/src/zlib/gzwrite.c

Source
/* gzwrite.c -- zlib functions for writing gzip files
 * Copyright (C) 2004-2026 Mark Adler
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#include "gzguts.h"

/* Initialize state for writing a gzip file.  Mark initialization by setting
   state->size to non-zero.  Return -1 on a memory allocation failure, or 0 on
   success. */
local int gz_init(gz_statep state) {
    int ret;
    z_streamp strm = &(state->strm);

    /* allocate input buffer (double size for gzprintf) */
    state->in = (unsigned char *)malloc(state->want << 1);
    if (state->in == NULL) {
        gz_error(state, Z_MEM_ERROR, "out of memory");
        return -1;
    }

    /* only need output buffer and deflate state if compressing */
    if (!state->direct) {
        /* allocate output buffer */
        state->out = (unsigned char *)malloc(state->want);
        if (state->out == NULL) {
            free(state->in);
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }

        /* allocate deflate memory, set up for gzip compression */
        strm->zalloc = Z_NULL;
        strm->zfree = Z_NULL;
        strm->opaque = Z_NULL;
        ret = deflateInit2(strm, state->level, Z_DEFLATED,
                           MAX_WBITS + 16, DEF_MEM_LEVEL, state->strategy);
        if (ret != Z_OK) {
            free(state->out);
            free(state->in);
            gz_error(state, Z_MEM_ERROR, "out of memory");
            return -1;
        }
        strm->next_in = NULL;
    }

    /* mark state as initialized */
    state->size = state->want;

    /* initialize write buffer if compressing */
    if (!state->direct) {
        strm->avail_out = state->size;
        strm->next_out = state->out;
        state->x.next = strm->next_out;
    }
    return 0;
}

/* Compress whatever is at avail_in and next_in and write to the output file.
   Return -1 if there is an error writing to the output file or if gz_init()
   fails to allocate memory, otherwise 0.  flush is assumed to be a valid
   deflate() flush value.  If flush is Z_FINISH, then the deflate() state is
   reset to start a new gzip stream.  If gz->direct is true, then simply write
   to the output file without compressing, and ignore flush. */
local int gz_comp(gz_statep state, int flush) {
    int ret, writ;
    unsigned have, put, max = ((unsigned)-1 >> 2) + 1;
    z_streamp strm = &(state->strm);

    /* allocate memory if this is the first time through */
    if (state->size == 0 && gz_init(state) == -1)
        return -1;

    /* write directly if requested */
    if (state->direct) {
        while (strm->avail_in) {
            errno = 0;
            state->again = 0;
            put = strm->avail_in > max ? max : strm->avail_in;
            writ = (int)write(state->fd, strm->next_in, put);
            if (writ < 0) {
                if (errno == EAGAIN || errno == EWOULDBLOCK)
                    state->again = 1;
                gz_error(state, Z_ERRNO, zstrerror());
                return -1;
            }
            strm->avail_in -= (unsigned)writ;
            strm->next_in += writ;
        }
        return 0;
    }

    /* check for a pending reset */
    if (state->reset) {
        /* don't start a new gzip member unless there is data to write and
           we're not flushing */
        if (strm->avail_in == 0 && flush == Z_NO_FLUSH)
            return 0;
        deflateReset(strm);
        state->reset = 0;
    }

    /* run deflate() on provided input until it produces no more output */
    ret = Z_OK;
    do {
        /* write out current buffer contents if full, or if flushing, but if
           doing Z_FINISH then don't write until we get to Z_STREAM_END */
        if (strm->avail_out == 0 || (flush != Z_NO_FLUSH &&
            (flush != Z_FINISH || ret == Z_STREAM_END))) {
            while (strm->next_out > state->x.next) {
                errno = 0;
                state->again = 0;
                put = strm->next_out - state->x.next > (int)max ? max :
                      (unsigned)(strm->next_out - state->x.next);
                writ = (int)write(state->fd, state->x.next, put);
                if (writ < 0) {
                    if (errno == EAGAIN || errno == EWOULDBLOCK)
                        state->again = 1;
                    gz_error(state, Z_ERRNO, zstrerror());
                    return -1;
                }
                state->x.next += writ;
            }
            if (strm->avail_out == 0) {
                strm->avail_out = state->size;
                strm->next_out = state->out;
                state->x.next = state->out;
            }
        }

