/**

 * xzlib.c: front end for the transparent suport of lzma compression

 *          at the I/O layer, based on an example file from lzma project

 *

 * See Copyright for the status of this software.

 *

 * Anders F Bjorklund <afb@users.sourceforge.net>

 */

#define IN_LIBXML

#include "libxml.h"

#ifdef LIBXML_LZMA_ENABLED

#include <string.h>

#ifdef HAVE_ERRNO_H

#include <errno.h>

#endif

#ifdef HAVE_SYS_TYPES_H

#include <sys/types.h>

#endif

#ifdef HAVE_SYS_STAT_H

#include <sys/stat.h>

#endif

#ifdef HAVE_FCNTL_H

#include <fcntl.h>

#endif

#ifdef HAVE_UNISTD_H

#include <unistd.h>

#endif

#ifdef HAVE_STDLIB_H

#include <stdlib.h>

#endif

#ifdef HAVE_ZLIB_H

#include <zlib.h>

#endif

#ifdef HAVE_LZMA_H

#include <lzma.h>

#endif

#include "xzlib.h"

#include <libxml/xmlmemory.h>

/* values for xz_state how */

#define LOOK 0                  /* look for a gzip/lzma header */

#define COPY 1                  /* copy input directly */

#define GZIP 2                  /* decompress a gzip stream */

#define LZMA 3                  /* decompress a lzma stream */

/* internal lzma file state data structure */

typedef struct {

    int mode;                   /* see lzma modes above */

    int fd;                     /* file descriptor */

    char *path;                 /* path or fd for error messages */

    uint64_t pos;               /* current position in uncompressed data */

    unsigned int size;          /* buffer size, zero if not allocated yet */

    unsigned int want;          /* requested buffer size, default is BUFSIZ */

    unsigned char *in;          /* input buffer */

    unsigned char *out;         /* output buffer (double-sized when reading) */

    unsigned char *next;        /* next output data to deliver or write */

    unsigned int have;          /* amount of output data unused at next */

    int eof;                    /* true if end of input file reached */

    uint64_t start;             /* where the lzma data started, for rewinding */

    uint64_t raw;               /* where the raw data started, for seeking */

    int how;                    /* 0: get header, 1: copy, 2: decompress */

    int direct;                 /* true if last read direct, false if lzma */

    /* seek request */

    uint64_t skip;              /* amount to skip (already rewound if backwards) */

    int seek;                   /* true if seek request pending */

    /* error information */

    int err;                    /* error code */

    char *msg;                  /* error message */

    /* lzma stream */

    int init;                   /* is the iniflate stream initialized */

    lzma_stream strm;           /* stream structure in-place (not a pointer) */

    char padding1[32];          /* padding allowing to cope with possible

                                   extensions of above structure without

				   too much side effect */

#ifdef HAVE_ZLIB_H

    /* zlib inflate or deflate stream */

    z_stream zstrm;             /* stream structure in-place (not a pointer) */

#endif

    char padding2[32];          /* padding allowing to cope with possible

                                   extensions of above structure without

				   too much side effect */

} xz_state, *xz_statep;

static void

xz_error(xz_statep state, int err, const char *msg)

{

    /* free previously allocated message and clear */

    if (state->msg != NULL) {

        if (state->err != LZMA_MEM_ERROR)

            xmlFree(state->msg);

        state->msg = NULL;

    }

    /* set error code, and if no message, then done */

    state->err = err;

    if (msg == NULL)

        return;

    /* for an out of memory error, save as static string */

    if (err == LZMA_MEM_ERROR) {

        state->msg = (char *) msg;

        return;

    }

    /* construct error message with path */

    if ((state->msg =

         xmlMalloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {

        state->err = LZMA_MEM_ERROR;

        state->msg = (char *) "out of memory";

        return;

    }

    strcpy(state->msg, state->path);

    strcat(state->msg, ": ");

    strcat(state->msg, msg);

    return;

}

static void

xz_reset(xz_statep state)

{

    state->have = 0;            /* no output data available */

    state->eof = 0;             /* not at end of file */

    state->how = LOOK;          /* look for gzip header */

    state->direct = 1;          /* default for empty file */

    state->seek = 0;            /* no seek request pending */

    xz_error(state, LZMA_OK, NULL);     /* clear error */

    state->pos = 0;             /* no uncompressed data yet */

    state->strm.avail_in = 0;   /* no input data yet */

#ifdef HAVE_ZLIB_H

    state->zstrm.avail_in = 0;  /* no input data yet */

#endif

}

static xzFile

xz_open(const char *path, int fd, const char *mode ATTRIBUTE_UNUSED)

