Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:lib\xz\xz_dec_stream.c Create Date:2022-07-28 07:08:28
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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Name:dec_main

Proto:static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b)

Type:enum xz_ret

Parameter:

TypeParameterName
struct xz_dec *s
struct xz_buf *b
557  Saved in_pos and out_pos = in_pos
559  When (true) cycle
561  Case Position in dec_main() == SEQ_STREAM_HEADER
570  If Not Fill s->temp by copying data starting from b->in[b->in_pos]. Caller* must have set s->temp.pos to indicate how much data we are supposed* to copy into s->temp.buf. Return true once s->temp.pos has reached Then Return XZ_OK
580  Position in dec_main() = SEQ_BLOCK_START
582  ret = Decode the Stream Header field (the first 12 bytes of the .xz Stream).
583  If ret != XZ_OK Then Return ret
588  Case Position in dec_main() == SEQ_BLOCK_START
590  If in_pos == in_size Then Return XZ_OK
594  If in[in_pos] == 0 Then
604  Size of the Block Header field = (in[in_pos] + 1) * 4
607  size = Size of the Block Header field
608  pos = 0
609  Position in dec_main() = SEQ_BLOCK_HEADER
613  Case Position in dec_main() == SEQ_BLOCK_HEADER
614  If Not Fill s->temp by copying data starting from b->in[b->in_pos]. Caller* must have set s->temp.pos to indicate how much data we are supposed* to copy into s->temp.buf. Return true once s->temp.pos has reached Then Return XZ_OK
617  ret = Decode the Block Header and initialize the filter chain.
618  If ret != XZ_OK Then Return ret
621  Position in dec_main() = SEQ_BLOCK_UNCOMPRESS
625  Case Position in dec_main() == SEQ_BLOCK_UNCOMPRESS
626  ret = Decode the Compressed Data field from a Block
627  If ret != XZ_STREAM_END Then Return ret
630  Position in dec_main() = SEQ_BLOCK_PADDING
634  Case Position in dec_main() == SEQ_BLOCK_PADDING
642  When Observed compressed size of the current Block & 3 cycle
643  If in_pos == in_size Then Return XZ_OK
646  If in[in_pos++] != 0 Then Return XZ_DATA_ERROR
649  ++Observed compressed size of the current Block
652  Position in dec_main() = SEQ_BLOCK_CHECK
656  Case Position in dec_main() == SEQ_BLOCK_CHECK
657  If Type of the integrity check calculated from uncompressed data == XZ_CHECK_CRC32 Then
668  Position in dec_main() = SEQ_BLOCK_START
669  Break
671  Case Position in dec_main() == SEQ_INDEX
672  ret = Decode the Number of Records, Unpadded Size, and Uncompressed Size* fields from the Index field. That is, Index Padding and CRC32 are not* decoded by this function.* This can return XZ_OK (more input needed), XZ_STREAM_END (everything
673  If ret != XZ_STREAM_END Then Return ret
676  Position in dec_main() = SEQ_INDEX_PADDING
680  Case Position in dec_main() == SEQ_INDEX_PADDING
681  When Size of the Index in bytes + in_pos - Saved in_pos and out_pos & 3 cycle
683  If in_pos == in_size Then
688  If in[in_pos++] != 0 Then Return XZ_DATA_ERROR
693  Update the Index size and the CRC32 value.
696  If Not FIXME: Not all basic memory functions are provided in architecture-specific* files (yet). We define our own versions here for now, but this should be* only a temporary solution.* memeq and memzero are not used much and any remotely sane implementation Then Return XZ_DATA_ERROR
700  Position in dec_main() = SEQ_INDEX_CRC32
704  Case Position in dec_main() == SEQ_INDEX_CRC32
705  ret = Validate that the next four input bytes match the value of s->crc32.
706  If ret != XZ_STREAM_END Then Return ret
709  size = See the .xz file format specification at* http://tukaani.org/xz/xz-file-format.txt* to understand the container format.
710  Position in dec_main() = SEQ_STREAM_FOOTER
714  Case Position in dec_main() == SEQ_STREAM_FOOTER
715  If Not Fill s->temp by copying data starting from b->in[b->in_pos]. Caller* must have set s->temp.pos to indicate how much data we are supposed* to copy into s->temp.buf. Return true once s->temp.pos has reached Then Return XZ_OK
718  Return Decode the Stream Footer field (the last 12 bytes of the .xz Stream)
Caller
NameDescribe
xz_dec_runxz_dec_run() is a wrapper for dec_main() to handle some special cases in* multi-call and single-call decoding.* In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we* are not going to make any progress anymore