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htslib release 1.10:

Brief summary
-------------

There are many changes in this release, so the executive summary is:

* Addition of support for references longer than 2Gb (NB: SAM and
  VCF formats only, not their binary counterparts).  This may need
  changes in code using HTSlib.  See README.large_positions.md for
  more information.

* Added a SAM header API.

* Major speed up to SAM reading and writing.  This also now supports
  multi-threading.

* We can now auto-index on-the-fly while writing a file.  This also
  includes to bgzipped SAM.gz.

* Overhaul of the S3 interface, which now supports version 4
  signatures.  This also makes writing to S3 work.

  These also required some ABI changes.  See below for full details.

Features / updates
------------------

* A new SAM/BAM/CRAM header API has been added to HTSlib, allowing
  header data to be updated without having to parse or rewrite
  large parts of the header text.  See htslib/sam.h for function
  definitions and documentation. (#812)

  The header typedef and several pre-existing functions have been
  renamed to have a sam_hdr_ prefix: sam_hdr_t, sam_hdr_init(),
  sam_hdr_destroy(), and sam_hdr_dup().  (The existing
  bam_hdr_-prefixed names are still provided for compatibility with
  existing code.) (#887, thanks to John Marshall)

* Changes to hfile_s3, which provides support for the AWS S3 API.
  (#839)

  - hfile_s3 now uses version 4 signatures by default.  Attempting
    to write to an S3 bucket will also now work correctly.  It is
    possible to force version 2 signatures by creating environment
    variable HTS_S3_V2 (the exact value does not matter, it just
    has to exist).  Note that writing depends on features that need
    version 4 signatures, so forcing version 2 will disable writes.

  - hfile_s3 will automatically retry requests where the region
    endpoint was not specified correctly, either by following the
    301 redirect (when using path-style requests) or reading the
    400 response (when using virtual-hosted style requests and
    version 4 signatures).  The first region to try can be set by
    using the AWS_DEFAULT_REGION environment variable, by setting
    "region" in ".aws/credentials" or by setting "bucket_location"
    in ".s3cfg".

  - hfile_s3 now percent-escapes the path component of s3:// URLs. 
    For backwards-compatibility it will ignore any paths that have
    already been escaped (detected by looking for '%' followed by two
    hexadecimal digits.)

  - New environment variables HTS_S3_V2, HTS_S3_HOST, HTS_S3_S3CFG
    and HTS_S3_PART_SIZE to force version-2 signatures, control the
    S3 server hostname, the configuration file and upload chunk sizes
    respectively.

* Numerous SAM format improvements.

  - Bgzipped SAM files can now be indexed and queried.  The library
    now recognises sam.gz as a format name to ease this usage. (#718,
    #916)

  - The SAM reader and writer now supports multi-threading via the
    thread-pool. (#916)

    Note that the multi-threaded SAM reader does not currently support
    seek operations.  Trying to do this (for example with an iterator
    range request) will result in the SAM readers dropping back to
    single-threaded mode.

  - Major speed up of SAM decoding and encoding, by around 2x. (#722)

  - SAM format can now handle 64-bit coordinates and references. 
    This has implications for the ABI too (see below).  Note BAM and
    CRAM currently cannot handle references longer than 2Gb, however
    given the speed and threading improvements SAM.gz is a viable
    workaround. (#709)

* We can now automatically build indices on-the-fly while writing
  SAM, BAM, CRAM, VCF and BCF files.  (Note for SAM and VCF this only
  works when bgzipped.) (#718)

* HTSlib now supports the @SQ-AN header field, which lists
  alternative names for reference sequences.  This means given
  "@SQ SN:1 AN:chr1", tools like samtools can accept requests for
  "1" or "chr1" equivalently.  (#931)

* Zero-length files are no longer considered to be valid SAM files
  (with no header and no alignments).  This has been changed so that
  pipelines such as `somecmd | samtools ...` with `somecmd` aborting
  before outputting anything will now propagate the error to the
  second command. (#721, thanks to John Marshall; #261 reported by
  Adrian Tan)

* Added support for use of non-standard index names by pasting
  the data filename and index filename with ##idx##.  For example
  "/path1/my_data.bam##idx##/path2/my_index.csi" will open bam
  file "/path1/my_data.bam" and index file "/path2/my_index.csi".
  (#884)

  This affects hts_idx_load() and hts_open() functions.