{

    xz_statep state;

    /* allocate xzFile structure to return */

    state = xmlMalloc(sizeof(xz_state));

    if (state == NULL)

        return NULL;

    state->size = 0;            /* no buffers allocated yet */

    state->want = BUFSIZ;       /* requested buffer size */

    state->msg = NULL;          /* no error message yet */

    state->init = 0;            /* initialization of zlib data */

    /* save the path name for error messages */

    state->path = xmlMalloc(strlen(path) + 1);

    if (state->path == NULL) {

        xmlFree(state);

        return NULL;

    }

    strcpy(state->path, path);

    /* open the file with the appropriate mode (or just use fd) */

    state->fd = fd != -1 ? fd : open(path,

#ifdef O_LARGEFILE

                                     O_LARGEFILE |

#endif

#ifdef O_BINARY

                                     O_BINARY |

#endif

                                     O_RDONLY, 0666);

    if (state->fd == -1) {

        xmlFree(state->path);

        xmlFree(state);

        return NULL;

    }

    /* save the current position for rewinding (only if reading) */

    state->start = lseek(state->fd, 0, SEEK_CUR);

    if (state->start == (uint64_t) - 1)

        state->start = 0;

    /* initialize stream */

    xz_reset(state);

    /* return stream */

    return (xzFile) state;

}

static int

xz_compressed(xzFile f) {

    xz_statep state;

    if (f == NULL)

        return(-1);

    state = (xz_statep) f;

    if (state->init <= 0)

        return(-1);

    switch (state->how) {

        case COPY:

	    return(0);

	case GZIP:

	case LZMA:

	    return(1);

    }

    return(-1);

}

xzFile

__libxml2_xzopen(const char *path, const char *mode)

{

    return xz_open(path, -1, mode);

}

int

__libxml2_xzcompressed(xzFile f) {

    return xz_compressed(f);

}

xzFile

__libxml2_xzdopen(int fd, const char *mode)

{

    char *path;                 /* identifier for error messages */

    xzFile xz;

    if (fd == -1 || (path = xmlMalloc(7 + 3 * sizeof(int))) == NULL)

        return NULL;

    sprintf(path, "<fd:%d>", fd);       /* for debugging */

    xz = xz_open(path, fd, mode);

    xmlFree(path);

    return xz;

}

static int

xz_load(xz_statep state, unsigned char *buf, unsigned int len,

        unsigned int *have)

{

    int ret;

    *have = 0;

    do {

        ret = read(state->fd, buf + *have, len - *have);

        if (ret <= 0)

            break;

        *have += ret;

    } while (*have < len);

    if (ret < 0) {

        xz_error(state, -1, strerror(errno));

        return -1;

    }

    if (ret == 0)

        state->eof = 1;

    return 0;

}

static int

xz_avail(xz_statep state)

{

    lzma_stream *strm = &(state->strm);

    if (state->err != LZMA_OK)

        return -1;

    if (state->eof == 0) {

        /* avail_in is size_t, which is not necessary sizeof(unsigned) */

        unsigned tmp = strm->avail_in;

        if (xz_load(state, state->in, state->size, &tmp) == -1) {

            strm->avail_in = tmp;

            return -1;

        }

        strm->avail_in = tmp;

        strm->next_in = state->in;

    }

    return 0;

}

#ifdef HAVE_ZLIB_H

static int

xz_avail_zstrm(xz_statep state)

{

    int ret;

    state->strm.avail_in = state->zstrm.avail_in;

    state->strm.next_in = state->zstrm.next_in;

    ret = xz_avail(state);

    state->zstrm.avail_in = (uInt) state->strm.avail_in;

    state->zstrm.next_in = (Bytef *) state->strm.next_in;

    return ret;

}

#endif

static int

is_format_xz(xz_statep state)

{

    lzma_stream *strm = &(state->strm);

    return strm->avail_in >= 6 && memcmp(state->in, "\3757zXZ", 6) == 0;

}

static int

is_format_lzma(xz_statep state)

