rfc822/encodeautodetect.c

   1 /*
   2 ** Copyright 2003-2009 Double Precision, Inc.  See COPYING for
   3 ** distribution information.
   4 */
   5
   6 /*
   7 ** $Id: encodeautodetect.c,v 1.2 2009/11/08 18:14:47 mrsam Exp $
   8 */
   9 #include        "encode.h"
  10 #include        <string.h>
  11 #include        <stdlib.h>
  12 #include        "../unicode/unicode.h"
  13
  14 static const char *libmail_encode_autodetect(const char *charset,
  15                                              int (*func)(void *), void *arg)
  16 {
  17         const char *encoding="7bit";
  18         int     l=0;
  19         int     longline=0;
  20         int c;
  21         const struct unicode_info *ci = unicode_find(charset);
  22
  23         while ((c = (*func)(arg)) != EOF)
  24         {
  25                 unsigned char ch= (unsigned char)c;
  26
  27                 if (ch >= 0x80)
  28                 {
  29
  30                         if (!charset || !*charset)
  31                                 encoding="8bit";
  32                         else if (ci && ci->flags & UNICODE_BODY_QUOPRI)
  33                                 encoding="quoted-printable";
  34                         else if (!ci || ci->flags & UNICODE_BODY_BASE64)
  35                                 encoding="base64";
  36                         else
  37                                 encoding="8bit";
  38                 }
  39
  40                 if (ch < 0x20 &&
  41                     ch != '\t' && ch != '\r' && ch != '\n')
  42                 {
  43                         if (!charset || !*charset)
  44                                 ;
  45                         else if (ci && ci->flags & UNICODE_BODY_QUOPRI)
  46                                 encoding="quoted-printable";
  47                         else if (!ci || ci->flags & UNICODE_BODY_BASE64)
  48                                 encoding="base64";
  49                 }
  50
  51                 if (ch == 0)
  52                         return "base64";
  53
  54                 if (ch == '\n') l=0;
  55                 else if (++l > 990)
  56                 {
  57                         longline=1;
  58                         if (ci && ci->flags & UNICODE_BODY_QUOPRI)
  59                                 encoding="quoted-printable";
  60                 }
  61
  62         }
  63
  64         if (longline)
  65         {
  66                 if (ci && ci->flags & UNICODE_BODY_QUOPRI)
  67                         encoding="quoted-printable";
  68                 else
  69                         encoding="base64";
  70         }
  71         return encoding;
  72 }
  73
  74 struct file_info {
  75         FILE *fp;
  76         off_t pos;
  77         off_t end;
  78 };
  79
  80 static int read_file(void *arg)
  81 {
  82 int c;
  83 struct file_info *fi = (struct file_info *)arg;
  84         if (fi->end >= 0 && fi->pos > fi->end)
  85                 return EOF;
  86         c = getc(fi->fp);
  87         fi->pos++;
  88         return c;
  89 }
  90
  91 static int read_string(void * arg)
  92 {
  93 int c;
  94 unsigned char **strp = (unsigned char **)arg;
  95         if (**strp == 0)
  96                 return EOF;
  97         c = (int)**strp;
  98         (*strp)++;
  99         return c;
 100 }
 101
 102 const char *libmail_encode_autodetect_fp(FILE *fp, int okQp)
 103 {
 104         if (okQp)
 105                 return libmail_encode_autodetect_fppos(fp, "ISO-8859-1", 0, -1);
 106         else
 107                 return libmail_encode_autodetect_fppos(fp, NULL, 0, -1);
 108 }
 109
 110 const char *libmail_encode_autodetect_fppos(FILE *fp, const char *charset,
 111                                             off_t start_pos, off_t end_pos)
 112 {
 113 struct file_info fi;
 114 off_t orig_pos = ftell(fp);
 115 off_t pos = orig_pos;
 116 const char *rc;
 117
 118         if (start_pos >= 0)
 119         {
 120                 if (fseek(fp, start_pos, SEEK_SET) == (off_t)-1)
 121                         return NULL;
 122                 else
 123                         pos = start_pos;
 124         }
 125
 126         fi.fp = fp;
 127         fi.pos = pos;
 128         fi.end = end_pos;
 129         rc = libmail_encode_autodetect(charset, &read_file, &fi);
 130
 131         if (fseek(fp, orig_pos, SEEK_SET) == (off_t)-1)
 132                 return NULL;
 133         return rc;
 134 }
 135
 136 const char *libmail_encode_autodetect_str(const char *str, const char *charset)
 137 {
 138         return libmail_encode_autodetect(charset, &read_string, &str);
 139 }