The R13B03 release.OTP_R13B03

1 files changed, 822 insertions, 0 deletions

diff --git a/erts/emulator/drivers/common/gzio.c b/erts/emulator/drivers/common/gzio.c
new file mode 100644
index 0000000000..801bc61d4d
--- /dev/null
+++ b/erts/emulator/drivers/common/gzio.c
@@ -0,0 +1,822 @@
+/*
+ * Original version by Jean-loup Gailly. Modified for use by the
+ * Erlang run-time system and efile_driver; names of all external
+ * functions changed to avoid conflicts with the official gzio.c file.
+ *
+ * gzio.c -- IO on .gz files
+ * Copyright (C) 1995-1996 Jean-loup Gailly.
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+/* %ExternalCopyright% */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+#include <stdio.h>
+#include <errno.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+#include <ctype.h>
+#include "erl_driver.h"
+#include "sys.h"
+
+#ifdef VXWORKS
+/* pull in FOPEN from zutil.h instead */
+#undef F_OPEN
+#endif
+
+#ifdef __WIN32__
+#define HAVE_CONFLICTING_FREAD_DECLARATION
+#endif
+
+#ifdef STDC
+#  define zstrerror(errnum) strerror(errnum)
+#else
+#  define zstrerror(errnum) ""
+#endif
+
+#include "gzio_zutil.h"
+#include "erl_zlib.h"
+#include "gzio.h"
+
+/********struct internal_state {int dummy;}; / * for buggy compilers */
+
+#define Z_BUFSIZE 4096
+
+#define ALLOC(size) driver_alloc(size)
+#define TRYFREE(p) {if (p) driver_free(p);}
+
+static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
+
+/* gzip flag byte */
+#define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
+#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 */
+#ifdef UNIX
+    int      file;    /* .gz file descriptor */
+#else
+    FILE     *file;   /* .gz file */
+#endif
+    Byte     *inbuf;  /* input buffer */
+    Byte     *outbuf; /* output buffer */
+    uLong    crc;     /* crc32 of uncompressed data */
+    char     *msg;    /* error message */
+    char     *path;   /* path name for debugging only */
+    int      transparent; /* 1 if input file is not a .gz file */
+    char     mode;    /* 'w' or 'r' */
+    int      position; /* Position (for seek) */
+    int (*destroy)OF((struct gz_stream*)); /* Function to destroy
+					    *  this structure. */
+} gz_stream;
+
+local gzFile gz_open      OF((const char *path, const char *mode));
+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));
+
+#ifdef UNIX
+/*
+ * In Solaris 8 and earlier, fopen() and its friends cannot handle 
+ * file descriptors larger than 255. Therefore, we use read()/write()
+ * on all Unix systems.
+ */
+# define ERTS_GZWRITE(File, Buf, Count) write((File), (Buf), (Count))
+# define ERTS_GZREAD(File, Buf, Count) read((File), (Buf), (Count))
+#else
+/*
+ * On all other operating systems, using fopen(), fread()/fwrite(), since
+ * there is not guaranteed to exist any read()/write() (not part of
+ * ANSI/ISO-C).
+ */
+# define ERTS_GZWRITE(File, Buf, Count) fwrite((Buf), 1, (Count), (File))
+# define ERTS_GZREAD(File, Buf, Count) fread((Buf), 1, (Count), (File))
+#endif
+
+/* ===========================================================================
+     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 return 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).
