zlib: Update from 1.2.5 to 1.2.13

The updated files were extracted from:

https://www.zlib.net/zlib-1.2.13.tar.xz

The archive had an SHA-256 hash value of:

d14c38e313afc35a9a8760dadf26042f51ea0f5d154b0630a31da0540107fb98

Close #4902.

1 files changed, 282 insertions, 285 deletions

diff --git a/cpukit/zlib/gzread.c b/cpukit/zlib/gzread.c
index 548201ab00..dd77381596 100644
--- a/cpukit/zlib/gzread.c
+++ b/cpukit/zlib/gzread.c
@@ -1,5 +1,5 @@
 /* gzread.c -- zlib functions for reading gzip files
- * Copyright (C) 2004, 2005, 2010 Mark Adler
+ * Copyright (C) 2004-2017 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -8,11 +8,11 @@
 /* Local functions */
 local int gz_load OF((gz_statep, unsigned char *, unsigned, unsigned *));
 local int gz_avail OF((gz_statep));
-local int gz_next4 OF((gz_statep, unsigned long *));
-local int gz_head OF((gz_statep));
+local int gz_look OF((gz_statep));
 local int gz_decomp OF((gz_statep));
-local int gz_make OF((gz_statep));
+local int gz_fetch OF((gz_statep));
 local int gz_skip OF((gz_statep, z_off64_t));
+local z_size_t gz_read OF((gz_statep, voidp, z_size_t));
 
 /* Use read() to load a buffer -- return -1 on error, otherwise 0.  Read from
    state->fd, and update state->eof, state->err, and state->msg as appropriate.
@@ -25,13 +25,17 @@ local int gz_load(state, buf, len, have)
     unsigned *have;
 {
     int ret;
+    unsigned get, max = ((unsigned)-1 >> 2) + 1;
 
     *have = 0;
     do {
-        ret = read(state->fd, buf + *have, len - *have);
+        get = len - *have;
+        if (get > max)
+            get = max;
+        ret = read(state->fd, buf + *have, get);
         if (ret <= 0)
             break;
-        *have += ret;
+        *have += (unsigned)ret;
     } while (*have < len);
     if (ret < 0) {
         gz_error(state, Z_ERRNO, zstrerror());
@@ -46,78 +50,57 @@ local int gz_load(state, buf, len, have)
    error, 0 otherwise.  Note that the eof flag is set when the end of the input
    file is reached, even though there may be unused data in the buffer.  Once
    that data has been used, no more attempts will be made to read the file.
-   gz_avail() assumes that strm->avail_in == 0. */
+   If strm->avail_in != 0, then the current data is moved to the beginning of
+   the input buffer, and then the remainder of the buffer is loaded with the
+   available data from the input file. */
 local int gz_avail(state)
     gz_statep state;
 {
+    unsigned got;
     z_streamp strm = &(state->strm);
 
-    if (state->err != Z_OK)
+    if (state->err != Z_OK && state->err != Z_BUF_ERROR)
         return -1;
     if (state->eof == 0) {
-        if (gz_load(state, state->in, state->size,
-                (unsigned *)&(strm->avail_in)) == -1)
+        if (strm->avail_in) {       /* copy what's there to the start */
+            unsigned char *p = state->in;
+            unsigned const char *q = strm->next_in;
+            unsigned n = strm->avail_in;
+            do {
+                *p++ = *q++;
+            } while (--n);
+        }
+        if (gz_load(state, state->in + strm->avail_in,
+                    state->size - strm->avail_in, &got) == -1)
             return -1;
+        strm->avail_in += got;
         strm->next_in = state->in;
     }
     return 0;
 }
 
