path: root/camel/camel-iconv.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */
/*
 *  Authors: Jeffrey Stedfast <fejj@ximian.com>
 *
 *  Copyright 2003 Ximian, Inc. (www.ximian.com)
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Street #330, Boston, MA 02111-1307, USA.
 *
 */


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <glib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "e-util/e-memory.h"
#include "camel/camel-charset-map.h"
#include "camel-iconv.h"


#define ICONV_CACHE_SIZE   (16)

struct _iconv_cache_bucket {
    struct _iconv_cache_bucket *next;
    struct _iconv_cache_bucket *prev;
    guint32 refcount;
    gboolean used;
    iconv_t cd;
    char *key;
};


/* a useful website on charset alaises:
 * http://www.li18nux.org/subgroups/sa/locnameguide/v1.1draft/CodesetAliasTable-V11.html */

struct {
    char *charset;
    char *iconv_name;
} known_iconv_charsets[] = {
#if 0
    /* charset name, iconv-friendly charset name */
    { "iso-8859-1",      "iso-8859-1" },
    { "iso8859-1",       "iso-8859-1" },
    /* the above mostly serves as an example for iso-style charsets,
       but we have code that will populate the iso-*'s if/when they
       show up in camel_iconv_charset_name() so I'm
       not going to bother putting them all in here... */
    { "windows-cp1251",  "cp1251"     },
    { "windows-1251",    "cp1251"     },
    { "cp1251",          "cp1251"     },
    /* the above mostly serves as an example for windows-style
       charsets, but we have code that will parse and convert them
       to their cp#### equivalents if/when they show up in
       camel_iconv_charset_name() so I'm not going to bother
       putting them all in here either... */
#endif
    /* charset name (lowercase!), iconv-friendly name (sometimes case sensitive) */
    { "utf-8",           "UTF-8"      },
    { "utf8",            "UTF-8"      },
    
    /* 10646 is a special case, its usually UCS-2 big endian */
    /* This might need some checking but should be ok for solaris/linux */
    { "iso-10646-1",     "UCS-2BE"    },
    { "iso_10646-1",     "UCS-2BE"    },
    { "iso10646-1",      "UCS-2BE"    },
    { "iso-10646",       "UCS-2BE"    },
    { "iso_10646",       "UCS-2BE"    },
    { "iso10646",        "UCS-2BE"    },
    
    /* "ks_c_5601-1987" seems to be the most common of this lot */
    { "ks_c_5601-1987",  "EUC-KR"     },
    { "5601",            "EUC-KR"     },
    { "ksc-5601",        "EUC-KR"     },
    { "ksc-5601-1987",   "EUC-KR"     },
    { "ksc-5601_1987",   "EUC-KR"     },
    
    /* FIXME: Japanese/Korean/Chinese stuff needs checking */
    { "euckr-0",         "EUC-KR"     },
    { "5601",            "EUC-KR"     },
    { "big5-0",          "BIG5"       },
    { "big5.eten-0",     "BIG5"       },
    { "big5hkscs-0",     "BIG5HKCS"   },
    { "gb2312-0",        "gb2312"     },
    { "gb2312.1980-0",   "gb2312"     },
    { "euc-cn",          "gb2312"     },
    { "gb18030-0",       "gb18030"    },
    { "gbk-0",           "GBK"        },
    
    { "eucjp-0",         "eucJP"      },  /* should this map to "EUC-JP" instead? */
    { "ujis-0",          "ujis"       },  /* we might want to map this to EUC-JP */
    { "jisx0208.1983-0", "SJIS"       },
    { "jisx0212.1990-0", "SJIS"       },
    { "pck",         "SJIS"       },
    { NULL,              NULL         }
};


static GHashTable *iconv_charsets;

static EMemChunk *cache_chunk;
static struct _iconv_cache_bucket *iconv_cache_buckets;
static GHashTable *iconv_cache;
static GHashTable *iconv_open_hash;
static unsigned int iconv_cache_size = 0;

