Date: 27 Jan 2001 23:43:02 +0100 From: Dag-Erling Smorgrav <des@ofug.org> To: "Justin T. Gibbs" <gibbs@scsiguy.com> Cc: freebsd-arch@FreeBSD.ORG Subject: Re: Proposed change to sbuf semantics Message-ID: <xzp66j0r4zt.fsf@flood.ping.uio.no> In-Reply-To: "Justin T. Gibbs"'s message of "Sat, 27 Jan 2001 15:30:32 -0700" References: <200101272230.f0RMUWO30395@aslan.scsiguy.com>
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--=-=-=
"Justin T. Gibbs" <gibbs@scsiguy.com> writes:
> >Is this acceptable to you?
> I still would need an "sbuf_empty()" type method.
This better?
DES
--
Dag-Erling Smorgrav - des@ofug.org
--=-=-=
Content-Type: text/x-patch
Content-Disposition: attachment; filename=sbuf.diff
Content-Description: sbuf patch
Index: sys/kern/subr_sbuf.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/subr_sbuf.c,v
retrieving revision 1.1
diff -u -r1.1 subr_sbuf.c
--- sys/kern/subr_sbuf.c 2000/12/13 19:51:07 1.1
+++ sys/kern/subr_sbuf.c 2001/01/27 22:41:08
@@ -38,6 +38,23 @@
MALLOC_DEFINE(M_SBUF, "sbuf", "string buffers");
+/*
+ * Predicates
+ */
+#define SBUF_ISDYNAMIC(s) ((s)->s_flags & SBUF_DYNAMIC)
+#define SBUF_ISFINISHED(s) ((s)->s_flags & SBUF_FINISHED)
+#define SBUF_HASOVERFLOWED(s) ((s)->s_flags & SBUF_OVERFLOWED)
+#define SBUF_HASROOM(s) ((s)->s_len < (s)->s_size - 1)
+
+/*
+ * Set / clear flags
+ */
+#define SBUF_SETFLAG(s, f) do { (s)->s_flags |= (f); } while (0)
+#define SBUF_CLEARFLAG(s, f) do { (s)->s_flags &= ~(f); } while (0)
+
+/*
+ * Debugging support
+ */
#ifdef INVARIANTS
static void
assert_sbuf_integrity(struct sbuf *s)
@@ -68,8 +85,10 @@
* big enough to hold at least length characters.
*/
int
-sbuf_new(struct sbuf *s, char *buf, size_t length, int flags)
+sbuf_new(struct sbuf *s, char *buf, int length, int flags)
{
+ KASSERT(length >= 0,
+ ("attempt to create an sbuf of negative length (%d)", length));
KASSERT(flags == 0,
(__FUNCTION__ " called with non-zero flags"));
KASSERT(s != NULL,
@@ -89,10 +108,23 @@
}
/*
+ * Clear an sbuf and reset its position
+ */
+void
+sbuf_clear(struct sbuf *s)
+{
+ assert_sbuf_integrity(s);
+
+ SBUF_CLEARFLAG(s, SBUF_FINISHED);
+ SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
+ s->s_len = 0;
+}
+
+/*
* Set the sbuf's position to an arbitrary value
*/
int
-sbuf_setpos(struct sbuf *s, size_t pos)
+sbuf_setpos(struct sbuf *s, int pos)
{
assert_sbuf_integrity(s);
assert_sbuf_state(s, 0);
@@ -138,7 +170,7 @@
assert_sbuf_integrity(s);
assert_sbuf_state(s, 0);
- s->s_len = 0;
+ sbuf_clear(s);
return (sbuf_cat(s, str));
}
@@ -168,7 +200,7 @@
sbuf_printf(struct sbuf *s, char *fmt, ...)
{
va_list ap;
- size_t len;
+ int len;
assert_sbuf_integrity(s);
assert_sbuf_state(s, 0);
@@ -212,20 +244,26 @@
}
/*
- * Finish off an sbuf.
+ * Check if an sbuf overflowed
*/
int
+sbuf_overflowed(struct sbuf *s)
+{
+ return SBUF_HASOVERFLOWED(s);
+}
+
+/*
+ * Finish off an sbuf.
