mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 12:03:41 +00:00
9b29358511
Status lines for Emacs and Vim have been added to Python sources so they'll be easier to edit using Python's preferred coding style. Some DNS helper functions have been broken up into multiple files. It's nice to have one function per file whenever possible, since that way we don't need -ffunction-sections. Another reason it's good to have small source files, is because the build will be enforcing resource limits on compilation and testing soon.
113 lines
4.2 KiB
C
113 lines
4.2 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
|
|
│vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8 :vi│
|
|
╞══════════════════════════════════════════════════════════════════════════════╡
|
|
│ Python 3 │
|
|
│ https://docs.python.org/3/license.html │
|
|
╚─────────────────────────────────────────────────────────────────────────────*/
|
|
#include "libc/assert.h"
|
|
#include "libc/fmt/fmt.h"
|
|
#include "third_party/python/Include/pyerrors.h"
|
|
/* clang-format off */
|
|
|
|
/* snprintf() wrappers. If the platform has vsnprintf, we use it, else we
|
|
emulate it in a half-hearted way. Even if the platform has it, we wrap
|
|
it because platforms differ in what vsnprintf does in case the buffer
|
|
is too small: C99 behavior is to return the number of characters that
|
|
would have been written had the buffer not been too small, and to set
|
|
the last byte of the buffer to \0. At least MS _vsnprintf returns a
|
|
negative value instead, and fills the entire buffer with non-\0 data.
|
|
|
|
The wrappers ensure that str[size-1] is always \0 upon return.
|
|
|
|
PyOS_snprintf and PyOS_vsnprintf never write more than size bytes
|
|
(including the trailing '\0') into str.
|
|
|
|
If the platform doesn't have vsnprintf, and the buffer size needed to
|
|
avoid truncation exceeds size by more than 512, Python aborts with a
|
|
Py_FatalError.
|
|
|
|
Return value (rv):
|
|
|
|
When 0 <= rv < size, the output conversion was unexceptional, and
|
|
rv characters were written to str (excluding a trailing \0 byte at
|
|
str[rv]).
|
|
|
|
When rv >= size, output conversion was truncated, and a buffer of
|
|
size rv+1 would have been needed to avoid truncation. str[size-1]
|
|
is \0 in this case.
|
|
|
|
When rv < 0, "something bad happened". str[size-1] is \0 in this
|
|
case too, but the rest of str is unreliable. It could be that
|
|
an error in format codes was detected by libc, or on platforms
|
|
with a non-C99 vsnprintf simply that the buffer wasn't big enough
|
|
to avoid truncation, or on platforms without any vsnprintf that
|
|
PyMem_Malloc couldn't obtain space for a temp buffer.
|
|
|
|
CAUTION: Unlike C99, str != NULL and size > 0 are required.
|
|
*/
|
|
|
|
int
|
|
PyOS_snprintf(char *str, size_t size, const char *format, ...)
|
|
{
|
|
int rc;
|
|
va_list va;
|
|
|
|
va_start(va, format);
|
|
rc = PyOS_vsnprintf(str, size, format, va);
|
|
va_end(va);
|
|
return rc;
|
|
}
|
|
|
|
int
|
|
PyOS_vsnprintf(char *str, size_t size, const char *format, va_list va)
|
|
{
|
|
int len; /* # bytes written, excluding \0 */
|
|
#ifdef HAVE_SNPRINTF
|
|
#define _PyOS_vsnprintf_EXTRA_SPACE 1
|
|
#else
|
|
#define _PyOS_vsnprintf_EXTRA_SPACE 512
|
|
char *buffer;
|
|
#endif
|
|
assert(str != NULL);
|
|
assert(size > 0);
|
|
assert(format != NULL);
|
|
/* We take a size_t as input but return an int. Sanity check
|
|
* our input so that it won't cause an overflow in the
|
|
* vsnprintf return value or the buffer malloc size. */
|
|
if (size > INT_MAX - _PyOS_vsnprintf_EXTRA_SPACE) {
|
|
len = -666;
|
|
goto Done;
|
|
}
|
|
|
|
#ifdef HAVE_SNPRINTF
|
|
len = vsnprintf(str, size, format, va);
|
|
#else
|
|
/* Emulate it. */
|
|
buffer = PyMem_MALLOC(size + _PyOS_vsnprintf_EXTRA_SPACE);
|
|
if (buffer == NULL) {
|
|
len = -666;
|
|
goto Done;
|
|
}
|
|
|
|
len = vsprintf(buffer, format, va);
|
|
if (len < 0)
|
|
/* ignore the error */;
|
|
|
|
else if ((size_t)len >= size + _PyOS_vsnprintf_EXTRA_SPACE)
|
|
Py_FatalError("Buffer overflow in PyOS_snprintf/PyOS_vsnprintf");
|
|
|
|
else {
|
|
const size_t to_copy = (size_t)len < size ?
|
|
(size_t)len : size - 1;
|
|
assert(to_copy < size);
|
|
memcpy(str, buffer, to_copy);
|
|
str[to_copy] = '\0';
|
|
}
|
|
PyMem_FREE(buffer);
|
|
#endif
|
|
Done:
|
|
if (size > 0)
|
|
str[size-1] = '\0';
|
|
return len;
|
|
#undef _PyOS_vsnprintf_EXTRA_SPACE
|
|
}
|