{

    lzma_stream *strm = &(state->strm);

    lzma_filter filter;

    lzma_options_lzma *opt;

    uint32_t dict_size;

    uint64_t uncompressed_size;

    size_t i;

    if (strm->avail_in < 13)

        return 0;

    filter.id = LZMA_FILTER_LZMA1;

    if (lzma_properties_decode(&filter, NULL, state->in, 5) != LZMA_OK)

        return 0;

    opt = filter.options;

    dict_size = opt->dict_size;

    free(opt); /* we can't use xmlFree on a string returned by zlib */

    /* A hack to ditch tons of false positives: We allow only dictionary

     * sizes that are 2^n or 2^n + 2^(n-1) or UINT32_MAX. LZMA_Alone

     * created only files with 2^n, but accepts any dictionary size.

     * If someone complains, this will be reconsidered.

     */

    if (dict_size != UINT32_MAX) {

        uint32_t d = dict_size - 1;

        d |= d >> 2;

        d |= d >> 3;

        d |= d >> 4;

        d |= d >> 8;

        d |= d >> 16;

        ++d;

        if (d != dict_size || dict_size == 0)

            return 0;

    }

    /* Another hack to ditch false positives: Assume that if the

     * uncompressed size is known, it must be less than 256 GiB.

     * Again, if someone complains, this will be reconsidered.

     */

    uncompressed_size = 0;

    for (i = 0; i < 8; ++i)

        uncompressed_size |= (uint64_t) (state->in[5 + i]) << (i * 8);

    if (uncompressed_size != UINT64_MAX

        && uncompressed_size > (UINT64_C(1) << 38))

        return 0;

    return 1;

}

#ifdef HAVE_ZLIB_H

/* Get next byte from input, or -1 if end or error. */

#define NEXT() ((strm->avail_in == 0 && xz_avail(state) == -1) ? -1 : \

                (strm->avail_in == 0 ? -1 : \

                 (strm->avail_in--, *(strm->next_in)++)))

/* Same thing, but from zstrm */

#define NEXTZ() ((strm->avail_in == 0 && xz_avail_zstrm(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. */

static int

gz_next4(xz_statep state, unsigned long *ret)

{

    int ch;

    unsigned long val;

    z_streamp strm = &(state->zstrm);

    val = NEXTZ();

    val += (unsigned) NEXTZ() << 8;

    val += (unsigned long) NEXTZ() << 16;

    ch = NEXTZ();

    if (ch == -1)

        return -1;

    val += (unsigned long) ch << 24;

    *ret = val;

    return 0;

}

#endif

static int

xz_head(xz_statep state)

{

    lzma_stream *strm = &(state->strm);

    lzma_stream init = LZMA_STREAM_INIT;

    int flags;

    unsigned len;

    /* allocate read buffers and inflate memory */

    if (state->size == 0) {

        /* allocate buffers */

        state->in = xmlMalloc(state->want);

        state->out = xmlMalloc(state->want << 1);

        if (state->in == NULL || state->out == NULL) {

            if (state->out != NULL)

                xmlFree(state->out);

            if (state->in != NULL)

                xmlFree(state->in);

            xz_error(state, LZMA_MEM_ERROR, "out of memory");

            return -1;

        }

        state->size = state->want;

        /* allocate decoder memory */

        state->strm = init;

        state->strm.avail_in = 0;

        state->strm.next_in = NULL;

        if (lzma_auto_decoder(&state->strm, 100000000, 0) != LZMA_OK) {

            xmlFree(state->out);

            xmlFree(state->in);

            state->size = 0;

            xz_error(state, LZMA_MEM_ERROR, "out of memory");

            return -1;

        }

#ifdef HAVE_ZLIB_H

        /* allocate inflate memory */

        state->zstrm.zalloc = Z_NULL;

        state->zstrm.zfree = Z_NULL;

        state->zstrm.opaque = Z_NULL;

        state->zstrm.avail_in = 0;

        state->zstrm.next_in = Z_NULL;

        if (state->init == 0) {

            if (inflateInit2(&(state->zstrm), -15) != Z_OK) {/* raw inflate */

                xmlFree(state->out);

                xmlFree(state->in);

                state->size = 0;

                xz_error(state, LZMA_MEM_ERROR, "out of memory");

                return -1;

