Second commit

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 22 insertions, 697 deletions

diff --git a/apsh.c b/apsh.c
index f732b20..4e7183b 100644
--- a/apsh.c
+++ b/apsh.c
@@ -1,709 +1,32 @@
 /* See LICENSE file for copyright and license details. */
-#include <libsimple.h>
-#include <libsimple-arg.h>
-#include "config.h"
+#include "common.h"
 
 USAGE("");
 
-enum argument_type {
-	VERBATIM,
-	ESCAPED,
-	SPECIAL,
-	FUNCTION_MARK,
-	SUBSHELL_INPUT, /* >(...) */
-	SUBSHELL_OUTPUT, /* <(...) */
-	SUBSHELL_INPUT_OUTPUT, /* <>(...) ## create socket for both input and output of subshell */
-	SUBSHELL_SUBSTITUTION,
-	SUBSHELL, /* (...) or ((...)) ## if non-first argument: format shell code into a string (can be used for a clean subshell) */
-	REDIRECTION /* at beginning of argument, use next redirection and use reminder of argument as right-hand side */
-};
 
-enum redirection_type {
-	REDIRECT_INPUT,
-	REDIRECT_INPUT_TO_FD,
-	REDIRECT_OUTPUT,
-	REDIRECT_OUTPUT_APPEND,
-	REDIRECT_OUTPUT_CLOBBERING,
-	REDIRECT_OUTPUT_TO_FD,
-	REDIRECT_INPUT_OUTPUT,
-	REDIRECT_INPUT_OUTPUT_TO_FD,
-	HERE_STRING,
-	HERE_DOCUMENT,
-	HERE_DOCUMENT_INDENTED
-};
-
-enum command_terminal {
-	DOUBLE_SEMICOLON,
-	SEMICOLON,
-	AMPERSAND,
-	SOCKET_PIPE,
-	PIPE,
-	PIPE_AMPERSAND,
-	AND,
-	OR
-};
-
-enum shell_terminator {
-	END_OF_FILE,
-	ROUND,
-	ROUND_ROUND,
-	SQUARE,
-	BACKTICK,
-};
-
-struct parser_state;
-
-struct argument {
-	enum argument_type type;
-	union {
-		struct { /* VERBATIM, ESCAPED */
-			char *text;
-			size_t length;
-		};
-		char symbol; /* SPECIAL */
-		struct parser_state *root; /* SUBSHELL, SUBSHELL_* */
-	}; /* none for FUNCTION_MARK, REDIRECTION */
-	struct argument *next_part;
-};
-
-struct redirection {
-	enum redirection_type type;
-	struct argument *left_hand_side;
-};
-
-struct command {
-	enum command_terminal terminal;
-	struct argument **arguments;
-	size_t narguments;
-	struct redirection **redirections;
-	size_t nredirections;
-};
-
-struct parser_state {
-	struct parser_state *parent;
-	struct command **commands;
-	size_t ncommands;
-	struct argument **arguments;
-	size_t narguments;
-	struct redirection **redirections;
-	size_t nredirections;
-	struct argument *current_argument;
-	struct argument *current_argument_end;
-	enum shell_terminator exit_on;
-	char at_dollar;
-	char is_expr_shell;
-	char need_right_hand_side;
-};
-
-struct here_document {
-	struct redirection *redirection;
-	struct argument *argument;
-	struct here_document *next;
-};
-
-static size_t line_number = 1;
-static int tty_input = 0;
-
-static struct parser_state *state;
-static struct here_document *here_documents_first = NULL;
-static struct here_document **here_documents_next = &here_documents_first;
-
-static void flush_dollar(void);
-static void verbatim(const char *text, size_t text_length, int from_quote);
-
-static void
-whitespace(int strict)
-{
-	flush_dollar();
-
-	if (state->need_right_hand_side) {
-		if (strict)
-			eprintf("premature end of command\n");
-		return;
-	}
-
-	if (state->current_argument) {
-		state->arguments = erealloc(state->arguments, (state->narguments + 1) * sizeof(*state->arguments));
-		state->arguments[state->narguments++] = state->current_argument;
-		state->current_argument = NULL;
-		state->current_argument_end = NULL;
-	}
-}
-
-static void
-terminate_command(enum command_terminal terminal)
-{
-	whitespace(1);
-
-	state->commands = erealloc(state->commands, (state->ncommands + 1) * sizeof(*state->commands));
-	state->commands[state->ncommands] = ecalloc(1, sizeof(**state->commands));
-	state->commands[state->ncommands]->terminal = terminal;
-	state->commands[state->ncommands]->arguments = state->arguments;
-	state->commands[state->ncommands]->narguments = state->narguments;
