API Reference: Constants

Error Codes

HS_SUCCESS

The engine completed normally.

HS_INVALID

A parameter passed to this function was invalid.

This error is only returned in cases where the function can detect an invalid parameter it cannot be relied upon to detect (for example) pointers to freed memory or other invalid data.

HS_NOMEM

A memory allocation failed.

HS_SCAN_TERMINATED

The engine was terminated by callback.

This return value indicates that the target buffer was partially scanned, but that the callback function requested that scanning cease after a match was located.

HS_COMPILER_ERROR

The pattern compiler failed, and the hs_compile_error_t should be inspected for more detail.

HS_DB_VERSION_ERROR

The given database was built for a different version of Hyperscan.

HS_DB_PLATFORM_ERROR

The given database was built for a different platform (i.e., CPU type).

HS_DB_MODE_ERROR

The given database was built for a different mode of operation. This error is returned when streaming calls are used with a block or vectored database and vice versa.

HS_BAD_ALIGN

A parameter passed to this function was not correctly aligned.

HS_BAD_ALLOC

The memory allocator (either malloc() or the allocator set with hs_set_allocator()) did not correctly return memory suitably aligned for the largest representable data type on this platform.

HS_SCRATCH_IN_USE

The scratch region was already in use.

This error is returned when Hyperscan is able to detect that the scratch region given is already in use by another Hyperscan API call.

A separate scratch region, allocated with hs_alloc_scratch() or hs_clone_scratch(), is required for every concurrent caller of the Hyperscan API.

For example, this error might be returned when hs_scan() has been called inside a callback delivered by a currently-executing hs_scan() call using the same scratch region.

Note: Not all concurrent uses of scratch regions may be detected. This error is intended as a best-effort debugging tool, not a guarantee.

HS_ARCH_ERROR

Unsupported CPU architecture.

This error is returned when Hyperscan is able to detect that the current system does not support the required instruction set.

At a minimum, Hyperscan requires Supplemental Streaming SIMD Extensions 3 (SSSE3).

HS_INSUFFICIENT_SPACE

Provided buffer was too small.

This error indicates that there was insufficient space in the buffer. The call should be repeated with a larger provided buffer.

Note: in this situation, it is normal for the amount of space required to be returned in the same manner as the used space would have been returned if the call was successful.

HS_UNKNOWN_ERROR

Unexpected internal error.

This error indicates that there was unexpected matching behaviors. This could be related to invalid usage of stream and scratch space or invalid memory operations by users.

hs_expr_ext flags

HS_EXT_FLAG_MIN_OFFSET

Flag indicating that the hs_expr_ext::min_offset field is used.

HS_EXT_FLAG_MAX_OFFSET

Flag indicating that the hs_expr_ext::max_offset field is used.

HS_EXT_FLAG_MIN_LENGTH

Flag indicating that the hs_expr_ext::min_length field is used.

HS_EXT_FLAG_EDIT_DISTANCE

Flag indicating that the hs_expr_ext::edit_distance field is used.

HS_EXT_FLAG_HAMMING_DISTANCE

Flag indicating that the hs_expr_ext::hamming_distance field is used.

Pattern flags

HS_FLAG_CASELESS

Compile flag: Set case-insensitive matching.

This flag sets the expression to be matched case-insensitively by default. The expression may still use PCRE tokens (notably (?i) and (?-i)) to switch case-insensitive matching on and off.

HS_FLAG_DOTALL

Compile flag: Matching a . will not exclude newlines.

This flag sets any instances of the . token to match newline characters as well as all other characters. The PCRE specification states that the . token does not match newline characters by default, so without this flag the . token will not cross line boundaries.

HS_FLAG_MULTILINE

Compile flag: Set multi-line anchoring.

This flag instructs the expression to make the ^ and $ tokens match newline characters as well as the start and end of the stream. If this flag is not specified, the ^ token will only ever match at the start of a stream, and the $ token will only ever match at the end of a stream within the guidelines of the PCRE specification.

HS_FLAG_SINGLEMATCH

Compile flag: Set single-match only mode.

This flag sets the expression’s match ID to match at most once. In streaming mode, this means that the expression will return only a single match over the lifetime of the stream, rather than reporting every match as per standard Hyperscan semantics. In block mode or vectored mode, only the first match for each invocation of hs_scan() or hs_scan_vector() will be returned.

If multiple expressions in the database share the same match ID, then they either must all specify HS_FLAG_SINGLEMATCH or none of them specify HS_FLAG_SINGLEMATCH. If a group of expressions sharing a match ID specify the flag, then at most one match with the match ID will be generated per stream.

Note: The use of this flag in combination with HS_FLAG_SOM_LEFTMOST is not currently supported.

HS_FLAG_ALLOWEMPTY

Compile flag: Allow expressions that can match against empty buffers.

This flag instructs the compiler to allow expressions that can match against empty buffers, such as .?, .*, (a|). Since Hyperscan can return every possible match for an expression, such expressions generally execute very slowly; the default behaviour is to return an error when an attempt to compile one is made. Using this flag will force the compiler to allow such an expression.

HS_FLAG_UTF8

Compile flag: Enable UTF-8 mode for this expression.

This flag instructs Hyperscan to treat the pattern as a sequence of UTF-8 characters. The results of scanning invalid UTF-8 sequences with a Hyperscan library that has been compiled with one or more patterns using this flag are undefined.

HS_FLAG_UCP

Compile flag: Enable Unicode property support for this expression.

This flag instructs Hyperscan to use Unicode properties, rather than the default ASCII interpretations, for character mnemonics like \w and \s as well as the POSIX character classes. It is only meaningful in conjunction with HS_FLAG_UTF8.

