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gh-112301: Use literal format strings in unicode_fromformat_arg #124203

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Merged
encukou merged 3 commits into from
Sep 25, 2024
Merged

gh-112301: Use literal format strings in unicode_fromformat_arg #124203

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1ebc9ee
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encukou Sep 18, 2024
b562a43
Macros
encukou Sep 18, 2024
218929c
Put ;break; in the switch
encukou Sep 24, 2024
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@encukou
encukou committed Sep 18, 2024
commit b562a43154cab877c89abbdd33b5665d8c497ca1
131 changes: 37 additions & 94 deletions Objects/unicodeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2835,102 +2835,45 @@ unicode_fromformat_arg(_PyUnicodeWriter *writer,
case 'd': case 'i':
case 'o': case 'u': case 'x': case 'X':
{
char buffer[MAX_INTMAX_CHARS]; // used by sprintf
char buffer[MAX_INTMAX_CHARS];

// Fill buffer using sprinf, with one of many possible format
// strings, like "%llX" for `long long` in hexadecimal.
// The type/size is in `sizemod`; the format is in `*f`.

// Use macros with nested switches to keep the sprintf format strings
// as compile-time literals, avoiding warnings and maybe allowing
// optimizations.

// `SPRINT` macro does one sprintf
// Example usage: SPRINT("l", "X", unsigned long) expands to
// sprintf(buffer, "%" "l" "X", va_arg(*vargs, unsigned long))
#define SPRINT(SIZE_SPEC, FMT_CHAR, TYPE) \
sprintf(buffer, "%" SIZE_SPEC FMT_CHAR, va_arg(*vargs, TYPE))

// One inner switch to handle all format variants
#define DO_SPRINTS(SIZE_SPEC, SIGNED_TYPE, UNSIGNED_TYPE) \
switch (*f) { \
case 'o': len = SPRINT(SIZE_SPEC, "o", UNSIGNED_TYPE); break; \
case 'u': len = SPRINT(SIZE_SPEC, "u", UNSIGNED_TYPE); break; \
case 'x': len = SPRINT(SIZE_SPEC, "x", UNSIGNED_TYPE); break; \
case 'X': len = SPRINT(SIZE_SPEC, "X", UNSIGNED_TYPE); break; \
default: len = SPRINT(SIZE_SPEC, "d", SIGNED_TYPE); break; \
} \
break;

