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1 /**
2  * xzlib.c: front end for the transparent suport of lzma compression
3  *          at the I/O layer, based on an example file from lzma project
4  *
5  * See Copyright for the status of this software.
6  *
7  * Anders F Bjorklund <afb@users.sourceforge.net>
8  */
9 #define IN_LIBXML
10 #include "libxml.h"
11 #ifdef LIBXML_LZMA_ENABLED
12 
13 #include <string.h>
14 #ifdef HAVE_ERRNO_H
15 #include <errno.h>
16 #endif
17 
18 
19 #ifdef HAVE_SYS_TYPES_H
20 #include <sys/types.h>
21 #endif
22 #ifdef HAVE_SYS_STAT_H
23 #include <sys/stat.h>
24 #endif
25 #ifdef HAVE_FCNTL_H
26 #include <fcntl.h>
27 #endif
28 #ifdef HAVE_UNISTD_H
29 #include <unistd.h>
30 #endif
31 #ifdef HAVE_STDLIB_H
32 #include <stdlib.h>
33 #endif
34 #ifdef LIBXML_ZLIB_ENABLED
35 #include <zlib.h>
36 #endif
37 #ifdef LIBXML_LZMA_ENABLED
38 #include <lzma.h>
39 #endif
40 
41 #include "xzlib.h"
42 #include <libxml/xmlmemory.h>
43 
44 /* values for xz_state how */
45 #define LOOK 0                  /* look for a gzip/lzma header */
46 #define COPY 1                  /* copy input directly */
47 #define GZIP 2                  /* decompress a gzip stream */
48 #define LZMA 3                  /* decompress a lzma stream */
49 
50 /* internal lzma file state data structure */
51 typedef struct {
52     int mode;                   /* see lzma modes above */
53     int fd;                     /* file descriptor */
54     char *path;                 /* path or fd for error messages */
55     uint64_t pos;               /* current position in uncompressed data */
56     unsigned int size;          /* buffer size, zero if not allocated yet */
57     unsigned int want;          /* requested buffer size, default is BUFSIZ */
58     unsigned char *in;          /* input buffer */
59     unsigned char *out;         /* output buffer (double-sized when reading) */
60     unsigned char *next;        /* next output data to deliver or write */
61     unsigned int have;          /* amount of output data unused at next */
62     int eof;                    /* true if end of input file reached */
63     uint64_t start;             /* where the lzma data started, for rewinding */
64     uint64_t raw;               /* where the raw data started, for seeking */
65     int how;                    /* 0: get header, 1: copy, 2: decompress */
66     int direct;                 /* true if last read direct, false if lzma */
67     /* seek request */
68     uint64_t skip;              /* amount to skip (already rewound if backwards) */
69     int seek;                   /* true if seek request pending */
70     /* error information */
71     int err;                    /* error code */
72     char *msg;                  /* error message */
73     /* lzma stream */
74     int init;                   /* is the iniflate stream initialized */
75     lzma_stream strm;           /* stream structure in-place (not a pointer) */
76     char padding1[32];          /* padding allowing to cope with possible
77                                    extensions of above structure without
78 				   too much side effect */
79 #ifdef LIBXML_ZLIB_ENABLED
80     /* zlib inflate or deflate stream */
81     z_stream zstrm;             /* stream structure in-place (not a pointer) */
82 #endif
83     char padding2[32];          /* padding allowing to cope with possible
84                                    extensions of above structure without
85 				   too much side effect */
86 } xz_state, *xz_statep;
87 
88 static void
xz_error(xz_statep state,int err,const char * msg)89 xz_error(xz_statep state, int err, const char *msg)
90 {
91     /* free previously allocated message and clear */
92     if (state->msg != NULL) {
93         if (state->err != LZMA_MEM_ERROR)
