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gh-67766: Improve struct.pack out of range error messages #132857

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gh-67766: Improve struct.pack out of range error messages #132857

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439a9dd
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StanFromIreland Apr 23, 2025
dfdd4b7
Clean up
StanFromIreland Apr 23, 2025
551ae17
Update error message
StanFromIreland Apr 24, 2025
8f2c341
!fixup
StanFromIreland Apr 24, 2025
3393c37
Escape test
StanFromIreland Apr 24, 2025
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4 changes: 4 additions & 0 deletions Doc/library/struct.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,10 @@ The module defines the following exception and functions:
Exception raised on various occasions; argument is a string describing what
is wrong.

.. versionchanged:: next
Out of range errors are more descriptive specifying which argument resulted
in the exception.


.. function:: pack(format, v1, v2, ...)

Expand Down
2 changes: 1 addition & 1 deletion Lib/test/test_struct.py
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Expand Up @@ -742,7 +742,7 @@ def test_error_msg(prefix, int_type, is_unsigned):
else:
max_ = 2 ** (size * 8 - 1) - 1
min_ = -2 ** (size * 8 - 1)
error_msg = f"'{int_type}' format requires {min_} <= number <= {max_}"
error_msg = f"'{int_type}' format requires {min_} <= arg 1 <= {max_}"
for number in [int(-1e50), min_ - 1, max_ + 1, int(1e50)]:
with self.subTest(format_str=fmt_str, number=number):
with self.assertRaisesRegex(struct.error, error_msg):
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2025-04-23-21-40-00.gh-issue-67766.0x8FFFF.rst
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@@ -0,0 +1 @@
:func:`struct.pack` raises more informative errors when an argument is out of range.
79 changes: 44 additions & 35 deletions Modules/_struct.c
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Expand Up @@ -27,6 +27,7 @@ typedef struct {
PyObject *PyStructType;
PyObject *unpackiter_type;
PyObject *StructError;
Py_ssize_t current_arg;
} _structmodulestate;

static inline _structmodulestate*
Expand Down Expand Up @@ -290,7 +291,7 @@ get_size_t(_structmodulestate *state, PyObject *v, size_t *p)
}


#define RANGE_ERROR(state, f, flag) return _range_error(state, f, flag)
#define RANGE_ERROR(state, f, flag, loc) return _range_error(state, f, flag, loc)


/* Floating-point helpers */
Expand Down Expand Up @@ -347,7 +348,7 @@ unpack_double(const char *p, /* start of 8-byte string */

/* Helper to format the range error exceptions */
static int
_range_error(_structmodulestate *state, const formatdef *f, int is_unsigned)
_range_error(_structmodulestate *state, const formatdef *f, int is_unsigned, Py_ssize_t loc)
{
/* ulargest is the largest unsigned value with f->size bytes.
* Note that the simpler:
Expand All @@ -361,15 +362,17 @@ _range_error(_structmodulestate *state, const formatdef *f, int is_unsigned)
assert(f->size >= 1 && f->size <= SIZEOF_SIZE_T);
if (is_unsigned)
PyErr_Format(state->StructError,
"'%c' format requires 0 <= number <= %zu",
"'%c' format requires 0 <= arg %zd <= %zu",
f->format,
loc,
ulargest);
else {
const Py_ssize_t largest = (Py_ssize_t)(ulargest >> 1);
PyErr_Format(state->StructError,
"'%c' format requires %zd <= number <= %zd",
"'%c' format requires %zd <= arg %zd <= %zd",
f->format,
~ largest,
loc,
largest);
}

