musl/src/stdio/ungetc.c

#include "stdio_impl.h"

int ungetc(int c, FILE *f)
{
	if (c == EOF) return c;

	FLOCK(f);

	if ((!f->rend && __toread(f)) || f->rpos <= f->buf - UNGET) {
		FUNLOCK(f);
		return EOF;
	}

	*--f->rpos = c;
	f->flags &= ~F_EOF;

	FUNLOCK(f);
	return c;
}
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00			`#include "stdio_impl.h"`

			`int ungetc(int c, FILE *f)`
			`{`
			`if (c == EOF) return c;`

			`FLOCK(f);`

major stdio overhaul, using readv/writev, plus other changes the biggest change in this commit is that stdio now uses readv to fill the caller's buffer and the FILE buffer with a single syscall, and likewise writev to flush the FILE buffer and write out the caller's buffer in a single syscall. making this change required fundamental architectural changes to stdio, so i also made a number of other improvements in the process: - the implementation no longer assumes that further io will fail following errors, and no longer blocks io when the error flag is set (though the latter could easily be changed back if desired) - unbuffered mode is no longer implemented as a one-byte buffer. as a consequence, scanf unreading has to use ungetc, to the unget buffer has been enlarged to hold at least 2 wide characters. - the FILE structure has been rearranged to maintain the locations of the fields that might be used in glibc getc/putc type macros, while shrinking the structure to save some space. - error cases for fflush, fseek, etc. should be more correct. - library-internal macros are used for getc_unlocked and putc_unlocked now, eliminating some ugly code duplication. __uflow and __overflow are no longer used anywhere but these macros. switch to read or write mode is also separated so the code can be better shared, e.g. with ungetc. - lots of other small things. 2011-03-28 01:14:44 -04:00			`if ((!f->rend && __toread(f)) \|\| f->rpos <= f->buf - UNGET) {`
initial check-in, version 0.5.0 2011-02-12 00:22:29 -05:00			`FUNLOCK(f);`
			`return EOF;`
			`}`

			`*--f->rpos = c;`
			`f->flags &= ~F_EOF;`

			`FUNLOCK(f);`
			`return c;`
			`}`