FreeBSD/Linux Kernel Cross Reference
sys/contrib/zlib/gzlib.c

     /* gzlib.c -- zlib functions common to reading and writing gzip files
      * Copyright (C) 2004-2019 Mark Adler
      * For conditions of distribution and use, see copyright notice in zlib.h
      */
     
     /* $FreeBSD$ */
     
     #include "gzguts.h"
     #include "zutil.h"
    #include <unistd.h>
    
    #if defined(_WIN32) && !defined(__BORLANDC__)
    #  define LSEEK _lseeki64
    #else
    #if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
    #  define LSEEK lseek64
    #else
    #  define LSEEK lseek
    #endif
    #endif
    
    /* Local functions */
    local void gz_reset OF((gz_statep));
    local gzFile gz_open OF((const void *, int, const char *));
    
    #if defined UNDER_CE
    
    /* Map the Windows error number in ERROR to a locale-dependent error message
       string and return a pointer to it.  Typically, the values for ERROR come
       from GetLastError.
    
       The string pointed to shall not be modified by the application, but may be
       overwritten by a subsequent call to gz_strwinerror
    
       The gz_strwinerror function does not change the current setting of
       GetLastError. */
    char ZLIB_INTERNAL *gz_strwinerror (error)
         DWORD error;
    {
        static char buf[1024];
    
        wchar_t *msgbuf;
        DWORD lasterr = GetLastError();
        DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
            | FORMAT_MESSAGE_ALLOCATE_BUFFER,
            NULL,
            error,
            0, /* Default language */
            (LPVOID)&msgbuf,
            0,
            NULL);
        if (chars != 0) {
            /* If there is an \r\n appended, zap it.  */
            if (chars >= 2
                && msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
                chars -= 2;
                msgbuf[chars] = 0;
            }
    
            if (chars > sizeof (buf) - 1) {
                chars = sizeof (buf) - 1;
                msgbuf[chars] = 0;
            }
    
            wcstombs(buf, msgbuf, chars + 1);
            LocalFree(msgbuf);
        }
        else {
            sprintf(buf, "unknown win32 error (%ld)", error);
        }
    
        SetLastError(lasterr);
        return buf;
    }
    
    #endif /* UNDER_CE */
    
    /* Reset gzip file state */
    local void gz_reset(state)
        gz_statep state;
    {
        state->x.have = 0;              /* no output data available */
        if (state->mode == GZ_READ) {   /* for reading ... */
            state->eof = 0;             /* not at end of file */
            state->past = 0;            /* have not read past end yet */
            state->how = LOOK;          /* look for gzip header */
        }
        else                            /* for writing ... */
            state->reset = 0;           /* no deflateReset pending */
        state->seek = 0;                /* no seek request pending */
        gz_error(state, Z_OK, NULL);    /* clear error */
        state->x.pos = 0;               /* no uncompressed data yet */
        state->strm.avail_in = 0;       /* no input data yet */
    }
    
    /* Open a gzip file either by name or file descriptor. */
    local gzFile gz_open(path, fd, mode)
        const void *path;
        int fd;
       const char *mode;
   {
       gz_statep state;
       z_size_t len;
       int oflag;
   #ifdef O_CLOEXEC
       int cloexec = 0;
   #endif
   #ifdef O_EXCL
       int exclusive = 0;
   #endif
   
       /* check input */
       if (path == NULL)
           return NULL;
   
       /* allocate gzFile structure to return */
       state = (gz_statep)malloc(sizeof(gz_state));
       if (state == NULL)
           return NULL;
       state->size = 0;            /* no buffers allocated yet */
       state->want = GZBUFSIZE;    /* requested buffer size */
       state->msg = NULL;          /* no error message yet */
   