HS_FLAG_PREFILTER

Compile flag: Enable prefiltering mode for this expression.

This flag instructs Hyperscan to compile an “approximate” version of this pattern for use in a prefiltering application, even if Hyperscan does not support the pattern in normal operation.

The set of matches returned when this flag is used is guaranteed to be a superset of the matches specified by the non-prefiltering expression.

If the pattern contains pattern constructs not supported by Hyperscan (such as zero-width assertions, back-references or conditional references) these constructs will be replaced internally with broader constructs that may match more often.

Furthermore, in prefiltering mode Hyperscan may simplify a pattern that would otherwise return a “Pattern too large” error at compile time, or for performance reasons (subject to the matching guarantee above).

It is generally expected that the application will subsequently confirm prefilter matches with another regular expression matcher that can provide exact matches for the pattern.

Note: The use of this flag in combination with HS_FLAG_SOM_LEFTMOST is not currently supported.

HS_FLAG_SOM_LEFTMOST

Compile flag: Enable leftmost start of match reporting.

This flag instructs Hyperscan to report the leftmost possible start of match offset when a match is reported for this expression. (By default, no start of match is returned.)

Enabling this behaviour may reduce performance and increase stream state requirements in streaming mode.

HS_FLAG_COMBINATION

Compile flag: Logical combination.

This flag instructs Hyperscan to parse this expression as logical combination syntax. Logical constraints consist of operands, operators and parentheses. The operands are expression indices, and operators can be ‘!’(NOT), ‘&’(AND) or ‘|’(OR). For example: (101&102&103)|(104&!105) ((301|302)&303)&(304|305)

HS_FLAG_QUIET

Compile flag: Don’t do any match reporting.

This flag instructs Hyperscan to ignore match reporting for this expression. It is designed to be used on the sub-expressions in logical combinations.

CPU feature support flags

HS_CPU_FEATURES_AVX2

CPU features flag - Intel(R) Advanced Vector Extensions 2 (Intel(R) AVX2)

Setting this flag indicates that the target platform supports AVX2 instructions.

HS_CPU_FEATURES_AVX512

CPU features flag - Intel(R) Advanced Vector Extensions 512 (Intel(R) AVX512)

Setting this flag indicates that the target platform supports AVX512 instructions, specifically AVX-512BW. Using AVX512 implies the use of AVX2.

CPU tuning flags

HS_TUNE_FAMILY_GENERIC

Tuning Parameter - Generic

This indicates that the compiled database should not be tuned for any particular target platform.

HS_TUNE_FAMILY_SNB

Tuning Parameter - Intel(R) microarchitecture code name Sandy Bridge

This indicates that the compiled database should be tuned for the Sandy Bridge microarchitecture.

HS_TUNE_FAMILY_IVB

Tuning Parameter - Intel(R) microarchitecture code name Ivy Bridge

This indicates that the compiled database should be tuned for the Ivy Bridge microarchitecture.

HS_TUNE_FAMILY_HSW

Tuning Parameter - Intel(R) microarchitecture code name Haswell

This indicates that the compiled database should be tuned for the Haswell microarchitecture.

HS_TUNE_FAMILY_SLM

Tuning Parameter - Intel(R) microarchitecture code name Silvermont

This indicates that the compiled database should be tuned for the Silvermont microarchitecture.

HS_TUNE_FAMILY_BDW

Tuning Parameter - Intel(R) microarchitecture code name Broadwell

This indicates that the compiled database should be tuned for the Broadwell microarchitecture.

HS_TUNE_FAMILY_SKL

Tuning Parameter - Intel(R) microarchitecture code name Skylake

This indicates that the compiled database should be tuned for the Skylake microarchitecture.

HS_TUNE_FAMILY_SKX

Tuning Parameter - Intel(R) microarchitecture code name Skylake Server

This indicates that the compiled database should be tuned for the Skylake Server microarchitecture.

HS_TUNE_FAMILY_GLM

Tuning Parameter - Intel(R) microarchitecture code name Goldmont

This indicates that the compiled database should be tuned for the Goldmont microarchitecture.

Compile mode flags

HS_MODE_BLOCK

Compiler mode flag: Block scan (non-streaming) database.

HS_MODE_NOSTREAM

Compiler mode flag: Alias for HS_MODE_BLOCK.

HS_MODE_STREAM

Compiler mode flag: Streaming database.

HS_MODE_VECTORED

Compiler mode flag: Vectored scanning database.

HS_MODE_SOM_HORIZON_LARGE

Compiler mode flag: use full precision to track start of match offsets in stream state.

This mode will use the most stream state per pattern, but will always return an accurate start of match offset regardless of how far back in the past it was found.

One of the SOM_HORIZON modes must be selected to use the HS_FLAG_SOM_LEFTMOST expression flag.

HS_MODE_SOM_HORIZON_MEDIUM

Compiler mode flag: use medium precision to track start of match offsets in stream state.

This mode will use less stream state than HS_MODE_SOM_HORIZON_LARGE and will limit start of match accuracy to offsets within 2^32 bytes of the end of match offset reported.

One of the SOM_HORIZON modes must be selected to use the HS_FLAG_SOM_LEFTMOST expression flag.

HS_MODE_SOM_HORIZON_SMALL

Compiler mode flag: use limited precision to track start of match offsets in stream state.

This mode will use less stream state than HS_MODE_SOM_HORIZON_LARGE and will limit start of match accuracy to offsets within 2^16 bytes of the end of match offset reported.

One of the SOM_HORIZON modes must be selected to use the HS_FLAG_SOM_LEFTMOST expression flag.