94             xmlFree(state->msg);
95         state->msg = NULL;
96     }
97 
98     /* set error code, and if no message, then done */
99     state->err = err;
100     if (msg == NULL)
101         return;
102 
103     /* for an out of memory error, save as static string */
104     if (err == LZMA_MEM_ERROR) {
105         state->msg = (char *) msg;
106         return;
107     }
108 
109     /* construct error message with path */
110     if ((state->msg =
111          xmlMalloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {
112         state->err = LZMA_MEM_ERROR;
113         state->msg = (char *) "out of memory";
114         return;
115     }
116     strcpy(state->msg, state->path);
117     strcat(state->msg, ": ");
118     strcat(state->msg, msg);
119     return;
120 }
121 
122 static void
xz_reset(xz_statep state)123 xz_reset(xz_statep state)
124 {
125     state->have = 0;            /* no output data available */
126     state->eof = 0;             /* not at end of file */
127     state->how = LOOK;          /* look for gzip header */
128     state->direct = 1;          /* default for empty file */
129     state->seek = 0;            /* no seek request pending */
130     xz_error(state, LZMA_OK, NULL);     /* clear error */
131     state->pos = 0;             /* no uncompressed data yet */
132     state->strm.avail_in = 0;   /* no input data yet */
133 #ifdef LIBXML_ZLIB_ENABLED
134     state->zstrm.avail_in = 0;  /* no input data yet */
135 #endif
136 }
137 
138 static xzFile
xz_open(const char * path,int fd,const char * mode ATTRIBUTE_UNUSED)139 xz_open(const char *path, int fd, const char *mode ATTRIBUTE_UNUSED)
140 {
141     xz_statep state;
142 
143     /* allocate xzFile structure to return */
144     state = xmlMalloc(sizeof(xz_state));
145     if (state == NULL)
146         return NULL;
147     state->size = 0;            /* no buffers allocated yet */
148     state->want = BUFSIZ;       /* requested buffer size */
149     state->msg = NULL;          /* no error message yet */
150     state->init = 0;            /* initialization of zlib data */
151 
152     /* save the path name for error messages */
153     state->path = xmlMalloc(strlen(path) + 1);
154     if (state->path == NULL) {
155         xmlFree(state);
156         return NULL;
157     }
158     strcpy(state->path, path);
159 
160     /* open the file with the appropriate mode (or just use fd) */
161     state->fd = fd != -1 ? fd : open(path,
162 #ifdef O_LARGEFILE
163                                      O_LARGEFILE |
164 #endif
165 #ifdef O_BINARY
166                                      O_BINARY |
167 #endif
168                                      O_RDONLY, 0666);
169     if (state->fd == -1) {
170         xmlFree(state->path);
171         xmlFree(state);
172         return NULL;
173     }
174 
175     /* save the current position for rewinding (only if reading) */
176     state->start = lseek(state->fd, 0, SEEK_CUR);
177     if (state->start == (uint64_t) - 1)
178         state->start = 0;
179 
180     /* initialize stream */
181     xz_reset(state);
182 
183     /* return stream */
184     return (xzFile) state;
185 }
186 
187 static int
xz_compressed(xzFile f)188 xz_compressed(xzFile f) {
189     xz_statep state;
190 
191     if (f == NULL)
192         return(-1);
193     state = (xz_statep) f;
194     if (state->init <= 0)
195         return(-1);
196 
197     switch (state->how) {
198         case COPY:
199 	    return(0);
200 	case GZIP:
201 	case LZMA:
202 	    return(1);
203     }
204     return(-1);
205 }
206 
207 xzFile
__libxml2_xzopen(const char * path,const char * mode)208 __libxml2_xzopen(const char *path, const char *mode)
209 {
210     return xz_open(path, -1, mode);
211 }
212 
213 int
__libxml2_xzcompressed(xzFile f)214 __libxml2_xzcompressed(xzFile f) {
215     return xz_compressed(f);