            }

            state->init = 1;

        }

#endif

    }

    /* get some data in the input buffer */

    if (strm->avail_in == 0) {

        if (xz_avail(state) == -1)

            return -1;

        if (strm->avail_in == 0)

            return 0;

    }

    /* look for the xz magic header bytes */

    if (is_format_xz(state) || is_format_lzma(state)) {

        state->how = LZMA;

        state->direct = 0;

        return 0;

    }

#ifdef HAVE_ZLIB_H

    /* 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 && xz_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 */

                xz_error(state, LZMA_DATA_ERROR,

                         "unknown compression method");

                return -1;

            }

            flags = NEXT();

            if (flags & 0xe0) { /* reserved flag bits */

                xz_error(state, LZMA_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(&state->zstrm);

            state->zstrm.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;

        }

    }

#endif

    /* 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;

        strm->avail_in = 0;

    }

    state->how = COPY;

    state->direct = 1;

    return 0;

}

static int

xz_decomp(xz_statep state)

{

    int ret;

    unsigned had;

    unsigned long crc, len;

    lzma_stream *strm = &(state->strm);

    lzma_action action = LZMA_RUN;

    /* fill output buffer up to end of deflate stream */

    had = strm->avail_out;

    do {

        /* get more input for inflate() */

        if (strm->avail_in == 0 && xz_avail(state) == -1)

            return -1;

        if (strm->avail_in == 0) {

            xz_error(state, LZMA_DATA_ERROR, "unexpected end of file");

            return -1;

        }

        if (state->eof)

            action = LZMA_FINISH;

        /* decompress and handle errors */

#ifdef HAVE_ZLIB_H

        if (state->how == GZIP) {

            state->zstrm.avail_in = (uInt) state->strm.avail_in;

            state->zstrm.next_in = (Bytef *) state->strm.next_in;

            state->zstrm.avail_out = (uInt) state->strm.avail_out;

            state->zstrm.next_out = (Bytef *) state->strm.next_out;

            ret = inflate(&state->zstrm, Z_NO_FLUSH);

            if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {

                xz_error(state, Z_STREAM_ERROR,

                         "internal error: inflate stream corrupt");

                return -1;

            }

            if (ret == Z_MEM_ERROR)

                ret = LZMA_MEM_ERROR;

            if (ret == Z_DATA_ERROR)

                ret = LZMA_DATA_ERROR;

            if (ret == Z_STREAM_END)

                ret = LZMA_STREAM_END;

            state->strm.avail_in = state->zstrm.avail_in;

            state->strm.next_in = state->zstrm.next_in;

            state->strm.avail_out = state->zstrm.avail_out;

            state->strm.next_out = state->zstrm.next_out;

        } else                  /* state->how == LZMA */

#endif

            ret = lzma_code(strm, action);

        if (ret == LZMA_MEM_ERROR) {

            xz_error(state, LZMA_MEM_ERROR, "out of memory");

            return -1;

        }

        if (ret == LZMA_DATA_ERROR) {

            xz_error(state, LZMA_DATA_ERROR, "compressed data error");

            return -1;

        }

        if (ret == LZMA_PROG_ERROR) {

            xz_error(state, LZMA_PROG_ERROR, "compression error");

            return -1;

        }

    } while (strm->avail_out && ret != LZMA_STREAM_END);

    /* update available output and crc check value */

    state->have = had - strm->avail_out;

    state->next = strm->next_out - state->have;

#ifdef HAVE_ZLIB_H

    state->zstrm.adler =

        crc32(state->zstrm.adler, state->next, state->have);

#endif

    if (ret == LZMA_STREAM_END) {

#ifdef HAVE_ZLIB_H

        if (state->how == GZIP) {

            if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {

                /*

               xz_error(state, LZMA_DATA_ERROR, "unexpected end of file");

               return -1;

                */

            } else {

               if (crc != state->zstrm.adler) {

                   xz_error(state, LZMA_DATA_ERROR, "incorrect data check");

                   return -1;

               }

               if (len != (state->zstrm.total_out & 0xffffffffL)) {

                   xz_error(state, LZMA_DATA_ERROR, "incorrect length check");

                   return -1;

               }

           }

            state->strm.avail_in = 0;

            state->strm.next_in = NULL;

            state->strm.avail_out = 0;

            state->strm.next_out = NULL;

