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/*
* Parses unix mail boxes into headers and bodies.
*/
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
using namespace std;
#define BUFSIZE 2048
/* A growable buffer for collecting headers. */
struct Buffer
{
Buffer() : data(0), allocated(0), length(0) { }
~Buffer() { empty(); }
void append( char p ) {
if ( ++length > allocated )
upAllocate( length*2 );
data[length-1] = p;
}
void clear() { length = 0; }
void upAllocate( int len );
void empty();
char *data;
int allocated;
int length;
};
struct MailboxScanner
{
Buffer headName;
Buffer headContent;
int cs, top, stack[1];
int init( );
int execute( const char *data, int len, bool isEof );
int finish( );
};
%%{
machine MailboxScanner;
# Buffer the header names.
action bufHeadName { headName.append(fc); }
# Prints a blank line after the end of the headers of each message.
action blankLine { cout << endl; }
# Helpers we will use in matching the date section of the from line.
day = /[A-Z][a-z][a-z]/;
month = /[A-Z][a-z][a-z]/;
year = /[0-9][0-9][0-9][0-9]/;
time = /[0-9][0-9]:[0-9][0-9]/ . ( /:[0-9][0-9]/ | '' );
letterZone = /[A-Z][A-Z][A-Z]/;
numZone = /[+\-][0-9][0-9][0-9][0-9]/;
zone = letterZone | numZone;
dayNum = /[0-9 ][0-9]/;
# These are the different formats of the date minus an obscure
# type that has a funny string 'remote from xxx' on the end. Taken
# from c-client in the imap-2000 distribution.
date = day . ' ' . month . ' ' . dayNum . ' ' . time . ' ' .
( year | year . ' ' . zone | zone . ' ' . year );
# From lines separate messages. We will exclude fromLine from a message
# body line. This will cause us to stay in message line up until an
# entirely correct from line is matched.
fromLine = 'From ' . (any-'\n')* . ' ' . date . '\n';
# The types of characters that can be used as a header name.
hchar = print - [ :];
# Simply eat up an uninteresting header. Return at the first non-ws
# character following a newline.
consumeHeader := (
[^\n] |
'\n' [ \t] |
'\n' [^ \t] @{fhold; fret;}
)*;
action hchar {headContent.append(fc);}
action hspace {headContent.append(' ');}
action hfinish {
headContent.append(0);
cout << headContent.data << endl;
headContent.clear();
fhold;
fret;
}
# Display the contents of a header as it is consumed. Collapses line
# continuations to a single space.
printHeader := (
[^\n] @hchar |
( '\n' ( [ \t]+ '\n' )* [ \t]+ ) %hspace
)** $!hfinish;
action onHeader
{
headName.append(0);
if ( strcmp( headName.data, "From" ) == 0 ||
strcmp( headName.data, "To" ) == 0 ||
strcmp( headName.data, "Subject" ) == 0 )
{
/* Print the header name, then jump to a machine the will display
* the contents. */
cout << headName.data << ":";
headName.clear();
fcall printHeader;
}
headName.clear();
fcall consumeHeader;
}
header = hchar+ $bufHeadName ':' @onHeader;
# Exclude fromLine from a messageLine, otherwise when encountering a
# fromLine we will be simultaneously matching the old message and a new
# message.
messageLine = ( [^\n]* '\n' - fromLine );
# An entire message.
message = ( fromLine . header* . '\n' @blankLine . messageLine* );
# File is a series of messages.
main := message*;
}%%
%% write data;
int MailboxScanner::init( )
{
%% write init;
return 1;
}
int MailboxScanner::execute( const char *data, int len, bool isEof )
{
const char *p = data;
const char *pe = data + len;
const char *eof = isEof ? pe : 0;
%% write exec;
if ( cs == MailboxScanner_error )
return -1;
if ( cs >= MailboxScanner_first_final )
return 1;
return 0;
}
int MailboxScanner::finish( )
{
if ( cs == MailboxScanner_error )
return -1;
if ( cs >= MailboxScanner_first_final )
return 1;
return 0;
}
void Buffer::empty()
{
if ( data != 0 ) {
free( data );
data = 0;
length = 0;
allocated = 0;
}
}
void Buffer::upAllocate( int len )
{
if ( data == 0 )
data = (char*) malloc( len );
else
data = (char*) realloc( data, len );
allocated = len;
}
MailboxScanner mailbox;
char buf[BUFSIZE];
int main()
{
mailbox.init();
while ( 1 ) {
int len = fread( buf, 1, BUFSIZE, stdin );
mailbox.execute( buf, len, len != BUFSIZE );
if ( len != BUFSIZE )
break;
}
if ( mailbox.finish() <= 0 )
cerr << "mailbox: error parsing input" << endl;
return 0;
}
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