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plt-scheme  4.2.1
gzio.c
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00001 /* gzio.c -- IO on .gz files
00002  * Copyright (C) 1995-2002 Jean-loup Gailly.
00003  * For conditions of distribution and use, see copyright notice in zlib.h
00004  *
00005  * Compile this file with -DNO_DEFLATE to avoid the compression code.
00006  */
00007 
00008 /* @(#) $Id: gzio.c,v 1.1 2004/03/01 20:54:49 cozmic Exp $ */
00009 
00010 #include <stdio.h>
00011 
00012 #include "zutil.h"
00013 
00014 struct internal_state {int dummy;}; /* for buggy compilers */
00015 
00016 #ifndef Z_BUFSIZE
00017 #  ifdef MAXSEG_64K
00018 #    define Z_BUFSIZE 4096 /* minimize memory usage for 16-bit DOS */
00019 #  else
00020 #    define Z_BUFSIZE 16384
00021 #  endif
00022 #endif
00023 #ifndef Z_PRINTF_BUFSIZE
00024 #  define Z_PRINTF_BUFSIZE 4096
00025 #endif
00026 
00027 #define ALLOC(size) malloc(size)
00028 #define TRYFREE(p) {if (p) free(p);}
00029 
00030 static int gz_magic[2] = {0x1f, 0x8b}; /* gzip magic header */
00031 
00032 /* gzip flag byte */
00033 #define ASCII_FLAG   0x01 /* bit 0 set: file probably ascii text */
00034 #define HEAD_CRC     0x02 /* bit 1 set: header CRC present */
00035 #define EXTRA_FIELD  0x04 /* bit 2 set: extra field present */
00036 #define ORIG_NAME    0x08 /* bit 3 set: original file name present */
00037 #define COMMENT      0x10 /* bit 4 set: file comment present */
00038 #define RESERVED     0xE0 /* bits 5..7: reserved */
00039 
00040 typedef struct gz_stream {
00041     z_stream stream;
00042     int      z_err;   /* error code for last stream operation */
00043     int      z_eof;   /* set if end of input file */
00044     FILE     *file;   /* .gz file */
00045     Byte     *inbuf;  /* input buffer */
00046     Byte     *outbuf; /* output buffer */
00047     uLong    crc;     /* crc32 of uncompressed data */
00048     char     *msg;    /* error message */
00049     char     *path;   /* path name for debugging only */
00050     int      transparent; /* 1 if input file is not a .gz file */
00051     char     mode;    /* 'w' or 'r' */
00052     long     startpos; /* start of compressed data in file (header skipped) */
00053 } gz_stream;
00054 
00055 
00056 local gzFile gz_open      OF((const char *path, const char *mode, int  fd));
00057 local int do_flush        OF((gzFile file, int flush));
00058 local int    get_byte     OF((gz_stream *s));
00059 local void   check_header OF((gz_stream *s));
00060 local int    destroy      OF((gz_stream *s));
00061 local void   putLong      OF((FILE *file, uLong x));
00062 local uLong  getLong      OF((gz_stream *s));
00063 
00064 /* ===========================================================================
00065      Opens a gzip (.gz) file for reading or writing. The mode parameter
00066    is as in fopen ("rb" or "wb"). The file is given either by file descriptor
00067    or path name (if fd == -1).
00068      gz_open return NULL if the file could not be opened or if there was
00069    insufficient memory to allocate the (de)compression state; errno
00070    can be checked to distinguish the two cases (if errno is zero, the
00071    zlib error is Z_MEM_ERROR).
