在语法或code中的错误？ [英] Is the bug in the grammar or in the code?

问题描述

我不知道这是语法的shell命令语言，还应该能够执行单引号和双引号是正确的。如此看来，非普通的命令，例如工作 LS -al |排序|厕所-l ，但简单的不使用单引号工作：回声'富巴不起作用。

I'm not sure if this grammar is correct for a shell command language that should also be able to execute single-quotes and double-quotes. It seems that non-trivial commands work e.g. ls -al | sort | wc -l but the simple one does not work with single-quotes: echo 'foo bar' does not work.

%{
    #include "shellparser.h"
%}

%option reentrant
%option noyywrap

%x SINGLE_QUOTED
%x DOUBLE_QUOTED

%%

"|"                     { return PIPE; }

[ \t\r]                 { }
[\n]                    { return EOL; }

[a-zA-Z0-9_\.\-]+       { return FILENAME; }

[']                     { BEGIN(SINGLE_QUOTED); }
<SINGLE_QUOTED>[^']+    { }
<SINGLE_QUOTED>[']      { BEGIN(INITIAL); return ARGUMENT; }
<SINGLE_QUOTED><<EOF>>  { return -1; }

["]                     { BEGIN(DOUBLE_QUOTED); }
<DOUBLE_QUOTED>[^"]+    { }
<DOUBLE_QUOTED>["]      { BEGIN(INITIAL); return ARGUMENT; }
<DOUBLE_QUOTED><<EOF>>  { return -1; }

[^ \t\r\n|'"]+          { return ARGUMENT; }

%%

我的code，扫描和解析壳

My code that scans and parses the shell is

 params[0] = NULL;
    printf("> ");
    i=1;
    do {
        lexCode = yylex(scanner);
        text = strdup(yyget_text(scanner));//yyget_text(scanner);
        /*printf("lexCode %d command %s inc:%d", lexCode, text, i);*/
        ca = text;
        if (lexCode != EOL) {
            params[i++] = text;
        }
        Parse(shellParser, lexCode, text);
        if (lexCode == EOL) {
            dump_argv("Before exec_arguments", i, params);
            exec_arguments(i, params);
            corpse_collector();
            Parse(shellParser, 0, NULL);
            i=1;
        }
    } while (lexCode > 0);

    if (-1 == lexCode) {
        fprintf(stderr, "The scanner encountered an error.\n");
    }

CMake的构建文件

The CMake build file is

cmake_minimum_required(VERSION 3.0)
project(openshell)
find_package(FLEX)
FLEX_TARGET(ShellScanner shellscanner.l shellscanner.c)
set(CMAKE_VERBOSE_MAKEFILE on)
include_directories(/usr/include/readline)
ADD_EXECUTABLE(lemon lemon.c)
add_custom_command(OUTPUT shellparser.c COMMAND lemon -s shellparser.y DEPENDS shellparser.y)
add_executable(openshell shellparser.c ${FLEX_ShellScanner_OUTPUTS} main.c openshell.h errors.c errors.h util.c util.h stack.c stack.h shellscanner.l shellscanner.h)
file(GLOB SOURCES "./*.c")
target_link_libraries(openshell ${READLINE_LIBRARY} ${FLEX_LIBRARIES})
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -O3 -std=c99")

我的项目可在我github上。一个典型的shell会话，其中只有一些命令来一些bug因工作，如下。

My project is available on my github. A typical shell session, where only some commands work due to some bug, is as follows.

> ls -al | sort | wc
argument ::= FILENAME .
argumentList ::= argument .
command ::= FILENAME argumentList .
command ::= FILENAME .
command ::= FILENAME .
commandList ::= command .
commandList ::= command PIPE commandList .
commandList ::= command PIPE commandList .
 {(null)} {ls} {-al} {|} {sort} {|} {wc}
     45     398    2270
3874: child 3881 status 0x0000
in ::= in commandList EOL .
> who
command ::= FILENAME .
commandList ::= command .
 {(null)} {who}
dac      :0           2016-04-18 05:17 (:0)
dac      pts/2        2016-04-18 05:20 (:0)
3874: child 3887 status 0x0000
in ::= in commandList EOL .
> ls -al | awk '{print $1}'
argument ::= FILENAME .
argumentList ::= argument .
command ::= FILENAME argumentList .
argument ::= ARGUMENT .
argumentList ::= argument .
command ::= FILENAME argumentList .
commandList ::= command .
commandList ::= command PIPE commandList .
 {(null)} {ls} {-al} {|} {awk} {'}
awk: cmd. line:1: '
awk: cmd. line:1: ^ invalid char ''' in expression
3874: child 3896 status 0x0100
in ::= in commandList EOL .
> 

我可以观察到两个命令得到同样的错误：回声'富巴被乱码到 {回声} {'} 的时候，我们希望它导致 {回声} {foo的酒吧} ，使壳去掉引号像这样执行命令

I can observe that both commands get the same bug: echo 'foo bar' gets garbled to {echo} {'} when we want it to result in {echo} {foo bar} so that the shell strips the quotes and executes the command like this

的char * CMD [] = {在/ usr /斌/回声，富巴，0};

推荐答案

这个问题在规则

＆LT; SINGLE_QUOTED＆GT; [^'] + {}

，因为它消除了引号内的所有字符。你得到的是yytext中为收盘报价（由于规则＆LT; SINGLE_QUOTED＆GT;'] ... ）。你必须从某个地方存储文本，并在检测结束引号时使用它。例如。 （非常差的编码风格，错误检查等省略了，不好意思）

since it removes all characters inside quotes. All you get as "yytext" is the closing quote (due to rule <SINGLE_QUOTED>['] ...). You have to store somewhere the text and use it when the closing quote is detected. E.g. (very poor coding style, error checking etc. omitted, sorry)

<SINGLE_QUOTED>[^']+    { mystring = strdup(yytext); }

<SINGLE_QUOTED>[']      { BEGIN(INITIAL);
      /*  mystring contains the whole string now,
           yytext contains only "'" */
                          return ARGUMENT; }

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