fmemopen fixes

disallow seek past end of buffer (per posix)
fix position accounting to include data buffered for read
don't set eof flag when no data was requested

diff --git a/src/stdio/fmemopen.c b/src/stdio/fmemopen.c
index f518528..ddb2433 100644 (file)
--- a/src/stdio/fmemopen.c
+++ b/src/stdio/fmemopen.c
@@ -16,7 +16,7 @@ fail:
                return -1;
        }
        base = (size_t [3]){0, c->pos, c->len}[whence];
-       if (off < -base || off > SSIZE_MAX-base) goto fail;
+       if (off < -base || off > (ssize_t)c->size-base) goto fail;
        return c->pos = base+off;
 }
 
@@ -24,6 +24,7 @@ static size_t mread(FILE *f, unsigned char *buf, size_t len)
 {
        struct cookie *c = f->cookie;
        size_t rem = c->size - c->pos;
+       if (!len) return 0;
        if (len > rem) len = rem;
        memcpy(buf, c->buf+c->pos, len);
        c->pos += len;
@@ -32,6 +33,7 @@ static size_t mread(FILE *f, unsigned char *buf, size_t len)
        f->rpos = f->buf;
        f->rend = f->buf + rem;
        memcpy(f->rpos, c->buf+c->pos, rem);
+       c->pos += rem;
        if (!len) f->flags |= F_EOF;
        return len;
 }