https://github.com/python/cpython/commit/d8e69b2c1b3388c31a6083cfdd9dc9afff5b9860
commit: d8e69b2c1b3388c31a6083cfdd9dc9afff5b9860
branch: main
author: Victor Stinner <[email protected]>
committer: vstinner <[email protected]>
date: 2024-08-30T15:42:27Z
summary:
gh-122854: Add Py_HashBuffer() function (#122855)
files:
A Misc/NEWS.d/next/C_API/2024-08-09-13-12-20.gh-issue-122854.-1OgvU.rst
M Doc/c-api/hash.rst
M Doc/whatsnew/3.14.rst
M Include/cpython/pyhash.h
M Include/internal/pycore_pyhash.h
M Lib/test/test_capi/test_hash.py
M Modules/_datetimemodule.c
M Modules/_hashopenssl.c
M Modules/_sre/sre.c
M Modules/_testcapi/hash.c
M Modules/_xxtestfuzz/fuzzer.c
M Objects/bytesobject.c
M Objects/codeobject.c
M Objects/memoryobject.c
M Objects/unicodeobject.c
M Python/import.c
M Python/pyhash.c
diff --git a/Doc/c-api/hash.rst b/Doc/c-api/hash.rst
index 7345a048a4128b..00f8cb887dc7eb 100644
--- a/Doc/c-api/hash.rst
+++ b/Doc/c-api/hash.rst
@@ -89,6 +89,25 @@ See also the :c:member:`PyTypeObject.tp_hash` member and
:ref:`numeric-hash`.
.. versionadded:: 3.13
+
+.. c:function:: Py_hash_t Py_HashBuffer(const void *ptr, Py_ssize_t len)
+
+ Compute and return the hash value of a buffer of *len* bytes
+ starting at address *ptr*. The hash is guaranteed to match that of
+ :class:`bytes`, :class:`memoryview`, and other built-in objects
+ that implement the :ref:`buffer protocol <bufferobjects>`.
+
+ Use this function to implement hashing for immutable objects whose
+ :c:member:`~PyTypeObject.tp_richcompare` function compares to another
+ object's buffer.
+
+ *len* must be greater than or equal to ``0``.
+
+ This function always succeeds.
+
+ .. versionadded:: 3.14
+
+
.. c:function:: Py_hash_t PyObject_GenericHash(PyObject *obj)
Generic hashing function that is meant to be put into a type
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index 975af420f9b375..bbff8ecdd12117 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -489,6 +489,9 @@ New Features
similar to ``sep.join(iterable)`` in Python.
(Contributed by Victor Stinner in :gh:`121645`.)
+* Add :c:func:`Py_HashBuffer` to compute and return the hash value of a buffer.
+ (Contributed by Antoine Pitrou and Victor Stinner in :gh:`122854`.)