216 }
217 
218 xzFile
__libxml2_xzdopen(int fd,const char * mode)219 __libxml2_xzdopen(int fd, const char *mode)
220 {
221     char *path;                 /* identifier for error messages */
222     xzFile xz;
223 
224     if (fd == -1 || (path = xmlMalloc(7 + 3 * sizeof(int))) == NULL)
225         return NULL;
226     sprintf(path, "<fd:%d>", fd);       /* for debugging */
227     xz = xz_open(path, fd, mode);
228     xmlFree(path);
229     return xz;
230 }
231 
232 static int
xz_load(xz_statep state,unsigned char * buf,unsigned int len,unsigned int * have)233 xz_load(xz_statep state, unsigned char *buf, unsigned int len,
234         unsigned int *have)
235 {
236     int ret;
237 
238     *have = 0;
239     do {
240         ret = read(state->fd, buf + *have, len - *have);
241         if (ret <= 0)
242             break;
243         *have += ret;
244     } while (*have < len);
245     if (ret < 0) {
246         xz_error(state, -1, strerror(errno));
247         return -1;
248     }
249     if (ret == 0)
250         state->eof = 1;
251     return 0;
252 }
253 
254 static int
xz_avail(xz_statep state)255 xz_avail(xz_statep state)
256 {
257     lzma_stream *strm = &(state->strm);
258 
259     if (state->err != LZMA_OK)
260         return -1;
261     if (state->eof == 0) {
262         /* avail_in is size_t, which is not necessary sizeof(unsigned) */
263         unsigned tmp = strm->avail_in;
264 
265         if (xz_load(state, state->in, state->size, &tmp) == -1) {
266             strm->avail_in = tmp;
267             return -1;
268         }
269         strm->avail_in = tmp;
270         strm->next_in = state->in;
271     }
272     return 0;
273 }
274 
275 #ifdef LIBXML_ZLIB_ENABLED
276 static int
xz_avail_zstrm(xz_statep state)277 xz_avail_zstrm(xz_statep state)
278 {
279     int ret;
280     state->strm.avail_in = state->zstrm.avail_in;
281     state->strm.next_in = state->zstrm.next_in;
282     ret = xz_avail(state);
283     state->zstrm.avail_in = (uInt) state->strm.avail_in;
284     state->zstrm.next_in = (Bytef *) state->strm.next_in;
285     return ret;
286 }
287 #endif
288 
289 static int
is_format_xz(xz_statep state)290 is_format_xz(xz_statep state)
291 {
292     lzma_stream *strm = &(state->strm);
293 
294     return strm->avail_in >= 6 && memcmp(state->in, "\3757zXZ", 6) == 0;
295 }
296 
297 static int
is_format_lzma(xz_statep state)298 is_format_lzma(xz_statep state)
299 {
300     lzma_stream *strm = &(state->strm);
301 
302     lzma_filter filter;
303     lzma_options_lzma *opt;
304     uint32_t dict_size;
305     uint64_t uncompressed_size;
306     size_t i;
307 
308     if (strm->avail_in < 13)
309         return 0;
310 
311     filter.id = LZMA_FILTER_LZMA1;
312     if (lzma_properties_decode(&filter, NULL, state->in, 5) != LZMA_OK)
313         return 0;
314 
315     opt = filter.options;
316     dict_size = opt->dict_size;
317     free(opt); /* we can't use xmlFree on a string returned by zlib */
318 
319     /* A hack to ditch tons of false positives: We allow only dictionary
320      * sizes that are 2^n or 2^n + 2^(n-1) or UINT32_MAX. LZMA_Alone
321      * created only files with 2^n, but accepts any dictionary size.
322      * If someone complains, this will be reconsidered.
323      */
324     if (dict_size != UINT32_MAX) {
325         uint32_t d = dict_size - 1;
326 
327         d |= d >> 2;
328         d |= d >> 3;
329         d |= d >> 4;
330         d |= d >> 8;
331         d |= d >> 16;
332         ++d;
333         if (d != dict_size || dict_size == 0)
334             return 0;
335     }
336 
337     /* Another hack to ditch false positives: Assume that if the
338      * uncompressed size is known, it must be less than 256 GiB.
339      * Again, if someone complains, this will be reconsidered.
