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dbus/dbus/dbus-shell.c

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
/* dbus-shell.c Shell command line utility functions.
*
* Copyright (C) 2002, 2003 Red Hat, Inc.
* Copyright (C) 2003 CodeFactory AB
*
* Licensed under the Academic Free License version 2.1
*
* 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 2 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, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <config.h>
#include <string.h>
#include "dbus-internals.h"
#include "dbus-list.h"
#include "dbus-memory.h"
#include "dbus-protocol.h"
#include "dbus-shell.h"
#include "dbus-string.h"
/* Single quotes preserve the literal string exactly. escape
* sequences are not allowed; not even \' - if you want a '
* in the quoted text, you have to do something like 'foo'\''bar'
*
* Double quotes allow $ ` " \ and newline to be escaped with backslash.
* Otherwise double quotes preserve things literally.
*/
static dbus_bool_t
unquote_string_inplace (char* str, char** end)
{
char* dest;
char* s;
char quote_char;
dest = s = str;
quote_char = *s;
if (!(*s == '"' || *s == '\''))
{
*end = str;
return FALSE;
}
/* Skip the initial quote mark */
++s;
if (quote_char == '"')
{
while (*s)
{
_dbus_assert(s > dest); /* loop invariant */
switch (*s)
{
case '"':
/* End of the string, return now */
*dest = '\0';
++s;
*end = s;
return TRUE;
case '\\':
/* Possible escaped quote or \ */
++s;
switch (*s)
{
case '"':
case '\\':
case '`':
case '$':
case '\n':
*dest = *s;
++s;
++dest;
break;
default:
/* not an escaped char */
*dest = '\\';
++dest;
/* ++s already done. */
break;
}
break;
default:
*dest = *s;
++dest;
++s;
break;
}
_dbus_assert(s > dest); /* loop invariant */
}
}
else
{
while (*s)
{
_dbus_assert(s > dest); /* loop invariant */
if (*s == '\'')
{
/* End of the string, return now */
*dest = '\0';
++s;
*end = s;
return TRUE;
}
else
{
*dest = *s;
++dest;
++s;
}
_dbus_assert(s > dest); /* loop invariant */
}
}
/* If we reach here this means the close quote was never encountered */
*dest = '\0';
*end = s;
return FALSE;
}
/**
* Unquotes a string as the shell (/bin/sh) would. Only handles
* quotes; if a string contains file globs, arithmetic operators,
* variables, backticks, redirections, or other special-to-the-shell
* features, the result will be different from the result a real shell
* would produce (the variables, backticks, etc. will be passed
* through literally instead of being expanded). This function is
* guaranteed to succeed if applied to the result of
* _dbus_shell_quote(). If it fails, it returns %NULL.
* The @quoted_string need not actually contain quoted or
* escaped text; _dbus_shell_unquote() simply goes through the string and
* unquotes/unescapes anything that the shell would. Both single and
* double quotes are handled, as are escapes including escaped
* newlines. The return value must be freed with dbus_free().
*
* Shell quoting rules are a bit strange. Single quotes preserve the
* literal string exactly. escape sequences are not allowed; not even
* \' - if you want a ' in the quoted text, you have to do something
* like 'foo'\''bar'. Double quotes allow $, `, ", \, and newline to
* be escaped with backslash. Otherwise double quotes preserve things
* literally.
*
* @quoted_string: shell-quoted string
**/
char*
_dbus_shell_unquote (const char *quoted_string)
{
char *unquoted;
char *end;
char *start;
char *ret;
DBusString retval;
unquoted = _dbus_strdup (quoted_string);
if (unquoted == NULL)
return NULL;
start = unquoted;
end = unquoted;
if (!_dbus_string_init (&retval))
{
dbus_free (unquoted);
return NULL;
}
/* The loop allows cases such as
* "foo"blah blah'bar'woo foo"baz"la la la\'\''foo'
*/
while (*start)
{
/* Append all non-quoted chars, honoring backslash escape
*/
while (*start && !(*start == '"' || *start == '\''))
{
if (*start == '\\')
{
/* all characters can get escaped by backslash,
* except newline, which is removed if it follows
* a backslash outside of quotes
*/
++start;
if (*start)
{
if (*start != '\n')
{
if (!_dbus_string_append_byte (&retval, *start))
goto error;
}
++start;
}
}
else
{
if (!_dbus_string_append_byte (&retval, *start))
goto error;
++start;
}
}
if (*start)
{
if (!unquote_string_inplace (start, &end))
goto error;
else
{
if (!_dbus_string_append (&retval, start))
goto error;
start = end;
}
}
}
ret = _dbus_strdup (_dbus_string_get_data (&retval));
if (!ret)
goto error;
dbus_free (unquoted);
_dbus_string_free (&retval);
return ret;
error:
dbus_free (unquoted);
_dbus_string_free (&retval);
return NULL;
}
/* _dbus_shell_parse_argv() does a semi-arbitrary weird subset of the way
* the shell parses a command line. We don't do variable expansion,
* don't understand that operators are tokens, don't do tilde expansion,
* don't do command substitution, no arithmetic expansion, IFS gets ignored,
* don't do filename globs, don't remove redirection stuff, etc.