#ifdef G_THREADS_ENABLED
static GStaticMutex iconv_cache_lock = G_STATIC_MUTEX_INIT;
static GStaticMutex iconv_charset_lock = G_STATIC_MUTEX_INIT;
#define ICONV_CACHE_LOCK()   g_static_mutex_lock (&iconv_cache_lock)
#define ICONV_CACHE_UNLOCK() g_static_mutex_unlock (&iconv_cache_lock)
#define ICONV_CHARSET_LOCK() g_static_mutex_lock (&iconv_charset_lock)
#define ICONV_CHARSET_UNLOCK() g_static_mutex_unlock (&iconv_charset_lock)
#else
#define ICONV_CACHE_LOCK()
#define ICONV_CACHE_UNLOCK()
#define ICONV_CHARSET_LOCK()
#define ICONV_CHARSET_UNLOCK()
#endif /* G_THREADS_ENABLED */


/* caller *must* hold the iconv_cache_lock to call any of the following functions */


/**
 * iconv_cache_bucket_new:
 * @key: cache key
 * @cd: iconv descriptor
 *
 * Creates a new cache bucket, inserts it into the cache and
 * increments the cache size.
 *
 * Returns a pointer to the newly allocated cache bucket.
 **/
static struct _iconv_cache_bucket *
iconv_cache_bucket_new (const char *key, iconv_t cd)
{
    struct _iconv_cache_bucket *bucket;
    
    bucket = e_memchunk_alloc (cache_chunk);
    bucket->next = NULL;
    bucket->prev = NULL;
    bucket->key = g_strdup (key);
    bucket->refcount = 1;
    bucket->used = TRUE;
    bucket->cd = cd;
    
    g_hash_table_insert (iconv_cache, bucket->key, bucket);
    
    /* FIXME: Since iconv_cache_expire_unused() traverses the list
       from head to tail, perhaps it might be better to append new
       nodes rather than prepending? This way older cache buckets
       expire first? */
    bucket->next = iconv_cache_buckets;
    iconv_cache_buckets = bucket;
    
    iconv_cache_size++;
    
    return bucket;
}


/**
 * iconv_cache_bucket_expire:
 * @bucket: cache bucket
 *
 * Expires a single cache bucket @bucket. This should only ever be
 * called on a bucket that currently has no used iconv descriptors
 * open.
 **/
static void
iconv_cache_bucket_expire (struct _iconv_cache_bucket *bucket)
{
    g_hash_table_remove (iconv_cache, bucket->key);
    
    if (bucket->prev) {
        bucket->prev->next = bucket->next;
        if (bucket->next)
            bucket->next->prev = bucket->prev;
    } else {
        iconv_cache_buckets = bucket->next;
        if (bucket->next)
            bucket->next->prev = NULL;
    }
    
    g_free (bucket->key);
    iconv_close (bucket->cd);
    e_memchunk_free (cache_chunk, bucket);
    
    iconv_cache_size--;
}


/**
 * iconv_cache_expire_unused:
 *
 * Expires as many unused cache buckets as it needs to in order to get
 * the total number of buckets < ICONV_CACHE_SIZE.
 **/
static void
iconv_cache_expire_unused (void)
{
    struct _iconv_cache_bucket *bucket, *next;
    
    bucket = iconv_cache_buckets;
    while (bucket && iconv_cache_size >= ICONV_CACHE_SIZE) {
        next = bucket->next;
        
        if (bucket->refcount == 0)
            iconv_cache_bucket_expire (bucket);
        
        bucket = next;
    }
}


static void
iconv_charset_free (char *name, char *iname, gpointer user_data)
{
    g_free (name);
    g_free (iname);
}

void
camel_iconv_shutdown (void)
{
    struct _iconv_cache_bucket *bucket, *next;
    
    g_hash_table_foreach (iconv_charsets, (GHFunc) iconv_charset_free, NULL);
    g_hash_table_destroy (iconv_charsets);
    
    bucket = iconv_cache_buckets;
    while (bucket) {
        next = bucket->next;
        