+
Porting to Python 3.14
----------------------
diff --git a/Include/cpython/pyhash.h b/Include/cpython/pyhash.h
index 825c034a8d8474..876a7f0ea44f4d 100644
--- a/Include/cpython/pyhash.h
+++ b/Include/cpython/pyhash.h
@@ -45,3 +45,5 @@ PyAPI_FUNC(PyHash_FuncDef*) PyHash_GetFuncDef(void);
PyAPI_FUNC(Py_hash_t) Py_HashPointer(const void *ptr);
PyAPI_FUNC(Py_hash_t) PyObject_GenericHash(PyObject *);
+
+PyAPI_FUNC(Py_hash_t) Py_HashBuffer(const void *ptr, Py_ssize_t len);
diff --git a/Include/internal/pycore_pyhash.h b/Include/internal/pycore_pyhash.h
index 0ce08900e96f0b..9414e7761171d2 100644
--- a/Include/internal/pycore_pyhash.h
+++ b/Include/internal/pycore_pyhash.h
@@ -20,9 +20,6 @@ _Py_HashPointerRaw(const void *ptr)
return (Py_hash_t)x;
}
-// Export for '_datetime' shared extension
-PyAPI_FUNC(Py_hash_t) _Py_HashBytes(const void*, Py_ssize_t);
-
/* Hash secret
*
* memory layout on 64 bit systems
diff --git a/Lib/test/test_capi/test_hash.py b/Lib/test/test_capi/test_hash.py
index cb2b3635f01328..f553ffb0d90f33 100644
--- a/Lib/test/test_capi/test_hash.py
+++ b/Lib/test/test_capi/test_hash.py
@@ -78,6 +78,16 @@ def python_hash_pointer(x):
VOID_P_MAX = -1 & (2 ** (8 * SIZEOF_VOID_P) - 1)
self.assertEqual(hash_pointer(VOID_P_MAX), -2)
+ def test_hash_buffer(self):
+ hash_buffer = _testcapi.hash_buffer
+
+ def check(data):
+ self.assertEqual(hash_buffer(data), hash(data))
+
+ check(b'')
+ check(b'abc')
+ check(b'x' * 1024)
+
if __name__ == "__main__":
unittest.main()
diff --git
a/Misc/NEWS.d/next/C_API/2024-08-09-13-12-20.gh-issue-122854.-1OgvU.rst
b/Misc/NEWS.d/next/C_API/2024-08-09-13-12-20.gh-issue-122854.-1OgvU.rst
new file mode 100644
index 00000000000000..b94d8f4e483bda
--- /dev/null
+++ b/Misc/NEWS.d/next/C_API/2024-08-09-13-12-20.gh-issue-122854.-1OgvU.rst
@@ -0,0 +1,2 @@
+Add :c:func:`Py_HashBuffer` to compute and return the hash value of a buffer.
+Patch by Antoine Pitrou and Victor Stinner.
diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c
index 1f7d44bffe6683..f6e6ba4e8eb297 100644
--- a/Modules/_datetimemodule.c
+++ b/Modules/_datetimemodule.c
@@ -3842,7 +3842,7 @@ datetime_date_replace_impl(PyDateTime_Date *self, int
year, int month,
static Py_hash_t
generic_hash(unsigned char *data, int len)
{
- return _Py_HashBytes(data, len);
+ return Py_HashBuffer(data, len);
}
diff --git a/Modules/_hashopenssl.c b/Modules/_hashopenssl.c
index 14d9c186151232..2c9a9feecc79f0 100644
--- a/Modules/_hashopenssl.c
+++ b/Modules/_hashopenssl.c
@@ -25,7 +25,6 @@
#include <stdbool.h>
#include "Python.h"
#include "pycore_hashtable.h"
-#include "pycore_pyhash.h" // _Py_HashBytes()
#include "pycore_strhex.h" // _Py_strhex()
#include "hashlib.h"
@@ -186,7 +185,7 @@ static const py_hashentry_t py_hashes[] = {
static Py_uhash_t
py_hashentry_t_hash_name(const void *key) {
