diff --git a/libstream/gzio.c b/libstream/gzio.c
new file mode 100644
index 0000000..a066ecd
--- /dev/null
+++ b/libstream/gzio.c
@@ -0,0 +1,522 @@
+/* gzio.c -- IO on .gz files
+ * Copyright (C) 1995-2005 Jean-loup Gailly.
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ *
+ * modified to use in EMILE by Laurent Vivier, 2005
+ *
+ */
+
+/* @(#) $Id: gzio.c,v 1.1 2005/11/22 23:14:01 lvivier Exp $ */
+
+#include <stdio.h>
+
+#include "zutil.h"
+#include "libstream.h"
+
+#ifndef NO_DUMMY_DECL
+struct internal_state {int dummy;}; /* for buggy compilers */
+#endif
+
+#ifndef Z_BUFSIZE
+#  ifdef MAXSEG_64K
+#    define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
+#  else
+#    define Z_BUFSIZE 16384
+#  endif
+#endif
+#ifndef Z_PRINTF_BUFSIZE
+#  define Z_PRINTF_BUFSIZE 4096
+#endif
+
+#ifndef STDC
+extern voidp  malloc OF((uInt size));
+extern void   free   OF((voidpf ptr));
+#endif
+
+#define ALLOC(size) malloc(size)
+#define TRYFREE(p) {if (p) free(p);}
+
+static int const gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
+
+/* gzip flag byte */
+#define HEAD_CRC     0x02 /* bit 1 set: header CRC present */
+#define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
+#define ORIG_NAME    0x08 /* bit 3 set: original file name present */
+#define COMMENT      0x10 /* bit 4 set: file comment present */
+#define RESERVED     0xE0 /* bits 5..7: reserved */
+
+typedef struct gz_stream {
+    z_stream stream;
+    int      z_err;   /* error code for last stream operation */
+    int      z_eof;   /* set if end of input file */
+    Byte     *inbuf;  /* input buffer */
+    Byte     *outbuf; /* output buffer */
+    uLong    crc;     /* crc32 of uncompressed data */
+    int      transparent; /* 1 if input file is not a .gz file */
+    z_off_t  start;   /* start of compressed data in file (header skipped) */
+    z_off_t  in;      /* bytes into deflate or inflate */
+    z_off_t  out;     /* bytes out of deflate or inflate */
+    int      back;    /* one character push-back */
+    int      last;    /* true if push-back is last character */
+
+    filesystem_io_t fs;
+} gz_stream;
+
+
+local int    get_byte     OF((gz_stream *s));
+local void   check_header OF((gz_stream *s));
+local int    destroy      OF((gz_stream *s));
+local uLong  getLong      OF((gz_stream *s));
+
+/* ===========================================================================
+     Opens a gzip (.gz) file for reading or writing. The mode parameter
+   is as in fopen ("rb" or "wb"). The file is given either by file descriptor
+   or path name (if fd == -1).
+     gz_open returns NULL if the file could not be opened or if there was
+   insufficient memory to allocate the (de)compression state; errno
+   can be checked to distinguish the two cases (if errno is zero, the
+   zlib error is Z_MEM_ERROR).
+*/
+gzFile gzopen (fs)
+	filesystem_io_t *fs;
+{
+    int err;
+    gz_stream *s;
+
+    s = (gz_stream *)ALLOC(sizeof(gz_stream));
+    if (!s) return Z_NULL;
+
+    s->stream.zalloc = (alloc_func)0;
+    s->stream.zfree = (free_func)0;
+    s->stream.opaque = (voidpf)0;
+    s->stream.next_in = s->inbuf = Z_NULL;
+    s->stream.next_out = s->outbuf = Z_NULL;
+    s->stream.avail_in = s->stream.avail_out = 0;
+    s->z_err = Z_OK;
+    s->z_eof = 0;
+    s->in = 0;
+    s->out = 0;
+    s->back = EOF;
+    s->crc = crc32(0L, Z_NULL, 0);
+    s->transparent = 0;
+
+    s->fs = *fs;
+
+    s->stream.next_in  = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
+
+    err = inflateInit2(&(s->stream), -MAX_WBITS);
+    /* windowBits is passed < 0 to tell that there is no zlib header.
+    * Note that in this case inflate *requires* an extra "dummy" byte
+    * after the compressed stream in order to complete decompression and
+    * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
+    * present after the compressed stream.