-/* Get next byte from input, or -1 if end or error. */
-#define NEXT() ((strm->avail_in == 0 && gz_avail(state) == -1) ? -1 : \
-                (strm->avail_in == 0 ? -1 : \
-                 (strm->avail_in--, *(strm->next_in)++)))
-
-/* Get a four-byte little-endian integer and return 0 on success and the value
-   in *ret.  Otherwise -1 is returned and *ret is not modified. */
-local int gz_next4(state, ret)
-    gz_statep state;
-    unsigned long *ret;
-{
-    int ch;
-    unsigned long val;
-    z_streamp strm = &(state->strm);
-
-    val = NEXT();
-    val += (unsigned)NEXT() << 8;
-    val += (unsigned long)NEXT() << 16;
-    ch = NEXT();
-    if (ch == -1)
-        return -1;
-    val += (unsigned long)ch << 24;
-    *ret = val;
-    return 0;
-}
-
-/* Look for gzip header, set up for inflate or copy.  state->have must be zero.
+/* Look for gzip header, set up for inflate or copy.  state->x.have must be 0.
    If this is the first time in, allocate required memory.  state->how will be
    left unchanged if there is no more input data available, will be set to COPY
    if there is no gzip header and direct copying will be performed, or it will
-   be set to GZIP for decompression, and the gzip header will be skipped so
-   that the next available input data is the raw deflate stream.  If direct
-   copying, then leftover input data from the input buffer will be copied to
-   the output buffer.  In that case, all further file reads will be directly to
-   either the output buffer or a user buffer.  If decompressing, the inflate
-   state and the check value will be initialized.  gz_head() will return 0 on
-   success or -1 on failure.  Failures may include read errors or gzip header
-   errors.  */
-local int gz_head(state)
+   be set to GZIP for decompression.  If direct copying, then leftover input
+   data from the input buffer will be copied to the output buffer.  In that
+   case, all further file reads will be directly to either the output buffer or
+   a user buffer.  If decompressing, the inflate state will be initialized.
+   gz_look() will return 0 on success or -1 on failure. */
+local int gz_look(state)
     gz_statep state;
 {
     z_streamp strm = &(state->strm);
-    int flags;
-    unsigned len;
 
     /* allocate read buffers and inflate memory */
     if (state->size == 0) {
         /* allocate buffers */
-        state->in = malloc(state->want);
-        state->out = malloc(state->want << 1);
+        state->in = (unsigned char *)malloc(state->want);
+        state->out = (unsigned char *)malloc(state->want << 1);
         if (state->in == NULL || state->out == NULL) {
-            if (state->out != NULL)
-                free(state->out);
-            if (state->in != NULL)
-                free(state->in);
+            free(state->out);
+            free(state->in);
             gz_error(state, Z_MEM_ERROR, "out of memory");
             return -1;
         }
@@ -129,7 +112,7 @@ local int gz_head(state)
         state->strm.opaque = Z_NULL;
         state->strm.avail_in = 0;
         state->strm.next_in = Z_NULL;
-        if (inflateInit2(&(state->strm), -15) != Z_OK) {    /* raw inflate */
+        if (inflateInit2(&(state->strm), 15 + 16) != Z_OK) {    /* gunzip */
             free(state->out);
             free(state->in);
             state->size = 0;
@@ -138,104 +121,60 @@ local int gz_head(state)
         }
     }
 
-    /* get some data in the input buffer */
-    if (strm->avail_in == 0) {
+    /* get at least the magic bytes in the input buffer */
+    if (strm->avail_in < 2) {
         if (gz_avail(state) == -1)
             return -1;
         if (strm->avail_in == 0)
             return 0;
     }
 
-    /* look for the gzip magic header bytes 31 and 139 */
-    if (strm->next_in[0] == 31) {
-        strm->avail_in--;
-        strm->next_in++;
-        if (strm->avail_in == 0 && gz_avail(state) == -1)
-            return -1;
-        if (strm->avail_in && strm->next_in[0] == 139) {
-            /* we have a gzip header, woo hoo! */
-            strm->avail_in--;
-            strm->next_in++;
-
-            /* skip rest of header */
-            if (NEXT() != 8) {      /* compression method */
-                gz_error(state, Z_DATA_ERROR, "unknown compression method");
-                return -1;
-            }
-            flags = NEXT();
-            if (flags & 0xe0) {     /* reserved flag bits */
-                gz_error(state, Z_DATA_ERROR, "unknown header flags set");
-                return -1;
-            }
-            NEXT();                 /* modification time */
-            NEXT();
-            NEXT();
-            NEXT();
-            NEXT();                 /* extra flags */
-            NEXT();                 /* operating system */
-            if (flags & 4) {        /* extra field */
-                len = (unsigned)NEXT();
-                len += (unsigned)NEXT() << 8;
-                while (len--)
-                    if (NEXT() < 0)
-                        break;
-            }
-            if (flags & 8)          /* file name */
-                while (NEXT() > 0)
-                    ;
-            if (flags & 16)         /* comment */
-                while (NEXT() > 0)
-                    ;
-            if (flags & 2) {        /* header crc */
-                NEXT();
-                NEXT();
-            }
-            /* an unexpected end of file is not checked for here -- it will be
-               noticed on the first request for uncompressed data */
-
-            /* set up for decompression */
-            inflateReset(strm);
-            strm->adler = crc32(0L, Z_NULL, 0);
-            state->how = GZIP;
-            state->direct = 0;
-            return 0;
-        }
-        else {
-            /* not a gzip file -- save first byte (31) and fall to raw i/o */
-            state->out[0] = 31;
-            state->have = 1;
-        }
+    /* look for gzip magic bytes -- if there, do gzip decoding (note: there is
+       a logical dilemma here when considering the case of a partially written
+       gzip file, to wit, if a single 31 byte is written, then we cannot tell
+       whether this is a single-byte file, or just a partially written gzip
+       file -- for here we assume that if a gzip file is being written, then
+       the header will be written in a single operation, so that reading a
+       single byte is sufficient indication that it is not a gzip file) */
+    if (strm->avail_in > 1 &&
+            strm->next_in[0] == 31 && strm->next_in[1] == 139) {
+        inflateReset(strm);
+        state->how = GZIP;
+        state->direct = 0;
+        return 0;
     }
 