340      */
341     uncompressed_size = 0;
342     for (i = 0; i < 8; ++i)
343         uncompressed_size |= (uint64_t) (state->in[5 + i]) << (i * 8);
344 
345     if (uncompressed_size != UINT64_MAX
346         && uncompressed_size > (UINT64_C(1) << 38))
347         return 0;
348 
349     return 1;
350 }
351 
352 #ifdef LIBXML_ZLIB_ENABLED
353 
354 /* Get next byte from input, or -1 if end or error. */
355 #define NEXT() ((strm->avail_in == 0 && xz_avail(state) == -1) ? -1 : \
356                 (strm->avail_in == 0 ? -1 : \
357                  (strm->avail_in--, *(strm->next_in)++)))
358 /* Same thing, but from zstrm */
359 #define NEXTZ() ((strm->avail_in == 0 && xz_avail_zstrm(state) == -1) ? -1 : \
360                 (strm->avail_in == 0 ? -1 : \
361                  (strm->avail_in--, *(strm->next_in)++)))
362 
363 /* Get a four-byte little-endian integer and return 0 on success and the value
364    in *ret.  Otherwise -1 is returned and *ret is not modified. */
365 static int
gz_next4(xz_statep state,unsigned long * ret)366 gz_next4(xz_statep state, unsigned long *ret)
367 {
368     int ch;
369     unsigned long val;
370     z_streamp strm = &(state->zstrm);
371 
372     val = NEXTZ();
373     val += (unsigned) NEXTZ() << 8;
374     val += (unsigned long) NEXTZ() << 16;
375     ch = NEXTZ();
376     if (ch == -1)
377         return -1;
378     val += (unsigned long) ch << 24;
379     *ret = val;
380     return 0;
381 }
382 #endif
383 
384 static int
xz_head(xz_statep state)385 xz_head(xz_statep state)
386 {
387     lzma_stream *strm = &(state->strm);
388     lzma_stream init = LZMA_STREAM_INIT;
389     int flags;
390     unsigned len;
391 
392     /* allocate read buffers and inflate memory */
393     if (state->size == 0) {
394         /* allocate buffers */
395         state->in = xmlMalloc(state->want);
396         state->out = xmlMalloc(state->want << 1);
397         if (state->in == NULL || state->out == NULL) {
398             if (state->out != NULL)
399                 xmlFree(state->out);
400             if (state->in != NULL)
401                 xmlFree(state->in);
402             xz_error(state, LZMA_MEM_ERROR, "out of memory");
403             return -1;
404         }
405         state->size = state->want;
406 
407         /* allocate decoder memory */
408         state->strm = init;
409         state->strm.avail_in = 0;
410         state->strm.next_in = NULL;
411         if (lzma_auto_decoder(&state->strm, 100000000, 0) != LZMA_OK) {
412             xmlFree(state->out);
413             xmlFree(state->in);
414             state->size = 0;
415             xz_error(state, LZMA_MEM_ERROR, "out of memory");
416             return -1;
417         }
418 #ifdef LIBXML_ZLIB_ENABLED
419         /* allocate inflate memory */
420         state->zstrm.zalloc = Z_NULL;
421         state->zstrm.zfree = Z_NULL;
422         state->zstrm.opaque = Z_NULL;
423         state->zstrm.avail_in = 0;
424         state->zstrm.next_in = Z_NULL;
425         if (state->init == 0) {
426             if (inflateInit2(&(state->zstrm), -15) != Z_OK) {/* raw inflate */
427                 xmlFree(state->out);
428                 xmlFree(state->in);
429                 state->size = 0;
430                 xz_error(state, LZMA_MEM_ERROR, "out of memory");
431                 return -1;
432             }
433             state->init = 1;
434         }
435 #endif
436     }
437 
438     /* get some data in the input buffer */
439     if (strm->avail_in == 0) {
440         if (xz_avail(state) == -1)
441             return -1;
442         if (strm->avail_in == 0)
443             return 0;
444     }
445 
446     /* look for the xz magic header bytes */
447     if (is_format_xz(state) || is_format_lzma(state)) {
448         state->how = LZMA;
449         state->direct = 0;
450         return 0;
451     }
452 #ifdef LIBXML_ZLIB_ENABLED
453     /* look for the gzip magic header bytes 31 and 139 */
454     if (strm->next_in[0] == 31) {
455         strm->avail_in--;
456         strm->next_in++;
457         if (strm->avail_in == 0 && xz_avail(state) == -1)