// Outer switch to handle all the sizes/types
switch (sizemod) {
/*[python input]
# Use generated code so that the `sprintf` format strings
# are compile-time literals, which avoids a warning and possibly
# allows optimizations.
if 1:
indent = ' ' * 11
cases = [
('F_LONG', 'l', 'long', 'unsigned long'),
('F_LONGLONG', 'll', 'long long', 'unsigned long long'),
('F_SIZE', 'z', 'Py_ssize_t', 'size_t'),
('F_PTRDIFF', 't', 'ptrdiff_t', 'ptrdiff_t'),
('F_INTMAX', 'j', 'intmax_t', 'uintmax_t'),
(None, '', 'int', 'unsigned int'),
]
for (size, sizechar, stype, utype) in cases:
if size is None:
print(indent, f'default:')
else:
print(indent, f'case {size}:')
print(indent, f' switch (*f) {{')
for c in 'ouxX':
# signed
print(
indent,
f" case '{c}':",
f'len = sprintf(buffer, "%{sizechar}{c}",',
f'va_arg(*vargs, {utype}));',
'break;')
# unsigned
print(
indent,
f" default: ",
f'len = sprintf(buffer, "%{sizechar}d",',
f'va_arg(*vargs, {stype}));',
'break;')
print(indent, f' }}')
print(indent, f' break;')
[python start generated code]*/
case F_LONG:
switch (*f) {
case 'o': len = sprintf(buffer, "%lo", va_arg(*vargs, unsigned long)); break;
case 'u': len = sprintf(buffer, "%lu", va_arg(*vargs, unsigned long)); break;
case 'x': len = sprintf(buffer, "%lx", va_arg(*vargs, unsigned long)); break;
case 'X': len = sprintf(buffer, "%lX", va_arg(*vargs, unsigned long)); break;
default: len = sprintf(buffer, "%ld", va_arg(*vargs, long)); break;
}
break;
case F_LONGLONG:
switch (*f) {
case 'o': len = sprintf(buffer, "%llo", va_arg(*vargs, unsigned long long)); break;
case 'u': len = sprintf(buffer, "%llu", va_arg(*vargs, unsigned long long)); break;
case 'x': len = sprintf(buffer, "%llx", va_arg(*vargs, unsigned long long)); break;
case 'X': len = sprintf(buffer, "%llX", va_arg(*vargs, unsigned long long)); break;
default: len = sprintf(buffer, "%lld", va_arg(*vargs, long long)); break;
}
break;
case F_SIZE:
switch (*f) {
case 'o': len = sprintf(buffer, "%zo", va_arg(*vargs, size_t)); break;
case 'u': len = sprintf(buffer, "%zu", va_arg(*vargs, size_t)); break;
case 'x': len = sprintf(buffer, "%zx", va_arg(*vargs, size_t)); break;
case 'X': len = sprintf(buffer, "%zX", va_arg(*vargs, size_t)); break;
default: len = sprintf(buffer, "%zd", va_arg(*vargs, Py_ssize_t)); break;
}
break;
case F_PTRDIFF:
switch (*f) {
case 'o': len = sprintf(buffer, "%to", va_arg(*vargs, ptrdiff_t)); break;
case 'u': len = sprintf(buffer, "%tu", va_arg(*vargs, ptrdiff_t)); break;
case 'x': len = sprintf(buffer, "%tx", va_arg(*vargs, ptrdiff_t)); break;
case 'X': len = sprintf(buffer, "%tX", va_arg(*vargs, ptrdiff_t)); break;
default: len = sprintf(buffer, "%td", va_arg(*vargs, ptrdiff_t)); break;
}
break;
case F_INTMAX:
switch (*f) {
case 'o': len = sprintf(buffer, "%jo", va_arg(*vargs, uintmax_t)); break;
case 'u': len = sprintf(buffer, "%ju", va_arg(*vargs, uintmax_t)); break;
case 'x': len = sprintf(buffer, "%jx", va_arg(*vargs, uintmax_t)); break;
case 'X': len = sprintf(buffer, "%jX", va_arg(*vargs, uintmax_t)); break;
default: len = sprintf(buffer, "%jd", va_arg(*vargs, intmax_t)); break;
}
break;
default:
switch (*f) {
case 'o': len = sprintf(buffer, "%o", va_arg(*vargs, unsigned int)); break;
case 'u': len = sprintf(buffer, "%u", va_arg(*vargs, unsigned int)); break;
case 'x': len = sprintf(buffer, "%x", va_arg(*vargs, unsigned int)); break;
case 'X': len = sprintf(buffer, "%X", va_arg(*vargs, unsigned int)); break;
default: len = sprintf(buffer, "%d", va_arg(*vargs, int)); break;
}
break;
/*[python end generated code: output=e37b56d7b69e78f3 input=b77dfc89939506ed]*/
case F_LONG: DO_SPRINTS("l", long, unsigned long)

@vstinner vstinner Sep 18, 2024

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Can you put the break here? Something like:

Suggested change
case F_LONG: DO_SPRINTS("l", long, unsigned long)
case F_LONG: DO_SPRINTS("l", long, unsigned long); break;

@encukou encukou Sep 24, 2024

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OK!
One line is 85 characters now, but I think it's most readable this way.

case F_LONGLONG: DO_SPRINTS("ll", long long, unsigned long long)
case F_SIZE: DO_SPRINTS("z", Py_ssize_t, size_t)
case F_PTRDIFF: DO_SPRINTS("t", ptrdiff_t, ptrdiff_t)
case F_INTMAX: DO_SPRINTS("j", intmax_t, uintmax_t)
default: DO_SPRINTS("", int, unsigned int)
}
#undef SPRINT
#undef DO_SPRINTS

assert(len >= 0);

int sign = (buffer[0] == '-');
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