+ */
+void
sbuf_finish(struct sbuf *s)
{
assert_sbuf_integrity(s);
assert_sbuf_state(s, 0);
- if (SBUF_HASOVERFLOWED(s))
- return (-1);
-
s->s_buf[s->s_len++] = '\0';
+ SBUF_CLEARFLAG(s, SBUF_OVERFLOWED);
SBUF_SETFLAG(s, SBUF_FINISHED);
- return (0);
}
/*
@@ -237,22 +275,20 @@
assert_sbuf_integrity(s);
assert_sbuf_state(s, SBUF_FINISHED);
- if (SBUF_HASOVERFLOWED(s))
- return (NULL);
return s->s_buf;
}
/*
* Return the length of the sbuf data.
*/
-size_t
+int
sbuf_len(struct sbuf *s)
{
assert_sbuf_integrity(s);
assert_sbuf_state(s, SBUF_FINISHED);
if (SBUF_HASOVERFLOWED(s))
- return (0);
+ return (-1);
return s->s_len;
}
Index: sys/sys/sbuf.h
===================================================================
RCS file: /home/ncvs/src/sys/sys/sbuf.h,v
retrieving revision 1.1
diff -u -r1.1 sbuf.h
--- sys/sys/sbuf.h 2000/12/13 19:51:07 1.1
+++ sys/sys/sbuf.h 2001/01/27 22:35:52
@@ -37,8 +37,8 @@
struct sbuf {
char *s_buf; /* storage buffer */
struct sbuf *s_next; /* next in chain */
- size_t s_size; /* size of storage buffer */
- size_t s_len; /* current length of string */
+ int s_size; /* size of storage buffer */
+ int s_len; /* current length of string */
#define SBUF_AUTOEXTEND 0x00000001 /* automatically extend buffer */
#define SBUF_DYNAMIC 0x00010000 /* s_buf must be freed */
#define SBUF_FINISHED 0x00020000 /* set by sbuf_finish() */
@@ -47,30 +47,19 @@
};
/*
- * Predicates
- */
-#define SBUF_ISDYNAMIC(s) ((s)->s_flags & SBUF_DYNAMIC)
-#define SBUF_ISFINISHED(s) ((s)->s_flags & SBUF_FINISHED)
-#define SBUF_HASOVERFLOWED(s) ((s)->s_flags & SBUF_OVERFLOWED)
-#define SBUF_HASROOM(s) ((s)->s_len < (s)->s_size - 1)
-
-/*
- * Other macros
- */
-#define SBUF_SETFLAG(s, f) do { (s)->s_flags |= (f); } while (0)
-
-/*
* API functions
*/
-int sbuf_new(struct sbuf *s, char *buf, size_t length, int flags);
-int sbuf_setpos(struct sbuf *s, size_t pos);
+int sbuf_new(struct sbuf *s, char *buf, int length, int flags);
+void sbuf_clear(struct sbuf *s);
+int sbuf_setpos(struct sbuf *s, int pos);
int sbuf_cat(struct sbuf *s, char *str);
int sbuf_cpy(struct sbuf *s, char *str);
int sbuf_printf(struct sbuf *s, char *fmt, ...);
int sbuf_putc(struct sbuf *s, int c);
-int sbuf_finish(struct sbuf *s);
+int sbuf_overflowed(struct sbuf *s);
+void sbuf_finish(struct sbuf *s);
char *sbuf_data(struct sbuf *s);
-size_t sbuf_len(struct sbuf *s);
+int sbuf_len(struct sbuf *s);
void sbuf_delete(struct sbuf *s);
#endif
Index: share/man/man9/sbuf.9
===================================================================
RCS file: /home/ncvs/src/share/man/man9/sbuf.9,v
retrieving revision 1.2
diff -u -r1.2 sbuf.9
--- share/man/man9/sbuf.9 2000/12/14 09:36:49 1.2
+++ share/man/man9/sbuf.9 2001/01/27 22:40:33
@@ -30,11 +30,13 @@
.Os FreeBSD
.Sh NAME
.Nm sbuf_new ,
+.Nm sbuf_clear ,
.Nm sbuf_setpos ,