        /* compress */
        have = strm->avail_out;
        ret = deflate(strm, flush);
        if (ret == Z_STREAM_ERROR) {
            gz_error(state, Z_STREAM_ERROR,
                      "internal error: deflate stream corrupt");
            return -1;
        }
        have -= strm->avail_out;
    } while (have);

    /* if that completed a deflate stream, allow another to start */
    if (flush == Z_FINISH)
        state->reset = 1;

    /* all done, no errors */
    return 0;
}

/* Compress state->skip (> 0) zeros to output.  Return -1 on a write error or
   memory allocation failure by gz_comp(), or 0 on success. state->skip is
   updated with the number of successfully written zeros, in case there is a
   stall on a non-blocking write destination. */
local int gz_zero(gz_statep state) {
    int first, ret;
    unsigned n;
    z_streamp strm = &(state->strm);

    /* consume whatever's left in the input buffer */
    if (strm->avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
        return -1;

    /* compress state->skip zeros */
    first = 1;
    do {
        n = GT_OFF(state->size) || (z_off64_t)state->size > state->skip ?
            (unsigned)state->skip : state->size;
        if (first) {
            memset(state->in, 0, n);
            first = 0;
        }
        strm->avail_in = n;
        strm->next_in = state->in;
        ret = gz_comp(state, Z_NO_FLUSH);
        n -= strm->avail_in;
        state->x.pos += n;
        state->skip -= n;
        if (ret == -1)
            return -1;
    } while (state->skip);
    return 0;
}

/* Write len bytes from buf to file.  Return the number of bytes written.  If
   the returned value is less than len, then there was an error. If the error
   was a non-blocking stall, then the number of bytes consumed is returned.
   For any other error, 0 is returned. */
local z_size_t gz_write(gz_statep state, voidpc buf, z_size_t len) {
    z_size_t put = len;
    int ret;

    /* if len is zero, avoid unnecessary operations */
    if (len == 0)
        return 0;

    /* allocate memory if this is the first time through */
    if (state->size == 0 && gz_init(state) == -1)
        return 0;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return 0;

    /* for small len, copy to input buffer, otherwise compress directly */
    if (len < state->size) {
        /* copy to input buffer, compress when full */
        for (;;) {
            unsigned have, copy;

            if (state->strm.avail_in == 0)
                state->strm.next_in = state->in;
            have = (unsigned)((state->strm.next_in + state->strm.avail_in) -
                              state->in);
            copy = state->size - have;
            if (copy > len)
                copy = (unsigned)len;
            memcpy(state->in + have, buf, copy);
            state->strm.avail_in += copy;
            state->x.pos += copy;
            buf = (const char *)buf + copy;
            len -= copy;
            if (len == 0)
                break;
            if (gz_comp(state, Z_NO_FLUSH) == -1)
                return state->again ? put - len : 0;
        }
    }
    else {
        /* consume whatever's left in the input buffer */
        if (state->strm.avail_in && gz_comp(state, Z_NO_FLUSH) == -1)
            return 0;

        /* directly compress user buffer to file */
        state->strm.next_in = (z_const Bytef *)buf;
        do {
            unsigned n = (unsigned)-1;

            if (n > len)
                n = (unsigned)len;
            state->strm.avail_in = n;
            ret = gz_comp(state, Z_NO_FLUSH);
            n -= state->strm.avail_in;
            state->x.pos += n;
            len -= n;
            if (ret == -1)
                return state->again ? put - len : 0;
        } while (len);
    }

    /* input was all buffered or compressed */
    return put;
}

/* -- see zlib.h -- */
int ZEXPORT gzwrite(gzFile file, voidpc buf, unsigned len) {
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return 0;
    state = (gz_statep)file;

