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Contribution by Hannu Krosing (with some changes).

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Added 'p' format character for Pascal string (i.e. leading length
byte).  This uses the count prefix line 's' does, except that the
count includes the length byte; i.e. '10p' takes 10 bytes packed but
has space for a length byte and 9 data bytes.
This commit is contained in:
Guido van Rossum 1997-09-05 07:08:39 +00:00
parent bd4435abcc
commit 9eb671fac3
1 changed files with 38 additions and 0 deletions
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38
Modules/structmodule.c
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@ -631,6 +631,7 @@ static formatdef native_table[] = {
{'B', sizeof(char), 0, nu_ubyte, np_byte},
{'c', sizeof(char), 0, nu_char, np_char},
{'s', sizeof(char), 0, NULL},
{'p', sizeof(char), 0, NULL},
{'h', sizeof(short), SHORT_ALIGN, nu_short, np_short},
{'H', sizeof(short), SHORT_ALIGN, nu_ushort, np_short},
{'i', sizeof(int), INT_ALIGN, nu_int, np_int},
@ -761,6 +762,7 @@ static formatdef bigendian_table[] = {
{'B', 1, 0, bu_uint, bp_int},
{'c', 1, 0, nu_char, np_char},
{'s', 1, 0, NULL},
{'p', 1, 0, NULL},
{'h', 2, 0, bu_int, bp_int},
{'H', 2, 0, bu_uint, bp_uint},
{'i', 4, 0, bu_int, bp_int},
@ -891,6 +893,7 @@ static formatdef lilendian_table[] = {
{'B', 1, 0, lu_uint, lp_int},
{'c', 1, 0, nu_char, np_char},
{'s', 1, 0, NULL},
{'p', 1, 0, NULL},
{'h', 2, 0, lu_int, lp_int},
{'H', 2, 0, lu_uint, lp_uint},
{'i', 4, 0, lu_int, lp_int},
@ -1132,6 +1135,28 @@ struct_pack(self, args)
res += num;
break;
}
else if (c == 'p') {
/* num is string size + 1,
to fit in the count byte */
int n;
num--; /* now num is max string size */
if (!PyString_Check(v)) {
PyErr_SetString(StructError,
"argument for 'p' must be a string");
goto fail;
}
n = PyString_Size(v);
if (n > num)
n = num;
if (n > 0)
memcpy(res+1, PyString_AsString(v), n);
if (n < num)
/* no real need, just to be nice */
memset(res+1+n, '\0', num-n);
*res++ = n; /* store the length byte */
res += num;
break;
}
else {
if (e->pack(res, v, e) < 0)
goto fail;
@ -1216,6 +1241,19 @@ struct_unpack(self, args)
str += num;
num = 0;
}
else if (c == 'p') {
/* num is string buffer size,
not repeat count */
int n = *(unsigned char*)str;
/* first byte (unsigned) is string size */
if (n >= num)
n = num-1;
v = PyString_FromStringAndSize(str+1, n);
if (v == NULL)
goto fail;
str += num;
num = 0;
}
else {
v = e->unpack(str, e);
if (v == NULL)