wordexp.c

Axis 221 camera embedded programing interface

			*result *= arg;
		} else if (**expr == '/') {
			++(*expr);
			if (eval_expr_val(expr, &arg) != 0)
				return WRDE_SYNTAX;

			*result /= arg;
		} else
			break;
	}

	return 0;
}

static int eval_expr(char *expr, long int *result)
{
	long int arg;

	/* Read a Multdiv */
	if (eval_expr_multdiv(&expr, result) != 0)
		return WRDE_SYNTAX;

	while (*expr) {
		/* Skip white space */
		for (; expr && *expr && isspace(*expr); ++expr);

		if (*expr == '+') {
			++expr;
			if (eval_expr_multdiv(&expr, &arg) != 0)
				return WRDE_SYNTAX;

			*result += arg;
		} else if (*expr == '-') {
			++expr;
			if (eval_expr_multdiv(&expr, &arg) != 0)
				return WRDE_SYNTAX;

			*result -= arg;
		} else
			break;
	}

	return 0;
}

static int
parse_arith(char **word, size_t * word_length, size_t * max_length,
			const char *words, size_t * offset, int flags, int bracket)
{
	/* We are poised just after "$((" or "$[" */
	int error;
	int paren_depth = 1;
	size_t expr_length;
	size_t expr_maxlen;
	char *expr;

	expr = w_newword(&expr_length, &expr_maxlen);
	for (; words[*offset]; ++(*offset)) {
		switch (words[*offset]) {
		case '$':
			error = parse_dollars(&expr, &expr_length, &expr_maxlen,
								  words, offset, flags, NULL, NULL, NULL,
								  1);
			/* The ``1'' here is to tell parse_dollars not to
			 * split the fields.
			 */
			if (error) {
				free(expr);
				return error;
			}
			break;

		case '`':
			(*offset)++;
			error = parse_backtick(&expr, &expr_length, &expr_maxlen,
								   words, offset, flags, NULL, NULL, NULL);
			/* The first NULL here is to tell parse_backtick not to
			 * split the fields.
			 */
			if (error) {
				free(expr);
				return error;
			}
			break;

		case '\\':
			error = parse_qtd_backslash(&expr, &expr_length, &expr_maxlen,
										words, offset);
			if (error) {
				free(expr);
				return error;
			}
			/* I think that a backslash within an
			 * arithmetic expansion is bound to
			 * cause an error sooner or later anyway though.
			 */
			break;

		case ')':
			if (--paren_depth == 0) {
				char result[21];	/* 21 = ceil(log10(2^64)) + 1 */
				long int numresult = 0;
				long long int convertme;

				if (bracket || words[1 + *offset] != ')') {
					free(expr);
					return WRDE_SYNTAX;
				}

				++(*offset);

				/* Go - evaluate. */
				if (*expr && eval_expr(expr, &numresult) != 0) {
					free(expr);
					return WRDE_SYNTAX;
				}

				if (numresult < 0) {
					convertme = -numresult;
					*word = w_addchar(*word, word_length, max_length, '-');
					if (!*word) {
						free(expr);
						return WRDE_NOSPACE;
					}
				} else
					convertme = numresult;

				result[20] = '\0';
				*word = w_addstr(*word, word_length, max_length,
								 _itoa(convertme, &result[20]));
				free(expr);
				return *word ? 0 : WRDE_NOSPACE;
			}
			expr =
				w_addchar(expr, &expr_length, &expr_maxlen,
						  words[*offset]);
			if (expr == NULL)
				return WRDE_NOSPACE;

			break;

		case ']':
			if (bracket && paren_depth == 1) {
				char result[21];	/* 21 = ceil(log10(2^64)) + 1 */
				long int numresult = 0;

				/* Go - evaluate. */
				if (*expr && eval_expr(expr, &numresult) != 0) {
					free(expr);
					return WRDE_SYNTAX;
				}

				result[20] = '\0';
				*word = w_addstr(*word, word_length, max_length,
								 _itoa(numresult, &result[20]));
				free(expr);
				return *word ? 0 : WRDE_NOSPACE;
			}

			free(expr);
			return WRDE_SYNTAX;

		case '\n':
		case ';':
		case '{':
		case '}':
			free(expr);
			return WRDE_BADCHAR;

		case '(':
			++paren_depth;
		default:
			expr =
				w_addchar(expr, &expr_length, &expr_maxlen,
						  words[*offset]);
			if (expr == NULL)
				return WRDE_NOSPACE;
		}
	}

	/* Premature end */
	free(expr);
	return WRDE_SYNTAX;
}

/* Function called by child process in exec_comm() */
static void
exec_comm_child(char *comm, int *fildes, int showerr, int noexec)
{
	const char *args[4] = { _PATH_BSHELL, "-c", comm, NULL };

	/* Execute the command, or just check syntax? */
	if (noexec)
		args[1] = "-nc";