* Improved the region parsing code to handle colons in reference
  names.  Strings can be disambiguated by the use of braces, so for
  example when reference sequences called "chr1" and "chr1:100-200"
  are both present, the regions "{chr1}:100-200" and "{chr1:100-200}"
  unambiguously indicate which reference is being used. (#708)

  A new function hts_parse_region() has been added along with
  specialisations for sam_parse_region() and fai_parse_region().

* CRAM encoding now has additional checks for MD/NM validity.  If
  they are incorrect, it stores the (incorrect copy) verbatim so
  round-trips "work". (#792)

* Sped up decoding of CRAM by around 10% when the MD tag is being
  generated. (#874)

* CRAM REF_PATH now supports %Ns (where N is a single digit)
  expansion in http URLs, similar to how it already supported
  this for directories. (#791)

* BGZF now permits indexing and seeking using virtual offsets in
  completely uncompressed streams. (#904, thanks to Adam Novak)

* bgzip now asks for extra confirmation before decompressing files
  that don't have a known compression extension (e.g. .gz).  This
  avoids `bgzip -d foo.bam.bai` producing a foo.bam file that is very
  much not a BAM-formatted file. (#927, thanks to John Marshall)

* The htsfile utility can now copy files (including to/from URLs
  using HTSlib's remote access facilities) with the --copy option,
  in addition to its existing uses of identifying file formats and
  displaying sequence or variant data. (#756, thanks to John
  Marshall)

* Added tabix --min-shift option. (#752, thanks to Garrett Stevens)

* Tabix now has an -D option to disable storing a local copy of a
  remote index. (#870)

* Improved support for MSYS Windows compiler environment. (#966)

* External htslib plugins are now supported on Windows. (#966)

API additions and improvements
------------------------------

* New API functions bam_set_mempolicy() and bam_get_mempolicy() have
  been added.  These allow more control over the ownership of bam1_t
  alignment record data; see documentation in htslib/sam.h for more
  information. (#922)

* Added more HTS_RESULT_USED checks, this time for VCF I/O. (#805)

* khash can now hash kstrings.  This makes it easier to hash
  non-NUL-terminated strings. (#713)

* New haddextension() filename extension API function. (#788, thanks
  to John Marshall)

* New hts_resize() macro, designed to replace uses of hts_expand()
  and hts_expand0(). (#805)

* Added way of cleaning up unused jobs in the thread pool via the new
  hts_tpool_dispatch3() function. (#830)

* New API functions hts_reglist_create() and sam_itr_regarray() are
  added to create hts_reglist_t region lists from `chr:<from>-<to>`
  type region specifiers. (#836)

* Ksort has been improved to facilitate library use.  See
  KSORT_INIT2 (adds scope / namespace capabilities) and
  KSORT_INIT_STATIC interfaces. (#851, thanks to John Marshall)

* New kstring functions (#879):
    KS_INITIALIZE   -  Initializer for structure assignment
    ks_initialize() -  Initializer for pointed-to kstrings
    ks_expand()     -  Increase kstring capacity by a given amount
    ks_clear()      -  Set kstring length to zero
    ks_free()       -  Free the underlying buffer
    ks_c_str()      -  Returns the kstring buffer as a const char *,
                       or an empty string if the length is zero.