*
* READ THE UNIX98 SPEC on "Shell Command Language" before changing
* the behavior of this code.
*
* Steps to parsing the argv string:
*
* - tokenize the string (but since we ignore operators,
* our tokenization may diverge from what the shell would do)
* note that tokenization ignores the internals of a quoted
* word and it always splits on spaces, not on IFS even
* if we used IFS. We also ignore "end of input indicator"
* (I guess this is control-D?)
*
* Tokenization steps, from UNIX98 with operator stuff removed,
* are:
*
* 1) "If the current character is backslash, single-quote or
* double-quote (\, ' or ") and it is not quoted, it will affect
* quoting for subsequent characters up to the end of the quoted
* text. The rules for quoting are as described in Quoting
* . During token recognition no substitutions will be actually
* performed, and the result token will contain exactly the
* characters that appear in the input (except for newline
* character joining), unmodified, including any embedded or
* enclosing quotes or substitution operators, between the quote
* mark and the end of the quoted text. The token will not be
* delimited by the end of the quoted field."
*
* 2) "If the current character is an unquoted newline character,
* the current token will be delimited."
*
* 3) "If the current character is an unquoted blank character, any
* token containing the previous character is delimited and the
* current character will be discarded."
*
* 4) "If the previous character was part of a word, the current
* character will be appended to that word."
*
* 5) "If the current character is a "#", it and all subsequent
* characters up to, but excluding, the next newline character
* will be discarded as a comment. The newline character that
* ends the line is not considered part of the comment. The
* "#" starts a comment only when it is at the beginning of a
* token. Since the search for the end-of-comment does not
* consider an escaped newline character specially, a comment
* cannot be continued to the next line."
*
* 6) "The current character will be used as the start of a new word."
*
*
* - for each token (word), perform portions of word expansion, namely
* field splitting (using default whitespace IFS) and quote
* removal. Field splitting may increase the number of words.
* Quote removal does not increase the number of words.
*
* "If the complete expansion appropriate for a word results in an
* empty field, that empty field will be deleted from the list of
* fields that form the completely expanded command, unless the
* original word contained single-quote or double-quote characters."
* - UNIX98 spec
*
*
*/
static dbus_bool_t
delimit_token (DBusString *token,
DBusList **retval,
DBusError *error)
{
char *str;
str = _dbus_strdup (_dbus_string_get_data (token));
if (!str)
{
_DBUS_SET_OOM (error);
return FALSE;
}
if (!_dbus_list_append (retval, str))
{
dbus_free (str);
_DBUS_SET_OOM (error);
return FALSE;
}
return TRUE;
}
static DBusList*
tokenize_command_line (const char *command_line, DBusError *error)
{
char current_quote;
const char *p;
DBusString current_token;
DBusList *retval = NULL;
dbus_bool_t quoted;;
current_quote = '\0';
quoted = FALSE;
p = command_line;
if (!_dbus_string_init (&current_token))
{
_DBUS_SET_OOM (error);
return NULL;
}
while (*p)
{
if (current_quote == '\\')
{
if (*p == '\n')
{
/* we append nothing; backslash-newline become nothing */
}
else
{
if (!_dbus_string_append_byte (&current_token, '\\') ||
!_dbus_string_append_byte (&current_token, *p))
{
_DBUS_SET_OOM (error);
goto error;
}
}
current_quote = '\0';
}
else if (current_quote == '#')
{
/* Discard up to and including next newline */
while (*p && *p != '\n')
++p;
current_quote = '\0';
if (*p == '\0')
break;
}
else if (current_quote)
{
if (*p == current_quote &&
/* check that it isn't an escaped double quote */
!(current_quote == '"' && quoted))
{
/* close the quote */
current_quote = '\0';
}
/* Everything inside quotes, and the close quote,
* gets appended literally.
*/
if (!_dbus_string_append_byte (&current_token, *p))
{
_DBUS_SET_OOM (error);
goto error;
}
}
else
{
switch (*p)
{
case '\n':
if (!delimit_token (&current_token, &retval, error))
goto error;
_dbus_string_free (&current_token);
if (!_dbus_string_init (&current_token))
{
_DBUS_SET_OOM (error);
goto init_error;
}
break;
case ' ':
case '\t':
/* If the current token contains the previous char, delimit
* the current token. A nonzero length
* token should always contain the previous char.