	/* Redirect output.  */
	dup2(fildes[1], 1);
	close(fildes[1]);

	/* Redirect stderr to /dev/null if we have to.  */
	if (showerr == 0) {
		int fd;

		close(2);
		fd = open(_PATH_DEVNULL, O_WRONLY);
		if (fd >= 0 && fd != 2) {
			dup2(fd, 2);
			close(fd);
		}
	}

	/* Make sure the subshell doesn't field-split on our behalf. */
	unsetenv("IFS");

	close(fildes[0]);
	execve(_PATH_BSHELL, (char *const *) args, __environ);

	/* Bad.  What now?  */
	abort();
}

/* Function to execute a command and retrieve the results */
/* pwordexp contains NULL if field-splitting is forbidden */
static int
exec_comm(char *comm, char **word, size_t * word_length,
		  size_t * max_length, int flags, wordexp_t * pwordexp,
		  const char *ifs, const char *ifs_white)
{
	int fildes[2];
	int bufsize = 128;
	int buflen;
	int i;
	int status = 0;
	size_t maxnewlines = 0;
	char *buffer;
	pid_t pid;

	/* Don't fork() unless necessary */
	if (!comm || !*comm)
		return 0;

	if (pipe(fildes))
		/* Bad */
		return WRDE_NOSPACE;

	if ((pid = fork()) < 0) {
		/* Bad */
		close(fildes[0]);
		close(fildes[1]);
		return WRDE_NOSPACE;
	}

	if (pid == 0)
		exec_comm_child(comm, fildes, (flags & WRDE_SHOWERR), 0);

	/* Parent */

	close(fildes[1]);
	buffer = alloca(bufsize);

	if (!pwordexp)
		/* Quoted - no field splitting */
	{
		while (1) {
			if ((buflen = read(fildes[0], buffer, bufsize)) < 1) {
				if (waitpid(pid, &status, WNOHANG) == 0)
					continue;
				if ((buflen = read(fildes[0], buffer, bufsize)) < 1)
					break;
			}

			maxnewlines += buflen;

			*word = w_addmem(*word, word_length, max_length, buffer, buflen);
			if (*word == NULL)
				goto no_space;
		}
	} else
		/* Not quoted - split fields */
	{
		int copying = 0;

		/* 'copying' is:
		 *  0 when searching for first character in a field not IFS white space
		 *  1 when copying the text of a field
		 *  2 when searching for possible non-whitespace IFS
		 *  3 when searching for non-newline after copying field
		 */

		while (1) {
			if ((buflen = read(fildes[0], buffer, bufsize)) < 1) {
				if (waitpid(pid, &status, WNOHANG) == 0)
					continue;
				if ((buflen = read(fildes[0], buffer, bufsize)) < 1)
					break;
			}

			for (i = 0; i < buflen; ++i) {
				if (strchr(ifs, buffer[i]) != NULL) {
					/* Current character is IFS */
					if (strchr(ifs_white, buffer[i]) == NULL) {
						/* Current character is IFS but not whitespace */
						if (copying == 2) {
							/*            current character
							 *                   |
							 *                   V
							 * eg: text<space><comma><space>moretext
							 *
							 * So, strip whitespace IFS (like at the start)
							 */
							copying = 0;
							continue;
						}

						copying = 0;
						/* fall through and delimit field.. */
					} else {
						if (buffer[i] == '\n') {
							/* Current character is (IFS) newline */

							/* If copying a field, this is the end of it,
							   but maybe all that's left is trailing newlines.
							   So start searching for a non-newline. */
							if (copying == 1)
								copying = 3;

							continue;
						} else {
							/* Current character is IFS white space, but
							   not a newline */

							/* If not either copying a field or searching
							   for non-newline after a field, ignore it */
							if (copying != 1 && copying != 3)
								continue;

							/* End of field (search for non-ws IFS afterwards) */
							copying = 2;
						}
					}

					/* First IFS white space (non-newline), or IFS non-whitespace.
					 * Delimit the field.  Nulls are converted by w_addword. */
					if (w_addword(pwordexp, *word) == WRDE_NOSPACE)
						goto no_space;

					*word = w_newword(word_length, max_length);

					maxnewlines = 0;
					/* fall back round the loop.. */
				} else {
					/* Not IFS character */

					if (copying == 3) {
						/* Nothing but (IFS) newlines since the last field,
						   so delimit it here before starting new word */
						if (w_addword(pwordexp, *word) == WRDE_NOSPACE)
							goto no_space;

						*word = w_newword(word_length, max_length);
					}

					copying = 1;

					if (buffer[i] == '\n')	/* happens if newline not in IFS */
						maxnewlines++;
					else
						maxnewlines = 0;

					*word = w_addchar(*word, word_length, max_length,
									  buffer[i]);
					if (*word == NULL)
						goto no_space;
				}
			}
		}
	}

