add buffer_peekc

buffer.h

@@ -125,6 +125,7 @@ __writememsz__(2,3)
 ssize_t buffer_get(buffer* b,char* x,size_t len);
 ssize_t buffer_feed(buffer* b);
 ssize_t buffer_getc(buffer* b,char* x);
+ssize_t buffer_peekc(buffer* b,char* x);
 __writememsz__(2,3)
 ssize_t buffer_getn(buffer* b,char* x,size_t len);
 

buffer/buffer_peekc.3

@@ -0,0 +1,17 @@
+.TH buffer_peekc 3
+.SH NAME
+buffer_peekc \- read one char from buffer
+.SH SYNTAX
+.B #include <libowfat/buffer.h>
+
+int \fBbuffer_peekc\fP(buffer* \fIb\fR,char* \fIx\fR);
+.SH DESCRIPTION
+buffer_peekc(b,x) is like buffer_get(b,x,1) but without
+advancing the buffer pointer. If you call it again, or call
+\fIbuffer_getc\fR after it, you will get the same data again.
+
+.SH "RETURN VALUE"
+\fIbuffer_peekc\fR returns 1 on success, 0 when at the end of the file, 
+or -1 if there was an I/O error (setting \fIerrno\fR appropriately).
+.SH "SEE ALSO"
+buffer_init(3), buffer_get(3), buffer_getc(3), buffer(3)

buffer/buffer_peekc.c

@@ -0,0 +1,11 @@
+#include "byte.h"
+#include "buffer.h"
+
+ssize_t buffer_peekc(buffer* b,char* x) {
+  if (b->p==b->n) {
+    register ssize_t blen;
+    if ((blen=buffer_feed(b))<=0) return blen;
+  }
+  *x=b->x[b->p];
+  return 1;
+}