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Issue #25626: Change zlib to accept Py_ssize_t and cap to UINT_MAX

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The underlying zlib library stores sizes in “unsigned int”. The corresponding
Python parameters are all sizes of buffers filled in by zlib, so it is okay
to reduce higher values to the UINT_MAX internal cap. OverflowError is still
raised for sizes that do not fit in Py_ssize_t.

Sizes are now limited to Py_ssize_t rather than unsigned long, because Python
byte strings cannot be larger than Py_ssize_t. Previously this could result
in a SystemError on 32-bit platforms.

This resolves a regression in the gzip module when reading more than UINT_MAX
or LONG_MAX bytes in one call, introduced by revision 62723172412c.
This commit is contained in:
Martin Panter 2015-11-20 08:13:35 +00:00
parent d13cade381
commit e99e97762c
7 changed files with 120 additions and 47 deletions
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58
Modules/zlibmodule.c
View file

@ -226,42 +226,42 @@ zlib_compress_impl(PyModuleDef *module, Py_buffer *bytes, int level)
/*[python input]
class uint_converter(CConverter):
class capped_uint_converter(CConverter):
type = 'unsigned int'
converter = 'uint_converter'
converter = 'capped_uint_converter'
c_ignored_default = "0"
[python start generated code]*/
/*[python end generated code: output=da39a3ee5e6b4b0d input=22263855f7a3ebfd]*/
/*[python end generated code: output=da39a3ee5e6b4b0d input=35521e4e733823c7]*/
static int
uint_converter(PyObject *obj, void *ptr)
capped_uint_converter(PyObject *obj, void *ptr)
{
long val;
unsigned long uval;
PyObject *long_obj;
Py_ssize_t val;
val = PyLong_AsLong(obj);
long_obj = (PyObject *)_PyLong_FromNbInt(obj);
if (long_obj == NULL) {
return 0;
}
val = PyLong_AsSsize_t(long_obj);
Py_DECREF(long_obj);
if (val == -1 && PyErr_Occurred()) {
uval = PyLong_AsUnsignedLong(obj);
if (uval == (unsigned long)-1 && PyErr_Occurred())
return 0;
return 0;
}
else {
if (val < 0) {
PyErr_SetString(PyExc_ValueError,
"value must be positive");
return 0;
}
uval = (unsigned long)val;
}
if (uval > UINT_MAX) {
PyErr_SetString(PyExc_OverflowError,
"Python int too large for C unsigned int");
if (val < 0) {
PyErr_SetString(PyExc_ValueError,
"value must be positive");
return 0;
}
*(unsigned int *)ptr = Py_SAFE_DOWNCAST(uval, unsigned long, unsigned int);
if ((size_t)val > UINT_MAX) {
*(unsigned int *)ptr = UINT_MAX;
}
else {
*(unsigned int *)ptr = Py_SAFE_DOWNCAST(val, Py_ssize_t,
unsigned int);
}
return 1;
}
@ -272,7 +272,7 @@ zlib.decompress
Compressed data.
wbits: int(c_default="MAX_WBITS") = MAX_WBITS
The window buffer size.
bufsize: uint(c_default="DEF_BUF_SIZE") = DEF_BUF_SIZE
bufsize: capped_uint(c_default="DEF_BUF_SIZE") = DEF_BUF_SIZE
The initial output buffer size.
/
@ -282,7 +282,7 @@ Returns a bytes object containing the uncompressed data.
static PyObject *
zlib_decompress_impl(PyModuleDef *module, Py_buffer *data, int wbits,
unsigned int bufsize)
/*[clinic end generated code: output=444d0987f3429574 input=0f4b9abb7103f50e]*/
/*[clinic end generated code: output=444d0987f3429574 input=da095118b3243b27]*/
{
PyObject *result_str = NULL;
Byte *input;
@ -691,7 +691,7 @@ zlib.Decompress.decompress
data: Py_buffer
The binary data to decompress.
max_length: uint = 0
max_length: capped_uint = 0
The maximum allowable length of the decompressed data.
Unconsumed input data will be stored in
the unconsumed_tail attribute.
@ -707,7 +707,7 @@ Call the flush() method to clear these buffers.
static PyObject *
zlib_Decompress_decompress_impl(compobject *self, Py_buffer *data,
unsigned int max_length)
/*[clinic end generated code: output=b82e2a2c19f5fe7b input=02cfc047377cec86]*/
/*[clinic end generated code: output=b82e2a2c19f5fe7b input=68b6508ab07c2cf0]*/
{
int err;
unsigned int old_length, length = DEF_BUF_SIZE;
@ -1048,7 +1048,7 @@ error:
/*[clinic input]
zlib.Decompress.flush
length: uint(c_default="DEF_BUF_SIZE") = zlib.DEF_BUF_SIZE
length: capped_uint(c_default="DEF_BUF_SIZE") = zlib.DEF_BUF_SIZE
the initial size of the output buffer.
/
@ -1057,7 +1057,7 @@ Return a bytes object containing any remaining decompressed data.
static PyObject *
zlib_Decompress_flush_impl(compobject *self, unsigned int length)
/*[clinic end generated code: output=db6fb753ab698e22 input=1580956505978993]*/
/*[clinic end generated code: output=db6fb753ab698e22 input=1bb961eb21b62aa0]*/
{
int err;
unsigned int new_length;