458             return -1;
459         if (strm->avail_in && strm->next_in[0] == 139) {
460             /* we have a gzip header, woo hoo! */
461             strm->avail_in--;
462             strm->next_in++;
463 
464             /* skip rest of header */
465             if (NEXT() != 8) {  /* compression method */
466                 xz_error(state, LZMA_DATA_ERROR,
467                          "unknown compression method");
468                 return -1;
469             }
470             flags = NEXT();
471             if (flags & 0xe0) { /* reserved flag bits */
472                 xz_error(state, LZMA_DATA_ERROR,
473                          "unknown header flags set");
474                 return -1;
475             }
476             NEXT();             /* modification time */
477             NEXT();
478             NEXT();
479             NEXT();
480             NEXT();             /* extra flags */
481             NEXT();             /* operating system */
482             if (flags & 4) {    /* extra field */
483                 len = (unsigned) NEXT();
484                 len += (unsigned) NEXT() << 8;
485                 while (len--)
486                     if (NEXT() < 0)
487                         break;
488             }
489             if (flags & 8)      /* file name */
490                 while (NEXT() > 0) ;
491             if (flags & 16)     /* comment */
492                 while (NEXT() > 0) ;
493             if (flags & 2) {    /* header crc */
494                 NEXT();
495                 NEXT();
496             }
497             /* an unexpected end of file is not checked for here -- it will be
498              * noticed on the first request for uncompressed data */
499 
500             /* set up for decompression */
501             inflateReset(&state->zstrm);
502             state->zstrm.adler = crc32(0L, Z_NULL, 0);
503             state->how = GZIP;
504             state->direct = 0;
505             return 0;
506         } else {
507             /* not a gzip file -- save first byte (31) and fall to raw i/o */
508             state->out[0] = 31;
509             state->have = 1;
510         }
511     }
512 #endif
513 
514     /* doing raw i/o, save start of raw data for seeking, copy any leftover
515      * input to output -- this assumes that the output buffer is larger than
516      * the input buffer, which also assures space for gzungetc() */
517     state->raw = state->pos;
518     state->next = state->out;
519     if (strm->avail_in) {
520         memcpy(state->next + state->have, strm->next_in, strm->avail_in);
521         state->have += strm->avail_in;
522         strm->avail_in = 0;
523     }
524     state->how = COPY;
525     state->direct = 1;
526     return 0;
527 }
528 
529 static int
xz_decomp(xz_statep state)530 xz_decomp(xz_statep state)
531 {
532     int ret;
533     unsigned had;
534     unsigned long crc, len;
535     lzma_stream *strm = &(state->strm);
536 
537     lzma_action action = LZMA_RUN;
538 
539     /* fill output buffer up to end of deflate stream */
540     had = strm->avail_out;
541     do {
542         /* get more input for inflate() */
543         if (strm->avail_in == 0 && xz_avail(state) == -1)
544             return -1;
545         if (strm->avail_in == 0) {
546             xz_error(state, LZMA_DATA_ERROR, "unexpected end of file");
547             return -1;
548         }
549         if (state->eof)
550             action = LZMA_FINISH;
551 
552         /* decompress and handle errors */
553 #ifdef LIBXML_ZLIB_ENABLED
554         if (state->how == GZIP) {
555             state->zstrm.avail_in = (uInt) state->strm.avail_in;
556             state->zstrm.next_in = (Bytef *) state->strm.next_in;
557             state->zstrm.avail_out = (uInt) state->strm.avail_out;
558             state->zstrm.next_out = (Bytef *) state->strm.next_out;
559             ret = inflate(&state->zstrm, Z_NO_FLUSH);
560             if (ret == Z_STREAM_ERROR || ret == Z_NEED_DICT) {
561                 xz_error(state, Z_STREAM_ERROR,