* New API functions hts_idx_load3(), sam_index_load3(),
  tbx_index_load3() and bcf_index_load3() have been added.  These
  allow control of whether remote indexes should be cached
  locally, and allow the error message printed when the index
  does not exist to be suppressed. (#870)

* Improved hts_detect_format() so it no longer assumes all text is
  SAM unless positively identified otherwise.  It also makes a stab
  at detecting bzip2 format and identifying BED, FASTA and FASTQ
  files. (#721, thanks to John Marshall; #200, #719 both reported by
  Torsten Seemann)

* File format errors now set errno to EFTYPE (BSD, MacOS) when
  available instead of ENOEXEC. (#721)

* New API function bam_set_qname (#942)

* In addition to the existing hts_version() function, which reflects
  the HTSlib version being used at runtime, <htslib/hts.h> now also
  provides HTS_VERSION, a preprocessor macro reflecting the HTSlib
  version that a program is being compiled against.  (#951, thanks to
  John Marshall; #794)

ABI changes
-----------

This release contains a number of things which change the
ApplicationBinary Interface (ABI).  This means code compiled
against an earlierlibrary will require recompiling.  The shared
library soversion hasbeen bumped.

* On systems that support it, the default symbol visibility has
  been changed to hidden and the only exported symbols are ones
  that form part of the officially supported ABI.  This is to
  make clear exactly which symbols are considered parts of the
  library interface.  It also helps packagers who want to check
  compatibility between HTSlib versions. (#946; see for example
  issues #311, #616, and #695)

* HTSlib now supports 64 bit reference positions.  This means several
  structures, function parameters, and return values have been made
  bigger to allow larger values to be stored.  While most code that
  uses HTSlib interfaces should still build after this change, some
  alterations may be needed - notably to printf() formats where the
  values of structure members are being printed. (#709)

  Due to file format limitations, large positions are only supported
  when reading and writing SAM and VCF files.

  See README.large_positions.md for more information.

* An extra field has been added to the kbitset_t struct so bitsets
  can be made smaller (and later enlarged) without involving memory
  allocation. (#710, thanks to John Marshall)

* A new field has been added to the bam_pileup1_t structure to keep
  track of which CIGAR operator is being processed.  This is used by
  a new bam_plp_insertion() function which can be used to return the
  sequence of any inserted bases at a given pileup location.  If the
  alignment includes CIGAR P operators, the returned sequence will
  include pads. (#699)

* The hts_itr_t and hts_itr_multi_t structures have been merged and
  can be used interchangeably.  Extra fields have been added to
  hts_itr_t to support this.  hts_itr_multi_t is now a typedef for
  hts_itr_t; sam_itr_multi_next() is now an alias for sam_itr_next()
  and hts_itr_multi_destroy() is an alias for hts_itr_destroy().
  (#836)

* An improved regidx interface has been added.  To allow this, struct
  reg_t has been removed, regitr_t has been modified and various new
  API functions have been added to htslib/regidx.h.  While parts of
  the old regidx API have been retained for backwards compatibility,
  it is recommended that all code using regidx should be changed to
  use the new interface. (#761)

* Elements in the hts_reglist_t structure have been reordered
  slightly so that they pack together better. (#761)

* bgzf_utell() and bgzf_useek() now use type off_t instead of long
  for the offset.  This allows them to work correctly on files longer
  than 2G bytes on Windows and 32-bit Linux. (#868)

* A number of functions that used to return void now return int so
  that they can report problems like memory allocation failures. 
  Callers should take care to check the return values from these
  functions. (#834)

  The affected functions are:
    ksort.h:             ks_introsort(), ks_mergesort()
    sam.h:               bam_mplp_init_overlaps()
    synced_bcf_reader.h: bcf_sr_regions_flush()
    vcf.h:               bcf_format_gt(), bcf_fmt_array(),
                         bcf_enc_int1(), bcf_enc_size(),
                         bcf_enc_vchar(), bcf_enc_vfloat(),
                         bcf_enc_vint(), bcf_hdr_set_version(),
                         bcf_hrec_format()
    vcfutils.h:          bcf_remove_alleles()