+    */
+
+    if (err != Z_OK || s->inbuf == Z_NULL) {
+        return destroy(s), (gzFile)Z_NULL;
+    }
+    s->stream.avail_out = Z_BUFSIZE;
+
+    check_header(s); /* skip the .gz header */
+    s->start = s->fs.lseek(s->fs.file, 0, SEEK_CUR) - s->stream.avail_in;
+
+    return (gzFile)s;
+}
+
+/* ===========================================================================
+     Read a byte from a gz_stream; update next_in and avail_in. Return EOF
+   for end of file.
+   IN assertion: the stream s has been sucessfully opened for reading.
+*/
+local int get_byte(s)
+    gz_stream *s;
+{
+    if (s->z_eof) return EOF;
+    if (s->stream.avail_in == 0) {
+        s->stream.avail_in = (uInt)s->fs.read(s->fs.file, s->inbuf, Z_BUFSIZE);
+        if (s->stream.avail_in == 0) {
+            s->z_eof = 1;
+            return EOF;
+        }
+        s->stream.next_in = s->inbuf;
+    }
+    s->stream.avail_in--;
+    return *(s->stream.next_in)++;
+}
+
+/* ===========================================================================
+      Check the gzip header of a gz_stream opened for reading. Set the stream
+    mode to transparent if the gzip magic header is not present; set s->err
+    to Z_DATA_ERROR if the magic header is present but the rest of the header
+    is incorrect.
+    IN assertion: the stream s has already been created sucessfully;
+       s->stream.avail_in is zero for the first time, but may be non-zero
+       for concatenated .gz files.
+*/
+local void check_header(s)
+    gz_stream *s;
+{
+    int method; /* method byte */
+    int flags;  /* flags byte */
+    uInt len;
+    int c;
+
+    /* Assure two bytes in the buffer so we can peek ahead -- handle case
+       where first byte of header is at the end of the buffer after the last
+       gzip segment */
+    len = s->stream.avail_in;
+    if (len < 2) {
+        if (len) s->inbuf[0] = s->stream.next_in[0];
+        len = (uInt)s->fs.read(s->fs.file, s->inbuf + len, Z_BUFSIZE >> len);
+        s->stream.avail_in += len;
+        s->stream.next_in = s->inbuf;
+        if (s->stream.avail_in < 2) {
+            s->transparent = s->stream.avail_in;
+            return;
+        }
+    }
+
+    /* Peek ahead to check the gzip magic header */
+    if (s->stream.next_in[0] != gz_magic[0] ||
+        s->stream.next_in[1] != gz_magic[1]) {
+        s->transparent = 1;
+        return;
+    }
+    s->stream.avail_in -= 2;
+    s->stream.next_in += 2;
+
+    /* Check the rest of the gzip header */
+    method = get_byte(s);
+    flags = get_byte(s);
+    if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
+        s->z_err = Z_DATA_ERROR;
+        return;
+    }
+
+    /* Discard time, xflags and OS code: */
+    for (len = 0; len < 6; len++) (void)get_byte(s);
+
+    if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
+        len  =  (uInt)get_byte(s);
+        len += ((uInt)get_byte(s))<<8;
+        /* len is garbage if EOF but the loop below will quit anyway */
+        while (len-- != 0 && get_byte(s) != EOF) ;
+    }
+    if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
+        while ((c = get_byte(s)) != 0 && c != EOF) ;
+    }
+    if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
+        while ((c = get_byte(s)) != 0 && c != EOF) ;
+    }
+    if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
+        for (len = 0; len < 2; len++) (void)get_byte(s);
+    }
+    s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
+}
+
+ /* ===========================================================================
+ * Cleanup then free the given gz_stream. Return a zlib error code.
+   Try freeing in the reverse order of allocations.
+ */
+local int destroy (s)
+    gz_stream *s;
+{
+    int err = Z_OK;
+
+    if (!s) return Z_STREAM_ERROR;
+
+    if (s->stream.state != NULL) {
+       err = inflateEnd(&(s->stream));
+    }
+    if (s->z_err < 0) err = s->z_err;
+
+    TRYFREE(s->inbuf);
+    TRYFREE(s->outbuf);
+    TRYFREE(s);
+    return err;
+}
+
+/* ===========================================================================
+     Reads the given number of uncompressed bytes from the compressed file.
