[klibc] Replace the stdio offset with a stdio data pointer

There are almost no places where the offset is the useful piece,
so replace the offset with a data pointer.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

5 files changed, 10 insertions, 15 deletions

diff --git a/usr/include/stdio.h b/usr/include/stdio.h
index ea775006974a4..8dc178e19e86f 100644
--- a/usr/include/stdio.h
+++ b/usr/include/stdio.h
@@ -11,17 +11,12 @@
 #include <stddef.h>
 #include <unistd.h>
 
-/* Unidirectional buffer */
-struct _IO_buf {
-	char *buf;		/* Actual buffer */
-};
-
 /* Actual FILE structure */
 struct _IO_file {
 	struct _IO_file *prev, *next;
 	off_t filepos;		/* File position */
 	char *buf;		/* Buffer */
-	int offset;		/* Offset to data in buffer */
+	char *data;		/* Data in buffer */
 	int bytes;		/* Data bytes in buffer */
 	int bufsiz;		/* Total size of buffer */
 	int fd;			/* Underlying file descriptor */
diff --git a/usr/klibc/stdio/fflush.c b/usr/klibc/stdio/fflush.c
index 0970c68a678ef..8c78be4720eec 100644
--- a/usr/klibc/stdio/fflush.c
+++ b/usr/klibc/stdio/fflush.c
@@ -38,7 +38,7 @@ int fflush(FILE *f)
 		p += rv;
 		f->bytes -= rv;
 	}
-	f->offset = _IO_UNGET_SLOP;
+	f->data = f->buf + _IO_UNGET_SLOP;
 	f->flags &= ~_IO_FILE_FLAG_WRITE;
 
 	return 0;
diff --git a/usr/klibc/stdio/fread.c b/usr/klibc/stdio/fread.c
index b318dac506ad6..6eecfc0da0b6f 100644
--- a/usr/klibc/stdio/fread.c
+++ b/usr/klibc/stdio/fread.c
@@ -18,8 +18,8 @@ size_t _fread(void *buf, size_t count, FILE *f)
 		nb = f->bytes;
 		nb = (count < nb) ? count : nb;
 		if (nb) {
-			memcpy(p, f->buf+f->offset, nb);
-			f->offset += nb;
+			memcpy(p, f->data, nb);
+			f->data += nb;
 			f->bytes  -= nb;
 			p += nb;
 			count -= nb;
@@ -33,9 +33,9 @@ size_t _fread(void *buf, size_t count, FILE *f)
 			break;	/* Done... */
 
 		/* If we get here, f->ibuf must be empty */
-		f->offset = _IO_UNGET_SLOP;
+		f->data = f->buf + _IO_UNGET_SLOP;
 
-		rv = read(f->fd, f->buf+_IO_UNGET_SLOP, BUFSIZ);
+		rv = read(f->fd, f->data, BUFSIZ);
 		if (rv == -1) {
 			if (errno == EINTR || errno == EAGAIN)
 				continue;
diff --git a/usr/klibc/stdio/fxopen.c b/usr/klibc/stdio/fxopen.c
index 7c596ec0da925..5f9d61d1d6edc 100644
--- a/usr/klibc/stdio/fxopen.c
+++ b/usr/klibc/stdio/fxopen.c
@@ -60,8 +60,8 @@ FILE *__fxopen(int fd, int flags, int close_on_err)
 		goto err;
 
 	f->bufsiz = BUFSIZ;
-	f->offset = _IO_UNGET_SLOP;
-	f->bytes = 0;		/* No bytes in buffer */
+	f->data = f->buf + _IO_UNGET_SLOP;
+	f->bytes = 0;		/* No data in buffer */
 	f->flags = isatty(fd) ? _IO_FILE_FLAG_LINE_BUF : 0;
 
 	/* Insert into linked list */
diff --git a/usr/klibc/stdio/ungetc.c b/usr/klibc/stdio/ungetc.c
index b2a304cdfb803..f8ed58dffa1aa 100644
--- a/usr/klibc/stdio/ungetc.c
+++ b/usr/klibc/stdio/ungetc.c
@@ -6,10 +6,10 @@
 
 int ungetc(int c, FILE *f)
 {
-	if (f->flags & _IO_FILE_FLAG_WRITE || f->offset <= 0)
+	if (f->flags & _IO_FILE_FLAG_WRITE || f->data <= f->buf)
 		return EOF;
 
-	f->buf[--f->offset] = c;
+	*(--f->data) = c;
 	f->bytes++;
 	f->flags |= _IO_FILE_FLAG_READ;
 	return c;