* bcf_set_variant_type() now outputs VCF_OVERLAP for spanning
  deletions (ALT=*). (#726)

* A new field (hrecs) has been added to the bam_hdr_t structure
  for use by the new header API.  The old sdict field is now not
  used and marked as deprecated.  The l_text field has been
  changed from uint32_t to size_t, to allow for very large headers
  in SAM files.  The text and l_text fields have been left for
  backwards compatibility, but should not be accessed directly in
  code that uses the new header API. To access the header text,
  the new functions sam_hdr_length() and sam_hdr_str() should be
  used instead. (#812)

* The old cigar_tab field is now marked as deprecated; use the new
  bam_cigar_table[] instead. (#891, thanks to John Marshall)

* The bam1_core_t structure's l_qname and l_extranul fields have been
  rearranged and enlarged; l_qname still includes the extra NULs.
  (Almost all code should use bam_get_qname(), bam_get_cigar(), etc,
  and has no need to use these fields directly.)  HTSlib now supports
  the SAM specification's full 254 QNAME length again.  (#900, thanks
  to John Marshall; #520)

* bcf_index_load() no longer tries the '.tbi' suffix when looking for
  BCF index files (.tbi indexes are for text files, not binary BCF).
  (#870)

* htsFile has a new 'state' member to support SAM multi-threading.
  (#916)

* A new field has been added to the bam1_t structure, and others have
  been rearranged to remove structure holes. (#709; #922)

Bug fixes
---------

* Several BGZF format fixes:

  - Support for multi-member gzip files. (#744, thanks to Adam Novak;
    #742)

  - Fixed error handling code for native gzip formatted files.
    (64c4927)

  - CRCs checked when threading too (previously only when
    non-threaded). (#745)

  - Made bgzf_useek function work with threads. (#818)

  - Fixed rare threading deadlocks. (#831)

  - Reading of very short files (<28 bytes) that do not contain an
    EOF block. (#910)

* Fixed some thread pool deadlocks caused by race conditions. (#746,
  #906)

* Many additional memory allocation checks in VCF, BCF, SAM and CRAM
  code. This also changes the return type of some functions.  See ABI
  changes above. (#920 amongst others)

* Replace some sam parsing abort() calls with proper errors. (#721,
  thanks to John Marshall; #576)

* Fixed to permit SAM read names of length 252 to 254 (the
  maximum specified by the SAM specification). (#900, thanks to
  John Marshall)

* Fixed mpileup overlap detection heuristic to work with BAMs having
  long CIGARs (more than 65536 operations). (#802)

* Security fix: CIGAR strings starting with the "N" operation can
  no longer cause underflow on the bam CIGAR structure.  Similarly
  CIGAR strings that are entirely "D" ops could leak the contents
  of uninitialised variables. (#699)

* Fixed bug where alignments starting 0M could cause an invalid
  memory access in sam_prob_realn(). (#699)

* Fixed out of bounds memory access in mpileup when given a
  reference with binary characters (top-bit set). (#808, thanks
  to John Marshall)

* Fixed crash in mpileup overlap_push() function. (#882; #852
  reported by Pierre Lindenbaum)

* Fixed various potential CRAM memory leaks when recovering from
  error cases.

* Fixed CRAM index queries for unmapped reads (#911;
  samtools/samtools#958 reported by @acorvelo)

* Fixed the combination of CRAM embedded references and multiple
  slices per container.  This was incorrectly setting the header
  MD5sum.  (No impact on default CRAM behaviour.) (b2552fd)

* Removed unwanted explicit data flushing in CRAM writing, which on
  some OSes caused major slowdowns. (#883)

* Fixed inefficiencies in CRAM encoding when many small references
  occur within the middle of large chromosomes.  Previously it
  switched into multi-ref mode, but not back out of it which caused
  the read POS field to be stored poorly. (#896)