       /* interpret mode */
       state->mode = GZ_NONE;
       state->level = Z_DEFAULT_COMPRESSION;
       state->strategy = Z_DEFAULT_STRATEGY;
       state->direct = 0;
       while (*mode) {
           if (*mode >= '' && *mode <= '9')
               state->level = *mode - '';
           else
               switch (*mode) {
               case 'r':
                   state->mode = GZ_READ;
                   break;
   #ifndef NO_GZCOMPRESS
               case 'w':
                   state->mode = GZ_WRITE;
                   break;
               case 'a':
                   state->mode = GZ_APPEND;
                   break;
   #endif
               case '+':       /* can't read and write at the same time */
                   free(state);
                   return NULL;
               case 'b':       /* ignore -- will request binary anyway */
                   break;
   #ifdef O_CLOEXEC
               case 'e':
                   cloexec = 1;
                   break;
   #endif
   #ifdef O_EXCL
               case 'x':
                   exclusive = 1;
                   break;
   #endif
               case 'f':
                   state->strategy = Z_FILTERED;
                   break;
               case 'h':
                   state->strategy = Z_HUFFMAN_ONLY;
                   break;
               case 'R':
                   state->strategy = Z_RLE;
                   break;
               case 'F':
                   state->strategy = Z_FIXED;
                   break;
               case 'T':
                   state->direct = 1;
                   break;
               default:        /* could consider as an error, but just ignore */
                   ;
               }
           mode++;
       }
   
       /* must provide an "r", "w", or "a" */
       if (state->mode == GZ_NONE) {
           free(state);
           return NULL;
       }
   
       /* can't force transparent read */
       if (state->mode == GZ_READ) {
           if (state->direct) {
               free(state);
               return NULL;
           }
           state->direct = 1;      /* for empty file */
       }
   
       /* save the path name for error messages */
   #ifdef WIDECHAR
       if (fd == -2) {
           len = wcstombs(NULL, path, 0);
           if (len == (z_size_t)-1)
               len = 0;
       }
       else
   #endif
           len = strlen((const char *)path);
       state->path = (char *)malloc(len + 1);
       if (state->path == NULL) {
           free(state);
           return NULL;
       }
   #ifdef WIDECHAR
       if (fd == -2)
           if (len)
               wcstombs(state->path, path, len + 1);
           else
               *(state->path) = 0;
       else
   #endif
   #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
           (void)snprintf(state->path, len + 1, "%s", (const char *)path);
   #else
           strcpy(state->path, path);
   #endif
   
       /* compute the flags for open() */
       oflag =
   #ifdef O_LARGEFILE
           O_LARGEFILE |
   #endif
   #ifdef O_BINARY
           O_BINARY |
   #endif
   #ifdef O_CLOEXEC
           (cloexec ? O_CLOEXEC : 0) |
   #endif
           (state->mode == GZ_READ ?
            O_RDONLY :
            (O_WRONLY | O_CREAT |
   #ifdef O_EXCL
             (exclusive ? O_EXCL : 0) |
   #endif
             (state->mode == GZ_WRITE ?
              O_TRUNC :
              O_APPEND)));
   
       /* open the file with the appropriate flags (or just use fd) */
       state->fd = fd > -1 ? fd : (
   #ifdef WIDECHAR
           fd == -2 ? _wopen(path, oflag, 0666) :
   #endif
           open((const char *)path, oflag, 0666));
       if (state->fd == -1) {
           free(state->path);
           free(state);
           return NULL;
       }
       if (state->mode == GZ_APPEND) {
           LSEEK(state->fd, 0, SEEK_END);  /* so gzoffset() is correct */
           state->mode = GZ_WRITE;         /* simplify later checks */
       }
   
       /* save the current position for rewinding (only if reading) */
       if (state->mode == GZ_READ) {
           state->start = LSEEK(state->fd, 0, SEEK_CUR);
           if (state->start == -1) state->start = 0;
       }
   
       /* initialize stream */
       gz_reset(state);
   
       /* return stream */
       return (gzFile)state;
   }
   
   /* -- see zlib.h -- */
   gzFile ZEXPORT gzopen(path, mode)
       const char *path;
       const char *mode;
   {
       return gz_open(path, -1, mode);
   }
   
   /* -- see zlib.h -- */
   gzFile ZEXPORT gzopen64(path, mode)
       const char *path;
       const char *mode;
   {
       return gz_open(path, -1, mode);
   }
   
   /* -- see zlib.h -- */
   gzFile ZEXPORT gzdopen(fd, mode)
       int fd;
       const char *mode;
   {
       char *path;         /* identifier for error messages */
       gzFile gz;
   
       if (fd == -1 || (path = (char *)malloc(7 + 3 * sizeof(int))) == NULL)
           return NULL;
   #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
       (void)snprintf(path, 7 + 3 * sizeof(int), "<fd:%d>", fd);
   #else
       sprintf(path, "<fd:%d>", fd);   /* for debugging */
   #endif
       gz = gz_open(path, fd, mode);
       free(path);
       return gz;
   }
   
