ifndef __WVSYSTEM_H
   6 #define __WVSYSTEM_H
   7
   8 #include "wvsubproc.h"
   9
  10 /**
  11  * WvSystem is a mostly-replacement for the libc system() function call,
  12  * which people usually use because of its notational convenience, not
  13  * because it calls the Unix shell.  In fact, some people don't even realize
  14  * it calls the shell, leading to security holes when people forget to
  15  * quote user-provided parameters correctly.
  16  *
  17  * WvSystem() uses WvSubProc but makes sure it can be called in a single
  18  * line of C++ code with a minimum of fluff.  For example:
  19  *
  20  *    WvSystem("rm", "-rf", filename, NULL);
  21  * is like
  22  *    system(WvString("rm -rf %s", filename));
  23  * except that you don't have weird security bugs if "filename" contains
  24  * special characters like newline, space, quotation mark, etc.
  25  *
  26  * See WvSubProc and WvSubProcQueue for less concise, but more flexible ways
  27  * to run subprograms.
  28  */
  29 class WvSystem : private WvSubProc
  30 {
  31 public:
  32     /**
  33      * Construct a WvSystem from a simple list of strings.
  34      *
  35      * For example:
  36      *    WvSystem("rm", "-rf", dirname);
  37      *
  38      * Note: this is unlike WvSubProc::prepare(cmd, ...) because you
  39      * don't need to provide argv[0] yourself.  "cmd" is automatically
  40      * inserted as argv[0].  It also lets you pass WvString objects in
  41      * without manually calling cstr(), because it doesn't use varargs.
  42      * Unfortunately, that means it's limited to 20 arguments.
  43      */
  44     WvSystem(const char cmd[],
  45              const char *a0 = NULL,
  46              const char *a1 = NULL,
  47              const char *a2 = NULL,
  48              const char *a3 = NULL,
  49              const char *a4 = NULL,
  50              const char *a5 = NULL,
  51              const char *a6 = NULL,
  52              const char *a7 = NULL,
  53              const char *a8 = NULL,
  54              const char *a9 = NULL,
  55              const char *a10 = NULL,
  56              const char *a11 = NULL,
  57              const char *a12 = NULL,
  58              const char *a13 = NULL,
  59              const char *a14 = NULL,
  60              const char *a15 = NULL,
  61              const char *a16 = NULL,
  62              const char *a17 = NULL,
  63              const char *a18 = NULL,
  64              const char *a19 = NULL
  65              )
  66     {
  67         // this function is inline so it can be a little bit less wasteful...
  68         const char * const argv[] = {
  69             cmd,
  70             a0, a1, a2, a3, a4, a5, a6, a7, a8, a9,
  71             a10, a11, a12, a13, a14, a15, a16, a17, a18, a19,
  72             NULL
  73         };
  74         init(argv);
  75     }
  76
  77     /**
  78      * Construct a WvSystem from an argv array.  This is exactly the same
  79      * as WvSubProc's argv[] constructor, but the command name is always
  80      * taken from argv[0] rather than provided separately.
  81      *
  82      * For example:
  83      *     const char *argv[] = { "rm", "-rf", dirname, NULL };
  84      *     WvSystem(argv);
  85      */
  86     WvSystem(const char * const *argv)
  87         { init(argv); }
  88
  89     /**
  90      * Destroy the WvSystem object.  If you haven't yet called go(), the
  91      * command is run before destruction.
  92      */
  93     virtual ~WvSystem();
  94
  95     /**
  96      * Explicitly start the command running and wait for it to finish.
  97      * This will happen automatically at object destruction time, but if you
  98      * want to check the return code, you'll need to call go().
  99      */
 100     int go();
 101
 102     /** Redirect stdin from the given input file. */
 103     WvSystem &infile(WvStringParm filename);
 104
 105     /** Redirect stdout to the given output file, which is overwritten. */
 106     WvSystem &outfile(WvStringParm filename);
 107
 108     /** Redirect stderr to the given output file, which is overwritten. */
 109     WvSystem &errfile(WvStringParm filename);
 110
 111 private:
 112     bool started;
 113     WvString fdfiles[3]; // stdin, stdout, stderr
 114
 115     void init(const char * const *argv);
 116     virtual int fork(int *waitfd);
 117 };
 118
 119
 120 #endif // __WVSYSTEM_H