562                          "internal error: inflate stream corrupt");
563                 return -1;
564             }
565             if (ret == Z_MEM_ERROR)
566                 ret = LZMA_MEM_ERROR;
567             if (ret == Z_DATA_ERROR)
568                 ret = LZMA_DATA_ERROR;
569             if (ret == Z_STREAM_END)
570                 ret = LZMA_STREAM_END;
571             state->strm.avail_in = state->zstrm.avail_in;
572             state->strm.next_in = state->zstrm.next_in;
573             state->strm.avail_out = state->zstrm.avail_out;
574             state->strm.next_out = state->zstrm.next_out;
575         } else                  /* state->how == LZMA */
576 #endif
577             ret = lzma_code(strm, action);
578         if (ret == LZMA_MEM_ERROR) {
579             xz_error(state, LZMA_MEM_ERROR, "out of memory");
580             return -1;
581         }
582         if (ret == LZMA_DATA_ERROR) {
583             xz_error(state, LZMA_DATA_ERROR, "compressed data error");
584             return -1;
585         }
586         if (ret == LZMA_PROG_ERROR) {
587             xz_error(state, LZMA_PROG_ERROR, "compression error");
588             return -1;
589         }
590     } while (strm->avail_out && ret != LZMA_STREAM_END);
591 
592     /* update available output and crc check value */
593     state->have = had - strm->avail_out;
594     state->next = strm->next_out - state->have;
595 #ifdef LIBXML_ZLIB_ENABLED
596     state->zstrm.adler =
597         crc32(state->zstrm.adler, state->next, state->have);
598 #endif
599 
600     if (ret == LZMA_STREAM_END) {
601 #ifdef LIBXML_ZLIB_ENABLED
602         if (state->how == GZIP) {
603             if (gz_next4(state, &crc) == -1 || gz_next4(state, &len) == -1) {
604                 xz_error(state, LZMA_DATA_ERROR, "unexpected end of file");
605                 return -1;
606             }
607             if (crc != state->zstrm.adler) {
608                 xz_error(state, LZMA_DATA_ERROR, "incorrect data check");
609                 return -1;
610             }
611             if (len != (state->zstrm.total_out & 0xffffffffL)) {
612                 xz_error(state, LZMA_DATA_ERROR, "incorrect length check");
613                 return -1;
614             }
615             state->strm.avail_in = 0;
616             state->strm.next_in = NULL;
617             state->strm.avail_out = 0;
618             state->strm.next_out = NULL;
619         } else
620 #endif
621         if (strm->avail_in != 0 || !state->eof) {
622             xz_error(state, LZMA_DATA_ERROR, "trailing garbage");
623             return -1;
624         }
625         state->how = LOOK;      /* ready for next stream, once have is 0 (leave
626                                  * state->direct unchanged to remember how) */
627     }
628 
629     /* good decompression */
630     return 0;
631 }
632 
633 static int
xz_make(xz_statep state)634 xz_make(xz_statep state)
635 {
636     lzma_stream *strm = &(state->strm);
637 
638     if (state->how == LOOK) {   /* look for lzma / gzip header */
639         if (xz_head(state) == -1)
640             return -1;
641         if (state->have)        /* got some data from xz_head() */
642             return 0;
643     }
644     if (state->how == COPY) {   /* straight copy */
645         if (xz_load(state, state->out, state->size << 1, &(state->have)) ==
646             -1)
647             return -1;
648         state->next = state->out;
649     } else if (state->how == LZMA || state->how == GZIP) {      /* decompress */
650         strm->avail_out = state->size << 1;
651         strm->next_out = state->out;
652         if (xz_decomp(state) == -1)
653             return -1;
654     }
655     return 0;
656 }
657 
658 static int
xz_skip(xz_statep state,uint64_t len)659 xz_skip(xz_statep state, uint64_t len)
660 {
661     unsigned n;
662 
663     /* skip over len bytes or reach end-of-file, whichever comes first */
664     while (len)
665         /* skip over whatever is in output buffer */
666         if (state->have) {
667             n = (uint64_t) state->have > len ?
