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authorRich Felker <dalias@aerifal.cx>2011-09-04 21:40:42 -0400
committerRich Felker <dalias@aerifal.cx>2011-09-04 21:40:42 -0400
commite72ee5786b1f328da131b87388333c2e3a09b7b3 (patch)
treeb50b10ec6edb5fad79386c1cdb6b249a91ba69a3
parenta7778dae226fbae335383bc92b6cdfccc5ea9f2e (diff)
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fix some fmemopen behaviors
read should not be allowed past "current size".
append mode should write at "current size", not buffer size.
null termination should not be written except when "current size" grows.
-rw-r--r--src/stdio/fmemopen.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/src/stdio/fmemopen.c b/src/stdio/fmemopen.c
index e2adfb22..260d2889 100644
--- a/src/stdio/fmemopen.c
+++ b/src/stdio/fmemopen.c
@@ -23,7 +23,8 @@ fail:
 static size_t mread(FILE *f, unsigned char *buf, size_t len)
 {
 	struct cookie *c = f->cookie;
-	size_t rem = c->size - c->pos;
+	size_t rem = c->len - c->pos;
+	if (c->pos > c->len) rem = 0;
 	if (len > rem) {
 		len = rem;
 		f->flags |= F_EOF;
@@ -48,13 +49,15 @@ static size_t mwrite(FILE *f, const unsigned char *buf, size_t len)
 		f->wpos = f->wbase;
 		if (mwrite(f, f->wpos, len2) < len2) return 0;
 	}
-	if (c->mode == 'a') c->pos = c->size;
+	if (c->mode == 'a') c->pos = c->len;
 	rem = c->size - c->pos;
 	if (len > rem) len = rem;
 	memcpy(c->buf+c->pos, buf, len);
 	c->pos += len;
-	if (c->pos >= c->len) c->len = c->pos;
-	c->buf[c->len==c->size ? c->len-1 : c->len] = 0;
+	if (c->pos >= c->len) {
+		c->len = c->pos;
+		c->buf[c->len==c->size ? c->len-1 : c->len] = 0;
+	}
 	return len;
 }