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authorConrad Meyer <cem@FreeBSD.org>2019-08-07 19:27:14 +0000
committerConrad Meyer <cem@FreeBSD.org>2019-08-07 19:27:14 +0000
commit76cb1112da20279c59bc8189519c4122a4d0d96a (patch)
tree1866888e51f1ea8c830a5b119569d4c78b30d16f /sys/kern
parentd23813cdb9a927b0c2965fcb4979edaad5f21dae (diff)
downloadsrc-76cb1112da20279c59bc8189519c4122a4d0d96a.tar.gz
src-76cb1112da20279c59bc8189519c4122a4d0d96a.zip
sbuf(9): Add sbuf_nl_terminate() API
The API is used to gracefully terminate text line(s) with a single \n. If the formatted buffer was empty or already ended in \n, it is unmodified. Otherwise, a newline character is appended to it. The API, like other sbuf-modifying routines, is only valid while the sbuf is not FINISHED. Reviewed by: rlibby Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D21030
Notes
Notes: svn path=/head/; revision=350693
Diffstat (limited to 'sys/kern')
-rw-r--r--sys/kern/subr_sbuf.c52
1 files changed, 51 insertions, 1 deletions
diff --git a/sys/kern/subr_sbuf.c b/sys/kern/subr_sbuf.c
index ebde3bee6405..17fde523fc67 100644
--- a/sys/kern/subr_sbuf.c
+++ b/sys/kern/subr_sbuf.c
@@ -70,6 +70,7 @@ static MALLOC_DEFINE(M_SBUF, "sbuf", "string buffers");
#define SBUF_ISDYNAMIC(s) ((s)->s_flags & SBUF_DYNAMIC)
#define SBUF_ISDYNSTRUCT(s) ((s)->s_flags & SBUF_DYNSTRUCT)
#define SBUF_ISFINISHED(s) ((s)->s_flags & SBUF_FINISHED)
+#define SBUF_ISDRAINATEOL(s) ((s)->s_flags & SBUF_DRAINATEOL)
#define SBUF_HASROOM(s) ((s)->s_len < (s)->s_size - 1)
#define SBUF_FREESPACE(s) ((s)->s_size - ((s)->s_len + 1))
#define SBUF_CANEXTEND(s) ((s)->s_flags & SBUF_AUTOEXTEND)
@@ -225,6 +226,10 @@ sbuf_new(struct sbuf *s, char *buf, int length, int flags)
s->s_flags |= flags;
s->s_size = length;
s->s_buf = buf;
+ /*
+ * Never-written sbufs do not need \n termination.
+ */
+ SBUF_SETFLAG(s, SBUF_DRAINATEOL);
/*
* Allocate DYNAMIC, i.e., heap data buffer backing the sbuf, if no
@@ -310,6 +315,8 @@ sbuf_clear(struct sbuf *s)
assert_sbuf_integrity(s);
/* don't care if it's finished or not */
+ KASSERT(s->s_drain_func == NULL,
+ ("%s makes no sense on sbuf %p with drain", __func__, s));
SBUF_CLEARFLAG(s, SBUF_FINISHED);
s->s_error = 0;
@@ -384,6 +391,7 @@ sbuf_drain(struct sbuf *s)
KASSERT(s->s_len > 0, ("Shouldn't drain empty sbuf %p", s));
KASSERT(s->s_error == 0, ("Called %s with error on %p", __func__, s));
+
if (SBUF_DODRAINTOEOR(s) && s->s_rec_off == 0)
return (s->s_error = EDEADLK);
len = s->s_drain_func(s->s_drain_arg, s->s_buf,
@@ -400,8 +408,18 @@ sbuf_drain(struct sbuf *s)
* Fast path for the expected case where all the data was
* drained.
*/
- if (s->s_len == 0)
+ if (s->s_len == 0) {
+ /*
+ * When the s_buf is entirely drained, we need to remember if
+ * the last character was a '\n' or not for
+ * sbuf_nl_terminate().
+ */
+ if (s->s_buf[len - 1] == '\n')
+ SBUF_SETFLAG(s, SBUF_DRAINATEOL);
+ else
+ SBUF_CLEARFLAG(s, SBUF_DRAINATEOL);
return (0);
+ }
/*
* Move the remaining characters to the beginning of the
* string.
@@ -717,6 +735,38 @@ sbuf_putc(struct sbuf *s, int c)
}
/*
+ * Append a trailing newline to a non-empty sbuf, if one is not already
+ * present. Handles sbufs with drain functions correctly.
+ */
+int
+sbuf_nl_terminate(struct sbuf *s)
+{
+
+ assert_sbuf_integrity(s);
+ assert_sbuf_state(s, 0);
+
+ /*
+ * If the s_buf isn't empty, the last byte is simply s_buf[s_len - 1].
+ *
+ * If the s_buf is empty because a drain function drained it, we
+ * remember if the last byte was a \n with the SBUF_DRAINATEOL flag in
+ * sbuf_drain().
+ *
+ * In either case, we only append a \n if the previous character was
+ * something else.
+ */
+ if (s->s_len == 0) {
+ if (!SBUF_ISDRAINATEOL(s))
+ sbuf_put_byte(s, '\n');
+ } else if (s->s_buf[s->s_len - 1] != '\n')
+ sbuf_put_byte(s, '\n');
+
+ if (s->s_error != 0)
+ return (-1);
+ return (0);
+}
+
+/*
* Trim whitespace characters from end of an sbuf.
*/
int