+   gzread returns the number of bytes actually read (0 for end of file).
+*/
+int ZEXPORT gzread (file, buf, len)
+    gzFile file;
+    voidp buf;
+    unsigned len;
+{
+    gz_stream *s = (gz_stream*)file;
+    Bytef *start = (Bytef*)buf; /* starting point for crc computation */
+    Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
+
+    if (s == NULL) return Z_STREAM_ERROR;
+
+    if (s->z_err == Z_DATA_ERROR) return -1;
+    if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
+
+    next_out = (Byte*)buf;
+    s->stream.next_out = (Bytef*)buf;
+    s->stream.avail_out = len;
+
+    if (s->stream.avail_out && s->back != EOF) {
+        *next_out++ = s->back;
+        s->stream.next_out++;
+        s->stream.avail_out--;
+        s->back = EOF;
+        s->out++;
+        start++;
+        if (s->last) {
+            s->z_err = Z_STREAM_END;
+            return 1;
+        }
+    }
+
+    while (s->stream.avail_out != 0) {
+
+        if (s->transparent) {
+            /* Copy first the lookahead bytes: */
+            uInt n = s->stream.avail_in;
+            if (n > s->stream.avail_out) n = s->stream.avail_out;
+            if (n > 0) {
+                zmemcpy(s->stream.next_out, s->stream.next_in, n);
+                next_out += n;
+                s->stream.next_out = next_out;
+                s->stream.next_in   += n;
+                s->stream.avail_out -= n;
+                s->stream.avail_in  -= n;
+            }
+            if (s->stream.avail_out > 0) {
+                s->stream.avail_out -=
+                    (uInt)s->fs.read(s->fs.file, next_out, s->stream.avail_out);
+            }
+            len -= s->stream.avail_out;
+            s->in  += len;
+            s->out += len;
+            if (len == 0) s->z_eof = 1;
+            return (int)len;
+        }
+        if (s->stream.avail_in == 0 && !s->z_eof) {
+
+            s->stream.avail_in = (uInt)s->fs.read(s->fs.file, s->inbuf, Z_BUFSIZE);
+            if (s->stream.avail_in == 0) {
+                s->z_eof = 1;
+            }
+            s->stream.next_in = s->inbuf;
+        }
+        s->in += s->stream.avail_in;
+        s->out += s->stream.avail_out;
+        s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
+        s->in -= s->stream.avail_in;
+        s->out -= s->stream.avail_out;
+
+        if (s->z_err == Z_STREAM_END) {
+            /* Check CRC and original size */
+            s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
+            start = s->stream.next_out;
+
+            if (getLong(s) != s->crc) {
+                s->z_err = Z_DATA_ERROR;
+            } else {
+                (void)getLong(s);
+                /* The uncompressed length returned by above getlong() may be
+                 * different from s->out in case of concatenated .gz files.
+                 * Check for such files:
+                 */
+                check_header(s);
+                if (s->z_err == Z_OK) {
+                    inflateReset(&(s->stream));
+                    s->crc = crc32(0L, Z_NULL, 0);
+                }
+            }
+        }
+        if (s->z_err != Z_OK || s->z_eof) break;
+    }
+    s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
+
+    if (len == s->stream.avail_out &&
+        (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO))
+        return -1;
+    return (int)(len - s->stream.avail_out);
+}
+
+
+/* ===========================================================================
+      Sets the starting position for the next gzread or gzwrite on the given
+   compressed file. The offset represents a number of bytes in the
+      gzseek returns the resulting offset location as measured in bytes from
+   the beginning of the uncompressed stream, or -1 in case of error.
+      SEEK_END is not implemented, returns error.
+      In this version of the library, gzseek can be extremely slow.