00072 */
00073 local gzFile gz_open (path, mode, fd)
00074     const char *path;
00075     const char *mode;
00076     int  fd;
00077 {
00078     int err;
00079     int level = Z_DEFAULT_COMPRESSION; /* compression level */
00080     int strategy = Z_DEFAULT_STRATEGY; /* compression strategy */
00081     char *p = (char*)mode;
00082     gz_stream *s;
00083     char fmode[80]; /* copy of mode, without the compression level */
00084     char *m = fmode;
00085 
00086     if (!path || !mode) return Z_NULL;
00087 
00088     s = (gz_stream *)ALLOC(sizeof(gz_stream));
00089     if (!s) return Z_NULL;
00090 
00091     s->stream.zalloc = (alloc_func)0;
00092     s->stream.zfree = (free_func)0;
00093     s->stream.opaque = (voidpf)0;
00094     s->stream.next_in = s->inbuf = Z_NULL;
00095     s->stream.next_out = s->outbuf = Z_NULL;
00096     s->stream.avail_in = s->stream.avail_out = 0;
00097     s->file = NULL;
00098     s->z_err = Z_OK;
00099     s->z_eof = 0;
00100     s->crc = crc32(0L, Z_NULL, 0);
00101     s->msg = NULL;
00102     s->transparent = 0;
00103 
00104     s->path = (char*)ALLOC(strlen(path)+1);
00105     if (s->path == NULL) {
00106         return destroy(s), (gzFile)Z_NULL;
00107     }
00108     strcpy(s->path, path); /* do this early for debugging */
00109 
00110     s->mode = '\0';
00111     do {
00112         if (*p == 'r') s->mode = 'r';
00113         if (*p == 'w' || *p == 'a') s->mode = 'w';
00114         if (*p >= '0' && *p <= '9') {
00115            level = *p - '0';
00116        } else if (*p == 'f') {
00117          strategy = Z_FILTERED;
00118        } else if (*p == 'h') {
00119          strategy = Z_HUFFMAN_ONLY;
00120        } else {
00121            *m++ = *p; /* copy the mode */
00122        }
00123     } while (*p++ && m != fmode + sizeof(fmode));
00124     if (s->mode == '\0') return destroy(s), (gzFile)Z_NULL;
00125     
00126     if (s->mode == 'w') {
00127 #ifdef NO_DEFLATE
00128         err = Z_STREAM_ERROR;
00129 #else
00130         err = deflateInit2(&(s->stream), level,
00131                            Z_DEFLATED, -MAX_WBITS, DEF_MEM_LEVEL, strategy);
00132         /* windowBits is passed < 0 to suppress zlib header */
00133 
00134         s->stream.next_out = s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
00135 #endif
00136         if (err != Z_OK || s->outbuf == Z_NULL) {
00137             return destroy(s), (gzFile)Z_NULL;
00138         }
00139     } else {
00140         s->stream.next_in  = s->inbuf = (Byte*)ALLOC(Z_BUFSIZE);
00141 
00142         err = inflateInit2(&(s->stream), -MAX_WBITS);
00143         /* windowBits is passed < 0 to tell that there is no zlib header.
00144          * Note that in this case inflate *requires* an extra "dummy" byte
00145          * after the compressed stream in order to complete decompression and
00146          * return Z_STREAM_END. Here the gzip CRC32 ensures that 4 bytes are
00147          * present after the compressed stream.
00148          */
00149         if (err != Z_OK || s->inbuf == Z_NULL) {
00150             return destroy(s), (gzFile)Z_NULL;
00151         }
00152     }
00153     s->stream.avail_out = Z_BUFSIZE;
00154 
00155     errno = 0;
00156     s->file = fd < 0 ? F_OPEN(path, fmode) : (FILE*)fdopen(fd, fmode);
00157 
00158     if (s->file == NULL) {
00159         return destroy(s), (gzFile)Z_NULL;
00160     }
00161     if (s->mode == 'w') {
00162         /* Write a very simple .gz header:
00163          */
00164         fprintf(s->file, "%c%c%c%c%c%c%c%c%c%c", gz_magic[0], gz_magic[1],
00165              Z_DEFLATED, 0 /*flags*/, 0,0,0,0 /*time*/, 0 /*xflags*/, OS_CODE);
00166        s->startpos = 10L;
00167        /* We use 10L instead of ftell(s->file) to because ftell causes an
00168          * fflush on some systems. This version of the library doesn't use
00169          * startpos anyway in write mode, so this initialization is not
00170          * necessary.
00171          */
00172     } else {
00173        check_header(s); /* skip the .gz header */
00174        s->startpos = (ftell(s->file) - s->stream.avail_in);
00175     }
00176     
00177     return (gzFile)s;
00178 }
00179 
00180 /* ===========================================================================
00181      Opens a gzip (.gz) file for reading or writing.
00182 */
00183 gzFile ZEXPORT gzopen (path, mode)
00184     const char *path;
00185     const char *mode;
00186 {
00187     return gz_open (path, mode, -1);
00188 }
00189 
00190 /* ===========================================================================
00191      Associate a gzFile with the file descriptor fd. fd is not dup'ed here
00192    to mimic the behavio(u)r of fdopen.