+*/
+local gzFile gz_open (path, mode)
+    const char *path;
+    const char *mode;
+{
+    int err;
+    int level = Z_DEFAULT_COMPRESSION; /* compression level */
+    char *p = (char*)mode;
+    gz_stream *s;
+    char fmode[80]; /* copy of mode, without the compression level */
+    char *m = fmode;
+
+    if (!path || !mode) return Z_NULL;
+
+    s = (gz_stream *)ALLOC(sizeof(gz_stream));
+    if (!s) return Z_NULL;
+
+    erl_zlib_alloc_init(&s->stream);
+    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;
+#ifdef UNIX
+    s->file = -1;
+#else
+    s->file = NULL;
+#endif
+    s->z_err = Z_OK;
+    s->z_eof = 0;
+    s->crc = crc32(0L, Z_NULL, 0);
+    s->msg = NULL;
+    s->transparent = 0;
+    s->position = 0;
+    s->destroy = destroy;
+
+    s->path = (char*)ALLOC(strlen(path)+1);
+    if (s->path == NULL) {
+        return s->destroy(s), (gzFile)Z_NULL;
+    }
+    strcpy(s->path, path); /* do this early for debugging */
+
+    s->mode = '\0';
+    do {
+        if (*p == 'r')
+	    s->mode = 'r';
+	if (*p == 'w' || *p == 'a')
+	    s->mode = 'w';
+	if (isdigit((int)*p)) {
+	    level = *p - '0';
+	} else {
+	    *m++ = *p;		/* Copy the mode */
+	}
+    } while (*p++ && m < fmode + sizeof(fmode) - 1);
+    *m = '\0';
+    if (s->mode == '\0')
+	return s->destroy(s), (gzFile)Z_NULL;
+    
+    if (s->mode == 'w') {
+        err = deflateInit2(&(s->stream), level,
+                           Z_DEFLATED, MAX_WBITS+16, DEF_MEM_LEVEL, 0);
+        /* windowBits is passed < 0 to suppress zlib header */
+
+        s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
+
+        if (err != Z_OK || s->outbuf == Z_NULL) {
+            return s->destroy(s), (gzFile)Z_NULL;
+        }
+    } else {
+	/*
+	 * It is tempting to use the built-in support in zlib
+	 * for handling GZIP headers, but unfortunately it
+	 * cannot handle multiple GZIP headers (which occur when
+	 * several GZIP files have been concatenated).
+	 */
+
+	err = inflateInit2(&(s->stream), -MAX_WBITS);
+        s->stream.next_in  = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
+
+        if (err != Z_OK || s->inbuf == Z_NULL) {
+            return s->destroy(s), (gzFile)Z_NULL;
+        }
+    }
+    s->stream.avail_out = Z_BUFSIZE;
+
+    errno = 0;
+#ifdef UNIX
+    if (s->mode == 'r') {
+	s->file = open(path, O_RDONLY);
+    } else {
+	s->file = open(path, O_WRONLY | O_CREAT | O_TRUNC, 0666);
+    }
+    if (s->file == -1) {
+        return s->destroy(s), (gzFile)Z_NULL;
+    }
+#else
+    s->file = F_OPEN(path, fmode);
+    if (s->file == NULL) {
+        return s->destroy(s), (gzFile)Z_NULL;
+    }
+#endif
+    if (s->mode == 'r') {
+	check_header(s); /* skip the .gz header */
+    }
+    return (gzFile)s;
+}
+
+/* ===========================================================================
+   Rewind a gzfile back to the beginning.
+*/
+
+local int gz_rewind (gz_stream *s)
+{
+    TRYFREE(s->msg);
+
+#ifdef UNIX
+    lseek(s->file, 0L, SEEK_SET);
+#else
+    fseek(s->file, 0L, SEEK_SET);
+#endif
+    inflateReset(&(s->stream));
+    s->stream.next_in = Z_NULL;
+    s->stream.next_out = Z_NULL;
+    s->stream.avail_in = s->stream.avail_out = 0;
+    s->z_err = Z_OK;
+    s->z_eof = 0;
+    s->crc = crc32(0L, Z_NULL, 0);
+    s->msg = NULL;
+    s->position = 0;
+    s->stream.next_in = s->inbuf;
+
+    s->stream.avail_out = Z_BUFSIZE;
+
+    check_header(s);		/* skip the .gz header */
+    return 1;
+}
+
+/* ===========================================================================
+     Opens a gzip (.gz) file for reading or writing.