-	state->commands[state->ncommands]->redirections = state->redirections;
-	state->commands[state->ncommands]->nredirections = state->nredirections;
-	state->ncommands += 1;
-	state->arguments = NULL;
-	state->narguments = 0;
-	state->redirections = NULL;
-	state->nredirections = 0;
-
-	if (!state->parent) {
-		if (terminal == DOUBLE_SEMICOLON || terminal == SEMICOLON || terminal == AMPERSAND) {
-			/* TODO unless in a special construct such as while, case, for, if, or {, run and clear
-			 *      also require that any here-document is specified (count them and run when given)
-			 */
-		}
-	}
-}
-
-static void
-semicolon(int maybe)
-{
-	if (!maybe || state->narguments)
-		terminate_command(SEMICOLON);
-}
-
-static void
-end_subshell(void)
-{
-	semicolon(1);
-	/* TODO validate subshell content */
-	state = state->parent;
-}
-
-static void
-add_redirection(enum redirection_type type)
-{
-	state->redirections = erealloc(state->redirections, (state->nredirections + 1) * sizeof(*state->redirections));
-	state->redirections[state->nredirections] = ecalloc(1, sizeof(**state->redirections));
-	state->redirections[state->nredirections]->type = type;
-	if (state->current_argument) {
-		if (state->current_argument->type == REDIRECTION) {
-			whitespace(1);
-		} else {
-			state->redirections[state->nredirections]->left_hand_side = state->current_argument;
-			state->current_argument = NULL;
-			state->current_argument_end = NULL;
-		}
-	}
-	state->current_argument_end = state->current_argument = calloc(1, sizeof(*state->current_argument));
-	state->current_argument_end->type = REDIRECTION;
-	if (type == HERE_DOCUMENT || type == HERE_DOCUMENT_INDENTED) {
-		*here_documents_next = emalloc(sizeof(**here_documents_next));
-		(*here_documents_next)->redirection = state->redirections[state->nredirections];
-		(*here_documents_next)->argument = state->current_argument;
-		(*here_documents_next)->next = NULL;
-		here_documents_next = &(*here_documents_next)->next;
-	}
-	state->nredirections += 1;
-	state->need_right_hand_side = 1;
-}
-
-static void
-add_shell_io(enum argument_type type, enum shell_terminator exit_on)
-{
-	struct parser_state *new_state;
-
-	state->need_right_hand_side = 0;
-
-	if (!state->current_argument_end)
-		state->current_argument_end = state->current_argument = ecalloc(1, sizeof(struct argument));
-	else
-		state->current_argument_end = state->current_argument_end->next_part = ecalloc(1, sizeof(struct argument));
-
-	new_state = ecalloc(1, sizeof(*new_state));
-	new_state->parent = state;
-	new_state->exit_on = exit_on;
-
-	state->current_argument_end->type = type;
-	state->current_argument_end->root = state;
-
-	state = new_state;
-}
-
-static void
-add_function_mark(void)
+void
+initialise_parser_context(struct parser_context *ctx)
 {
-	whitespace(1);
-	if (!state->current_argument_end)
-		state->current_argument_end = state->current_argument = ecalloc(1, sizeof(struct argument));
-	else
-		state->current_argument_end = state->current_argument_end->next_part = ecalloc(1, sizeof(struct argument));
-	state->current_argument_end->type = FUNCTION_MARK;
-	whitespace(1);
-}
-
-static void
-parse_symbol(const char *token, size_t token_length)
-{
-	struct parser_state *old_state = state;
-
-	while (token_length) {
-		if (state->at_dollar) {
-			state->at_dollar = 0;
-			if (token_length >= 2 && token[0] == '(' && token[1] == '(') {
-				add_shell_io(SUBSHELL_SUBSTITUTION, ROUND_ROUND);
-				state->is_expr_shell = 1;
-				token = &token[2];
-				token_length -= 2;
-			} else if (token_length >= 1 && token[0] == '(') {
-				add_shell_io(SUBSHELL_SUBSTITUTION, ROUND);
-				token = &token[1];
-				token_length -= 1;
-			} else if (token_length >= 1 && token[0] == '[') {
-				add_shell_io(SUBSHELL_SUBSTITUTION, SQUARE);
