Null fastbuf: Implemented a new "/dev/null"-like fastbuf.

diff --git a/ucw/Makefile b/ucw/Makefile
index c098ce2f71c5b610d826136b2441dc050cb6c90c..5a13a35c7e3f2106c50eb9f9939dcbcf7a7cbbca 100644 (file)
--- a/ucw/Makefile
+++ b/ucw/Makefile
@@ -17,7 +17,7 @@ LIBUCW_MODS= \
        conf-context conf-alloc conf-dump conf-input conf-intr conf-journal conf-parse conf-section conf-getopt \
        ipaccess \
        fastbuf ff-binary ff-string ff-printf ff-unicode ff-varint ff-stkstring \
-       fb-file fb-mem fb-temp tempfile fb-mmap fb-limfd fb-buffer fb-grow fb-pool fb-atomic fb-param fb-socket fb-multi \
+       fb-file fb-mem fb-temp tempfile fb-mmap fb-limfd fb-buffer fb-grow fb-pool fb-atomic fb-param fb-socket fb-multi fb-null \
        char-cat char-upper char-lower unicode varint stkstring \
        wildmatch regex \
        prime primetable random \
@@ -137,9 +137,10 @@ $(o)/ucw/opt-test: $(o)/ucw/opt-test.o $(LIBUCW)
 
 TESTS+=$(addprefix $(o)/ucw/,regex.test unicode.test hash-test.test mempool.test stkstring.test \
     slists.test bbuf.test kmp-test.test getopt.test ff-unicode.test eltpool.test \
-    fb-socket.test trie-test.test string.test sha1.test asort-test.test binheap-test.test \
-    redblack-test.test fb-file.test fb-grow.test fb-pool.test fb-atomic.test \
-    fb-limfd.test fb-temp.test fb-mem.test fb-buffer.test fb-mmap.test fb-multi.test url.test strtonum-test.test \
+    trie-test.test string.test sha1.test asort-test.test binheap-test.test \
+    fb-file.test fb-socket.test fb-grow.test fb-pool.test fb-atomic.test fb-limfd.test fb-temp.test \
+    fb-mem.test fb-buffer.test fb-mmap.test fb-multi.test fb-null.test \
+    redblack-test.test url.test strtonum-test.test \
     gary.test time.test crc.test signames.test md5.test bitops.test opt.test)
 
 $(o)/ucw/varint.test: $(o)/ucw/varint-t
@@ -164,7 +165,7 @@ $(o)/ucw/binheap-test.test: $(o)/ucw/binheap-test
 $(o)/ucw/redblack-test.test: $(o)/ucw/redblack-test
 $(o)/ucw/strtonum-test.test: $(o)/ucw/strtonum-test
 $(addprefix $(o)/ucw/fb-,file.test grow.test pool.test socket.test atomic.test \
-       limfd.test temp.test mem.test buffer.test mmap.test multi.test): %.test: %-t
+       limfd.test temp.test mem.test buffer.test mmap.test multi.test null.test): %.test: %-t
 $(o)/ucw/url.test: $(o)/ucw/url-t
 $(o)/ucw/gary.test: $(o)/ucw/gary-t
 $(o)/ucw/time.test: $(o)/ucw/time-conf-t

diff --git a/ucw/fastbuf.h b/ucw/fastbuf.h
index d2904433afc6c3dbf31a1d66d3433a46e500a8d6..0fa48a432f96c0f0be9e262fe9bd283b2a2f8461 100644 (file)
--- a/ucw/fastbuf.h
+++ b/ucw/fastbuf.h
@@ -3,6 +3,7 @@
  *
  *     (c) 1997--2011 Martin Mares <mj@ucw.cz>
  *     (c) 2004 Robert Spalek <robert@ucw.cz>
+ *     (c) 2014 Pavel Charvat <pchar@ucw.cz>
  *
  *     This software may be freely distributed and used according to the terms
  *     of the GNU Lesser General Public License.
@@ -542,6 +543,25 @@ static inline void fbatomic_commit(struct fastbuf *b)
     fbatomic_internal_write(b);
 }
 