*/
if (_dbus_string_get_length (&current_token) > 0)
{
if (!delimit_token (&current_token, &retval, error))
goto error;
_dbus_string_free (&current_token);
if (!_dbus_string_init (&current_token))
{
_DBUS_SET_OOM (error);
goto init_error;
}
}
/* discard all unquoted blanks (don't add them to a token) */
break;
/* single/double quotes are appended to the token,
* escapes are maybe appended next time through the loop,
* comment chars are never appended.
*/
case '\'':
case '"':
if (!_dbus_string_append_byte (&current_token, *p))
{
_DBUS_SET_OOM (error);
goto error;
}
/* FALL THRU */
case '#':
case '\\':
current_quote = *p;
break;
default:
/* Combines rules 4) and 6) - if we have a token, append to it,
* otherwise create a new token.
*/
if (!_dbus_string_append_byte (&current_token, *p))
{
_DBUS_SET_OOM (error);
goto error;
}
break;
}
}
/* We need to count consecutive backslashes mod 2,
* to detect escaped doublequotes.
*/
if (*p != '\\')
quoted = FALSE;
else
quoted = !quoted;
++p;
}
if (!delimit_token (&current_token, &retval, error))
goto error;
if (current_quote)
{
dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "Unclosed quotes in command line");
goto error;
}
if (retval == NULL)
{
dbus_set_error_const (error, DBUS_ERROR_INVALID_ARGS, "No tokens found in command line");
goto error;
}
_dbus_string_free (&current_token);
return retval;
error:
_dbus_string_free (&current_token);
init_error:
if (retval)
{
_dbus_list_foreach (&retval, (DBusForeachFunction) dbus_free, NULL);
_dbus_list_clear (&retval);
}
return NULL;
}
/**
* _dbus_shell_parse_argv:
*
* Parses a command line into an argument vector, in much the same way
* the shell would, but without many of the expansions the shell would
* perform (variable expansion, globs, operators, filename expansion,
* etc. are not supported). The results are defined to be the same as
* those you would get from a UNIX98 /bin/sh, as long as the input
* contains none of the unsupported shell expansions. If the input
* does contain such expansions, they are passed through
* literally. Free the returned vector with dbus_free_string_array().
*
* @command_line: command line to parse
* @argcp: return location for number of args
* @argvp: return location for array of args
* @error: error information
**/
dbus_bool_t
_dbus_shell_parse_argv (const char *command_line,
int *argcp,
char ***argvp,
DBusError *error)
{
/* Code based on poptParseArgvString() from libpopt */
int argc = 0;
char **argv = NULL;
DBusList *tokens = NULL;
int i;
DBusList *tmp_list;
if (!command_line)
{
_dbus_verbose ("Command line is NULL\n");
return FALSE;
}
tokens = tokenize_command_line (command_line, error);
if (tokens == NULL)
{
_dbus_verbose ("No tokens for command line '%s'\n", command_line);
return FALSE;
}
/* Because we can't have introduced any new blank space into the
* tokens (we didn't do any new expansions), we don't need to
* perform field splitting. If we were going to honor IFS or do any
* expansions, we would have to do field splitting on each word
* here. Also, if we were going to do any expansion we would need to
* remove any zero-length words that didn't contain quotes
* originally; but since there's no expansion we know all words have
* nonzero length, unless they contain quotes.
*
* So, we simply remove quotes, and don't do any field splitting or
* empty word removal, since we know there was no way to introduce
* such things.
*/
argc = _dbus_list_get_length (&tokens);
argv = dbus_new (char *, argc + 1);
if (!argv)
{
_DBUS_SET_OOM (error);
goto error;
}
i = 0;
tmp_list = tokens;
while (tmp_list)
{
argv[i] = _dbus_shell_unquote (tmp_list->data);
if (!argv[i])
{
int j;
for (j = 0; j < i; j++)
dbus_free(argv[j]);
dbus_free (argv);
_DBUS_SET_OOM (error);
goto error;
}
tmp_list = _dbus_list_get_next_link (&tokens, tmp_list);
++i;
}
argv[argc] = NULL;
_dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
_dbus_list_clear (&tokens);
if (argcp)
*argcp = argc;
if (argvp)
*argvp = argv;
else
dbus_free_string_array (argv);
return TRUE;
error:
_dbus_list_foreach (&tokens, (DBusForeachFunction) dbus_free, NULL);
_dbus_list_clear (&tokens);
return FALSE;
}
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