    /* check that we're writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return 0;
    gz_error(state, Z_OK, NULL);

    /* 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_DATA_ERROR, "requested length does not fit in int");
        return 0;
    }

    /* write len bytes from buf (the return value will fit in an int) */
    return (int)gz_write(state, buf, len);
}

/* -- see zlib.h -- */
z_size_t ZEXPORT gzfwrite(voidpc 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 writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return 0;
    gz_error(state, Z_OK, NULL);

    /* 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;
    }

    /* write len bytes to buf, return the number of full items written */
    return len ? gz_write(state, buf, len) / size : 0;
}

/* -- see zlib.h -- */
int ZEXPORT gzputc(gzFile file, int c) {
    unsigned have;
    unsigned char buf[1];
    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 writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return -1;
    gz_error(state, Z_OK, NULL);

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return -1;

    /* try writing to input buffer for speed (state->size == 0 if buffer not
       initialized) */
    if (state->size) {
        if (strm->avail_in == 0)
            strm->next_in = state->in;
        have = (unsigned)((strm->next_in + strm->avail_in) - state->in);
        if (have < state->size) {
            state->in[have] = (unsigned char)c;
            strm->avail_in++;
            state->x.pos++;
            return c & 0xff;
        }
    }

    /* no room in buffer or not initialized, use gz_write() */
    buf[0] = (unsigned char)c;
    if (gz_write(state, buf, 1) != 1)
        return -1;
    return c & 0xff;
}

/* -- see zlib.h -- */
int ZEXPORT gzputs(gzFile file, const char *s) {
    z_size_t len, put;
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return -1;
    state = (gz_statep)file;

    /* check that we're writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return -1;
    gz_error(state, Z_OK, NULL);

    /* write string */
    len = strlen(s);
    if ((int)len < 0 || (unsigned)len != len) {
        gz_error(state, Z_STREAM_ERROR, "string length does not fit in int");
        return -1;
    }
    put = gz_write(state, s, len);
    return len && put == 0 ? -1 : (int)put;
}

#if (((!defined(STDC) && !defined(Z_HAVE_STDARG_H)) || !defined(NO_vsnprintf)) && \
     (defined(STDC) || defined(Z_HAVE_STDARG_H) || !defined(NO_snprintf))) || \
    defined(ZLIB_INSECURE)
/* If the second half of the input buffer is occupied, write out the contents.
   If there is any input remaining due to a non-blocking stall on write, move
   it to the start of the buffer. Return true if this did not open up the
   second half of the buffer.  state->err should be checked after this to
   handle a gz_comp() error. */
local int gz_vacate(gz_statep state) {
    z_streamp strm;

    strm = &(state->strm);
    if (strm->next_in == NULL ||
        strm->next_in + strm->avail_in <= state->in + state->size)
        return 0;
    (void)gz_comp(state, Z_NO_FLUSH);
    if (strm->avail_in == 0) {
        strm->next_in = state->in;
        return 0;
    }
    memmove(state->in, strm->next_in, strm->avail_in);
    strm->next_in = state->in;
    return strm->avail_in > state->size;
}
#endif

#if defined(STDC) || defined(Z_HAVE_STDARG_H)
#include <stdarg.h>

/* -- see zlib.h -- */
int ZEXPORTVA gzvprintf(gzFile file, const char *format, va_list va) {
#if defined(NO_vsnprintf) && !defined(ZLIB_INSECURE)
#warning "vsnprintf() not available -- gzprintf() stub returns Z_STREAM_ERROR"
#warning "you can recompile with ZLIB_INSECURE defined to use vsprintf()"
    /* prevent use of insecure vsprintf(), unless purposefully requested */
    (void)file, (void)format, (void)va;
    return Z_STREAM_ERROR;
#else
    int len, ret;
    char *next;
    gz_statep state;
    z_streamp strm;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;
    strm = &(state->strm);

    /* check that we're writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return Z_STREAM_ERROR;
    gz_error(state, Z_OK, NULL);