-    /* doing raw i/o, save start of raw data for seeking, copy any leftover
-       input to output -- this assumes that the output buffer is larger than
-       the input buffer, which also assures space for gzungetc() */
-    state->raw = state->pos;
-    state->next = state->out;
-    if (strm->avail_in) {
-        memcpy(state->next + state->have, strm->next_in, strm->avail_in);
-        state->have += strm->avail_in;
+    /* no gzip header -- if we were decoding gzip before, then this is trailing
+       garbage.  Ignore the trailing garbage and finish. */
+    if (state->direct == 0) {
         strm->avail_in = 0;
+        state->eof = 1;
+        state->x.have = 0;
+        return 0;
     }
+
+    /* doing raw i/o, copy any leftover input to output -- this assumes that
+       the output buffer is larger than the input buffer, which also assures
+       space for gzungetc() */
+    state->x.next = state->out;
+    memcpy(state->x.next, strm->next_in, strm->avail_in);
+    state->x.have = strm->avail_in;
+    strm->avail_in = 0;
     state->how = COPY;
     state->direct = 1;
     return 0;
 }
 
 /* Decompress from input to the provided next_out and avail_out in the state.
-   If the end of the compressed data is reached, then verify the gzip trailer
-   check value and length (modulo 2^32).  state->have and state->next are set
-   to point to the just decompressed data, and the crc is updated.  If the
-   trailer is verified, state->how is reset to LOOK to look for the next gzip
-   stream or raw data, once state->have is depleted.  Returns 0 on success, -1
-   on failure.  Failures may include invalid compressed data or a failed gzip
-   trailer verification. */
+   On return, state->x.have and state->x.next point to the just decompressed
+   data.  If the gzip stream completes, state->how is reset to LOOK to look for
+   the next gzip stream or raw data, once state->x.have is depleted.  Returns 0
+   on success, -1 on failure. */
 local int gz_decomp(state)
     gz_statep state;
 {
-    int ret;
+    int ret = Z_OK;
     unsigned had;
-    unsigned long crc, len;
     z_streamp strm = &(state->strm);
 
     /* fill output buffer up to end of deflate stream */
@@ -245,15 +184,15 @@ local int gz_decomp(state)
         if (strm->avail_in == 0 && gz_avail(state) == -1)
             return -1;
         if (strm->avail_in == 0) {
-            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
-            return -1;
+            gz_error(state, Z_BUF_ERROR, "unexpected end of file");
+            break;
         }
 
         /* decompress and handle errors */
         ret = inflate(strm, Z_NO_FLUSH);
         if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
             gz_error(state, Z_STREAM_ERROR,
-                      "internal error: inflate stream corrupt");
+                     "internal error: inflate stream corrupt");
             return -1;
         }
         if (ret == Z_MEM_ERROR) {
@@ -262,67 +201,55 @@ local int gz_decomp(state)
         }
         if (ret == Z_DATA_ERROR) {              /* deflate stream invalid */
             gz_error(state, Z_DATA_ERROR,
-                      strm->msg == NULL ? "compressed data error" : strm->msg);
+                     strm->msg == NULL ? "compressed data error" : strm->msg);
             return -1;
         }
     } while (strm->avail_out && ret != Z_STREAM_END);
 
