From: Mark Wooding <mdw@distorted.org.uk>
Date: Tue, 9 Jul 2024 17:09:03 +0000 (+0100)
Subject: struct/buf.c: Add new function `buf_fill' to include arbitrary padding.
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~mdw/git/mLib/commitdiff_plain/beee81ec8fc4857080e809c759575c4267f7bd1f?ds=sidebyside

struct/buf.c: Add new function `buf_fill' to include arbitrary padding.
---

diff --git a/struct/buf.3.in b/struct/buf.3.in
index f69d204..594cbdd 100644
--- a/struct/buf.3.in
+++ b/struct/buf.3.in
@@ -68,12 +68,14 @@
 .\" @buf_tryextend
 .\" @buf_get
 .\" @buf_put
+.\" @buf_fill
 .\" @dbuf_break
 .\" @dbuf_flip
 .\" @dbuf_ensure
 .\" @dbuf_tryextend
 .\" @dbuf_get
 .\" @dbuf_put
+.\" @dbuf_fill
 .
 .\" @buf_getbyte
 .\" @buf_putbyte
@@ -536,6 +538,7 @@ and taking a first argument of type
 .PP
 .BI "void *buf_get(buf *" b ", size_t " sz );
 .BI "int buf_put(buf *" b ", const void *" p ", size_t " sz );
+.BI "int buf_fill(buf *" b ", int " ch ", size_t " sz );
 .PP
 .BI "int buf_getbyte(buf *" b );
 .BI "int buf_putbyte(buf *" b ", int " ch );
@@ -827,6 +830,16 @@ function writes
 bytes of data starting at
 .I p
 to the buffer.  If it succeeded, it returns 0; otherwise it returns \-1.
+.PP
+The
+.B buf_fill
+function writes
+.I sz
+copies of the byte
+.I ch
+to the buffer, as if by calling
+.BR memset (3).
+If it succeeds, it returns 0; otherwise it returns \-1.
 .
 .SS "Formatted buffer access"
 The function
diff --git a/struct/buf.c b/struct/buf.c
index 67cc30e..4b02b28 100644
--- a/struct/buf.c
+++ b/struct/buf.c
@@ -200,6 +200,29 @@ int buf_put(buf *b, const void *p, size_t sz)
 int (dbuf_put)(dbuf *db, const void *p, size_t sz)
   { return (dbuf_put(db, p, sz)); }
 
+/* --- @{,d}buf_fill@ --- *
+ *
+ * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
+ *		@int ch@ = fill character
+ *		@size_t sz@ = size to fill
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Write @sz@ bytes with value @ch@ to the buffer, as if with
+ *		@memset@.
+ */
+
+int buf_fill(buf *b, int ch, size_t sz)
+{
+  void *p;
+
+  p = buf_get(b, sz); if (!p) return (-1);
+  if (sz) memset(p, ch, sz);
+  return (0);
+}
+int (dbuf_fill)(dbuf *db, int ch, size_t sz)
+  { return (dbuf_fill(db, ch, sz)); }
+
 /* --- @{,d}buf_getbyte@ --- *
  *
  * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
diff --git a/struct/buf.h b/struct/buf.h
index 2a37220..212bd72 100644
--- a/struct/buf.h
+++ b/struct/buf.h
@@ -273,6 +273,22 @@ extern int buf_put(buf */*b*/, const void */*p*/, size_t /*sz*/);
 extern int dbuf_put(dbuf */*db*/, const void */*p*/, size_t /*sz*/);
 #define dbuf_put(db, p, sz) (buf_put(DBUF_BUF(db), (p), (sz)))
 
+/* --- @{,d}buf_fill@ --- *
+ *
+ * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block
+ *		@int ch@ = fill character
+ *		@size_t sz@ = size to fill
+ *
+ * Returns:	Zero if it worked, nonzero if there wasn't enough space.
+ *
+ * Use:		Write @sz@ bytes with value @ch@ to the buffer, as if with
+ *		@memset@.
+ */
+
+extern int buf_fill(buf */*b*/, int /*ch*/, size_t /*sz*/);
+extern int dbuf_fill(dbuf */*db*/, int /*ch*/, size_t /*sz*/);
+#define dbuf_fill(db, ch, sz) (buf_fill(DBUF_BUF(db), (ch), (sz)))
+
 /* --- @{,d}buf_getbyte@ --- *
  *
  * Arguments:	@buf *b@ or @dbuf *db@ = pointer to a buffer block