gzio.c

完整的Bell实验室的嵌入式文件系统TFS

/* gzio.c -- IO on .gz files
 * Copyright (C) 1995-1998 Jean-loup Gailly.
 * For conditions of distribution and use, see copyright notice in zlib.h
 *
 * This has been seriously re-arranged for use within MicroMonitor.
 * The majority of the rework is to strip out unnecessary parts because this
 * will reside in flash space.  Also, there is no file system interface, all
 * decompression is done from one point in memory to another point in memory.
 */

#include "config.h"
#include "tfs.h"
#include "tfsprivate.h"
#include "genlib.h"
#include "zutil.h"

struct internal_state {int dummy;}; /* for buggy compilers */

#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

#define ALLOC(size) malloc(size)
#define TRYFREE(p) {if (p) free((char *)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 */
    Byte     *outbuf;       /* output buffer */
    uLong    crc;           /* crc32 of uncompressed data */
    char     *msg;          /* error message */
    int      transparent;    /* 1 if input file is not a .gz file */
    char     mode;          /* 'w' or 'r' */
} 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));

/* ===========================================================================
    gzInit():
    Rewritten (from gzopen()) to support only decompression of data in
    memory.  The next_in member points directly to the compressed data and
    avail_in is the number of bytes remaining.
    Things get simpler because of the removal of the file system interface
    as well as the "only decompression" mode.
*/
gz_stream *
gzInit(compressed_data, size)
int  size;
unsigned char *compressed_data;
{
    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 = compressed_data;
    s->stream.next_out = s->outbuf = Z_NULL;
    s->stream.avail_in = size;
    s->stream.avail_out = 0;
    s->z_err = Z_OK;
    s->z_eof = 0;
    s->crc = zcrc32(0L, Z_NULL, 0);
    s->msg = NULL;
    s->transparent = 0;
    s->mode = 'r';

    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) {
        destroy(s);
        return((gz_stream *)Z_NULL);
    }
    
    s->stream.avail_out = Z_BUFSIZE;
    check_header(s); /* skip the .gz header */
    return(s);
}

/* ===========================================================================
    get_byte()
    Simple now because we assume that avail_in is pointing to the number
    of bytes in the source buffer that are remaining to be decompressed
    and next_in is the pointer to the next byte to be retrieved from the
    buffer.
*/
local int
get_byte(s)
gz_stream *s;
{
    if (s->z_eof) 
        return EOF;
    if (s->stream.avail_in == 0) {
        s->z_eof = 1;
        return EOF;
    }
    s->stream.avail_in--;
    return *(s->stream.next_in)++;
}

/* ===========================================================================
    check_header():
    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;
}

/* ===========================================================================
    destroy():
    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)
        err = inflateEnd(&(s->stream));
    
    if (s->z_err < 0)
        err = s->z_err;

    TRYFREE(s->outbuf);
    TRYFREE(s);
    return err;
}

/* ===========================================================================
    gzRead():
    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 || 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 */

    next_out = (Byte*)buf;
    s->stream.next_out = (Bytef*)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) {
                int     i, c;
                Byte    *next;

                next = next_out;
                for(i=0;i<(int)(s->stream.avail_out);i++) {
                    c = get_byte(s);
                    if (c == EOF)
                        break;
                    *next_out++ = (Byte)c;
                    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;
            return (int)len;
        }
        s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
    
        if (s->z_err == Z_STREAM_END) {
            /* Check CRC and original size */
            s->crc = zcrc32(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 = zcrc32(0L, Z_NULL, 0);
            }
            }
        }
        if (s->z_err != Z_OK || s->z_eof)
            break;
    }
    s->crc = zcrc32(s->crc, start, (uInt)(s->stream.next_out - start));
    return (int)(len - s->stream.avail_out);
}

/* ===========================================================================
    getLong():
    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;
}

/* ===========================================================================
    unZip():
    This is the front end to the whole zlib decompressor.
    It is a chop-up of the original minigzip.c code that came with
    the zlib source.
*/
int
unZip(char *src, int srclen, char *dest, int destlen)
{
    int len;
    gz_stream   *s;

    if ((s = gzInit(src,srclen)) == Z_NULL) {
        printf("gzInit(0x%lx,%d) failed!\n",(ulong)src,srclen);
        return(-1);
    }
    len = gzRead(s,dest,destlen);
    if (len < 0)
        printf("gzRead() returned %d\n",len);

    destroy(s);
    return(len);
}

char *UnzipHelp[] = {
    "Decompress block of memory to some other block of memory.",
    "-[s:d:]",
    " -s {source}         filename or 'addr,len' (required option)",
    " -d {destination}    'addr[,len]' (default=APPRAMBASE,99999999)",
    "",
    "Works in conjunction with zlib's minigzip on host.",
    0,
};

/* Unzip():
    Access ZLIB decompressor from monitor command line.
*/
int
Unzip(int argc,char *argv[])
{
    extern  char *optarg;
    char    *asc_src, *asc_dst, *comma, *src, *dest;
    int     opt, tot;
    ulong   srclen, destlen;

    destlen = 99999999;
    dest = (char *)getAppRamStart();
    asc_src = asc_dst = (char *)0;

    while((opt=getopt(argc,argv,"d:s:")) != -1) {
        switch(opt) {
        case 's':
            asc_src = optarg;
            break;
        case 'd':
            asc_dst = optarg;
            break;
        default:
            return(0);
        }
    }
    if (!asc_src)
        return(-1);

    comma = strchr(asc_src,',');
    if (comma) {
        *comma = 0;
        src = (char *)strtoul(asc_src,(char **)0,0);
        srclen = strtoul(comma+1,(char **)0,0);
    }
    else {
        TFILE *tfp;
        tfp = tfsstat(asc_src);
        if (!tfp)
            return(-1);
        src = TFS_BASE(tfp);
        srclen = TFS_SIZE(tfp);
    }

    if (asc_dst) {
        comma = strchr(asc_dst,',');
        if (comma) {
            *comma = 0;
            destlen = strtoul(comma+1,(char **)0,0);
        }
        dest = (char *)strtoul(asc_dst,(char **)0,0);
    }

    tot = unZip(src,srclen,dest,destlen);
    printf("Decompressed %ld bytes from 0x%lx to %d bytes at 0x%lx.\n",
        srclen,(ulong)src,tot,(ulong)dest);
    return(0);
}

/* Front end to the rest of the unZip() stuff...
    Return the size of the decompressed data or -1 if failure.
    The same front API end is available if unpack is used instead of unzip.
*/
int
decompress(char *src,int srclen, char *dest)
{
    return(unZip(src,srclen,dest,99999999));
}