-				state->is_expr_shell = 1;
-				token = &token[1];
-				token_length -= 1;
-			} else if (token_length >= 1 && token[0] == '{') { /* TODO */
-				token = &token[1];
-				token_length -= 1;
-			} else {
-				state->at_dollar = 1;
-				flush_dollar();
-				continue;
-			}
-		}
-
-		if (token_length >= 3 && token[0] == '<' && token[1] == '<' && token[2] == '<') {
-			add_redirection(HERE_STRING);
-			token = &token[3];
-			token_length -= 3;
-
-		} else if (token_length >= 3 && token[0] == '<' && token[1] == '<' && token[2] == '-') {
-			add_redirection(HERE_DOCUMENT_INDENTED);
-			token = &token[3];
-			token_length -= 3;
-
-		} else if (token_length >= 3 && token[0] == '<' && token[1] == '>' && token[2] == '(') {
-			add_shell_io(SUBSHELL_INPUT_OUTPUT, ROUND);
-			token = &token[3];
-			token_length -= 3;
-
-		} else if (token_length >= 3 && token[0] == '<' && token[1] == '>' && token[2] == '|') {
-			terminate_command(SOCKET_PIPE);
-			token = &token[3];
-			token_length -= 3;
-
-		} else if (token_length >= 3 && token[0] == '<' && token[1] == '>' && token[2] == '&') {
-			add_redirection(REDIRECT_INPUT_OUTPUT_TO_FD);
-			token = &token[3];
-			token_length -= 3;
-
-		} else if (token_length >= 2 && token[0] == ')' && token[1] == ')') {
-			if (state->exit_on == ROUND_ROUND)
-				end_subshell();
-			else
-				eprintf("stray )) at line %zu\n", line_number);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '(' && token[1] == ')') {
-			add_function_mark();
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '(' && token[1] == '(') {
-			add_shell_io(SUBSHELL, ROUND_ROUND);
-			state->is_expr_shell = 1;
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == ';' && token[1] == ';') {
-			terminate_command(DOUBLE_SEMICOLON);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '<' && token[1] == '(') {
-			add_shell_io(SUBSHELL_OUTPUT, ROUND);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '<' && token[1] == '<') {
-			add_redirection(HERE_DOCUMENT);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '<' && token[1] == '>') {
-			add_redirection(REDIRECT_INPUT_OUTPUT);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '<' && token[1] == '&') {
-			add_redirection(REDIRECT_INPUT_TO_FD);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '>' && token[1] == '(') {
-			add_shell_io(SUBSHELL_INPUT, ROUND);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '>' && token[1] == '>') {
-			add_redirection(REDIRECT_OUTPUT_APPEND);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '>' && token[1] == '&') {
-			add_redirection(REDIRECT_OUTPUT_TO_FD);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '>' && token[1] == '|') {
-			add_redirection(REDIRECT_OUTPUT_CLOBBERING);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '|' && token[1] == '&') {
-			terminate_command(PIPE_AMPERSAND);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '|' && token[1] == '|') {
-			terminate_command(OR);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 2 && token[0] == '&' && token[1] == '&') {
-			terminate_command(AND);
-			token = &token[2];
-			token_length -= 2;
-
-		} else if (token_length >= 1 && token[0] == ')') {
-			if (state->exit_on == ROUND)
-				end_subshell();
-			else
-				eprintf("stray ) at line %zu\n", line_number);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == ']') {
-			if (state->exit_on == SQUARE)
-				end_subshell();
-			else
-				verbatim(token, 1, 0);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == '(') {
-			add_shell_io(SUBSHELL, ROUND);
-			state->is_expr_shell = old_state->is_expr_shell;
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == ';') {
-			semicolon(0);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == '<') {
-			add_redirection(REDIRECT_INPUT);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == '>') {