00193 */
00194 gzFile ZEXPORT gzdopen (fd, mode)
00195     int fd;
00196     const char *mode;
00197 {
00198     char name[20];
00199 
00200     if (fd < 0) return (gzFile)Z_NULL;
00201     sprintf(name, "<fd:%d>", fd); /* for debugging */
00202 
00203     return gz_open (name, mode, fd);
00204 }
00205 
00206 /* ===========================================================================
00207  * Update the compression level and strategy
00208  */
00209 int ZEXPORT gzsetparams (file, level, strategy)
00210     gzFile file;
00211     int level;
00212     int strategy;
00213 {
00214     gz_stream *s = (gz_stream*)file;
00215 
00216     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
00217 
00218     /* Make room to allow flushing */
00219     if (s->stream.avail_out == 0) {
00220 
00221        s->stream.next_out = s->outbuf;
00222        if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
00223            s->z_err = Z_ERRNO;
00224        }
00225        s->stream.avail_out = Z_BUFSIZE;
00226     }
00227 
00228     return deflateParams (&(s->stream), level, strategy);
00229 }
00230 
00231 /* ===========================================================================
00232      Read a byte from a gz_stream; update next_in and avail_in. Return EOF
00233    for end of file.
00234    IN assertion: the stream s has been sucessfully opened for reading.
00235 */
00236 local int get_byte(s)
00237     gz_stream *s;
00238 {
00239     if (s->z_eof) return EOF;
00240     if (s->stream.avail_in == 0) {
00241        errno = 0;
00242        s->stream.avail_in = fread(s->inbuf, 1, Z_BUFSIZE, s->file);
00243        if (s->stream.avail_in == 0) {
00244            s->z_eof = 1;
00245            if (ferror(s->file)) s->z_err = Z_ERRNO;
00246            return EOF;
00247        }
00248        s->stream.next_in = s->inbuf;
00249     }
00250     s->stream.avail_in--;
00251     return *(s->stream.next_in)++;
00252 }
00253 
00254 /* ===========================================================================
00255       Check the gzip header of a gz_stream opened for reading. Set the stream
00256     mode to transparent if the gzip magic header is not present; set s->err
00257     to Z_DATA_ERROR if the magic header is present but the rest of the header
00258     is incorrect.
00259     IN assertion: the stream s has already been created sucessfully;
00260        s->stream.avail_in is zero for the first time, but may be non-zero
00261        for concatenated .gz files.
00262 */
00263 local void check_header(s)
00264     gz_stream *s;
00265 {
00266     int method; /* method byte */
00267     int flags;  /* flags byte */
00268     uInt len;
00269     int c;
00270 
00271     /* Check the gzip magic header */
00272     for (len = 0; len < 2; len++) {
00273        c = get_byte(s);
00274        if (c != gz_magic[len]) {
00275            if (len != 0) s->stream.avail_in++, s->stream.next_in--;
00276            if (c != EOF) {
00277               s->stream.avail_in++, s->stream.next_in--;
00278               s->transparent = 1;
00279            }
00280            s->z_err = s->stream.avail_in != 0 ? Z_OK : Z_STREAM_END;
00281            return;
00282        }
00283     }
00284     method = get_byte(s);
00285     flags = get_byte(s);
00286     if (method != Z_DEFLATED || (flags & RESERVED) != 0) {
00287        s->z_err = Z_DATA_ERROR;
00288        return;
00289     }
00290 
00291     /* Discard time, xflags and OS code: */
00292     for (len = 0; len < 6; len++) (void)get_byte(s);
00293 
00294     if ((flags & EXTRA_FIELD) != 0) { /* skip the extra field */
00295        len  =  (uInt)get_byte(s);
00296        len += ((uInt)get_byte(s))<<8;
00297        /* len is garbage if EOF but the loop below will quit anyway */
00298        while (len-- != 0 && get_byte(s) != EOF) ;
00299     }
00300     if ((flags & ORIG_NAME) != 0) { /* skip the original file name */
00301        while ((c = get_byte(s)) != 0 && c != EOF) ;
00302     }
00303     if ((flags & COMMENT) != 0) {   /* skip the .gz file comment */
00304        while ((c = get_byte(s)) != 0 && c != EOF) ;
00305     }
00306     if ((flags & HEAD_CRC) != 0) {  /* skip the header crc */
00307        for (len = 0; len < 2; len++) (void)get_byte(s);
00308     }
00309     s->z_err = s->z_eof ? Z_DATA_ERROR : Z_OK;
00310 }
00311 
00312  /* ===========================================================================
00313  * Cleanup then free the given gz_stream. Return a zlib error code.