+*/
+gzFile erts_gzopen (path, mode)
+    const char *path;
+    const char *mode;
+{
+    return gz_open (path, mode);
+}
+
+
+/* ===========================================================================
+     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) {
+#ifdef UNIX
+	size_t res;
+	errno = 0;
+	res = ERTS_GZREAD(s->file, s->inbuf, Z_BUFSIZE);
+	if (res == 0) {
+	    s->stream.avail_in = 0;
+	    s->z_eof = 1;
+	    return EOF;
+	} else if (res < 0) {
+	    s->stream.avail_in = 0;
+	    s->z_eof = 1;
+	    s->z_err = Z_ERRNO;
+	    return EOF;
+	} else {
+	    s->stream.avail_in = (uInt) res;
+	}
+#else
+	errno = 0;
+	s->stream.avail_in = ERTS_GZREAD(s->file, s->inbuf, Z_BUFSIZE);
+	if (s->stream.avail_in == 0) {
+	    s->z_eof = 1;
+	    if (s->file && ferror(s->file))
+		s->z_err = Z_ERRNO;
+	    return EOF;
+	}
+#endif
+	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;
+
+    /* Check the gzip magic header */
+    for (len = 0; len < 2; len++) {
+	c = get_byte(s);
+	if (c != gz_magic[len]) {
+	    if (len != 0) s->stream.avail_in++, s->stream.next_in--;
+	    if (c != EOF) {
+		s->stream.avail_in++, s->stream.next_in--;
+		s->transparent = 1;
+	    }
+	    s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END;
+	    return;
+	}
+    }
+    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;
+
+    TRYFREE(s->msg);
+
+    if (s->stream.state != NULL) {
+       if (s->mode == 'w') {
+           err = deflateEnd(&(s->stream));
+       } else if (s->mode == 'r') {
+           err = inflateEnd(&(s->stream));
+       }
+    }
+#ifdef UNIX
+    if (s->file != -1 && close(s->file)) {
+        err = Z_ERRNO;
+    }
+#else
+    if (s->file != NULL && fclose(s->file)) {
+        err = Z_ERRNO;
+    }
+#endif
+    if (s->z_err < 0) err = s->z_err;
+
+    TRYFREE(s->inbuf);
+    TRYFREE(s->outbuf);
+    TRYFREE(s->path);
+    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
+erts_gzread(gzFile file, voidp buf, unsigned len)
+{
+    gz_stream *s = (gz_stream*)file;
+    Bytef *start = buf; /* starting point for crc computation */
+    Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
+
+    if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
+
+    if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
+    if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
+
+    s->stream.next_out = next_out = buf;
+    s->stream.avail_out = len;
+
+    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 -= ERTS_GZREAD(s->file, next_out,
+						   s->stream.avail_out);
+	    }
+	    len -= s->stream.avail_out;
+	    s->stream.total_in  += (uLong)len;
+	    s->stream.total_out += (uLong)len;
+            if (len == 0) s->z_eof = 1;
+	    s->position += (int)len;
+	    return (int)len;
+	}
+        if (s->stream.avail_in == 0 && !s->z_eof) {
+#ifdef UNIX
+	    size_t res;
+	    errno = 0;
+	    res = ERTS_GZREAD(s->file, s->inbuf, Z_BUFSIZE);
+	    if (res == 0) {
+		s->stream.avail_in = 0;
+		s->z_eof = 1;
+		return EOF;
+	    } else if (res < 0) {
+		s->stream.avail_in = 0;
+		s->z_eof = 1;
+		s->z_err = Z_ERRNO;
+		return EOF;
+	    } else {
+		s->stream.avail_in = (uInt) res;
+	    }
+#else
+	    errno = 0;
+            s->stream.avail_in = ERTS_GZREAD(s->file, s->inbuf, Z_BUFSIZE);
+            if (s->stream.avail_in == 0) {
+                s->z_eof = 1;
+		if (s->file && ferror(s->file)) {
+		    s->z_err = Z_ERRNO;
+		    break;
+		}
+            }
+#endif
+            s->stream.next_in = s->inbuf;
+        }
+        s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
+
+	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->stream.total_out) in case of
+		 * concatenated .gz files. Check for such files:
+		 */
+		check_header(s);
+		if (s->z_err == Z_OK) {
+		    uLong total_in = s->stream.total_in;
+		    uLong total_out = s->stream.total_out;
+
+		    inflateReset(&(s->stream));
+		    s->stream.total_in = total_in;
+		    s->stream.total_out = total_out;
+		    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));
+
+    s->position += (int)(len - s->stream.avail_out);
+
+    return (int)(len - s->stream.avail_out);
+}
+
+/* ===========================================================================
+     Writes the given number of uncompressed bytes into the compressed file.
+   gzwrite returns the number of bytes actually written (0 in case of error).
+*/
+int
+erts_gzwrite(gzFile file, voidp buf, unsigned len)
+{
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
+
+    s->stream.next_in = buf;
+    s->stream.avail_in = len;
+
+    while (s->stream.avail_in != 0) {
+
+        if (s->stream.avail_out == 0) {
+
+            s->stream.next_out = s->outbuf;
+            if (ERTS_GZWRITE(s->file, s->outbuf, Z_BUFSIZE) != Z_BUFSIZE) {
+                s->z_err = Z_ERRNO;
+                break;
+            }
+            s->stream.avail_out = Z_BUFSIZE;
+        }
+        s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
+        if (s->z_err != Z_OK) break;
+    }
+    s->position += (int)(len - s->stream.avail_in);
+    return (int)(len - s->stream.avail_in);
+}
+
+/*
+ * For use by Erlang file driver.
