From: Pavel Charvat <pavel.charvat@netcentrum.cz>
Date: Mon, 18 Sep 2006 12:57:07 +0000 (+0200)
Subject: printf to a growing buffer
X-Git-Tag: holmes-import~533
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=6a3e2a5bc9b84ac6b0b8efc38455fb93a212fea7;p=libucw.git

printf to a growing buffer
---

diff --git a/lib/bbuf.c b/lib/bbuf.c
new file mode 100644
index 00000000..b664a79d
--- /dev/null
+++ b/lib/bbuf.c
@@ -0,0 +1,70 @@
+/*
+ *	UCW Library -- A simple growing buffers for byte-sized items
+ *
+ *	(c) 2006 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 "lib/lib.h"
+#include "lib/bbuf.h"
+
+#include <stdio.h>
+
+char *
+bb_ofs_vprintf(bb_t *bb, uns ofs, char *fmt, va_list args)
+{
+  bb_grow(bb, ofs + 1);
+  va_list args2;
+  va_copy(args2, args);
+  int cnt = vsnprintf(bb->ptr + ofs, bb->len - ofs, fmt, args2);
+  va_end(args2);
+  if (cnt < 0)
+    {
+      /* Our C library doesn't support C99 return value of vsnprintf, so we need to iterate */
+      do
+        {
+	  bb_do_grow(bb, bb->len + 1);
+          va_copy(args2, args);
+          cnt = vsnprintf(bb->ptr + ofs, bb->len - ofs, fmt, args2);
+          va_end(args2);
+	}
+      while (cnt < 0);
+    }
+  else if (cnt >= bb->len - ofs)
+    {
+      bb_do_grow(bb, ofs + cnt + 1);
+      va_copy(args2, args);
+      int cnt2 = vsnprintf(bb->ptr + ofs, bb->len - ofs, fmt, args2);
+      va_end(args2);
+      ASSERT(cnt2 == cnt);
+    }
+  return bb->ptr + ofs;
+}
+
+char *
+bb_ofs_printf(bb_t *bb, uns ofs, char *fmt, ...)
+{
+  va_list args;
+  va_start(args, fmt);
+  char *res = bb_ofs_vprintf(bb, ofs, fmt, args);
+  va_end(args);
+  return res;
+}
+
+#ifdef TEST
+
+int main(void)
+{
+  bb_t bb;
+  bb_init(&bb);
+  char *x = bb_ofs_printf(&bb, 0, "<Hello, %s!>", "World");
+  fputs(x, stdout);
+  x = bb_ofs_printf(&bb, 5, "<Hello, %50s!>\n", "World");
+  fputs(x, stdout);
+  bb_done(&bb);
+  return 0;
+}
+
+#endif
diff --git a/lib/bbuf.h b/lib/bbuf.h
index 0d17f8cc..ad7ce39d 100644
--- a/lib/bbuf.h
+++ b/lib/bbuf.h
@@ -14,4 +14,7 @@
 #define	GBUF_PREFIX(x)	bb_##x
 #include "lib/gbuf.h"
 
+char *bb_ofs_vprintf(bb_t *bb, uns ofs, char *fmt, va_list args);
+char *bb_ofs_printf(bb_t *bb, uns ofs, char *fmt, ...);
+
 #endif
diff --git a/lib/bbuf.t b/lib/bbuf.t
new file mode 100644
index 00000000..cfc70b31
--- /dev/null
+++ b/lib/bbuf.t
@@ -0,0 +1,4 @@
+# Tests for growing buffers
+
+Run:	obj/lib/bbuf-t
+Out:	<Hello, World!><Hello,                                              World!>