00314    Try freeing in the reverse order of allocations.
00315  */
00316 local int destroy (s)
00317     gz_stream *s;
00318 {
00319     int err = Z_OK;
00320 
00321     if (!s) return Z_STREAM_ERROR;
00322 
00323     TRYFREE(s->msg);
00324 
00325     if (s->stream.state != NULL) {
00326        if (s->mode == 'w') {
00327 #ifdef NO_DEFLATE
00328            err = Z_STREAM_ERROR;
00329 #else
00330            err = deflateEnd(&(s->stream));
00331 #endif
00332        } else if (s->mode == 'r') {
00333            err = inflateEnd(&(s->stream));
00334        }
00335     }
00336     if (s->file != NULL && fclose(s->file)) {
00337 #ifdef ESPIPE
00338        if (errno != ESPIPE) /* fclose is broken for pipes in HP/UX */
00339 #endif
00340            err = Z_ERRNO;
00341     }
00342     if (s->z_err < 0) err = s->z_err;
00343 
00344     TRYFREE(s->inbuf);
00345     TRYFREE(s->outbuf);
00346     TRYFREE(s->path);
00347     TRYFREE(s);
00348     return err;
00349 }
00350 
00351 /* ===========================================================================
00352      Reads the given number of uncompressed bytes from the compressed file.
00353    gzread returns the number of bytes actually read (0 for end of file).
00354 */
00355 int ZEXPORT gzread (file, buf, len)
00356     gzFile file;
00357     voidp buf;
00358     unsigned len;
00359 {
00360     gz_stream *s = (gz_stream*)file;
00361     Bytef *start = (Bytef*)buf; /* starting point for crc computation */
00362     Byte  *next_out; /* == stream.next_out but not forced far (for MSDOS) */
00363 
00364     if (s == NULL || s->mode != 'r') return Z_STREAM_ERROR;
00365 
00366     if (s->z_err == Z_DATA_ERROR || s->z_err == Z_ERRNO) return -1;
00367     if (s->z_err == Z_STREAM_END) return 0;  /* EOF */
00368 
00369     next_out = (Byte*)buf;
00370     s->stream.next_out = (Bytef*)buf;
00371     s->stream.avail_out = len;
00372 
00373     while (s->stream.avail_out != 0) {
00374 
00375        if (s->transparent) {
00376            /* Copy first the lookahead bytes: */
00377            uInt n = s->stream.avail_in;
00378            if (n > s->stream.avail_out) n = s->stream.avail_out;
00379            if (n > 0) {
00380               zmemcpy(s->stream.next_out, s->stream.next_in, n);
00381               next_out += n;
00382               s->stream.next_out = next_out;
00383               s->stream.next_in   += n;
00384               s->stream.avail_out -= n;
00385               s->stream.avail_in  -= n;
00386            }
00387            if (s->stream.avail_out > 0) {
00388               s->stream.avail_out -= fread(next_out, 1, s->stream.avail_out,
00389                                         s->file);
00390            }
00391            len -= s->stream.avail_out;
00392            s->stream.total_in  += (uLong)len;
00393            s->stream.total_out += (uLong)len;
00394             if (len == 0) s->z_eof = 1;
00395            return (int)len;
00396        }
00397         if (s->stream.avail_in == 0 && !s->z_eof) {
00398 
00399             errno = 0;
00400             s->stream.avail_in = fread(s->inbuf, 1, Z_BUFSIZE, s->file);
00401             if (s->stream.avail_in == 0) {
00402                 s->z_eof = 1;
00403               if (ferror(s->file)) {
00404                   s->z_err = Z_ERRNO;
00405                   break;
00406               }
00407             }
00408             s->stream.next_in = s->inbuf;
00409         }
00410         s->z_err = inflate(&(s->stream), Z_NO_FLUSH);
00411 
00412        if (s->z_err == Z_STREAM_END) {
00413            /* Check CRC and original size */
00414            s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
00415            start = s->stream.next_out;
00416 
00417            if (getLong(s) != s->crc) {
00418               s->z_err = Z_DATA_ERROR;
00419            } else {
00420                (void)getLong(s);