- return _Py_HashBytes(key, strlen((const char *)key));
+ return Py_HashBuffer(key, strlen((const char *)key));
}
static int
diff --git a/Modules/_sre/sre.c b/Modules/_sre/sre.c
index 32f91af8dcf869..2c86f8869d8e58 100644
--- a/Modules/_sre/sre.c
+++ b/Modules/_sre/sre.c
@@ -2944,7 +2944,7 @@ pattern_hash(PatternObject *self)
return -1;
}
- hash2 = _Py_HashBytes(self->code, sizeof(self->code[0]) * self->codesize);
+ hash2 = Py_HashBuffer(self->code, sizeof(self->code[0]) * self->codesize);
hash ^= hash2;
hash ^= self->flags;
diff --git a/Modules/_testcapi/hash.c b/Modules/_testcapi/hash.c
index 809d537bfef0d3..1525344a93fbcf 100644
--- a/Modules/_testcapi/hash.c
+++ b/Modules/_testcapi/hash.c
@@ -45,6 +45,14 @@ hash_getfuncdef(PyObject *Py_UNUSED(module), PyObject
*Py_UNUSED(args))
}
+static PyObject *
+long_from_hash(Py_hash_t hash)
+{
+ Py_BUILD_ASSERT(sizeof(long long) >= sizeof(hash));
+ return PyLong_FromLongLong(hash);
+}
+
+
static PyObject *
hash_pointer(PyObject *Py_UNUSED(module), PyObject *arg)
{
@@ -54,8 +62,21 @@ hash_pointer(PyObject *Py_UNUSED(module), PyObject *arg)
}
Py_hash_t hash = Py_HashPointer(ptr);
- Py_BUILD_ASSERT(sizeof(long long) >= sizeof(hash));
- return PyLong_FromLongLong(hash);
+ return long_from_hash(hash);
+}
+
+
+static PyObject *
+hash_buffer(PyObject *Py_UNUSED(module), PyObject *args)
+{
+ char *ptr;
+ Py_ssize_t len;
+ if (!PyArg_ParseTuple(args, "y#", &ptr, &len)) {
+ return NULL;
+ }
+
+ Py_hash_t hash = Py_HashBuffer(ptr, len);
+ return long_from_hash(hash);
}
@@ -64,14 +85,14 @@ object_generichash(PyObject *Py_UNUSED(module), PyObject
*arg)
{
NULLABLE(arg);
Py_hash_t hash = PyObject_GenericHash(arg);
- Py_BUILD_ASSERT(sizeof(long long) >= sizeof(hash));
- return PyLong_FromLongLong(hash);
+ return long_from_hash(hash);
}
static PyMethodDef test_methods[] = {
{"hash_getfuncdef", hash_getfuncdef, METH_NOARGS},
{"hash_pointer", hash_pointer, METH_O},
+ {"hash_buffer", hash_buffer, METH_VARARGS},
{"object_generichash", object_generichash, METH_O},
{NULL},
};
diff --git a/Modules/_xxtestfuzz/fuzzer.c b/Modules/_xxtestfuzz/fuzzer.c
index 6ea9f64d628530..a04f1412eefda1 100644
--- a/Modules/_xxtestfuzz/fuzzer.c
+++ b/Modules/_xxtestfuzz/fuzzer.c
@@ -15,7 +15,6 @@
#endif
#include <Python.h>
-#include "pycore_pyhash.h" // _Py_HashBytes()
#include <stdlib.h>
#include <inttypes.h>
@@ -45,7 +44,7 @@ static int fuzz_builtin_int(const char* data, size_t size) {
/* Pick a random valid base. (When the fuzzed function takes extra
parameters, it's somewhat normal to hash the input to generate those
parameters. We want to exercise all code paths, so we do so here.) */
- int base = _Py_HashBytes(data, size) % 37;
+ int base = Py_HashBuffer(data, size) % 37;
if (base == 1) {
// 1 is the only number between 0 and 36 that is not a valid base.