        } else

#endif

        if (strm->avail_in != 0 || !state->eof) {

            xz_error(state, LZMA_DATA_ERROR, "trailing garbage");

            return -1;

        }

        state->how = LOOK;      /* ready for next stream, once have is 0 (leave

                                 * state->direct unchanged to remember how) */

    }

    /* good decompression */

    return 0;

}

static int

xz_make(xz_statep state)

{

    lzma_stream *strm = &(state->strm);

    if (state->how == LOOK) {   /* look for lzma / gzip header */

        if (xz_head(state) == -1)

            return -1;

        if (state->have)        /* got some data from xz_head() */

            return 0;

    }

    if (state->how == COPY) {   /* straight copy */

        if (xz_load(state, state->out, state->size << 1, &(state->have)) ==

            -1)

            return -1;

        state->next = state->out;

    } else if (state->how == LZMA || state->how == GZIP) {      /* decompress */

        strm->avail_out = state->size << 1;

        strm->next_out = state->out;

        if (xz_decomp(state) == -1)

            return -1;

    }

    return 0;

}

static int

xz_skip(xz_statep state, uint64_t len)

{

    unsigned n;

    /* 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 = (uint64_t) state->have > len ?

                (unsigned) len : state->have;

            state->have -= n;

            state->next += n;

            state->pos += n;

            len -= n;

        }

    /* output buffer empty -- return if we're at the end of the input */

        else if (state->eof && state->strm.avail_in == 0)

            break;

    /* need more data to skip -- load up output buffer */

        else {

            /* get more output, looking for header if required */

            if (xz_make(state) == -1)

                return -1;

        }

    return 0;

}

int

__libxml2_xzread(xzFile file, void *buf, unsigned len)

{

    unsigned got, n;

    xz_statep state;

    lzma_stream *strm;

    /* get internal structure */

    if (file == NULL)

        return -1;

    state = (xz_statep) file;

    strm = &(state->strm);

    /* check that we're reading and that there's no error */

    if (state->err != LZMA_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) {

        xz_error(state, LZMA_BUF_ERROR,

                 "requested length does not fit in int");

        return -1;

    }

    /* if len is zero, avoid unnecessary operations */

    if (len == 0)

        return 0;

    /* process a skip request */

    if (state->seek) {

        state->seek = 0;

        if (xz_skip(state, state->skip) == -1)

            return -1;

    }

    /* get len bytes to buf, or less than len if at the end */

    got = 0;

    do {

        /* 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;

        }

        /* output buffer empty -- return if we're at the end of the input */

        else if (state->eof && strm->avail_in == 0)

            break;

        /* need output data -- for small len or new stream load up our output

         * buffer */

        else if (state->how == LOOK || len < (state->size << 1)) {

            /* get more output, looking for header if required */

            if (xz_make(state) == -1)

                return -1;

            continue;           /* no progress yet -- go back to memcpy() 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 (xz_load(state, buf, len, &n) == -1)

                return -1;

        }

        /* large len -- decompress directly into user buffer */

        else {                  /* state->how == LZMA */

            strm->avail_out = len;

            strm->next_out = buf;

            if (xz_decomp(state) == -1)

                return -1;

            n = state->have;

            state->have = 0;

        }

        /* update progress */

        len -= n;

        buf = (char *) buf + n;

        got += n;

        state->pos += n;

    } while (len);

    /* return number of bytes read into user buffer (will fit in int) */

    return (int) got;

}

int

__libxml2_xzclose(xzFile file)

{

    int ret;

    xz_statep state;

    /* get internal structure */

    if (file == NULL)

        return LZMA_DATA_ERROR;

    state = (xz_statep) file;

    /* free memory and close file */

    if (state->size) {

        lzma_end(&(state->strm));

#ifdef HAVE_ZLIB_H

        if (state->init == 1)

            inflateEnd(&(state->zstrm));

        state->init = 0;

#endif

        xmlFree(state->out);

        xmlFree(state->in);

    }

    xmlFree(state->path);

    if ((state->msg != NULL) && (state->err != LZMA_MEM_ERROR))

        xmlFree(state->msg);

    ret = close(state->fd);

    xmlFree(state);

    return ret ? ret : LZMA_OK;

}

#endif /* LIBXML_LZMA_ENABLED */