-    /* update available output and crc check value */
-    state->have = had - strm->avail_out;
-    state->next = strm->next_out - state->have;
-    strm->adler = crc32(strm->adler, state->next, state->have);
+    /* update available output */
+    state->x.have = had - strm->avail_out;
+    state->x.next = strm->next_out - state->x.have;
 
-    /* check gzip trailer if at end of deflate stream */
-    if (ret == Z_STREAM_END) {
-        if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
-            gz_error(state, Z_DATA_ERROR, "unexpected end of file");
-            return -1;
-        }
-        if (crc != strm->adler) {
-            gz_error(state, Z_DATA_ERROR, "incorrect data check");
-            return -1;
-        }
-        if (len != (strm->total_out & 0xffffffffL)) {
-            gz_error(state, Z_DATA_ERROR, "incorrect length check");
-            return -1;
-        }
-        state->how = LOOK;      /* ready for next stream, once have is 0 (leave
-                                   state->direct unchanged to remember how) */
-    }
+    /* if the gzip stream completed successfully, look for another */
+    if (ret == Z_STREAM_END)
+        state->how = LOOK;
 
     /* good decompression */
     return 0;
 }
 
-/* Make data and put in the output buffer.  Assumes that state->have == 0.
+/* Fetch data and put it in the output buffer.  Assumes state->x.have is 0.
    Data is either copied from the input file or decompressed from the input
    file depending on state->how.  If state->how is LOOK, then a gzip header is
-   looked for (and skipped if found) to determine wither to copy or decompress.
-   Returns -1 on error, otherwise 0.  gz_make() will leave state->have as COPY
-   or GZIP unless the end of the input file has been reached and all data has
-   been processed.  */
-local int gz_make(state)
+   looked for to determine whether to copy or decompress.  Returns -1 on error,
+   otherwise 0.  gz_fetch() will leave state->how as COPY or GZIP unless the
+   end of the input file has been reached and all data has been processed.  */
+local int gz_fetch(state)
     gz_statep state;
 {
     z_streamp strm = &(state->strm);
 
-    if (state->how == LOOK) {           /* look for gzip header */
-        if (gz_head(state) == -1)
-            return -1;
-        if (state->have)                /* got some data from gz_head() */
+    do {
+        switch(state->how) {
+        case LOOK:      /* -> LOOK, COPY (only if never GZIP), or GZIP */
+            if (gz_look(state) == -1)
+                return -1;
+            if (state->how == LOOK)
+                return 0;
+            break;
+        case COPY:      /* -> COPY */
+            if (gz_load(state, state->out, state->size << 1, &(state->x.have))
+                    == -1)
+                return -1;
+            state->x.next = state->out;
             return 0;
-    }
-    if (state->how == COPY) {           /* straight copy */
-        if (gz_load(state, state->out, state->size << 1, &(state->have)) == -1)
-            return -1;
-        state->next = state->out;
-    }
-    else if (state->how == GZIP) {      /* decompress */
-        strm->avail_out = state->size << 1;
-        strm->next_out = state->out;
-        if (gz_decomp(state) == -1)
-            return -1;
-    }
+        case GZIP:      /* -> GZIP or LOOK (if end of gzip stream) */
+            strm->avail_out = state->size << 1;
+            strm->next_out = state->out;
+            if (gz_decomp(state) == -1)
+                return -1;
+        }
+    } while (state->x.have == 0 && (!state->eof || strm->avail_in));
     return 0;
 }
 
@@ -336,12 +263,12 @@ local int gz_skip(state, len)
     /* skip over len bytes or reach end-of-file, whichever comes first */
     while (len)
         /* skip over whatever is in output buffer */
-        if (state->have) {
-            n = GT_OFF(state->have) || (z_off64_t)state->have > len ?
-                (unsigned)len : state->have;
-            state->have -= n;
-            state->next += n;
-            state->pos += n;
+        if (state->x.have) {
+            n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > len ?
+                (unsigned)len : state->x.have;
+            state->x.have -= n;
+            state->x.next += n;
+            state->x.pos += n;
             len -= n;
         }
 