+ *
+ * XXX Limitations:
+ *  - SEEK_END is not allowed (length of file is not known).
+ *  - When writing, only forward seek is supported.
+ */
+
+int
+erts_gzseek(gzFile file, int offset, int whence)
+{
+    int pos;
+    gz_stream* s = (gz_stream *) file;
+
+    if (s == NULL) {
+	errno = EINVAL;
+	return -1;
+    }
+    if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) {
+	errno = EIO;
+	return -1;
+    }
+
+    switch (whence) {
+    case SEEK_SET: pos = offset; break;
+    case SEEK_CUR: pos = s->position+offset; break;
+    case SEEK_END: 
+    default:
+      errno = EINVAL; return -1;
+    }
+
+    if (pos == s->position) {
+	return pos;
+    }
+
+    if (pos < s->position) {
+	if (s->mode == 'w') {
+	    errno = EINVAL;
+	    return -1;
+	}
+	gz_rewind(s);
+    }
+
+    while (s->position < pos) {
+	char buf[512];
+	int n;
+
+	n = pos - s->position;
+	if (n > sizeof(buf))
+	    n = sizeof(buf);
+
+	if (s->mode == 'r') {
+	    erts_gzread(file, buf, n);
+	} else {
+	    memset(buf, '\0', n);
+	    erts_gzwrite(file, buf, n);
+	}
+    }
+
+    return s->position;
+}
+
+/* ===========================================================================
+     Flushes all pending output into the compressed file. The parameter
+   flush is as in the deflate() function.
+     gzflush should be called only when strictly necessary because it can
+   degrade compression.
+*/
+int
+erts_gzflush(gzFile file, int flush)
+{
+    uInt len;
+    int done = 0;
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
+
+    s->stream.avail_in = 0; /* should be zero already anyway */
+
+    for (;;) {
+        len = Z_BUFSIZE - s->stream.avail_out;
+
+        if (len != 0) {
+            if ((uInt)ERTS_GZWRITE(s->file, s->outbuf, len) != len) {
+                s->z_err = Z_ERRNO;
+                return Z_ERRNO;
+            }
+            s->stream.next_out = s->outbuf;
+            s->stream.avail_out = Z_BUFSIZE;
+        }
+        if (done) break;
+        s->z_err = deflate(&(s->stream), flush);
+
+        /* deflate has finished flushing only when it hasn't used up
+         * all the available space in the output buffer: 
+         */
+        done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
+ 
+        if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
+    }
+#ifndef UNIX
+    fflush(s->file);
+#endif
+    return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
+}
+
+/* ===========================================================================
+   Reads a long in LSB order from the given gz_stream. Sets 
+*/
+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
+erts_gzclose(gzFile file)
+{
+    int err;
+    gz_stream *s = (gz_stream*)file;
+
+    if (s == NULL) return Z_STREAM_ERROR;
+
+    if (s->mode == 'w') {
+        err = erts_gzflush (file, Z_FINISH);
+        if (err != Z_OK) return s->destroy(file);
+    }
+    return s->destroy(file);
+}
+
+
+/* ===========================================================================
+   Uncompresses the buffer given and returns a pointer to a binary.
+   If the buffer was not compressed with gzip, the buffer contents
+   will be copied unchanged into the binary.
+
+   If a `gzip' header was found, but there were subsequent errors,
+   a NULL pointer is returned.
+*/
+
+ErlDrvBinary*
+erts_gzinflate_buffer(char* start, uLong size)
+{
+    ErlDrvBinary* bin;
+    ErlDrvBinary* bin2;
+    z_stream zstr;
+    unsigned char* bptr;
+
+    /*
+     * Check for the magic bytes beginning a GZIP header.
+     */
+    bptr = (unsigned char *) start;
+    if (size < 2 || bptr[0] != gz_magic[0] || bptr[1] != gz_magic[1]) {
+	/* No GZIP header -- just copy the data into a new binary */
+	if ((bin = driver_alloc_binary(size)) == NULL) {
+	    return NULL;
+	}
+	memcpy(bin->orig_bytes, start, size);
+	return bin;
+    }
+
+    /*
+     * The magic bytes for a GZIP header are there. Now try to decompress.
