add support for caller-provided buffers to setvbuf

This commit is contained in:
Rich Felker 2018-04-18 15:29:18 -04:00
parent 6019459251
commit 0b80a7b040

View File

@ -1,22 +1,25 @@
#include "stdio_impl.h" #include "stdio_impl.h"
/* This function makes no attempt to protect the user from his/her own /* The behavior of this function is undefined except when it is the first
* stupidity. If called any time but when then ISO C standard specifically * operation on the stream, so the presence or absence of lockign is not
* allows it, all hell can and will break loose, especially with threads! * observable in a program whose behavior is defined. Thus no locking is
* * performed here. No allocation of buffers is performed, but a buffer
* This implementation ignores all arguments except the buffering type, * provided by the caller is used as long as it is suitably sized. */
* and uses the existing buffer allocated alongside the FILE object.
* In the case of stderr where the preexisting buffer is length 1, it
* is not possible to set line buffering or full buffering. */
int setvbuf(FILE *restrict f, char *restrict buf, int type, size_t size) int setvbuf(FILE *restrict f, char *restrict buf, int type, size_t size)
{ {
f->lbf = EOF; f->lbf = EOF;
if (type == _IONBF) if (type == _IONBF) {
f->buf_size = 0; f->buf_size = 0;
else if (type == _IOLBF) } else {
if (buf && size >= UNGET) {
f->buf = (void *)buf;
f->buf_size = size - UNGET;
}
if (type == _IOLBF && f->buf_size)
f->lbf = '\n'; f->lbf = '\n';
}
f->flags |= F_SVB; f->flags |= F_SVB;