test: cover sfsTest

src/sfsTest.c

@@ -781,3 +781,165 @@ KTEST(sfsSymlinkResolvesToTargetFile)
     if (!KT_TRUE(t, sfsFormat()))
         return;
 
+    int32 f = sfsCreateFile("real.txt");
+    KT_TRUE(t, f > 0);
+    const char* msg = "reached through a link";
+    uint64 len = strlen(msg);
+    KT_EQ(t, sfsWriteAt(f, 0, msg, len), (int64)len);
+
+    int32 link = sfsCreateSymlink("link.txt", "real.txt");
+    KT_TRUE(t, link > 0);
+    KT_NE(t, link, f);
+
+    /* sfsLookup follows the symlink: it must land on the SAME inode as
+       looking the real file up directly, not a copy of it. */
+    KT_EQ(t, sfsLookup("link.txt"), f);
+    KT_EQ(t, sfsTypeOf(sfsLookup("link.txt")), sfsTypeFile);
+
+    char back[64];
+    memset(back, 0, sizeof(back));
+    KT_EQ(t, sfsReadAt(sfsLookup("link.txt"), 0, back, len), (int64)len);
+    KT_EQ(t, memcmp(back, msg, len), 0);
+}
+
+KTEST(sfsReadlinkReturnsStoredTargetAndNoFollowSeesTheLinkItself)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    int32 f = sfsCreateFile("real.txt");
+    KT_TRUE(t, f > 0);
+    int32 link = sfsCreateSymlink("link.txt", "real.txt");
+    KT_TRUE(t, link > 0);
+
+    char target[32];
+    memset(target, 0, sizeof(target));
+    KT_TRUE(t, sfsReadlink(link, target, sizeof(target)));
+    KT_STREQ(t, target, "real.txt");
+
+    /* No-follow gives back the symlink's own inode (and its own type),
+       distinct from what sfsLookup (which follows) would give. */
+    int32 noFollow = sfsLookupNoFollow("link.txt");
+    KT_EQ(t, noFollow, link);
+    KT_EQ(t, sfsTypeOf(noFollow), sfsTypeSymlink);
+    KT_NE(t, noFollow, f);
+}
+
+KTEST(sfsReadlinkRejectsNonSymlinkAndUndersizedBuffer)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    int32 f = sfsCreateFile("plain.txt");
+    KT_TRUE(t, f > 0);
+    char buf[8];
+    KT_FALSE(t, sfsReadlink(f, buf, sizeof(buf)));
+
+    int32 link = sfsCreateSymlink("link.txt", "a target long enough to not fit");
+    KT_TRUE(t, link > 0);
+
+    char tiny[4];
+    KT_FALSE(t, sfsReadlink(link, tiny, sizeof(tiny)));
+}
+
+KTEST(sfsSymlinkToDirectoryAllowsDescendingThroughIt)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    KT_TRUE(t, sfsCreateDir("realdir") > 0);
+    int32 f = sfsCreateFile("realdir/inside.txt");
+    KT_TRUE(t, f > 0);
+    KT_EQ(t, sfsWriteAt(f, 0, "found me", 8), 8);
+
+    int32 link = sfsCreateSymlink("linkdir", "realdir");
+    KT_TRUE(t, link > 0);
+    KT_EQ(t, sfsTypeOf(link), sfsTypeSymlink);
+
+    /* The symlink is an INTERMEDIATE component here (there is more path
+       after it), which must still be followed even though sfsLookup's
+       "final component" special case does not apply. */
+    int32 viaLink = sfsLookup("linkdir/inside.txt");
+    KT_EQ(t, viaLink, f);
+
+    /* Creating a new file through the symlinked directory must land in the
+       real directory, reachable from both paths. */
+    KT_TRUE(t, sfsCreateFile("linkdir/new.txt") > 0);
+    KT_EQ(t, sfsLookup("realdir/new.txt"), sfsLookup("linkdir/new.txt"));
+}
+
+KTEST(sfsDanglingSymlinkFailsLookupButReadlinkStillWorks)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    int32 link = sfsCreateSymlink("broken.txt", "does/not/exist.txt");
+    KT_TRUE(t, link > 0);
+
+    KT_EQ(t, sfsLookup("broken.txt"), -1);
+
+    char target[64];
+    memset(target, 0, sizeof(target));
+    KT_TRUE(t, sfsReadlink(link, target, sizeof(target)));
+    KT_STREQ(t, target, "does/not/exist.txt");
+}
+
+KTEST(sfsSymlinkCycleFailsCleanlyInsteadOfHanging)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    KT_TRUE(t, sfsCreateSymlink("a", "b") > 0);
+    KT_TRUE(t, sfsCreateSymlink("b", "a") > 0);
+
+    /* The whole point: this must return with an error, not recurse forever
+       (or overflow the caller's stack) chasing a->b->a->b->... */
+    KT_EQ(t, sfsLookup("a"), -1);
+    KT_EQ(t, sfsLookup("b"), -1);
+
+    /* The table must still be in a usable state afterward - a failed
+       resolution is not the same thing as a corrupted filesystem. */
+    KT_TRUE(t, sfsCreateFile("stillworks.txt") > 0);
+}
+
+KTEST(sfsCreateSymlinkRejectsEmptyOrOversizedTarget)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    KT_EQ(t, sfsCreateSymlink("empty.txt", ""), -1);
+
+    char huge[sfsSymlinkTargetMax + 2];
+    memset(huge, 'x', sizeof(huge) - 1);
+    huge[sizeof(huge) - 1] = 0;
+    KT_EQ(t, sfsCreateSymlink("huge.txt", huge), -1);
+
+    /* Rejected attempts must not leave a half-created inode or directory
+       entry behind. */
+    KT_EQ(t, sfsLookupNoFollow("empty.txt"), -1);
+    KT_EQ(t, sfsLookupNoFollow("huge.txt"), -1);
+}
+
+KTEST(sfsRemoveSymlinkDoesNotAffectTarget)
+{
+    if (!KT_TRUE(t, sfsFormat()))
+        return;
+
+    int32 f = sfsCreateFile("real.txt");
+    KT_TRUE(t, f > 0);
+    KT_EQ(t, sfsWriteAt(f, 0, "untouched", 9), 9);
+    KT_TRUE(t, sfsCreateSymlink("link.txt", "real.txt") > 0);
+
+    KT_TRUE(t, sfsRemove("link.txt"));
+    KT_EQ(t, sfsLookupNoFollow("link.txt"), -1);
+
+    /* The target must survive with its data intact - unlink of a symlink
+       must never recurse into what it points at. */
+    int32 stillThere = sfsLookup("real.txt");
+    KT_EQ(t, stillThere, f);
+    char back[16];
+    memset(back, 0, sizeof(back));
+    KT_EQ(t, sfsReadAt(stillThere, 0, back, 9), 9);
+    KT_EQ(t, memcmp(back, "untouched", 9), 0);
+}
+