/* Quoting for a system command.

   Copyright (C) 2012-2017 Free Software Foundation, Inc.

   Written by Bruno Haible <bruno@clisp.org>, 2012.

   This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; either version 3 of the License, or

   (at your option) any later version.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */

#include "system-quote.h"

#include <stdbool.h>

#include <stdlib.h>

#include <string.h>

#include "sh-quote.h"

#include "xalloc.h"

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

/* The native Windows CreateProcess() function interprets characters like

   ' ', '\t', '\\', '"' (but not '<' and '>') in a special way:

   - Space and tab are interpreted as delimiters. They are not treated as

     delimiters if they are surrounded by double quotes: "...".

   - Unescaped double quotes are removed from the input. Their only effect is

     that within double quotes, space and tab are treated like normal

     characters.

   - Backslashes not followed by double quotes are not special.

   - But 2*n+1 backslashes followed by a double quote become

     n backslashes followed by a double quote (n >= 0):

       \" -> "

       \\\" -> \"

       \\\\\" -> \\"

   - '*', '?' characters may get expanded through wildcard expansion in the

     callee: By default, in the callee, the initialization code before main()

     takes the result of GetCommandLine(), wildcard-expands it, and passes it

     to main(). The exceptions to this rule are:

       - programs that inspect GetCommandLine() and ignore argv,

       - mingw programs that have a global variable 'int _CRT_glob = 0;',

       - Cygwin programs, when invoked from a Cygwin program.

 */

# define SHELL_SPECIAL_CHARS "\"\\ \001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037*?"

# define SHELL_SPACE_CHARS " \001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"

/* Copies the quoted string to p and returns the number of bytes needed.

   If p is non-NULL, there must be room for system_quote_length (string)

   bytes at p.  */

static size_t

windows_createprocess_quote (char *p, const char *string)

{

  size_t len = strlen (string);

  bool quote_around =

    (len == 0 || strpbrk (string, SHELL_SPECIAL_CHARS) != NULL);

  size_t backslashes = 0;

  size_t i = 0;

# define STORE(c) \

  do                 \

    {                \

      if (p != NULL) \

        p[i] = (c);  \

      i++;           \

    }                \

  while (0)

  if (quote_around)

    STORE ('"');

  for (; len > 0; string++, len--)

    {

      char c = *string;

      if (c == '"')

        {

          size_t j;

          for (j = backslashes + 1; j > 0; j--)

            STORE ('\\');

        }

      STORE (c);

      if (c == '\\')

        backslashes++;

      else

        backslashes = 0;

    }

  if (quote_around)

    {

      size_t j;

      for (j = backslashes; j > 0; j--)

        STORE ('\\');

      STORE ('"');

    }

# undef STORE

  return i;

}

/* The native Windows cmd.exe command interpreter also interprets:

   - '\n', '\r' as a command terminator - no way to escape it,

   - '<', '>' as redirections,

   - '|' as pipe operator,

   - '%var%' as a reference to the environment variable VAR (uppercase),

     even inside quoted strings,

   - '&' '[' ']' '{' '}' '^' '=' ';' '!' '\'' '+' ',' '`' '~' for other

     purposes, according to

     <http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/cmd.mspx?mfr=true>

   We quote a string like '%var%' by putting the '%' characters outside of

   double-quotes and the rest of the string inside double-quotes: %"var"%.

   This is guaranteed to not be a reference to an environment variable.

 */

# define CMD_SPECIAL_CHARS "\"\\ \001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037!%&'*+,;<=>?[]^`{|}~"

# define CMD_FORBIDDEN_CHARS "\n\r"

/* Copies the quoted string to p and returns the number of bytes needed.

   If p is non-NULL, there must be room for system_quote_length (string)

   bytes at p.  */

static size_t

windows_cmd_quote (char *p, const char *string)

{

  size_t len = strlen (string);

  bool quote_around =

    (len == 0 || strpbrk (string, CMD_SPECIAL_CHARS) != NULL);

  size_t backslashes = 0;

  size_t i = 0;

# define STORE(c) \

  do                 \

    {                \

      if (p != NULL) \

        p[i] = (c);  \

      i++;           \

    }                \

  while (0)

  if (quote_around)

    STORE ('"');

  for (; len > 0; string++, len--)

    {

      char c = *string;

      if (c == '"')

        {

          size_t j;

          for (j = backslashes + 1; j > 0; j--)

            STORE ('\\');

        }

      if (c == '%')

        {

          size_t j;

          for (j = backslashes; j > 0; j--)

            STORE ('\\');

          STORE ('"');

        }

      STORE (c);

      if (c == '%')

        STORE ('"');

      if (c == '\\')

        backslashes++;

      else

        backslashes = 0;

    }

  if (quote_around)

    {

      size_t j;

      for (j = backslashes; j > 0; j--)

        STORE ('\\');

      STORE ('"');

    }

  return i;

}

#endif

size_t

system_quote_length (enum system_command_interpreter interpreter,

                     const char *string)

{

  switch (interpreter)

    {

#if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)

    case SCI_SYSTEM:

#endif

    case SCI_POSIX_SH:

      return shell_quote_length (string);

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

    case SCI_WINDOWS_CREATEPROCESS:

      return windows_createprocess_quote (NULL, string);

    case SCI_SYSTEM:

    case SCI_WINDOWS_CMD:

      return windows_cmd_quote (NULL, string);

#endif

    default:

      /* Invalid interpreter.  */

      abort ();

    }

}

char *

system_quote_copy (char *p,

                   enum system_command_interpreter interpreter,

                   const char *string)

{

  switch (interpreter)

    {

#if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)

    case SCI_SYSTEM:

#endif

    case SCI_POSIX_SH:

      return shell_quote_copy (p, string);

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

    case SCI_WINDOWS_CREATEPROCESS:

      p += windows_createprocess_quote (p, string);

      *p = '\0';

      return p;

    case SCI_SYSTEM:

    case SCI_WINDOWS_CMD:

      p += windows_cmd_quote (p, string);

      *p = '\0';

      return p;

#endif

    default:

      /* Invalid interpreter.  */

      abort ();

    }

}

char *

system_quote (enum system_command_interpreter interpreter,

              const char *string)

{

  switch (interpreter)

    {

#if !((defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__)

    case SCI_SYSTEM:

#endif

    case SCI_POSIX_SH:

      return shell_quote (string);

#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

    case SCI_WINDOWS_CREATEPROCESS:

    case SCI_SYSTEM:

    case SCI_WINDOWS_CMD:

      {

        size_t length = system_quote_length (interpreter, string);

        char *quoted = XNMALLOC (length, char);

        system_quote_copy (quoted, interpreter, string);

        return quoted;

      }

#endif

    default:

      /* Invalid interpreter.  */

      abort ();

    }

}

char *

system_quote_argv (enum system_command_interpreter interpreter,

                   char * const *argv)

{

  if (*argv != NULL)

    {

      char * const *argp;

      size_t length;

      char *command;

      char *p;

      length = 0;

      for (argp = argv; ; )

        {

          length += system_quote_length (interpreter, *argp) + 1;

          argp++;

          if (*argp == NULL)

            break;

        }

      command = XNMALLOC (length, char);

      p = command;

      for (argp = argv; ; )

        {

          p = system_quote_copy (p, interpreter, *argp);

          argp++;

          if (*argp == NULL)

            break;

          *p++ = ' ';

        }

      *p = '\0';

      return command;

    }

  else

    return xstrdup ("");

}