00421                 /* The uncompressed length returned by above getlong() may
00422                  * be different from s->stream.total_out) in case of
00423                * concatenated .gz files. Check for such files:
00424                */
00425               check_header(s);
00426               if (s->z_err == Z_OK) {
00427                   uLong total_in = s->stream.total_in;
00428                   uLong total_out = s->stream.total_out;
00429 
00430                   inflateReset(&(s->stream));
00431                   s->stream.total_in = total_in;
00432                   s->stream.total_out = total_out;
00433                   s->crc = crc32(0L, Z_NULL, 0);
00434               }
00435            }
00436        }
00437        if (s->z_err != Z_OK || s->z_eof) break;
00438     }
00439     s->crc = crc32(s->crc, start, (uInt)(s->stream.next_out - start));
00440 
00441     return (int)(len - s->stream.avail_out);
00442 }
00443 
00444 
00445 /* ===========================================================================
00446       Reads one byte from the compressed file. gzgetc returns this byte
00447    or -1 in case of end of file or error.
00448 */
00449 int ZEXPORT gzgetc(file)
00450     gzFile file;
00451 {
00452     unsigned char c;
00453 
00454     return gzread(file, &c, 1) == 1 ? c : -1;
00455 }
00456 
00457 
00458 /* ===========================================================================
00459       Reads bytes from the compressed file until len-1 characters are
00460    read, or a newline character is read and transferred to buf, or an
00461    end-of-file condition is encountered.  The string is then terminated
00462    with a null character.
00463       gzgets returns buf, or Z_NULL in case of error.
00464 
00465       The current implementation is not optimized at all.
00466 */
00467 char * ZEXPORT gzgets(file, buf, len)
00468     gzFile file;
00469     char *buf;
00470     int len;
00471 {
00472     char *b = buf;
00473     if (buf == Z_NULL || len <= 0) return Z_NULL;
00474 
00475     while (--len > 0 && gzread(file, buf, 1) == 1 && *buf++ != '\n') ;
00476     *buf = '\0';
00477     return b == buf && len > 0 ? Z_NULL : b;
00478 }
00479 
00480 
00481 #ifndef NO_DEFLATE
00482 /* ===========================================================================
00483      Writes the given number of uncompressed bytes into the compressed file.
00484    gzwrite returns the number of bytes actually written (0 in case of error).
00485 */
00486 int ZEXPORT gzwrite (file, buf, len)
00487     gzFile file;
00488     const voidp buf;
00489     unsigned len;
00490 {
00491     gz_stream *s = (gz_stream*)file;
00492 
00493     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
00494 
00495     s->stream.next_in = (Bytef*)buf;
00496     s->stream.avail_in = len;
00497 
00498     while (s->stream.avail_in != 0) {
00499 
00500         if (s->stream.avail_out == 0) {
00501 
00502             s->stream.next_out = s->outbuf;
00503             if (fwrite(s->outbuf, 1, Z_BUFSIZE, s->file) != Z_BUFSIZE) {
00504                 s->z_err = Z_ERRNO;
00505                 break;
00506             }
00507             s->stream.avail_out = Z_BUFSIZE;
00508         }
00509         s->z_err = deflate(&(s->stream), Z_NO_FLUSH);
00510         if (s->z_err != Z_OK) break;
00511     }
00512     s->crc = crc32(s->crc, (const Bytef *)buf, len);
00513 
00514     return (int)(len - s->stream.avail_in);
00515 }
00516 
00517 /* ===========================================================================
00518      Converts, formats, and writes the args to the compressed file under
00519    control of the format string, as in fprintf. gzprintf returns the number of
00520    uncompressed bytes actually written (0 in case of error).
00521 */
00522 #ifdef STDC
00523 #include <stdarg.h>
00524 
00525 int ZEXPORTVA gzprintf (gzFile file, const char *format, /* args */ ...)
