CSV file parsing with ragel

I wanted to get my feet wet a bit more with Ragel to get acquainted with the ways it works. Some good examples demonstrating the syntax are here. It's definitely a very impressive piece of software. Setting up a toy language is a bit too much work for just toying around, so I decided to find out how to parse a CSV file. I started out with the sample to do parameter parsing from the command line and adjusted it to read a 3-column CSV file. It's probably not the most efficient code and leaves things to be improved:

#include 
#include 
#include 

#define MAX_BUF_LEN  1023

struct csvline {
 char *f1;
 char *f2;
 int   f3;
};

struct csvdata {
 int cs;
 int buflen;
 char buffer[ MAX_BUF_LEN + 1 ];
 int field;
 struct csvline line;
};

void print_data( struct csvdata *data, int lineno );

%%{
 machine csv;
 access data->;

 # Append to the buffer.
 action append {
  if ( data->buflen < MAX_BUF_LEN )
   data->buffer[ data->buflen++ ] = fc;
 }

 # Terminate a buffer.
 action term {
  if ( data->buflen < MAX_BUF_LEN )
   data->buffer[ data->buflen++ ] = 0;

  switch( data->field ) {
   case 0:
    data->line.f1 = (char *)calloc( data->buflen, sizeof( char ) );
    strncpy( data->line.f1, data->buffer, data->buflen );
    data->field++;
    break;
   case 1:
    data->line.f2 = (char *)calloc( data->buflen, sizeof( char ) );
    strncpy( data->line.f2, data->buffer, data->buflen );
    data->field++;
    break;
   case 2:
    data->line.f3 = atoi( data->buffer );
    data->field++;
    break;
   default:
    // ignore
    break;
  }
 }

 # Clear out the buffer
 action clear { data->buflen = 0; }

 # Helpers that collect strings
 LF = "\n";
 string = [^,]* >clear $append;
 string2 = [^,]* >clear $append %term;
 comma = "," %term;
 main := ( string comma )+ string2 ? LF;
}%%

%% write data;

void csv_init( struct csvdata *data ) {
 data->buflen = 0;
 %% write init;
}

void csv_exec( struct csvdata *data, const char *d, int len )
{
 const char *p = d;
 const char *pe = d + len;

 %% write exec;
}

int csv_finish( struct csvdata *data )
{
 if ( data->cs == csv_error )
  return -1;
 if ( data->cs >= csv_first_final )
  return 1;
 return 0;
}

#define BUFSIZE 2048

int main( int argc, char **argv )
{
 struct csvdata csvdata;
 FILE *csvfile;
 int lineno = 0;
 char buf[ MAX_BUF_LEN + 1 ] = {"\0"};

 if (( csvfile = fopen( "test.csv", "r" ) ) == NULL ) {
  fprintf( stderr, "Could not open file test.csv\n" );
  return -1;
 }
 
 while ( fgets( buf, MAX_BUF_LEN, csvfile ) != NULL ) {
  // One more line to process
  memset( &csvdata, 0x00, sizeof( csvdata ));
  csv_exec( &csvdata, buf, strlen( buf ) );
  if ( csv_finish( &csvdata ) != 1 ) {
   fprintf( stderr, "error occurred in line: %d\n", lineno );
  } else {
   print_data( &csvdata, lineno );
  }
  lineno++;
 }

 return 0;
}

void print_data( struct csvdata *data, int lineno ) {
 fprintf( stdout, "[line %d] f1: %s", lineno, data->line.f1 );
 fprintf( stdout, ", f2: %s", data->line.f2 );
 fprintf( stdout, ", f3: %d\n", data->line.f3 );
}

The following test.csv file was used:

test1,test2,4000
more,data,5032335
and,even,111
more,data,1213
errorhere
invalid line

And this is how to compile and visualize:

compile.sh:
-----------

#!/bin/bash

ragel main.rl
ragel -V main.rl > test.dot
gcc -o main main.c

visualize.sh:
-------------

#!/bin/bash

dot -Tpng -otest.png test.dot
eog test.png