   /* -- see zlib.h -- */
   #ifdef WIDECHAR
   gzFile ZEXPORT gzopen_w(path, mode)
       const wchar_t *path;
       const char *mode;
   {
       return gz_open(path, -2, mode);
   }
   #endif
   
   /* -- see zlib.h -- */
   int ZEXPORT gzbuffer(file, size)
       gzFile file;
       unsigned size;
   {
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return -1;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return -1;
   
       /* make sure we haven't already allocated memory */
       if (state->size != 0)
           return -1;
   
       /* check and set requested size */
       if ((size << 1) < size)
           return -1;              /* need to be able to double it */
       if (size < 2)
           size = 2;               /* need two bytes to check magic header */
       state->want = size;
       return 0;
   }
   
   /* -- see zlib.h -- */
   int ZEXPORT gzrewind(file)
       gzFile file;
   {
       gz_statep state;
   
       /* get internal structure */
       if (file == NULL)
           return -1;
       state = (gz_statep)file;
   
       /* check that we're reading and that there's no error */
       if (state->mode != GZ_READ ||
               (state->err != Z_OK && state->err != Z_BUF_ERROR))
           return -1;
   
       /* back up and start over */
       if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
           return -1;
       gz_reset(state);
       return 0;
   }
   
   /* -- see zlib.h -- */
   z_off64_t ZEXPORT gzseek64(file, offset, whence)
       gzFile file;
       z_off64_t offset;
       int whence;
   {
       unsigned n;
       z_off64_t ret;
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return -1;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return -1;
   
       /* check that there's no error */
       if (state->err != Z_OK && state->err != Z_BUF_ERROR)
           return -1;
   
       /* can only seek from start or relative to current position */
       if (whence != SEEK_SET && whence != SEEK_CUR)
           return -1;
   
       /* normalize offset to a SEEK_CUR specification */
       if (whence == SEEK_SET)
           offset -= state->x.pos;
       else if (state->seek)
           offset += state->skip;
       state->seek = 0;
   
       /* if within raw area while reading, just go there */
       if (state->mode == GZ_READ && state->how == COPY &&
               state->x.pos + offset >= 0) {
           ret = LSEEK(state->fd, offset - (z_off64_t)state->x.have, SEEK_CUR);
           if (ret == -1)
               return -1;
           state->x.have = 0;
           state->eof = 0;
           state->past = 0;
           state->seek = 0;
           gz_error(state, Z_OK, NULL);
           state->strm.avail_in = 0;
           state->x.pos += offset;
           return state->x.pos;
       }
   
       /* calculate skip amount, rewinding if needed for back seek when reading */
       if (offset < 0) {
           if (state->mode != GZ_READ)         /* writing -- can't go backwards */
               return -1;
           offset += state->x.pos;
           if (offset < 0)                     /* before start of file! */
               return -1;
           if (gzrewind(file) == -1)           /* rewind, then skip to offset */
               return -1;
       }
   
       /* if reading, skip what's in output buffer (one less gzgetc() check) */
       if (state->mode == GZ_READ) {
           n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset ?
               (unsigned)offset : state->x.have;
           state->x.have -= n;
           state->x.next += n;
           state->x.pos += n;
           offset -= n;
       }
   
       /* request skip (if not zero) */
       if (offset) {
           state->seek = 1;
           state->skip = offset;
       }
       return state->x.pos + offset;
   }
   
   /* -- see zlib.h -- */
   z_off_t ZEXPORT gzseek(file, offset, whence)
       gzFile file;
       z_off_t offset;
       int whence;
   {
       z_off64_t ret;
   
       ret = gzseek64(file, (z_off64_t)offset, whence);
       return ret == (z_off_t)ret ? (z_off_t)ret : -1;
   }
   
   /* -- see zlib.h -- */
   z_off64_t ZEXPORT gztell64(file)
       gzFile file;
   {
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return -1;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return -1;
   
       /* return position */
       return state->x.pos + (state->seek ? state->skip : 0);
   }
   