+/*** === Null fastbufs ***/
+
+/**
+ * Creates a new "/dev/null"-like  fastbuf.
+ * Any read attempt returns an EOF, any write attempt is silently ignored.
+ **/
+struct fastbuf *fbnull_open(uns bufsize);
+
+/**
+ * Can be used by any back-end to switch it to the null mode.
+ * You need to provide at least one byte long buffer for writing.
+ **/
+void fbnull_start(struct fastbuf *b, byte *buf, uns bufsize);
+
+/**
+ * Checks whether a fastbuf has been switched to the null mode.
+ **/
+bool fbnull_test(struct fastbuf *b);
+
 /***
  * === Fastbufs atop other fastbufs [[fbmulti]]
  *

diff --git a/ucw/fb-null.c b/ucw/fb-null.c
new file mode 100644 (file)
index 0000000..6f0a40a
--- /dev/null
+++ b/ucw/fb-null.c
@@ -0,0 +1,84 @@
+/*
+ *     UCW Library -- Null fastbuf
+ *
+ *     (c) 2014 Pavel Charvat <pchar@ucw.cz>
+ *
+ *     This software may be freely distributed and used according to the terms
+ *     of the GNU Lesser General Public License.
+ */
+
+#include <ucw/lib.h>
+#include <ucw/fastbuf.h>
+
+#include <stdio.h>
+
+static void fbnull_close(struct fastbuf *b)
+{
+  xfree(b);
+}
+
+struct fastbuf *fbnull_open(uns bufsize)
+{
+  struct fastbuf *b = xmalloc(sizeof(*b) + bufsize);
+  bzero(b, sizeof(*b));
+  b->close = fbnull_close;
+  fbnull_start(b, (byte *)(b + 1), bufsize);
+  return b;
+}
+
+static int fbnull_refill(struct fastbuf *b UNUSED)
+{
+  return 0;
+}
+
+static void fbnull_spout(struct fastbuf *b)
+{
+  b->pos += b->bptr - b->bstop;
+  b->bptr = b->bstop;
+}
+
+static int fbnull_seek(struct fastbuf *b, ucw_off_t pos, int whence)
+{
+  b->pos = (whence == SEEK_END) ? 0 : pos;
+  b->bptr = b->bstop;
+  return 1;
+}
+
+void fbnull_start(struct fastbuf *b, byte *buf, uns bufsize)
+{
+  ASSERT(buf && bufsize);
+  b->pos = btell(b);
+  b->buffer = b->bptr = b->bstop = buf;
+  b->bufend = buf + bufsize;
+  b->refill = fbnull_refill;
+  b->spout = fbnull_spout;
+  b->seek = fbnull_seek;
+  b->can_overwrite_buffer = 2;
+}
+
+bool fbnull_test(struct fastbuf *b)
+{
+  return b->refill == fbnull_refill;
+}
+
+#ifdef TEST
+int main(void)
+{
+  struct fastbuf *b = fbnull_open(7);
+  for (uns i = 0; i < 100; i++)
+    {
+      if (btell(b) != i * 10)
+       ASSERT(0);
+      if (bgetc(b) >= 0)
+        ASSERT(0);
+      bputs(b, "0123456789");
+      bflush(b);
+    }
+  if (bfilesize(b) != 0)
+    ASSERT(0);
+  if (btell(b) != 100 * 10)
+    ASSERT(0);
+  bclose(b);
+  return 0;
+}
+#endif

diff --git a/ucw/fb-null.t b/ucw/fb-null.t
new file mode 100644 (file)
index 0000000..c5be156
--- /dev/null
+++ b/ucw/fb-null.t
@@ -0,0 +1,3 @@
+# Tests for fb-null.c
+
+Run:   ../obj/ucw/fb-null-t