quote.c

#include "stralloc.h"
#include "str.h"
#include "quote.h"

/*
quote() encodes a box as per rfc 821 and rfc 822,
while trying to do as little quoting as possible.
no, 821 and 822 don't have the same encoding. they're not even close.
no special encoding here for bytes above 127.
*/

static const char ok[128] = {
 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
,0,7,0,7,7,7,7,7,0,0,7,7,0,7,7,7 ,7,7,7,7,7,7,7,7,7,7,0,0,0,7,0,7
,0,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 ,7,7,7,7,7,7,7,7,7,7,7,0,0,0,7,7
,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7 ,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,0
} ;

static int doit(stralloc *saout,const stralloc *sain)
{
 char ch;
 unsigned int i;
 int j;

 if (!stralloc_ready(saout,sain->len * 2 + 2)) return 0;
 j = 0;
 saout->s[j++] = '"';
 for (i = 0;i < sain->len;++i)
  {
   ch = sain->s[i];
   if ((ch == '\r') || (ch == '\n') || (ch == '"') || (ch == '\\'))
     saout->s[j++] = '\\';
   saout->s[j++] = ch;
  }
 saout->s[j++] = '"';
 saout->len = j;
 return 1;
}

int quote_need(const char *s,unsigned int n)
{
 unsigned char uch;
 unsigned int i;
 if (!n) return 0;
 for (i = 0;i < n;++i)
  {
   uch = s[i];
   if (uch >= 128) return 1;
   if (!ok[uch]) return 1;
  }
 if (s[0] == '.') return 1;
 if (s[n - 1] == '.') return 1;
 for (i = 0;i < n - 1;++i) if (s[i] == '.') if (s[i + 1] == '.') return 1;
 return 0;
}

int quote(stralloc *saout,const stralloc *sain)
{
 if (quote_need(sain->s,sain->len)) return doit(saout,sain);
 return stralloc_copy(saout,sain);
}

static stralloc foo = {0};

int quote2(stralloc *sa,const char *s)
{
 int j;
 j = str_rchr(s,'@');
 if (!stralloc_copys(&foo,s)) return 0;
 if (!s[j]) return quote(sa,&foo);
 foo.len = j;
 if (!quote(sa,&foo)) return 0;
 return stralloc_cats(sa,s + j);
}