	/* Chop off trailing newlines (required by POSIX.2)  */
	/* Ensure we don't go back further than the beginning of the
	   substitution (i.e. remove maxnewlines bytes at most) */
	while (maxnewlines-- != 0 &&
		   *word_length > 0 && (*word)[*word_length - 1] == '\n') {
		(*word)[--*word_length] = '\0';

		/* If the last word was entirely newlines, turn it into a new word
		 * which can be ignored if there's nothing following it. */
		if (*word_length == 0) {
			free(*word);
			*word = w_newword(word_length, max_length);
			break;
		}
	}

	close(fildes[0]);

	/* Check for syntax error (re-execute but with "-n" flag) */
	if (buflen < 1 && status != 0) {
		if ((pid = fork()) < 0) {
			/* Bad */
			return WRDE_NOSPACE;
		}

		if (pid == 0) {
			fildes[0] = fildes[1] = -1;
			exec_comm_child(comm, fildes, 0, 1);
		}

		if (waitpid(pid, &status, 0) == pid && status != 0)
			return WRDE_SYNTAX;
	}

	return 0;

  no_space:
	kill(pid, SIGKILL);
	waitpid(pid, NULL, 0);
	close(fildes[0]);
	return WRDE_NOSPACE;
}

static int
parse_comm(char **word, size_t * word_length, size_t * max_length,
		   const char *words, size_t * offset, int flags,
		   wordexp_t * pwordexp, const char *ifs, const char *ifs_white)
{
	/* We are poised just after "$(" */
	int paren_depth = 1;
	int error = 0;
	int quoted = 0;				/* 1 for singly-quoted, 2 for doubly-quoted */
	size_t comm_length;
	size_t comm_maxlen;
	char *comm = w_newword(&comm_length, &comm_maxlen);

	for (; words[*offset]; ++(*offset)) {
		switch (words[*offset]) {
		case '\'':
			if (quoted == 0)
				quoted = 1;
			else if (quoted == 1)
				quoted = 0;

			break;

		case '"':
			if (quoted == 0)
				quoted = 2;
			else if (quoted == 2)
				quoted = 0;

			break;

		case ')':
			if (!quoted && --paren_depth == 0) {
				/* Go -- give script to the shell */
				if (comm) {
					error = exec_comm(comm, word, word_length, max_length,
									  flags, pwordexp, ifs, ifs_white);
					free(comm);
				}

				return error;
			}

			/* This is just part of the script */
			break;

		case '(':
			if (!quoted)
				++paren_depth;
		}

		comm = w_addchar(comm, &comm_length, &comm_maxlen, words[*offset]);
		if (comm == NULL)
			return WRDE_NOSPACE;
	}

	/* Premature end */
	if (comm)
		free(comm);

	return WRDE_SYNTAX;
}

static int
parse_backtick(char **word, size_t * word_length, size_t * max_length,
			   const char *words, size_t * offset, int flags,
			   wordexp_t * pwordexp, const char *ifs,
			   const char *ifs_white)
{
	/* We are poised just after "`" */
	int error;
	int squoting = 0;
	size_t comm_length;
	size_t comm_maxlen;
	char *comm = w_newword(&comm_length, &comm_maxlen);

	for (; words[*offset]; ++(*offset)) {
		switch (words[*offset]) {
		case '`':
			/* Go -- give the script to the shell */
			error = exec_comm(comm, word, word_length, max_length, flags,
							  pwordexp, ifs, ifs_white);
			free(comm);
			return error;

		case '\\':
			if (squoting) {
				error = parse_qtd_backslash(&comm, &comm_length, &comm_maxlen,
										words, offset);

				if (error) {
					free(comm);
					return error;
				}

				break;
			}

			++(*offset);
			error = parse_backslash(&comm, &comm_length, &comm_maxlen, words,
								offset);

			if (error) {
				free(comm);
				return error;
			}

			break;

		case '\'':
			squoting = 1 - squoting;
		default:
			comm = w_addchar(comm, &comm_length, &comm_maxlen,
						  words[*offset]);
			if (comm == NULL)
				return WRDE_NOSPACE;
		}
	}

	/* Premature end */
	free(comm);
	return WRDE_SYNTAX;
}

static int
parse_param(char **word, size_t * word_length, size_t * max_length,
			const char *words, size_t * offset, int flags,
			wordexp_t * pwordexp, const char *ifs, const char *ifs_white,
			int quoted)
{
	/* We are poised just after "$" */
	enum action {
		ACT_NONE,
		ACT_RP_SHORT_LEFT = '#',
		ACT_RP_LONG_LEFT = 'L',
		ACT_RP_SHORT_RIGHT = '%',
		ACT_RP_LONG_RIGHT = 'R',
		ACT_NULL_ERROR = '?',
		ACT_NULL_SUBST = '-',
		ACT_NONNULL_SUBST = '+',
		ACT_NULL_ASSIGN = '='