+     * It is an error if the GZIP header is not correct.
+     */
+
+    zstr.next_in = (unsigned char*) start;
+    zstr.avail_in = size;
+    erl_zlib_alloc_init(&zstr);
+    size *= 2;
+    if ((bin = driver_alloc_binary(size)) == NULL) {
+	return NULL;
+    }
+    if (inflateInit2(&zstr, 15+16) != Z_OK) { /* Decode GZIP format */
+	driver_free(bin);
+	return NULL;
+    }
+    for (;;) {
+	int status;
+
+	zstr.next_out = (unsigned char *) bin->orig_bytes + zstr.total_out;
+	zstr.avail_out = size - zstr.total_out;
+	status = inflate(&zstr, Z_NO_FLUSH);
+	if (status == Z_OK) {
+	    size *= 2;
+	    if ((bin2 = driver_realloc_binary(bin, size)) == NULL) {
+	    error:
+		driver_free_binary(bin);
+		inflateEnd(&zstr);
+		return NULL;
+	    }
+	    bin = bin2;
+	} else if (status == Z_STREAM_END) {
+	    if ((bin2 = driver_realloc_binary(bin, zstr.total_out)) == NULL) {
+		goto error;
+	    }
+	    inflateEnd(&zstr);
+	    return bin2;
+	} else {
+	    goto error;
+	}
+    }
+}
+
+/* ===========================================================================
+   Compresses the buffer given and returns a pointer to a binary.
+   A NULL pointer is returned if any error occurs.
+   Writes a gzip header as well.
+*/
+
+#define GZIP_HD_SIZE 10
+#define GZIP_TL_SIZE 8
+
+#define GZIP_X_SIZE (GZIP_HD_SIZE+GZIP_TL_SIZE)
+
+ErlDrvBinary*
+erts_gzdeflate_buffer(char* start, uLong size)
+{
+    z_stream c_stream; /* compression stream */
+    ErlDrvBinary* bin;
+    ErlDrvBinary* bin2;
+    uLong    crc;     /* crc32 of uncompressed data */
+    uLong    szIn;
+    Byte* ptr;
+    int comprLen = size + (size/1000) + 1 + 12; /* see zlib.h */
+
+    crc = crc32(0L, Z_NULL, 0);
+    erl_zlib_alloc_init(&c_stream);
+
+    if (deflateInit2(&c_stream, Z_DEFAULT_COMPRESSION,
+		     Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, 0) != Z_OK)
+	return NULL;
+
+    if ((bin = driver_alloc_binary(comprLen+GZIP_X_SIZE)) == NULL)
+	return NULL;
+    sprintf(bin->orig_bytes, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
+	    Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
+
+    c_stream.next_out = ((Byte*) bin->orig_bytes)+GZIP_HD_SIZE;
+    c_stream.avail_out = (uInt) bin->orig_size - GZIP_HD_SIZE;
+    c_stream.next_in  = (Byte*) start;
+    c_stream.avail_in = (uInt) size;
+
+    if (deflate(&c_stream, Z_FINISH) != Z_STREAM_END) {
+	driver_free_binary(bin);
+	return NULL;	
+    }
+    crc = crc32(crc, (unsigned char*)start, size);
+    ptr = c_stream.next_out;
+    szIn = c_stream.total_in;
+
+    *ptr++ = (crc & 0xff); crc >>= 8;
+    *ptr++ = (crc & 0xff); crc >>= 8;
+    *ptr++ = (crc & 0xff); crc >>= 8;
+    *ptr++ = (crc & 0xff); crc >>= 8;
+
+    *ptr++ = (szIn & 0xff); szIn >>= 8;
+    *ptr++ = (szIn & 0xff); szIn >>= 8;
+    *ptr++ = (szIn & 0xff); szIn >>= 8;
+    *ptr++ = (szIn & 0xff); szIn >>= 8;
+
+    if (deflateEnd(&c_stream) != Z_OK) {
+	driver_free_binary(bin);
+	return NULL;	
+    }	
+    size = ptr - (Byte*)bin->orig_bytes;
+
+    if ((bin2 = driver_realloc_binary(bin, size)) == NULL)
+	driver_free_binary(bin);
+    return bin2;
+}
+