        g_free (bucket->key);
        g_iconv_close (bucket->cd);
        e_memchunk_free (cache_chunk, bucket);
        
        bucket = next;
    }
    
    g_hash_table_destroy (iconv_cache);
    g_hash_table_destroy (iconv_open_hash);
    
    e_memchunk_destroy (cache_chunk);
}


/**
 * camel_iconv_init:
 *
 * Initialize Camel's iconv cache. This *MUST* be called before any
 * camel-iconv interfaces will work correctly.
 **/
void
camel_iconv_init (void)
{
    static int initialized = FALSE;
    char *from, *to;
    int i;
    
    if (initialized)
        return;
    
    iconv_charsets = g_hash_table_new (g_str_hash, g_str_equal);
    
    for (i = 0; known_iconv_charsets[i].charset != NULL; i++) {
        from = g_strdup (known_iconv_charsets[i].charset);
        to = g_strdup (known_iconv_charsets[i].iconv_name);
        g_ascii_strdown (from, -1);
        
        g_hash_table_insert (iconv_charsets, from, to);
    }
    
    iconv_cache_buckets = NULL;
    iconv_cache = g_hash_table_new (g_str_hash, g_str_equal);
    iconv_open_hash = g_hash_table_new (g_direct_hash, g_direct_equal);
    
    cache_chunk = e_memchunk_new (ICONV_CACHE_SIZE, sizeof (struct _iconv_cache_bucket));
    
    initialized = TRUE;
}


/**
 * camel_iconv_charset_name:
 * @charset: charset name
 *
 * Maps charset names to the names that glib's g_iconv_open() is more
 * likely able to handle.
 *
 * Returns an iconv-friendly name for @charset.
 **/
const char *
camel_iconv_charset_name (const char *charset)
{
    char *name, *iname, *tmp;
    
    if (charset == NULL)
        return NULL;
    
    name = g_alloca (strlen (charset) + 1);
    strcpy (name, charset);
    g_ascii_strdown (name, -1);
    
    ICONV_CHARSET_LOCK ();
    if ((iname = g_hash_table_lookup (iconv_charsets, name)) != NULL) {
        ICONV_CHARSET_UNLOCK ();
        return iname;
    }
    
    /* Unknown, try to convert some basic charset types to something that should work */
    if (!strncmp (name, "iso", 3)) {
        /* camel_charset_canonical_name() can handle this case */
        ICONV_CHARSET_UNLOCK ();
        return camel_charset_canonical_name (charset);
    } else if (strncmp (name, "windows-", 8) == 0) {
        /* Convert windows-#### or windows-cp#### to cp#### */
        tmp = name + 8;
        if (!strncmp (tmp, "cp", 2))
            tmp += 2;
        iname = g_strdup_printf ("CP%s", tmp);
    } else if (strncmp (name, "microsoft-", 10) == 0) {
        /* Convert microsoft-#### or microsoft-cp#### to cp#### */
        tmp = name + 10;
        if (!strncmp (tmp, "cp", 2))
            tmp += 2;
        iname = g_strdup_printf ("CP%s", tmp);  
    } else {
        /* Just assume its ok enough as is, case and all - let g_iconv_open() handle this */
        iname = g_strdup (charset);
    }
    
    g_hash_table_insert (iconv_charsets, g_strdup (name), iname);
    ICONV_CHARSET_UNLOCK ();
    
    return iname;
}


/**
 * camel_iconv_open:
 * @to: charset to convert to
 * @from: charset to convert from
 *
 * Allocates a coversion descriptor suitable for converting byte
 * sequences from charset @from to charset @to. The resulting
 * descriptor can be used with iconv (or the camel_iconv wrapper) any
 * number of times until closed using camel_iconv_close.
 *
 * Returns a new conversion descriptor for use with iconv on success
 * or (iconv_t) -1 on fail as well as setting an appropriate errno
 * value.
 **/
iconv_t
camel_iconv_open (const char *to, const char *from)
{
    struct _iconv_cache_bucket *bucket;
    iconv_t cd;
    char *key;
    
    if (from == NULL || to == NULL) {
        errno = EINVAL;
        return (iconv_t) -1;
    }
    
    if (!strcasecmp (from, "x-unknown"))
        from = camel_charset_locale_name ();
    