00526 {
00527     char buf[Z_PRINTF_BUFSIZE];
00528     va_list va;
00529     int len;
00530 
00531     va_start(va, format);
00532 #ifdef HAS_vsnprintf
00533     (void)vsnprintf(buf, sizeof(buf), format, va);
00534 #else
00535     (void)vsprintf(buf, format, va);
00536 #endif
00537     va_end(va);
00538     len = strlen(buf); /* some *sprintf don't return the nb of bytes written */
00539     if (len <= 0) return 0;
00540 
00541     return gzwrite(file, buf, (unsigned)len);
00542 }
00543 #else /* not ANSI C */
00544 
00545 int ZEXPORTVA gzprintf (file, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
00546                       a11, a12, a13, a14, a15, a16, a17, a18, a19, a20)
00547     gzFile file;
00548     const char *format;
00549     int a1, a2, a3, a4, a5, a6, a7, a8, a9, a10,
00550        a11, a12, a13, a14, a15, a16, a17, a18, a19, a20;
00551 {
00552     char buf[Z_PRINTF_BUFSIZE];
00553     int len;
00554 
00555 #ifdef HAS_snprintf
00556     snprintf(buf, sizeof(buf), format, a1, a2, a3, a4, a5, a6, a7, a8,
00557             a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
00558 #else
00559     sprintf(buf, format, a1, a2, a3, a4, a5, a6, a7, a8,
00560            a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
00561 #endif
00562     len = strlen(buf); /* old sprintf doesn't return the nb of bytes written */
00563     if (len <= 0) return 0;
00564 
00565     return gzwrite(file, buf, len);
00566 }
00567 #endif
00568 
00569 /* ===========================================================================
00570       Writes c, converted to an unsigned char, into the compressed file.
00571    gzputc returns the value that was written, or -1 in case of error.
00572 */
00573 int ZEXPORT gzputc(file, c)
00574     gzFile file;
00575     int c;
00576 {
00577     unsigned char cc = (unsigned char) c; /* required for big endian systems */
00578 
00579     return gzwrite(file, &cc, 1) == 1 ? (int)cc : -1;
00580 }
00581 
00582 
00583 /* ===========================================================================
00584       Writes the given null-terminated string to the compressed file, excluding
00585    the terminating null character.
00586       gzputs returns the number of characters written, or -1 in case of error.
00587 */
00588 int ZEXPORT gzputs(file, s)
00589     gzFile file;
00590     const char *s;
00591 {
00592     return gzwrite(file, (char*)s, (unsigned)strlen(s));
00593 }
00594 
00595 
00596 /* ===========================================================================
00597      Flushes all pending output into the compressed file. The parameter
00598    flush is as in the deflate() function.
00599 */
00600 local int do_flush (file, flush)
00601     gzFile file;
00602     int flush;
00603 {
00604     uInt len;
00605     int done = 0;
00606     gz_stream *s = (gz_stream*)file;
00607 
00608     if (s == NULL || s->mode != 'w') return Z_STREAM_ERROR;
00609 
00610     s->stream.avail_in = 0; /* should be zero already anyway */
00611 
00612     for (;;) {
00613         len = Z_BUFSIZE - s->stream.avail_out;
00614 
00615         if (len != 0) {
00616             if ((uInt)fwrite(s->outbuf, 1, len, s->file) != len) {
00617                 s->z_err = Z_ERRNO;
00618                 return Z_ERRNO;
00619             }
00620             s->stream.next_out = s->outbuf;
00621             s->stream.avail_out = Z_BUFSIZE;
00622         }
00623         if (done) break;
00624         s->z_err = deflate(&(s->stream), flush);
00625 
00626        /* Ignore the second of two consecutive flushes: */
00627        if (len == 0 && s->z_err == Z_BUF_ERROR) s->z_err = Z_OK;
00628 
00629         /* deflate has finished flushing only when it hasn't used up
00630          * all the available space in the output buffer: 
00631          */
00632         done = (s->stream.avail_out != 0 || s->z_err == Z_STREAM_END);
00633  
00634         if (s->z_err != Z_OK && s->z_err != Z_STREAM_END) break;
00635     }
00636     return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
00637 }
00638 
00639 int ZEXPORT gzflush (file, flush)
00640      gzFile file;
00641      int flush;
00642 {
00643     gz_stream *s = (gz_stream*)file;
00644     int err = do_flush (file, flush);
00645 
00646     if (err) return err;
00647     fflush(s->file);
00648     return  s->z_err == Z_STREAM_END ? Z_OK : s->z_err;
00649 }
00650 #endif /* NO_DEFLATE */
00651 
00652 /* ===========================================================================
00653       Sets the starting position for the next gzread or gzwrite on the given
00654    compressed file. The offset represents a number of bytes in the
00655       gzseek returns the resulting offset location as measured in bytes from
00656    the beginning of the uncompressed stream, or -1 in case of error.