@@ -352,38 +279,23 @@ local int gz_skip(state, len)
         /* need more data to skip -- load up output buffer */
         else {
             /* get more output, looking for header if required */
-            if (gz_make(state) == -1)
+            if (gz_fetch(state) == -1)
                 return -1;
         }
     return 0;
 }
 
-/* -- see zlib.h -- */
-int ZEXPORT gzread(file, buf, len)
-    gzFile file;
+/* Read len bytes into buf from file, or less than len up to the end of the
+   input.  Return the number of bytes read.  If zero is returned, either the
+   end of file was reached, or there was an error.  state->err must be
+   consulted in that case to determine which. */
+local z_size_t gz_read(state, buf, len)
+    gz_statep state;
     voidp buf;
-    unsigned len;
+    z_size_t len;
 {
-    unsigned got, n;
-    gz_statep state;
-    z_streamp strm;
-
-    /* get internal structure */
-    if (file == NULL)
-        return -1;
-    state = (gz_statep)file;
-    strm = &(state->strm);
-
-    /* check that we're reading and that there's no error */
-    if (state->mode != GZ_READ || state->err != Z_OK)
-        return -1;
-
-    /* since an int is returned, make sure len fits in one, otherwise return
-       with an error (this avoids the flaw in the interface) */
-    if ((int)len < 0) {
-        gz_error(state, Z_BUF_ERROR, "requested length does not fit in int");
-        return -1;
-    }
+    z_size_t got;
+    unsigned n;
 
     /* if len is zero, avoid unnecessary operations */
     if (len == 0)
@@ -393,67 +305,146 @@ int ZEXPORT gzread(file, buf, len)
     if (state->seek) {
         state->seek = 0;
         if (gz_skip(state, state->skip) == -1)
-            return -1;
+            return 0;
     }
 
     /* get len bytes to buf, or less than len if at the end */
     got = 0;
     do {
+        /* set n to the maximum amount of len that fits in an unsigned int */
+        n = (unsigned)-1;
+        if (n > len)
+            n = (unsigned)len;
+
         /* first just try copying data from the output buffer */
-        if (state->have) {
-            n = state->have > len ? len : state->have;
-            memcpy(buf, state->next, n);
-            state->next += n;
-            state->have -= n;
+        if (state->x.have) {
+            if (state->x.have < n)
+                n = state->x.have;
+            memcpy(buf, state->x.next, n);
+            state->x.next += n;
+            state->x.have -= n;
         }
 
         /* output buffer empty -- return if we're at the end of the input */
-        else if (state->eof && strm->avail_in == 0)
+        else if (state->eof && state->strm.avail_in == 0) {
+            state->past = 1;        /* tried to read past end */
             break;
+        }
 
         /* need output data -- for small len or new stream load up our output
            buffer */
-        else if (state->how == LOOK || len < (state->size << 1)) {
+        else if (state->how == LOOK || n < (state->size << 1)) {
             /* get more output, looking for header if required */
-            if (gz_make(state) == -1)
-                return -1;
-            continue;       /* no progress yet -- go back to memcpy() above */
+            if (gz_fetch(state) == -1)
+                return 0;
+            continue;       /* no progress yet -- go back to copy above */
             /* the copy above assures that we will leave with space in the
                output buffer, allowing at least one gzungetc() to succeed */
         }
 
         /* large len -- read directly into user buffer */
         else if (state->how == COPY) {      /* read directly */
-            if (gz_load(state, buf, len, &n) == -1)
-                return -1;
+            if (gz_load(state, (unsigned char *)buf, n, &n) == -1)
+                return 0;
         }
 
         /* large len -- decompress directly into user buffer */
         else {  /* state->how == GZIP */
-            strm->avail_out = len;
-            strm->next_out = buf;
+            state->strm.avail_out = n;
+            state->strm.next_out = (unsigned char *)buf;
             if (gz_decomp(state) == -1)
-                return -1;
-            n = state->have;
-            state->have = 0;
+                return 0;
+            n = state->x.have;
+            state->x.have = 0;
         }
 
         /* update progress */
         len -= n;
         buf = (char *)buf + n;
         got += n;
-        state->pos += n;
+        state->x.pos += n;
     } while (len);
 
-    /* return number of bytes read into user buffer (will fit in int) */
-    return (int)got;
+    /* return number of bytes read into user buffer */
+    return got;
 }
 
