X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fstdio%2Fvsnprintf.c;h=b3510a63408abe2d4d08e630aa1ddf5b7ba1480a;hb=9b132e556774c744f9052581d2d8d0fab417e97c;hp=ff792e1717223c0dd51f2d46433961a5aa6677f1;hpb=5eb0d33ec0f08b123c5c10877d6258d05fa9453a;p=musl

diff --git a/src/stdio/vsnprintf.c b/src/stdio/vsnprintf.c
index ff792e17..b3510a63 100644
--- a/src/stdio/vsnprintf.c
+++ b/src/stdio/vsnprintf.c
@@ -1,34 +1,55 @@
 #include "stdio_impl.h"
+#include <limits.h>
+#include <string.h>
+#include <errno.h>
+#include <stdint.h>
+
+struct cookie {
+	char *s;
+	size_t n;
+};
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
 
 static size_t sn_write(FILE *f, const unsigned char *s, size_t l)
 {
-	/* pretend to succeed, but discard data */
+	struct cookie *c = f->cookie;
+	size_t k = MIN(c->n, f->wpos - f->wbase);
+	if (k) {
+		memcpy(c->s, f->wbase, k);
+		c->s += k;
+		c->n -= k;
+	}
+	k = MIN(c->n, l);
+	if (k) {
+		memcpy(c->s, s, k);
+		c->s += k;
+		c->n -= k;
+	}
+	*c->s = 0;
+	f->wpos = f->wbase = f->buf;
+	/* pretend to succeed, even if we discarded extra data */
 	return l;
 }
 
-int vsnprintf(char *s, size_t n, const char *fmt, va_list ap)
+int vsnprintf(char *restrict s, size_t n, const char *restrict fmt, va_list ap)
 {
-	int r;
-	FILE f;
 	unsigned char buf[1];
+	char dummy[1];
+	struct cookie c = { .s = n ? s : dummy, .n = n ? n-1 : 0 };
+	FILE f = {
+		.lbf = EOF,
+		.write = sn_write,
+		.lock = -1,
+		.buf = buf,
+		.cookie = &c,
+	};
 
-	memset(&f, 0, sizeof(FILE));
-	f.lbf = EOF;
-	f.write = sn_write;
-	f.buf_size = 1;
-	f.buf = buf;
-	f.owner = -1;
 	if (n > INT_MAX) {
 		errno = EOVERFLOW;
 		return -1;
-	} else if (n > 0) {
-		if (n > (char *)0+SIZE_MAX-s) n = (char *)0+SIZE_MAX-s;
-		f.wpos = s;
-		f.wbase = f.wend = s+n-1;
-		f.wstop = f.wend - 1;
 	}
-	r = vfprintf(&f, fmt, ap);
-	/* wpos points just after last byte written, or to s+n-1 (wbase) */
-	*f.wpos = 0;
-	return r;
+
+	*c.s = 0;
+	return vfprintf(&f, fmt, ap);
 }