-			add_redirection(REDIRECT_OUTPUT);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == '|') {
-			terminate_command(PIPE);
-			token = &token[1];
-			token_length -= 1;
-
-		} else if (token_length >= 1 && token[0] == '&') {
-			terminate_command(AMPERSAND);
-			token = &token[1];
-			token_length -= 1;
-
-		} else {
-			verbatim(token, 1, 0);
-			token = &token[1];
-			token_length -= 1;
-		}
-	}
-}
-
-static void
-symbol(char *token, size_t token_length, size_t escaped_newlines)
-{
-	size_t new_length, r, w;
-	if (escaped_newlines) {
-		r = w = 0;
-		new_length = token_length - 2 * escaped_newlines;
-		while (escaped_newlines--) {
-			if (token[r] == '\\')
-				r += 2;
-			else
-				token[w++] = token[r++];
-		}
-		memcpy(&token[w], &token[r], token_length - r);
-		token_length = new_length;
-	}
-	parse_symbol(token, token_length);
-}
-
-static void
-backtick(void)
-{
-	flush_dollar();
-	if (state->exit_on == BACKTICK)
-		end_subshell();
-	else
-		add_shell_io(SUBSHELL_SUBSTITUTION, BACKTICK);
-}
-
-static void
-double_quote(void)
-{
-	flush_dollar();
-	/* TODO */
-}
-
-static void
-verbatim(const char *text, size_t text_length, int from_quote)
-{
-	struct argument *argend;
-
-	state->need_right_hand_side = 0;
-
-	if (from_quote && state->at_dollar) {
-		state->at_dollar = 0;
-		if (!state->current_argument_end)
-			state->current_argument_end = state->current_argument = ecalloc(1, sizeof(struct argument));
-		else
-			state->current_argument_end = state->current_argument_end->next_part = ecalloc(1, sizeof(struct argument));
-		state->current_argument_end->type = ESCAPED;
-	} else {
-		flush_dollar();
-		if (!state->current_argument_end) {
-			state->current_argument_end = state->current_argument = ecalloc(1, sizeof(struct argument));
-			state->current_argument_end->type = VERBATIM;
-		} else if (state->current_argument_end->type != VERBATIM) {
-			state->current_argument_end = state->current_argument_end->next_part = ecalloc(1, sizeof(struct argument));
-			state->current_argument_end->type = VERBATIM;
-		}
-	}
-
-	argend = state->current_argument_end;
-
-	argend->text = erealloc(argend->text, argend->length + text_length + 1);
-	memcpy(&argend->text[argend->length], text, text_length);
-	argend->length += text_length;
-	argend->text[argend->length] = '\0';
-}
-
-static void
-flush_dollar(void)
-{
-	if (state->at_dollar) {
-		state->at_dollar = 0;
-		verbatim("$", 1, 0);
-	}
-}
-
-static void
-append_special(char symbol)
-{
-	state->need_right_hand_side = 0;
-
-	if (!state->current_argument_end)
-		state->current_argument_end = state->current_argument = ecalloc(1, sizeof(struct argument));
-	else
-		state->current_argument_end = state->current_argument_end->next_part = ecalloc(1, sizeof(struct argument));
-
-	state->current_argument_end->type = SPECIAL;
-	state->current_argument_end->symbol = symbol;
-}
-
-static void
-unverbatim(const char *text, size_t text_length)
-{
-	size_t verbatim_length;
-
-	/* TODO handle state->dollar */
-
-	while (text_length) {
-		for (verbatim_length = 0; verbatim_length < text_length; verbatim_length++)
-			if (*text == '*' || *text == '?' || *text == '[' || *text == ']' ||
-			    *text == ',' || *text == '.' || *text == '{' || *text == '}' ||
-			    *text == '~' || *text == '!' || *text == '=')
-				break;
-		if (verbatim_length) {
-			verbatim(text, verbatim_length, 0);
-			text = &text[verbatim_length];
-			text_length -= verbatim_length;
-		} else {
-			append_special(*text);
-			text = &text[1];
-			text_length -= 1;
-		}
-	}
-}
-
-static void
-dollar(void)
-{
-	/* TODO forbid $ if giving argument to here-document */
-	if (state->at_dollar)
-		unverbatim("$", 1);
-	else
-		state->at_dollar = 1;
-}
-
-static int
-end_of_file(void)