+*/
+z_off_t ZEXPORT gzseek (file, offset, whence)
+    gzFile file;
+    z_off_t offset;
+    int whence;
+{
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL || whence == SEEK_END ||
+        s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
+        return -1L;
+    }
+
+    /* Rest of function is for reading only */
+
+    /* compute absolute position */
+    if (whence == SEEK_CUR) {
+        offset += s->out;
+    }
+    if (offset < 0) return -1L;
+
+    if (s->transparent) {
+        /* map to lseek */
+        s->back = EOF;
+        s->stream.avail_in = 0;
+        s->stream.next_in = s->inbuf;
+        if (s->fs.lseek(s->fs.file, offset, SEEK_SET) < 0) return -1L;
+
+        s->in = s->out = offset;
+        return offset;
+    }
+
+    /* For a negative seek, rewind and use positive seek */
+    if (offset >= s->out) {
+        offset -= s->out;
+    } else if (gzrewind(file) < 0) {
+        return -1L;
+    }
+    /* offset is now the number of bytes to skip. */
+
+    if (offset != 0 && s->outbuf == Z_NULL) {
+        s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
+        if (s->outbuf == Z_NULL) return -1L;
+    }
+    if (offset && s->back != EOF) {
+        s->back = EOF;
+        s->out++;
+        offset--;
+        if (s->last) s->z_err = Z_STREAM_END;
+    }
+    while (offset > 0)  {
+        int size = Z_BUFSIZE;
+        if (offset < Z_BUFSIZE) size = (int)offset;
+
+        size = gzread(file, s->outbuf, (uInt)size);
+        if (size <= 0) return -1L;
+        offset -= size;
+    }
+    return s->out;
+}
+
+/* ===========================================================================
+     Rewinds input file.
+*/
+int ZEXPORT gzrewind (file)
+    gzFile file;
+{
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL) return -1;
+
+    s->z_err = Z_OK;
+    s->z_eof = 0;
+    s->back = EOF;
+    s->stream.avail_in = 0;
+    s->stream.next_in = s->inbuf;
+    s->crc = crc32(0L, Z_NULL, 0);
+    if (!s->transparent) (void)inflateReset(&s->stream);
+    s->in = 0;
+    s->out = 0;
+    return s->fs.lseek(s->fs.file, s->start, SEEK_SET);
+}
+
+/* ===========================================================================
+     Returns 1 when EOF has previously been detected reading the given
+   input stream, otherwise zero.
+*/
+int ZEXPORT gzeof (file)
+    gzFile file;
+{
+    gz_stream *s = (gz_stream*)file;
+
+    /* With concatenated compressed files that can have embedded
+     * crc trailers, z_eof is no longer the only/best indicator of EOF
+     * on a gz_stream. Handle end-of-stream error explicitly here.
+     */
+    if (s == NULL) return 0;
+    if (s->z_eof) return 1;
+    return s->z_err == Z_STREAM_END;
+}
+
+/* ===========================================================================
+   Reads a long in LSB order from the given gz_stream. Sets z_err in case
+   of error.
+*/
+local uLong getLong (s)
+    gz_stream *s;
+{
+    uLong x = (uLong)get_byte(s);
+    int c;
+
+    x += ((uLong)get_byte(s))<<8;
+    x += ((uLong)get_byte(s))<<16;
+    c = get_byte(s);
+    if (c == EOF) s->z_err = Z_DATA_ERROR;
+    x += ((uLong)c)<<24;
+    return x;
+}
+
+/* ===========================================================================
+     Flushes all pending output if necessary, closes the compressed file
+   and deallocates all the (de)compression state.
+*/
+int ZEXPORT gzclose (file)
+    gzFile file;
+{
+    filesystem_io_t fs;
+    gz_stream *s = (gz_stream*)file;
+    int ret;
+
+    fs = s->fs;
+
+    if (s == NULL) return Z_STREAM_ERROR;
+
+    ret = destroy((gz_stream*)file);
+    fs.close(fs.file);
+    fs.umount(fs.file);
+
+    return ret;
+}
+
+#ifdef STDC
+#  define zstrerror(errnum) strerror(errnum)
+#else
+#  define zstrerror(errnum) ""
+#endif
+
+/* ===========================================================================
+     Returns the error message for the last error which occurred on the
+   given compressed file. errnum is set to zlib error number. If an
+   error occurred in the file system and not in the compression library,
+   errnum is set to Z_ERRNO and the application may consult errno
+   to get the exact error code.
+*/
+const char * ZEXPORT gzerror (file, errnum)
+    gzFile file;
+    int *errnum;
+{
+	return "Unknown error";
+}
+
+/* ===========================================================================
+     Clear the error and end-of-file flags, and do the same for the real file.
+*/
+void ZEXPORT gzclearerr (file)
+    gzFile file;
+{
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL) return;
+    if (s->z_err != Z_STREAM_END) s->z_err = Z_OK;
+    s->z_eof = 0;
+}