 /* -- see zlib.h -- */
+int ZEXPORT gzread(file, buf, len)
+    gzFile file;
+    voidp buf;
+    unsigned len;
+{
+    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 (serious) error */
+    if (state->mode != GZ_READ ||
+            (state->err != Z_OK && state->err != Z_BUF_ERROR))
+        return -1;
+
+    /* since an int is returned, make sure len fits in one, otherwise return
+       with an error (this avoids a flaw in the interface) */
+    if ((int)len < 0) {
+        gz_error(state, Z_STREAM_ERROR, "request does not fit in an int");
+        return -1;
+    }
+
+    /* read len or fewer bytes to buf */
+    len = (unsigned)gz_read(state, buf, len);
+
+    /* check for an error */
+    if (len == 0 && state->err != Z_OK && state->err != Z_BUF_ERROR)
+        return -1;
+
+    /* return the number of bytes read (this is assured to fit in an int) */
+    return (int)len;
+}
+
+/* -- see zlib.h -- */
+z_size_t ZEXPORT gzfread(buf, size, nitems, file)
+    voidp buf;
+    z_size_t size;
+    z_size_t nitems;
+    gzFile file;
+{
+    z_size_t len;
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return 0;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no (serious) error */
+    if (state->mode != GZ_READ ||
+            (state->err != Z_OK && state->err != Z_BUF_ERROR))
+        return 0;
+
+    /* compute bytes to read -- error on overflow */
+    len = nitems * size;
+    if (size && len / size != nitems) {
+        gz_error(state, Z_STREAM_ERROR, "request does not fit in a size_t");
+        return 0;
+    }
+
+    /* read len or fewer bytes to buf, return the number of full items read */
+    return len ? gz_read(state, buf, len) / size : 0;
+}
+
+/* -- see zlib.h -- */
+#ifdef Z_PREFIX_SET
+#  undef z_gzgetc
+#else
+#  undef gzgetc
+#endif
 int ZEXPORT gzgetc(file)
     gzFile file;
 {
-    int ret;
     unsigned char buf[1];
     gz_statep state;
 
@@ -462,20 +453,26 @@ int ZEXPORT gzgetc(file)
         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)
+    /* check that we're reading and that there's no (serious) error */
+    if (state->mode != GZ_READ ||
+        (state->err != Z_OK && state->err != Z_BUF_ERROR))
         return -1;
 
     /* try output buffer (no need to check for skip request) */
-    if (state->have) {
-        state->have--;
-        state->pos++;
-        return *(state->next)++;
+    if (state->x.have) {
+        state->x.have--;
+        state->x.pos++;
+        return *(state->x.next)++;
     }
 
-    /* nothing there -- try gzread() */
-    ret = gzread(file, buf, 1);
-    return ret < 1 ? -1 : buf[0];
+    /* nothing there -- try gz_read() */
+    return gz_read(state, buf, 1) < 1 ? -1 : buf[0];
+}
+
+int ZEXPORT gzgetc_(file)
+gzFile file;
+{
+    return gzgetc(file);
 }
 
 /* -- see zlib.h -- */
@@ -490,8 +487,9 @@ int ZEXPORT gzungetc(c, file)
         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)
+    /* check that we're reading and that there's no (serious) error */
+    if (state->mode != GZ_READ ||
+        (state->err != Z_OK && state->err != Z_BUF_ERROR))
         return -1;
 
     /* process a skip request */
@@ -506,32 +504,34 @@ int ZEXPORT gzungetc(c, file)
         return -1;
 
     /* if output buffer empty, put byte at end (allows more pushing) */
-    if (state->have == 0) {
-        state->have = 1;
-        state->next = state->out + (state->size << 1) - 1;
-        state->next[0] = c;
-        state->pos--;
+    if (state->x.have == 0) {
+        state->x.have = 1;
+        state->x.next = state->out + (state->size << 1) - 1;
+        state->x.next[0] = (unsigned char)c;
+        state->x.pos--;
+        state->past = 0;
         return c;
     }
 
     /* if no room, give up (must have already done a gzungetc()) */
-    if (state->have == (state->size << 1)) {
-        gz_error(state, Z_BUF_ERROR, "out of room to push characters");
+    if (state->x.have == (state->size << 1)) {
+        gz_error(state, Z_DATA_ERROR, "out of room to push characters");
         return -1;
     }
 