-{
-	semicolon(1);
-	return !(state->parent || state->ncommands);
-}
-
-static size_t
-parse(char *code, size_t code_len, int end_of_file_reached)
-{
-#define IS_SYMBOL(C)\
-	((!state->is_expr_shell && (\
-	  (C) == '|' || (C) == '&' || (C) == ';' || \
-	  (C) == '<' || (C) == '>' || (C) == '-')) || \
-	 (C) == '{' || (C) == '}' || \
-	 (C) == '(' || (C) == ')' || \
-	 (C) == '[' || (C) == ']')
-
-	static int she_is_comment = 1;
-	static int in_comment = 0;
-	static int at_line_beginning = 1;
-
-	size_t read_bytes = 0;
-	size_t token_len;
-	size_t new_lines;
-
-	for (; read_bytes < code_len; read_bytes += token_len, code = &code[token_len]) {
-		if (at_line_beginning) {
-			if (here_documents_first) {
-				/* TODO read until terminator, remove indentation if <<- and then parse in "-mode but accept " */
-			}
-			at_line_beginning = 0;
-		}
-
-		if (in_comment) {
-			if (*code == '\n') {
-				in_comment = 0;
-			} else {
-				token_len = 1;
-				continue;
-			}
-		}
-
-		if (*code == '\0') {
-			if (!tty_input)
-				weprintf("ignoring NUL byte at line %zu\n", line_number);
-
-		} else if (*code == '\n') {
-			line_number += 1;
-			she_is_comment = 1;
-			whitespace(0);
-			semicolon(1);
-			token_len = 1;
-			at_line_beginning = 1;
-
-		} else if (isspace(*code)) {
-			she_is_comment = 1;
-			whitespace(0);
-			for (token_len = 1; token_len < code_len - read_bytes; token_len++)
-				if (!isspace(code[token_len]) || code[token_len] == '\n')
-					break;
-
-		} else if (*code == '#' && she_is_comment) {
-			in_comment = 1;
-			token_len = 1;
-
-		} else if (IS_SYMBOL(*code)) {
-			she_is_comment = 1;
-			new_lines = 0;
-			for (token_len = 1; token_len < code_len - read_bytes; token_len++) {
-				if (code[token_len] == '\\' && token_len + 1 < code_len - read_bytes && code[token_len] == '\n') {
-					new_lines += 1;
-				} else if (!IS_SYMBOL(code[token_len])) {
-					symbol(code, token_len, new_lines);
-					line_number += new_lines;
-					goto next;
-				}
-			}
-			if (end_of_file_reached) {
-				symbol(code, token_len, new_lines);
-				line_number += new_lines;
-			} else {
-				break;
-			}
-
-		} else if (*code == '\\') {
-			she_is_comment = 0;
-			if (code_len - read_bytes < 2)
-				break;
-			token_len = 2;
-			if (code[1] == '\n')
-				line_number += 1;
-			else
-				verbatim(&code[1], 1, 0);
-
-		} else if (*code == '$') {
-			she_is_comment = 0;
-			dollar();
-			token_len = 1;
-
-		} else if (*code == '`') {
-			she_is_comment = 1;
-			backtick();
-			token_len = 1;
-
-		} else if (*code == '"') {
-			she_is_comment = 0;
-			double_quote();
-
-		} else if (*code == '\'') {
-			she_is_comment = 0;
-			new_lines = 0;
-			for (token_len = 1; token_len < code_len - read_bytes; token_len++) {
-				if (code[token_len] == '\'') {
-					token_len += 1;
-					if (!state->at_dollar || code[token_len - 2] != '\\') {
-						verbatim(&code[1], token_len - 2, 1);
-						line_number += new_lines;
-						goto next;
-					}
-				} else if (code[token_len] == '\n') {
-					new_lines += 1;
-				}
-			}
-			break;
-
-		} else {
-			she_is_comment = 0;
-			for (token_len = 1; token_len < code_len - read_bytes; token_len++)
-				if (isspace(*code) || IS_SYMBOL(*code) || *code == '\\' ||
-				    *code == '$' || *code == '`' || *code == '"' || *code == '\'')
-					break;
-			unverbatim(code, token_len);
-		}
-
-	next:;
-	}
-
-	return read_bytes;
-
-#undef IS_SYMBOL
+	memset(ctx, 0, sizeof(*ctx));
+	ctx->preparser_line_number = 1;
+	ctx->tokeniser_line_number = 1;
+	ctx->mode_stack = ecalloc(1, sizeof(*ctx->mode_stack));
+	ctx->mode_stack->mode = NORMAL_MODE;
+	ctx->mode_stack->she_is_comment = 1;
+	ctx->parser_state = ecalloc(1, sizeof(*ctx->parser_state));
+	ctx->here_documents_next = &ctx->here_documents_first;
 }
 