    /* make sure we have some buffer space */
    if (state->size == 0 && gz_init(state) == -1)
        return state->err;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return state->err;

    /* do the printf() into the input buffer, put length in len -- the input
       buffer is double-sized just for this function, so there should be
       state->size bytes available after the current contents */
    ret = gz_vacate(state);
    if (state->err) {
        if (ret && state->again) {
            /* There was a non-blocking stall on write, resulting in the part
               of the second half of the output buffer being occupied.  Return
               a Z_BUF_ERROR to let the application know that this gzprintf()
               needs to be retried. */
            gz_error(state, Z_BUF_ERROR, "stalled write on gzprintf");
        }
        if (!state->again)
            return state->err;
    }
    if (strm->avail_in == 0)
        strm->next_in = state->in;
    next = (char *)(state->in + (strm->next_in - state->in) + strm->avail_in);
    next[state->size - 1] = 0;
#ifdef NO_vsnprintf
#  ifdef HAS_vsprintf_void
    (void)vsprintf(next, format, va);
    for (len = 0; len < state->size; len++)
        if (next[len] == 0) break;
#  else
    len = vsprintf(next, format, va);
#  endif
#else
#  ifdef HAS_vsnprintf_void
    (void)vsnprintf(next, state->size, format, va);
    len = strlen(next);
#  else
    len = vsnprintf(next, state->size, format, va);
#  endif
#endif

    /* check that printf() results fit in buffer */
    if (len == 0 || (unsigned)len >= state->size || next[state->size - 1] != 0)
        return 0;

    /* update buffer and position */
    strm->avail_in += (unsigned)len;
    state->x.pos += len;

    /* write out buffer if more than half is occupied */
    ret = gz_vacate(state);
    if (state->err && !state->again)
        return state->err;
    return len;
#endif
}

int ZEXPORTVA gzprintf(gzFile file, const char *format, ...) {
    va_list va;
    int ret;

    va_start(va, format);
    ret = gzvprintf(file, format, va);
    va_end(va);
    return ret;
}

#else /* !STDC && !Z_HAVE_STDARG_H */

/* -- see zlib.h -- */
int ZEXPORTVA gzprintf(gzFile file, const char *format, int a1, int a2, int a3,
                       int a4, int a5, int a6, int a7, int a8, int a9, int a10,
                       int a11, int a12, int a13, int a14, int a15, int a16,
                       int a17, int a18, int a19, int a20) {
#if defined(NO_snprintf) && !defined(ZLIB_INSECURE)
#warning "snprintf() not available -- gzprintf() stub returns Z_STREAM_ERROR"
#warning "you can recompile with ZLIB_INSECURE defined to use sprintf()"
    /* prevent use of insecure sprintf(), unless purposefully requested */
    (void)file, (void)format, (void)a1, (void)a2, (void)a3, (void)a4, (void)a5,
    (void)a6, (void)a7, (void)a8, (void)a9, (void)a10, (void)a11, (void)a12,
    (void)a13, (void)a14, (void)a15, (void)a16, (void)a17, (void)a18,
    (void)a19, (void)a20;
    return Z_STREAM_ERROR;
#else
    int ret;
    unsigned len, left;
    char *next;
    gz_statep state;
    z_streamp strm;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;
    strm = &(state->strm);

    /* check that can really pass pointer in ints */
    if (sizeof(int) != sizeof(void *))
        return Z_STREAM_ERROR;

    /* check that we're writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return Z_STREAM_ERROR;
    gz_error(state, Z_OK, NULL);

    /* make sure we have some buffer space */
    if (state->size == 0 && gz_init(state) == -1)
        return state->err;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return state->err;

