Add asprintf vasprintf

[ZERICO2005]

It would be nice to add asprintf and vasprintf. They are similar to sprintf, but they will allocate the buffers for you

int asprintf(char **__restrict strp, const char *__restrict fmt, ...);
int vasprintf(char **__restrict strp, const char *__restrict fmt, va_list ap);

https://www.man7.org/linux/man-pages/man3/asprintf.3.html

[mateoconlechuga]

No

[adriweb]

Elaborate? After all, they are in some TS extension Dynamic memory extensions <http://en.cppreference.com/w/c/experimental/dynamic> of the C standard, and other libc impls have them Could be useful especially when porting persons that use them and it would only get linked when used so 🤷‍♂️

[ZERICO2005]

Without asprintf, I have to do the alternative. Getting the length of the string with snprintf(NULL, 0, ...), malloc'ing length + 1 bytes, and then writing to the buffer. There is a lot of boilerplate involved for handling errors, it is easy to forget to allocate length + 1 bytes, and etc. which is why I think it is best implemented as a library function; allowing users to rely on a tested and verified implementation

int len_str = snprintf(NULL, 0, /* args */);
if (len_str < 0) {
	return NULL;
}
size_t str_size = (size_t)len_str + 1;
char* buf = (char*)malloc(str_size);
if (buf == NULL) {
	return NULL;
}
int status = snprintf(buf, str_size, /* args */);
if (status < 0) {
	free(buf);
	return NULL;
}
return buf;