kunit: string-stream: Replace strlcat() with strscpy() and seq_buf

In preparation for removing the strlcat() API[1], replace its uses in
string-stream.

string_stream_vadd() appends at most a single newline into space that
was explicitly reserved when the fragment was sized, so a bounded copy
at the end of the string is enough. The return value of strscpy()
keeps the length accounting unchanged. string_stream_get_string()
concatenates a variable number of fragments into a buffer sized to
hold them all, which is what seq_buf is for.

Link: https://lore.kernel.org/r/akenPvVk1xr_-480@dev
Link: https://github.com/KSPP/linux/issues/370
Signed-off-by: Ian Bridges <icb@fastmail.org>
Reviewed-by: David Gow <david@davidgow.net>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

diff --git a/lib/kunit/string-stream.c b/lib/kunit/string-stream.c
index 0d8f1b30559b5f813d4dc05cfb95ab9f2a854231..51ba40ebf19fff2423962b56b0447b253d27be3f 100644 (file)
--- a/lib/kunit/string-stream.c
+++ b/lib/kunit/string-stream.c
@@ -9,6 +9,7 @@
 #include <kunit/static_stub.h>
 #include <kunit/test.h>
 #include <linux/list.h>
+#include <linux/seq_buf.h>
 #include <linux/slab.h>
 
 #include "string-stream.h"
@@ -74,7 +75,8 @@ int string_stream_vadd(struct string_stream *stream,
 
                /* Append newline if necessary. */
                if (frag_container->fragment[result_len - 1] != '\n')
-                       result_len = strlcat(frag_container->fragment, "\n", buf_len);
+                       result_len += strscpy(frag_container->fragment + result_len,
+                                             "\n", buf_len - result_len);
        } else {
                result_len = vsnprintf(frag_container->fragment, buf_len, fmt, args);
        }
@@ -118,15 +120,18 @@ char *string_stream_get_string(struct string_stream *stream)
 {
        struct string_stream_fragment *frag_container;
        size_t buf_len = stream->length + 1; /* +1 for null byte. */
+       struct seq_buf sb;
        char *buf;
 
        buf = kzalloc(buf_len, stream->gfp);
        if (!buf)
                return NULL;
 
+       seq_buf_init(&sb, buf, buf_len);
+
        spin_lock(&stream->lock);
        list_for_each_entry(frag_container, &stream->fragments, node)
-               strlcat(buf, frag_container->fragment, buf_len);
+               seq_buf_puts(&sb, frag_container->fragment);
        spin_unlock(&stream->lock);
 
        return buf;