   /* -- see zlib.h -- */
   z_off_t ZEXPORT gztell(file)
       gzFile file;
   {
       z_off64_t ret;
   
       ret = gztell64(file);
       return ret == (z_off_t)ret ? (z_off_t)ret : -1;
   }
   
   /* -- see zlib.h -- */
   z_off64_t ZEXPORT gzoffset64(file)
       gzFile file;
   {
       z_off64_t offset;
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return -1;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return -1;
   
       /* compute and return effective offset in file */
       offset = LSEEK(state->fd, 0, SEEK_CUR);
       if (offset == -1)
           return -1;
       if (state->mode == GZ_READ)             /* reading */
           offset -= state->strm.avail_in;     /* don't count buffered input */
       return offset;
   }
   
   /* -- see zlib.h -- */
   z_off_t ZEXPORT gzoffset(file)
       gzFile file;
   {
       z_off64_t ret;
   
       ret = gzoffset64(file);
       return ret == (z_off_t)ret ? (z_off_t)ret : -1;
   }
   
   /* -- see zlib.h -- */
   int ZEXPORT gzeof(file)
       gzFile file;
   {
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return 0;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return 0;
   
       /* return end-of-file state */
       return state->mode == GZ_READ ? state->past : 0;
   }
   
   /* -- see zlib.h -- */
   const char * ZEXPORT gzerror(file, errnum)
       gzFile file;
       int *errnum;
   {
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return NULL;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return NULL;
   
       /* return error information */
       if (errnum != NULL)
           *errnum = state->err;
       return state->err == Z_MEM_ERROR ? "out of memory" :
                                          (state->msg == NULL ? "" : state->msg);
   }
   
   /* -- see zlib.h -- */
   void ZEXPORT gzclearerr(file)
       gzFile file;
   {
       gz_statep state;
   
       /* get internal structure and check integrity */
       if (file == NULL)
           return;
       state = (gz_statep)file;
       if (state->mode != GZ_READ && state->mode != GZ_WRITE)
           return;
   
       /* clear error and end-of-file */
       if (state->mode == GZ_READ) {
           state->eof = 0;
           state->past = 0;
       }
       gz_error(state, Z_OK, NULL);
   }
   
   /* Create an error message in allocated memory and set state->err and
      state->msg accordingly.  Free any previous error message already there.  Do
      not try to free or allocate space if the error is Z_MEM_ERROR (out of
      memory).  Simply save the error message as a static string.  If there is an
      allocation failure constructing the error message, then convert the error to
      out of memory. */
   void ZLIB_INTERNAL gz_error(state, err, msg)
       gz_statep state;
       int err;
       const char *msg;
   {
       /* free previously allocated message and clear */
       if (state->msg != NULL) {
           if (state->err != Z_MEM_ERROR)
               free(state->msg);
           state->msg = NULL;
       }
   
       /* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
       if (err != Z_OK && err != Z_BUF_ERROR)
           state->x.have = 0;
   
       /* set error code, and if no message, then done */
       state->err = err;
       if (msg == NULL)
           return;
   
       /* for an out of memory error, return literal string when requested */
       if (err == Z_MEM_ERROR)
           return;
   
       /* construct error message with path */
       if ((state->msg = (char *)malloc(strlen(state->path) + strlen(msg) + 3)) ==
               NULL) {
           state->err = Z_MEM_ERROR;
           return;
       }
   #if !defined(NO_snprintf) && !defined(NO_vsnprintf)
       (void)snprintf(state->msg, strlen(state->path) + strlen(msg) + 3,
                      "%s%s%s", state->path, ": ", msg);
   #else
       strcpy(state->msg, state->path);
       strcat(state->msg, ": ");
       strcat(state->msg, msg);
   #endif
   }
   
   #ifndef INT_MAX
   /* portably return maximum value for an int (when limits.h presumed not
      available) -- we need to do this to cover cases where 2's complement not
      used, since C standard permits 1's complement and sign-bit representations,
      otherwise we could just use ((unsigned)-1) >> 1 */
   unsigned ZLIB_INTERNAL gz_intmax()
   {
       unsigned p, q;
   
       p = 1;
       do {
           q = p;
           p <<= 1;
           p++;
       } while (p > q);
       return q >> 1;
   }
   #endif

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