00657       SEEK_END is not implemented, returns error.
00658       In this version of the library, gzseek can be extremely slow.
00659 */
00660 z_off_t ZEXPORT gzseek (file, offset, whence)
00661     gzFile file;
00662     z_off_t offset;
00663     int whence;
00664 {
00665     gz_stream *s = (gz_stream*)file;
00666 
00667     if (s == NULL || whence == SEEK_END ||
00668        s->z_err == Z_ERRNO || s->z_err == Z_DATA_ERROR) {
00669        return -1L;
00670     }
00671     
00672     if (s->mode == 'w') {
00673 #ifdef NO_DEFLATE
00674        return -1L;
00675 #else
00676        if (whence == SEEK_SET) {
00677            offset -= s->stream.total_in;
00678        }
00679        if (offset < 0) return -1L;
00680 
00681        /* At this point, offset is the number of zero bytes to write. */
00682        if (s->inbuf == Z_NULL) {
00683            s->inbuf = (Byte*)ALLOC(Z_BUFSIZE); /* for seeking */
00684            zmemzero(s->inbuf, Z_BUFSIZE);
00685        }
00686        while (offset > 0)  {
00687            uInt size = Z_BUFSIZE;
00688            if (offset < Z_BUFSIZE) size = (uInt)offset;
00689 
00690            size = gzwrite(file, s->inbuf, size);
00691            if (size == 0) return -1L;
00692 
00693            offset -= size;
00694        }
00695        return (z_off_t)s->stream.total_in;
00696 #endif
00697     }
00698     /* Rest of function is for reading only */
00699 
00700     /* compute absolute position */
00701     if (whence == SEEK_CUR) {
00702        offset += s->stream.total_out;
00703     }
00704     if (offset < 0) return -1L;
00705 
00706     if (s->transparent) {
00707        /* map to fseek */
00708        s->stream.avail_in = 0;
00709        s->stream.next_in = s->inbuf;
00710         if (fseek(s->file, offset, SEEK_SET) < 0) return -1L;
00711 
00712        s->stream.total_in = s->stream.total_out = (uLong)offset;
00713        return offset;
00714     }
00715 
00716     /* For a negative seek, rewind and use positive seek */
00717     if ((uLong)offset >= s->stream.total_out) {
00718        offset -= s->stream.total_out;
00719     } else if (gzrewind(file) < 0) {
00720        return -1L;
00721     }
00722     /* offset is now the number of bytes to skip. */
00723 
00724     if (offset != 0 && s->outbuf == Z_NULL) {
00725        s->outbuf = (Byte*)ALLOC(Z_BUFSIZE);
00726     }
00727     while (offset > 0)  {
00728        int size = Z_BUFSIZE;
00729        if (offset < Z_BUFSIZE) size = (int)offset;
00730 
00731        size = gzread(file, s->outbuf, (uInt)size);
00732        if (size <= 0) return -1L;
00733        offset -= size;
00734     }
00735     return (z_off_t)s->stream.total_out;
00736 }
00737 
00738 /* ===========================================================================
00739      Rewinds input file. 
00740 */
00741 int ZEXPORT gzrewind (file)
00742     gzFile file;
00743 {
00744     gz_stream *s = (gz_stream*)file;
00745     
00746     if (s == NULL || s->mode != 'r') return -1;
00747 
00748     s->z_err = Z_OK;
00749     s->z_eof = 0;
00750     s->stream.avail_in = 0;
00751     s->stream.next_in = s->inbuf;
00752     s->crc = crc32(0L, Z_NULL, 0);
00753        
00754     if (s->startpos == 0) { /* not a compressed file */
00755        rewind(s->file);
00756        return 0;
00757     }
00758 
00759     (void) inflateReset(&s->stream);
00760     return fseek(s->file, s->startpos, SEEK_SET);
00761 }
00762 
00763 /* ===========================================================================
00764      Returns the starting position for the next gzread or gzwrite on the
00765    given compressed file. This position represents a number of bytes in the
00766    uncompressed data stream.