base = 0;
diff --git a/Objects/bytesobject.c b/Objects/bytesobject.c
index c467b242b4cfc2..4a7c21f2f9d94c 100644
--- a/Objects/bytesobject.c
+++ b/Objects/bytesobject.c
@@ -1598,7 +1598,7 @@ _Py_COMP_DIAG_PUSH
_Py_COMP_DIAG_IGNORE_DEPR_DECLS
if (a->ob_shash == -1) {
/* Can't fail */
- a->ob_shash = _Py_HashBytes(a->ob_sval, Py_SIZE(a));
+ a->ob_shash = Py_HashBuffer(a->ob_sval, Py_SIZE(a));
}
return a->ob_shash;
_Py_COMP_DIAG_POP
diff --git a/Objects/codeobject.c b/Objects/codeobject.c
index ef24b51b961eeb..6f0b3f8b9a3262 100644
--- a/Objects/codeobject.c
+++ b/Objects/codeobject.c
@@ -2561,12 +2561,12 @@ hash_const(const void *key)
if (PySlice_Check(op)) {
PySliceObject *s = (PySliceObject *)op;
PyObject *data[3] = { s->start, s->stop, s->step };
- return _Py_HashBytes(&data, sizeof(data));
+ return Py_HashBuffer(&data, sizeof(data));
}
else if (PyTuple_CheckExact(op)) {
Py_ssize_t size = PyTuple_GET_SIZE(op);
PyObject **data = _PyTuple_ITEMS(op);
- return _Py_HashBytes(data, sizeof(PyObject *) * size);
+ return Py_HashBuffer(data, sizeof(PyObject *) * size);
}
Py_hash_t h = PyObject_Hash(op);
if (h == -1) {
diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index 226bd6defdec5a..498a37c1a3d869 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -3087,7 +3087,7 @@ memory_hash(PyObject *_self)
}
/* Can't fail */
- self->hash = _Py_HashBytes(mem, view->len);
+ self->hash = Py_HashBuffer(mem, view->len);
if (mem != view->buf)
PyMem_Free(mem);
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f4239cee8f7662..fc1fb78b7cab95 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -11688,7 +11688,7 @@ unicode_hash(PyObject *self)
if (hash != -1) {
return hash;
}
- x = _Py_HashBytes(PyUnicode_DATA(self),
+ x = Py_HashBuffer(PyUnicode_DATA(self),
PyUnicode_GET_LENGTH(self) * PyUnicode_KIND(self));
FT_ATOMIC_STORE_SSIZE_RELAXED(_PyUnicode_HASH(self), x);
diff --git a/Python/import.c b/Python/import.c
index f4c0d544fbdefa..c9212ec1ac0d7c 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -1174,7 +1174,7 @@ hashtable_key_from_2_strings(PyObject *str1, PyObject
*str2, const char sep)
static Py_uhash_t
hashtable_hash_str(const void *key)
{
- return _Py_HashBytes(key, strlen((const char *)key));
+ return Py_HashBuffer(key, strlen((const char *)key));
}
static int
diff --git a/Python/pyhash.c b/Python/pyhash.c
index 1504fa201c9902..216f437dd9a2d4 100644
--- a/Python/pyhash.c
+++ b/Python/pyhash.c
@@ -22,7 +22,7 @@ extern PyHash_FuncDef PyHash_Func;
static PyHash_FuncDef PyHash_Func;
#endif
-/* Count _Py_HashBytes() calls */
+/* Count Py_HashBuffer() calls */
#ifdef Py_HASH_STATS
#define Py_HASH_STATS_MAX 32
static Py_ssize_t hashstats[Py_HASH_STATS_MAX + 1] = {0};
@@ -146,9 +146,8 @@ PyObject_GenericHash(PyObject *obj)
}
Py_hash_t
-_Py_HashBytes(const void *src, Py_ssize_t len)
+Py_HashBuffer(const void *ptr, Py_ssize_t len)
{
- Py_hash_t x;
/*
We make the hash of the empty string be 0, rather than using
(prefix ^ suffix), since this slightly obfuscates the hash secret
@@ -161,11 +160,12 @@ _Py_HashBytes(const void *src, Py_ssize_t len)
hashstats[(len <= Py_HASH_STATS_MAX) ? len : 0]++;
#endif
+ Py_hash_t x;
#if Py_HASH_CUTOFF > 0
if (len < Py_HASH_CUTOFF) {
/* Optimize hashing of very small strings with inline DJBX33A. */
Py_uhash_t hash;
- const unsigned char *p = src;
+ const unsigned char *p = ptr;
hash = 5381; /* DJBX33A starts with 5381 */
switch(len) {
@@ -186,10 +186,13 @@ _Py_HashBytes(const void *src, Py_ssize_t len)
}
else
#endif /* Py_HASH_CUTOFF */
- x = PyHash_Func.hash(src, len);
+ {
+ x = PyHash_Func.hash(ptr, len);
+ }
- if (x == -1)
+ if (x == -1) {
return -2;
+ }
return x;
}
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