* Fixed CRAM handling of references when the order of sequences in a
  supplied fasta file differs to the order of the @SQ headers. (#935)

* Fixed BAM and CRAM multi-threaded decoding when used in
  conjunction with the multi-region iterator. (#830; #577, #822,
  #926 all reported by Brent Pedersen)

* Removed some unaligned memory accesses in CRAM encoder and
  undefined behaviour in BCF reading (#867, thanks to David Seifert)

* Repeated calling of bcf_empty() no longer crashes. (#741)

* Fixed bug where some 8 or 16-bit negative integers were stored
  using values reserved by the BCF specification.  These numbers are
  now promoted to the next size up, so -121 to -128 are stored using
  at least 16 bits, and -32761 to -32768 are stored using 32 bits.

  Note that while BCF files affected by this bug are technically
  incorrect, it is still possible to read them.  When converting to
  VCF format, HTSlib (and therefore bcftools) will interpret the
  values as intended and write out the correct negative numbers.
  (#766, thanks to John Marshall; samtools/bcftools#874)

* Allow repeated invocations of bcf_update_info() and
  bcf_update_format_*() functions. (#856, thanks to John
  Marshall; #813 reported by Steffen Möller)

* Memory leak removed in knetfile's kftp_parse_url() function. (#759,
  thanks to David Alexander)

* Fixed various crashes found by libfuzzer (invalid data leading to
  errors), mostly but not exclusively in CRAM, VCF and BCF decoding.
  (#805)

* Improved robustness of BAI and CSI index creation and loading.
  (#870; #967)

* Prevent (invalid) creation of TBI indices for BCF files. (#837;
  samtools/bcftools#707)

* Better parsing of handling of remote URLs with ?param=val
  components and their interaction with remote index URLs. (#790;
  #784 reported by Mark Ebbert)

* hts_idx_load() now checks locally for all possible index names
  before attempting to download a remote index.  It also checks that
  the remote file it downloads is actually an index before trying to
  save and use it.  (#870; samtools/samtools#1045 reported by Albert
  Vilella)

* hts_open_format() now honours the compression field, no longer also
  requiring an explicit "z" in the mode string.  Also fixed a 1 byte
  buffer overrun. (#880)

* Removed duplicate hts_tpool_process_flush prototype. (#816,
  reported by James S Blachly)

* Deleted defunct cram_tell declaration. (66c41e2; #915 reported by
  Martin Morgan)

* Fixed overly aggressive filename suffix checking in bgzip. (#927,
  thanks to John Marshall; #129, reported by @hguturu)

* Tabix and bgzip --help output now goes to standard output. (#754,
  thanks to John Marshall)

* Fixed bgzip index creation when using multiple threads. (#817)

* Made bgzip -b option honour -I (index filename). (#817)

* Bgzip -d no longer attempts to unlink(NULL) when decompressing
  stdin. (#718)

Miscellaneous other changes
---------------------------

* Integration with Google OSS fuzzing for automatic detection of more
  bugs. (Thanks to Google for their assistance and the bugs it has
  found.) (#796, thanks to Markus Kusano)

* aclocal.m4 now has the pkg-config macros. (6ec3b94d; #733 reported
  by Thomas Hickman)

* Improved C++ compatibility of some header files. (#772; #771
  reported by @cwrussell)

* Improved strict C99 compatibility. (#860, thanks to John Marshall)

* Travis and AppVeyor improvements to aid testing. (#747; #773 thanks
  to Lennard Berger; #781; #809; #804; #860; #909)

* Various minor compiler warnings fixed. (#708; #765; #846, #860,
  thanks to John Marshall; #865; #966; #973)

* Various new and improved error messages.

* Documentation updates (mostly in the header files).

* Even more testing with "make check".

* Corrected many copyright dates. (#979)

* The default non-configure Makefile now uses libcurl instead of
  knet, so it can support https. (#895)