    /* Even tho g_iconv_open will find the appropriate charset
     * format(s) for the to/from charset strings (hahaha, yea
     * right), we still convert them to their canonical format
     * here so that our key is in a standard format */
    from = camel_iconv_charset_name (from);
    to = camel_iconv_charset_name (to);
    key = g_alloca (strlen (from) + strlen (to) + 2);
    sprintf (key, "%s:%s", from, to);
    
    ICONV_CACHE_LOCK ();
    
    bucket = g_hash_table_lookup (iconv_cache, key);
    if (bucket) {
        if (bucket->used) {
            cd = g_iconv_open (to, from);
            if (cd == (iconv_t) -1)
                goto exception;
        } else {
            /* Apparently iconv on Solaris <= 7 segfaults if you pass in
             * NULL for anything but inbuf; work around that. (NULL outbuf
             * or NULL *outbuf is allowed by Unix98.)
             */
            size_t inleft = 0, outleft = 0;
            char *outbuf = NULL;
            
            cd = bucket->cd;
            bucket->used = TRUE;
            
            /* reset the descriptor */
            g_iconv (cd, NULL, &inleft, &outbuf, &outleft);
        }
        
        bucket->refcount++;
    } else {
        cd = g_iconv_open (to, from);
        if (cd == (iconv_t) -1)
            goto exception;
        
        iconv_cache_expire_unused ();
        
        bucket = iconv_cache_bucket_new (key, cd);
    }
    
    g_hash_table_insert (iconv_open_hash, cd, bucket->key);
    
    ICONV_CACHE_UNLOCK ();
    
    return cd;
    
 exception:
    
    ICONV_CACHE_UNLOCK ();
    
    if (errno == EINVAL)
        g_warning ("Conversion from '%s' to '%s' is not supported", from, to);
    else
        g_warning ("Could not open converter from '%s' to '%s': %s",
               from, to, g_strerror (errno));
    
    return cd;
}


/**
 * camel_iconv:
 * @cd: conversion descriptor
 * @inbuf: address of input buffer
 * @inleft: input bytes left
 * @outbuf: address of output buffer
 * @outleft: output bytes left
 *
 * Read `man 3 iconv`
 **/
size_t
camel_iconv (iconv_t cd, const char **inbuf, size_t *inleft, char **outbuf, size_t *outleft)
{
    return iconv (cd, inbuf, inleft, outbuf, outleft);
}


/**
 * camel_iconv_close:
 * @cd: iconv conversion descriptor
 *
 * Closes the iconv descriptor @cd.
 *
 * Returns 0 on success or -1 on fail as well as setting an
 * appropriate errno value.
 **/
int
camel_iconv_close (iconv_t cd)
{
    struct _iconv_cache_bucket *bucket;
    const char *key;
    
    if (cd == (iconv_t) -1)
        return 0;
    
    ICONV_CACHE_LOCK ();
    
    key = g_hash_table_lookup (iconv_open_hash, cd);
    if (key) {
        g_hash_table_remove (iconv_open_hash, cd);
        
        bucket = g_hash_table_lookup (iconv_cache, key);
        g_assert (bucket);
        
        bucket->refcount--;
        
        if (cd == bucket->cd)
            bucket->used = FALSE;
        else
            g_iconv_close (cd);
        
        if (!bucket->refcount && iconv_cache_size > ICONV_CACHE_SIZE) {
            /* expire this cache bucket */
            iconv_cache_bucket_expire (bucket);
        }
    } else {
        ICONV_CACHE_UNLOCK ();
        
        g_warning ("This iconv context wasn't opened using camel_iconv_open()");
        
        return g_iconv_close (cd);
    }
    
    ICONV_CACHE_UNLOCK ();
    
    return 0;
}