    /* do the printf() into the input buffer, put length in len -- the input
       buffer is double-sized just for this function, so there is guaranteed to
       be state->size bytes available after the current contents */
    ret = gz_vacate(state);
    if (state->err) {
        if (ret && state->again) {
            /* There was a non-blocking stall on write, resulting in the part
               of the second half of the output buffer being occupied.  Return
               a Z_BUF_ERROR to let the application know that this gzprintf()
               needs to be retried. */
            gz_error(state, Z_BUF_ERROR, "stalled write on gzprintf");
        }
        if (!state->again)
            return state->err;
    }
    if (strm->avail_in == 0)
        strm->next_in = state->in;
    next = (char *)(strm->next_in + strm->avail_in);
    next[state->size - 1] = 0;
#ifdef NO_snprintf
#  ifdef HAS_sprintf_void
    sprintf(next, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12,
            a13, a14, a15, a16, a17, a18, a19, a20);
    for (len = 0; len < size; len++)
        if (next[len] == 0)
            break;
#  else
    len = sprintf(next, format, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11,
                  a12, a13, a14, a15, a16, a17, a18, a19, a20);
#  endif
#else
#  ifdef HAS_snprintf_void
    snprintf(next, state->size, format, a1, a2, a3, a4, a5, a6, a7, a8, a9,
             a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
    len = strlen(next);
#  else
    len = snprintf(next, state->size, format, a1, a2, a3, a4, a5, a6, a7, a8,
                   a9, a10, a11, a12, a13, a14, a15, a16, a17, a18, a19, a20);
#  endif
#endif

    /* check that printf() results fit in buffer */
    if (len == 0 || len >= state->size || next[state->size - 1] != 0)
        return 0;

    /* update buffer and position, compress first half if past that */
    strm->avail_in += len;
    state->x.pos += len;

    /* write out buffer if more than half is occupied */
    ret = gz_vacate(state);
    if (state->err && !state->again)
        return state->err;
    return (int)len;
#endif
}

#endif

/* -- see zlib.h -- */
int ZEXPORT gzflush(gzFile file, int flush) {
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;

    /* check that we're writing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again))
        return Z_STREAM_ERROR;
    gz_error(state, Z_OK, NULL);

    /* check flush parameter */
    if (flush < 0 || flush > Z_FINISH)
        return Z_STREAM_ERROR;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return state->err;

    /* compress remaining data with requested flush */
    (void)gz_comp(state, flush);
    return state->err;
}

/* -- see zlib.h -- */
int ZEXPORT gzsetparams(gzFile file, int level, int strategy) {
    gz_statep state;
    z_streamp strm;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;
    strm = &(state->strm);

    /* check that we're compressing and that there's no (serious) error */
    if (state->mode != GZ_WRITE || (state->err != Z_OK && !state->again) ||
            state->direct)
        return Z_STREAM_ERROR;
    gz_error(state, Z_OK, NULL);

    /* if no change is requested, then do nothing */
    if (level == state->level && strategy == state->strategy)
        return Z_OK;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        return state->err;

    /* change compression parameters for subsequent input */
    if (state->size) {
        /* flush previous input with previous parameters before changing */
        if (strm->avail_in && gz_comp(state, Z_BLOCK) == -1)
            return state->err;
        deflateParams(strm, level, strategy);
    }
    state->level = level;
    state->strategy = strategy;
    return Z_OK;
}

/* -- see zlib.h -- */
int ZEXPORT gzclose_w(gzFile file) {
    int ret = Z_OK;
    gz_statep state;

    /* get internal structure */
    if (file == NULL)
        return Z_STREAM_ERROR;
    state = (gz_statep)file;

    /* check that we're writing */
    if (state->mode != GZ_WRITE)
        return Z_STREAM_ERROR;

    /* check for seek request */
    if (state->skip && gz_zero(state) == -1)
        ret = state->err;

    /* flush, free memory, and close file */
    if (gz_comp(state, Z_FINISH) == -1)
        ret = state->err;
    if (state->size) {
        if (!state->direct) {
            (void)deflateEnd(&(state->strm));
            free(state->out);
        }
        free(state->in);
    }
    gz_error(state, Z_OK, NULL);
    free(state->path);
    if (close(state->fd) == -1)
        ret = Z_ERRNO;
    free(state);
    return ret;
}

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Created: 2026-08-14 06:25