Expand Down Expand Up @@ -563,12 +566,12 @@ np_byte(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
long x;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
if (x < -128 || x > 127) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
*p = (char)x;
return 0;
Expand All @@ -580,12 +583,12 @@ np_ubyte(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
long x;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
if (x < 0 || x > 255) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
*(unsigned char *)p = (unsigned char)x;
return 0;
Expand All @@ -610,12 +613,12 @@ np_short(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
short y;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
if (x < SHRT_MIN || x > SHRT_MAX) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
y = (short)x;
memcpy(p, &y, sizeof y);
Expand All @@ -629,12 +632,12 @@ np_ushort(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned short y;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
if (x < 0 || x > USHRT_MAX) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
y = (unsigned short)x;
memcpy(p, &y, sizeof y);
Expand All @@ -648,13 +651,13 @@ np_int(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
int y;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
#if (SIZEOF_LONG > SIZEOF_INT)
if ((x < ((long)INT_MIN)) || (x > ((long)INT_MAX)))
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
#endif
y = (int)x;
memcpy(p, &y, sizeof y);
Expand All @@ -668,14 +671,14 @@ np_uint(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned int y;
if (get_ulong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
y = (unsigned int)x;
#if (SIZEOF_LONG > SIZEOF_INT)
if (x > ((unsigned long)UINT_MAX))
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
#endif
memcpy(p, &y, sizeof y);
return 0;
Expand All @@ -687,7 +690,7 @@ np_long(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
long x;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
Expand All @@ -701,7 +704,7 @@ np_ulong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned long x;
if (get_ulong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
Expand All @@ -715,7 +718,7 @@ np_ssize_t(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
Py_ssize_t x;
if (get_ssize_t(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
Expand All @@ -729,7 +732,7 @@ np_size_t(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
size_t x;
if (get_size_t(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
Expand All @@ -744,9 +747,10 @@ np_longlong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
if (get_longlong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
PyErr_Format(state->StructError,
"'%c' format requires %lld <= number <= %lld",
"'%c' format requires %lld <= arg %zd <= %lld",
f->format,
LLONG_MIN,
state->current_arg,
LLONG_MAX);
}
return -1;
Expand All @@ -762,8 +766,9 @@ np_ulonglong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f
if (get_ulonglong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
PyErr_Format(state->StructError,
"'%c' format requires 0 <= number <= %llu",
"'%c' format requires 0 <= arg %zd <= %llu",
f->format,
state->current_arg,
ULLONG_MAX);
}
return -1;
Expand Down Expand Up @@ -1065,17 +1070,17 @@ bp_int(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned char *q = (unsigned char *)p;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
i = f->size;
if (i != SIZEOF_LONG) {
if ((i == 2) && (x < -32768 || x > 32767))
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
#if (SIZEOF_LONG != 4)
else if ((i == 4) && (x < -2147483648L || x > 2147483647L))
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
#endif
}
do {
Expand All @@ -1093,7 +1098,7 @@ bp_uint(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned char *q = (unsigned char *)p;
if (get_ulong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
Expand All @@ -1102,7 +1107,7 @@ bp_uint(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned long maxint = 1;
maxint <<= (unsigned long)(i * 8);
if (x >= maxint)
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
do {
q[--i] = (unsigned char)(x & 0xffUL);
Expand All @@ -1127,9 +1132,10 @@ bp_longlong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
Py_DECREF(v);
if (res < 0) {
PyErr_Format(state->StructError,
"'%c' format requires %lld <= number <= %lld",
"'%c' format requires %lld <= arg %zd <= %lld",
f->format,
LLONG_MIN,
state->current_arg,
LLONG_MAX);
return -1;
}
Expand All @@ -1152,8 +1158,9 @@ bp_ulonglong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f
Py_DECREF(v);
if (res < 0) {
PyErr_Format(state->StructError,
"'%c' format requires 0 <= number <= %llu",
"'%c' format requires 0 <= arg %zd <= %llu",
f->format,
state->current_arg,
ULLONG_MAX);
return -1;
}
Expand Down Expand Up @@ -1398,17 +1405,17 @@ lp_int(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned char *q = (unsigned char *)p;
if (get_long(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
}
return -1;
}
i = f->size;
if (i != SIZEOF_LONG) {
if ((i == 2) && (x < -32768 || x > 32767))
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
#if (SIZEOF_LONG != 4)
else if ((i == 4) && (x < -2147483648L || x > 2147483647L))
RANGE_ERROR(state, f, 0);
RANGE_ERROR(state, f, 0, state->current_arg);
#endif
}
do {
Expand All @@ -1426,7 +1433,7 @@ lp_uint(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned char *q = (unsigned char *)p;
if (get_ulong(state, v, &x) < 0) {
if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
return -1;
}
Expand All @@ -1435,7 +1442,7 @@ lp_uint(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
unsigned long maxint = 1;
maxint <<= (unsigned long)(i * 8);
if (x >= maxint)
RANGE_ERROR(state, f, 1);
RANGE_ERROR(state, f, 1, state->current_arg);
}
do {
*q++ = (unsigned char)(x & 0xffUL);
Expand All @@ -1460,9 +1467,10 @@ lp_longlong(_structmodulestate *state, char *p, PyObject *v, const formatdef *f)
Py_DECREF(v);
if (res < 0) {
PyErr_Format(state->StructError,
"'%c' format requires %lld <= number <= %lld",
"'%c' format requires %lld <= arg %zd <= %lld",
f->format,
LLONG_MIN,
state->current_arg,
LLONG_MAX);
return -1;
}
Expand Down Expand Up @@ -2194,6 +2202,7 @@ s_pack_internal(PyStructObject *soself, PyObject *const *args, int offset,
Py_ssize_t j = code->repeat;
while (j--) {
PyObject *v = args[i++];
state->current_arg = i;
if (e->format == 's') {
Py_ssize_t n;
int isstring;
Expand Down
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