     /* slide output data if needed and insert byte before existing data */
-    if (state->next == state->out) {
-        unsigned char *src = state->out + state->have;
+    if (state->x.next == state->out) {
+        unsigned char *src = state->out + state->x.have;
         unsigned char *dest = state->out + (state->size << 1);
         while (src > state->out)
             *--dest = *--src;
-        state->next = dest;
+        state->x.next = dest;
     }
-    state->have++;
-    state->next--;
-    state->next[0] = c;
-    state->pos--;
+    state->x.have++;
+    state->x.next--;
+    state->x.next[0] = (unsigned char)c;
+    state->x.pos--;
+    state->past = 0;
     return c;
 }
 
@@ -551,8 +551,9 @@ char * ZEXPORT gzgets(file, buf, len)
         return NULL;
     state = (gz_statep)file;
 
-    /* check that we're reading and that there's no error */
-    if (state->mode != GZ_READ || state->err != Z_OK)
+    /* check that we're reading and that there's no (serious) error */
+    if (state->mode != GZ_READ ||
+        (state->err != Z_OK && state->err != Z_BUF_ERROR))
         return NULL;
 
     /* process a skip request */
@@ -569,32 +570,31 @@ char * ZEXPORT gzgets(file, buf, len)
     left = (unsigned)len - 1;
     if (left) do {
         /* assure that something is in the output buffer */
-        if (state->have == 0) {
-            if (gz_make(state) == -1)
-                return NULL;            /* error */
-            if (state->have == 0) {     /* end of file */
-                if (buf == str)         /* got bupkus */
-                    return NULL;
-                break;                  /* got something -- return it */
-            }
+        if (state->x.have == 0 && gz_fetch(state) == -1)
+            return NULL;                /* error */
+        if (state->x.have == 0) {       /* end of file */
+            state->past = 1;            /* read past end */
+            break;                      /* return what we have */
         }
 
         /* look for end-of-line in current output buffer */
-        n = state->have > left ? left : state->have;
-        eol = memchr(state->next, '\n', n);
+        n = state->x.have > left ? left : state->x.have;
+        eol = (unsigned char *)memchr(state->x.next, '\n', n);
         if (eol != NULL)
-            n = (unsigned)(eol - state->next) + 1;
+            n = (unsigned)(eol - state->x.next) + 1;
 
         /* copy through end-of-line, or remainder if not found */
-        memcpy(buf, state->next, n);
-        state->have -= n;
-        state->next += n;
-        state->pos += n;
+        memcpy(buf, state->x.next, n);
+        state->x.have -= n;
+        state->x.next += n;
+        state->x.pos += n;
         left -= n;
         buf += n;
     } while (left && eol == NULL);
 
-    /* found end-of-line or out of space -- terminate string and return it */
+    /* return terminated string, or if nothing, end of file */
+    if (buf == str)
+        return NULL;
     buf[0] = 0;
     return str;
 }
@@ -610,16 +610,12 @@ int ZEXPORT gzdirect(file)
         return 0;
     state = (gz_statep)file;
 
-    /* check that we're reading */
-    if (state->mode != GZ_READ)
-        return 0;
-
     /* if the state is not known, but we can find out, then do so (this is
        mainly for right after a gzopen() or gzdopen()) */
-    if (state->how == LOOK && state->have == 0)
-        (void)gz_head(state);
+    if (state->mode == GZ_READ && state->how == LOOK && state->x.have == 0)
+        (void)gz_look(state);
 
-    /* return 1 if reading direct, 0 if decompressing a gzip stream */
+    /* return 1 if transparent, 0 if processing a gzip stream */
     return state->direct;
 }
 
@@ -627,7 +623,7 @@ int ZEXPORT gzdirect(file)
 int ZEXPORT gzclose_r(file)
     gzFile file;
 {
-    int ret;
+    int ret, err;
     gz_statep state;
 
     /* get internal structure */
@@ -645,9 +641,10 @@ int ZEXPORT gzclose_r(file)
         free(state->out);
         free(state->in);
     }
+    err = state->err == Z_BUF_ERROR ? Z_BUF_ERROR : Z_OK;
     gz_error(state, Z_OK, NULL);
     free(state->path);
     ret = close(state->fd);
     free(state);
-    return ret ? Z_ERRNO : Z_OK;
+    return ret ? Z_ERRNO : err;
 }