Added fix for enca to exit 1 each time it prints 'unknown' #19.

[Syed-Shahrukh-OSSRevival]

• Updated the function return type which printed the unknown, so it return error in case of unknown.
• Added cover for edge cases of error.

[nijel]

Shouldn't the enca_charset_is_known logic be fixed instead?

[Syed-Shahrukh-OSSRevival]

This is the implementation of enca_charset_is_known which checks if the charset is know or not. ENCA_CS_UNKNOWN = -1

enca.h:139

#define enca_charset_is_known(cs) \
  ((cs) != ENCA_CS_UNKNOWN)

With the -m flag the charset is searched within CHARSET_INFO array by the function enca_charset_name encnames.c:137

The data structure that is used by the array is defined in internal.h:77

struct _EncaCharsetInfo {
  int enca;
  int rfc1345;
  int cstocs;
  int iconv;
  int mime;
  const char *human;
  unsigned int flags;
  unsigned int nsurface;
};

encoding.h:3

EncaCharsetInfo CHARSET_INFO[] =

For the charset this is the array entry. The value of mime is -1.

  {
     148, 150, -1, 149, -1,
     "Macintosh Cyrillic",
     ENCA_CHARSET_8BIT | ENCA_CHARSET_FIXED | ENCA_CHARSET_REGULAR,
     ENCA_SURFACE_EOL_CR
  }

Using the array data function enca_charset_name
enca.c:279

 case OTYPE_MIME:
    if (enca_charset_name(result.charset, ENCA_NAME_STYLE_MIME) != NULL)
      puts(enca_charset_name(result.charset, ENCA_NAME_STYLE_MIME));
    else {
      puts(enca_charset_name(ENCA_CS_UNKNOWN, ENCA_NAME_STYLE_MIME));
      res = ERR_CANNOT;
    }

The function returns NULL at
encnames.c:181

    case ENCA_NAME_STYLE_MIME:
    return cs->mime < 0 ? NULL : ALIAS_LIST[cs->mime];

So the else case is executed

encnames.c:142

  if (charset == ENCA_CS_UNKNOWN) {
    switch (whatname) {
      case ENCA_NAME_STYLE_RFC1345:
      case ENCA_NAME_STYLE_ENCA:
      case ENCA_NAME_STYLE_MIME:
      return UNKNOWN_CHARSET_NAME;

which prints unknown.

So to ensure that this unknown is covered a return type is added to print_results. enca.c:215

[nijel]

Merged, thanks for your contribution!