a

libc/vsmprint.c

@@ -0,0 +1,70 @@
+#include <u.h>
+#include <libc.h>
+#include "fmtdef.h"
+
+static int
+fmtStrFlush(Fmt *f)
+{
+	char *s;
+	int n;
+
+	if(f->start == nil)
+		return 0;
+	n = (int)f->farg;
+	n *= 2;
+	s = f->start;
+	f->start = realloc(s, n);
+	if(f->start == nil){
+		f->farg = nil;
+		f->to = nil;
+		f->stop = nil;
+		free(s);
+		return 0;
+	}
+	f->farg = (void*)n;
+	f->to = (char*)f->start + ((char*)f->to - s);
+	f->stop = (char*)f->start + n - 1;
+	return 1;
+}
+
+int
+fmtstrinit(Fmt *f)
+{
+	int n;
+
+	memset(f, 0, sizeof *f);
+	f->runes = 0;
+	n = 32;
+	f->start = malloc(n);
+	if(f->start == nil)
+		return -1;
+	f->to = f->start;
+	f->stop = (char*)f->start + n - 1;
+	f->flush = fmtStrFlush;
+	f->farg = (void*)n;
+	f->nfmt = 0;
+	return 0;
+}
+
+/*
+ * print into an allocated string buffer
+ */
+char*
+vsmprint(char *fmt, va_list args)
+{
+	Fmt f;
+	int n;
+
+	if(fmtstrinit(&f) < 0)
+		return nil;
+	f.args = args;
+	n = dofmt(&f, fmt);
+	if(f.start == nil)
+		return nil;
+	if(n < 0){
+		free(f.start);
+		return nil;
+	}
+	*(char*)f.to = '\0';
+	return f.start;
+}