00767 */
00768 z_off_t ZEXPORT gztell (file)
00769     gzFile file;
00770 {
00771     return gzseek(file, 0L, SEEK_CUR);
00772 }
00773 
00774 /* ===========================================================================
00775      Returns 1 when EOF has previously been detected reading the given
00776    input stream, otherwise zero.
00777 */
00778 int ZEXPORT gzeof (file)
00779     gzFile file;
00780 {
00781     gz_stream *s = (gz_stream*)file;
00782     
00783     return (s == NULL || s->mode != 'r') ? 0 : s->z_eof;
00784 }
00785 
00786 /* ===========================================================================
00787    Outputs a long in LSB order to the given file
00788 */
00789 local void putLong (file, x)
00790     FILE *file;
00791     uLong x;
00792 {
00793     int n;
00794     for (n = 0; n < 4; n++) {
00795         fputc((int)(x & 0xff), file);
00796         x >>= 8;
00797     }
00798 }
00799 
00800 /* ===========================================================================
00801    Reads a long in LSB order from the given gz_stream. Sets z_err in case
00802    of error.
00803 */
00804 local uLong getLong (s)
00805     gz_stream *s;
00806 {
00807     uLong x = (uLong)get_byte(s);
00808     int c;
00809 
00810     x += ((uLong)get_byte(s))<<8;
00811     x += ((uLong)get_byte(s))<<16;
00812     c = get_byte(s);
00813     if (c == EOF) s->z_err = Z_DATA_ERROR;
00814     x += ((uLong)c)<<24;
00815     return x;
00816 }
00817 
00818 /* ===========================================================================
00819      Flushes all pending output if necessary, closes the compressed file
00820    and deallocates all the (de)compression state.
00821 */
00822 int ZEXPORT gzclose (file)
00823     gzFile file;
00824 {
00825     int err;
00826     gz_stream *s = (gz_stream*)file;
00827 
00828     if (s == NULL) return Z_STREAM_ERROR;
00829 
00830     if (s->mode == 'w') {
00831 #ifdef NO_DEFLATE
00832        return Z_STREAM_ERROR;
00833 #else
00834         err = do_flush (file, Z_FINISH);
00835         if (err != Z_OK) return destroy((gz_stream*)file);
00836 
00837         putLong (s->file, s->crc);
00838         putLong (s->file, s->stream.total_in);
00839 #endif
00840     }
00841     return destroy((gz_stream*)file);
00842 }
00843 
00844 /* ===========================================================================
00845      Returns the error message for the last error which occured on the
00846    given compressed file. errnum is set to zlib error number. If an
00847    error occured in the file system and not in the compression library,
00848    errnum is set to Z_ERRNO and the application may consult errno
00849    to get the exact error code.
00850 */
00851 const char*  ZEXPORT gzerror (file, errnum)
00852     gzFile file;
00853     int *errnum;
00854 {
00855     char *m;
00856     gz_stream *s = (gz_stream*)file;
00857 
00858     if (s == NULL) {
00859         *errnum = Z_STREAM_ERROR;
00860         return (const char*)ERR_MSG(Z_STREAM_ERROR);
00861     }
00862     *errnum = s->z_err;
00863     if (*errnum == Z_OK) return (const char*)"";
00864 
00865     m =  (char*)(*errnum == Z_ERRNO ? zstrerror(errno) : s->stream.msg);
00866 
00867     if (m == NULL || *m == '\0') m = (char*)ERR_MSG(s->z_err);
00868 
00869     TRYFREE(s->msg);
00870     s->msg = (char*)ALLOC(strlen(s->path) + strlen(m) + 3);
00871     strcpy(s->msg, s->path);
00872     strcat(s->msg, ": ");
00873     strcat(s->msg, m);
00874     return (const char*)s->msg;
00875 }