668                 (unsigned) len : state->have;
669             state->have -= n;
670             state->next += n;
671             state->pos += n;
672             len -= n;
673         }
674 
675     /* output buffer empty -- return if we're at the end of the input */
676         else if (state->eof && state->strm.avail_in == 0)
677             break;
678 
679     /* need more data to skip -- load up output buffer */
680         else {
681             /* get more output, looking for header if required */
682             if (xz_make(state) == -1)
683                 return -1;
684         }
685     return 0;
686 }
687 
688 int
__libxml2_xzread(xzFile file,void * buf,unsigned len)689 __libxml2_xzread(xzFile file, void *buf, unsigned len)
690 {
691     unsigned got, n;
692     xz_statep state;
693     lzma_stream *strm;
694 
695     /* get internal structure */
696     if (file == NULL)
697         return -1;
698     state = (xz_statep) file;
699     strm = &(state->strm);
700 
701     /* check that we're reading and that there's no error */
702     if (state->err != LZMA_OK)
703         return -1;
704 
705     /* since an int is returned, make sure len fits in one, otherwise return
706      * with an error (this avoids the flaw in the interface) */
707     if ((int) len < 0) {
708         xz_error(state, LZMA_BUF_ERROR,
709                  "requested length does not fit in int");
710         return -1;
711     }
712 
713     /* if len is zero, avoid unnecessary operations */
714     if (len == 0)
715         return 0;
716 
717     /* process a skip request */
718     if (state->seek) {
719         state->seek = 0;
720         if (xz_skip(state, state->skip) == -1)
721             return -1;
722     }
723 
724     /* get len bytes to buf, or less than len if at the end */
725     got = 0;
726     do {
727         /* first just try copying data from the output buffer */
728         if (state->have) {
729             n = state->have > len ? len : state->have;
730             memcpy(buf, state->next, n);
731             state->next += n;
732             state->have -= n;
733         }
734 
735         /* output buffer empty -- return if we're at the end of the input */
736         else if (state->eof && strm->avail_in == 0)
737             break;
738 
739         /* need output data -- for small len or new stream load up our output
740          * buffer */
741         else if (state->how == LOOK || len < (state->size << 1)) {
742             /* get more output, looking for header if required */
743             if (xz_make(state) == -1)
744                 return -1;
745             continue;           /* no progress yet -- go back to memcpy() above */
746             /* the copy above assures that we will leave with space in the
747              * output buffer, allowing at least one gzungetc() to succeed */
748         }
749 
750         /* large len -- read directly into user buffer */
751         else if (state->how == COPY) {  /* read directly */
752             if (xz_load(state, buf, len, &n) == -1)
753                 return -1;
754         }
755 
756         /* large len -- decompress directly into user buffer */
757         else {                  /* state->how == LZMA */
758             strm->avail_out = len;
759             strm->next_out = buf;
760             if (xz_decomp(state) == -1)
761                 return -1;
762             n = state->have;
763             state->have = 0;
764         }
765 
766         /* update progress */
767         len -= n;
768         buf = (char *) buf + n;
769         got += n;
770         state->pos += n;
771     } while (len);
772 
773     /* return number of bytes read into user buffer (will fit in int) */
774     return (int) got;
775 }
776 
777 int
__libxml2_xzclose(xzFile file)778 __libxml2_xzclose(xzFile file)
779 {
780     int ret;
781     xz_statep state;
782 
783     /* get internal structure */
784     if (file == NULL)
785         return LZMA_DATA_ERROR;
786     state = (xz_statep) file;
787 
788     /* free memory and close file */
789     if (state->size) {
790         lzma_end(&(state->strm));
791 #ifdef LIBXML_ZLIB_ENABLED
792         if (state->init == 1)
793             inflateEnd(&(state->zstrm));
794         state->init = 0;
795 #endif
796         xmlFree(state->out);
797         xmlFree(state->in);
798     }
799     xmlFree(state->path);
800     if ((state->msg != NULL) && (state->err != LZMA_MEM_ERROR))
801         xmlFree(state->msg);
802     ret = close(state->fd);
803     xmlFree(state);
804     return ret ? ret : LZMA_OK;
805 }
806 #endif /* LIBXML_LZMA_ENABLED */
807