.Nm sbuf_cat ,
.Nm sbuf_cpy ,
.Nm sbuf_printf ,
.Nm sbuf_putc ,
+.Nm sbuf_overflowed ,
.Nm sbuf_finish ,
.Nm sbuf_data ,
.Nm sbuf_len ,
@@ -43,9 +45,11 @@
.Sh SYNOPSIS
.Fd #include <sys/sbuf.h>
.Ft int
-.Fn sbuf_new "struct sbuf *s" "char *buf" "size_t length" "int flags"
+.Fn sbuf_new "struct sbuf *s" "char *buf" "int length" "int flags"
+.Ft void
+.Fn sbuf_clear "struct sbuf *s"
.Ft int
-.Fn sbuf_setpos "struct sbuf *s" "size_t pos"
+.Fn sbuf_setpos "struct sbuf *s" "int pos"
.Ft int
.Fn sbuf_cat "struct sbuf *s" "char *str"
.Ft int
@@ -55,10 +59,12 @@
.Ft int
.Fn sbuf_putc "struct sbuf *s" "int c"
.Ft int
+.Fn sbuf_overflowed "struct sbuf *s"
+.Ft void
.Fn sbuf_finish "struct sbuf *s"
.Ft char *
.Fn sbuf_data "struct sbuf *s"
-.Ft size_t
+.Ft int
.Fn sbuf_len "struct sbuf *s"
.Ft void
.Fn sbuf_delete "struct sbuf *s"
@@ -102,6 +108,12 @@
characters.
.Pp
The
+.Fn sbuf_clear
+function invalidates the contents of the
+.Fa sbuf
+and resets its position to zero.
+.Pp
+The
.Fn sbuf_setpos
function sets the
.Fa sbuf Ns 's
@@ -129,6 +141,8 @@
with a fresh
.Fa sbuf
or one which position has been reset to zero with
+.Fn sbuf_clear
+or
.Fn sbuf_setpos .
.Pp
The
@@ -149,6 +163,12 @@
at the current position.
.Pp
The
+.Fn sbuf_overflowed
+function returns a non-zero value if the
+.Fa sbuf
+overflowed.
+.Pp
+The
.Fn sbuf_finish
function null-terminates the
.Fa sbuf
@@ -165,8 +185,9 @@
.Fn sbuf_data
and
.Fn sbuf_len
-functions return the actual string and its length, respectively, and
-only work on a finished and non-overflowed
+functions return the actual string and its length, respectively;
+.Fn sbuf_data
+only works on a finished
.Fa sbuf .
.Pp
Finally, the
@@ -178,12 +199,14 @@
.Sh NOTES
If an operation caused an
.Fa sbuf
-to overflow, most subsequent operations (including
-.Fn sbuf_finish )
-on it will fail until the
-.Fa sbuf Ns 's
-position is reset to a value between 0 and one less than the size of
-its storage buffer using
+to overflow, most subsequent operations on it will fail until the
+.Fa sbuf
+is finished using
+.Fn sbuf_finish
+or reset using
+.Fn sbuf_clear ,
+or its position is reset to a value between 0 and one less than the
+size of its storage buffer using
.Fn sbuf_setpos ,
or it is reinitialized to a sufficiently short string using
.Fn sbuf_cpy .
@@ -200,17 +223,19 @@
.Fn sbuf_cat ,
.Fn sbuf_cpy ,
.Fn sbuf_printf ,
-.Fn sbuf_putc ,
and
-.Fn sbuf_finish
+.Fn sbuf_putc
all return \-1 if the buffer overflowed, and zero otherwise.
.Pp
+.Fn sbuf_overflowed
+returns a non-zero value if the buffer overflowed, and zero otherwise.
+.Pp
.Fn sbuf_data
and
.Fn sbuf_len
return
.Dv NULL
-and 0, respectively, if the buffer overflowed.
+and \-1, respectively, if the buffer overflowed.
.Sh SEE ALSO
.Xr printf 3 ,
.Xr strcat 3 ,
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