 int
 main(int argc, char *argv[])
 {
+	struct parser_context ctx;
 	char *buffer = NULL;
 	size_t buffer_size = 0;
 	size_t buffer_head = 0;
 	size_t buffer_tail = 0;
 	ssize_t r;
-	size_t n;
+	size_t n, nremoved;
 
 	ARGBEGIN {
 	default:
@@ -713,12 +36,11 @@ main(int argc, char *argv[])
 	if (argc)
 		usage();
 
-	tty_input = isatty(STDIN_FILENO);
-	if (tty_input)
+	initialise_parser_context(&ctx);
+	ctx.tty_input = isatty(STDIN_FILENO);
+	if (ctx.tty_input)
 		weprintf("apsh is currently not implemented to be interactive\n");
 
-	state = ecalloc(1, sizeof(*state));
-
 	for (;;) {
 		if (buffer_size - buffer_head < PARSE_RINGBUFFER_MIN_AVAILABLE) {
 			if (buffer_tail && buffer_head - buffer_tail <= buffer_tail) {
@@ -739,11 +61,14 @@ main(int argc, char *argv[])
 		n = (size_t)r;
 
 		buffer_head += n;
-		buffer_tail += parse(&buffer[buffer_tail], buffer_head - buffer_tail, 0);
+		buffer_tail += n = parse(&ctx, &buffer[buffer_tail], buffer_head - buffer_tail, &nremoved);
+		buffer_head -= nremoved;
 	}
 
-	buffer_tail += parse(&buffer[buffer_tail], buffer_head - buffer_tail, 1);
-	if (buffer_tail != buffer_head || !end_of_file())
+	ctx.end_of_file_reached = 1;
+	buffer_tail += parse(&ctx, &buffer[buffer_tail], buffer_head - buffer_tail, &nremoved);
+	buffer_head -= nremoved;
+	if (buffer_tail != buffer_head || ctx.premature_end_of_file)
 		eprintf("premature end of file reached\n");
 
 	free(buffer);