[PATCH] fix: should process return value aux_close

From: Weixie Cui <[email protected]>

aux_close may return failed that should be handle.
reproduce error:

//failclose.c

static const char *hello_path = "/file";
static const char *hello_str  = "hello\n";

static int x_getattr(const char *path, struct stat *st, struct fuse_file_info *fi) {
    (void)fi;
    memset(st, 0, sizeof(*st));

    if (strcmp(path, "/") == 0) {
        st->st_mode = S_IFDIR | 0555;
        st->st_nlink = 2;
        return 0;
    }
    if (strcmp(path, hello_path) == 0) {
        st->st_mode = S_IFREG | 0444;
        st->st_nlink = 1;
        st->st_size = (off_t)strlen(hello_str);
        return 0;
    }
    return -ENOENT;
}

static int x_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
                     off_t off, struct fuse_file_info *fi,
                     enum fuse_readdir_flags flags) {
    (void)off; (void)fi; (void)flags;
    if (strcmp(path, "/") != 0) return -ENOENT;

    filler(buf, ".",  NULL, 0, 0);
    filler(buf, "..", NULL, 0, 0);
    filler(buf, hello_path + 1, NULL, 0, 0); // "file"
    return 0;
}

static int x_open(const char *path, struct fuse_file_info *fi) {
    if (strcmp(path, hello_path) != 0) return -ENOENT;
    // 只允许只读
    if ((fi->flags & O_ACCMODE) != O_RDONLY) return -EACCES;
    return 0;
}

static int x_read(const char *path, char *buf, size_t size, off_t off,
                  struct fuse_file_info *fi) {
    (void)fi;
    if (strcmp(path, hello_path) != 0) return -ENOENT;

    size_t len = strlen(hello_str);
    if ((size_t)off >= len) return 0;
    if (off + (off_t)size > (off_t)len) size = len - (size_t)off;

    memcpy(buf, hello_str + off, size);
    return (int)size;
}

// 关键：让 flush 返回错误 -> close(fd) 会失败
static int x_flush(const char *path, struct fuse_file_info *fi) {
    (void)path; (void)fi;
    return -EIO;  // 你也可以换成 -EPERM 等
}

static const struct fuse_operations ops = {
    .getattr = x_getattr,
    .readdir = x_readdir,
    .open    = x_open,
    .read    = x_read,
    .flush   = x_flush,
};

int main(int argc, char *argv[]) {
    return fuse_main(argc, argv, &ops, NULL);
}

mount fuse:
gcc failclose.c -o failclose $(pkg-config fuse3 --cflags --libs)
mkdir -p mnt
./failclose -f mnt

// t.lua
for line in io.lines("../mnt/file") do
  print(line)
end

execute command with lua with this patch:
lua t.lua

hello
./lua: t.lua:1: error closing file during lines iteration
stack traceback:
        [C]: in for iterator 'for iterator'
        t.lua:1: in main chunk
        [C]: in ?

Signed-off-by: Weixie Cui <[email protected]>
---
 liolib.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/liolib.c b/liolib.c
index 57615e6f..c3d8cee9 100644
--- a/liolib.c
+++ b/liolib.c
@@ -649,9 +649,13 @@ static int io_readline (lua_State *L) {
       return luaL_error(L, "%s", lua_tostring(L, -n + 1));
     }
     if (lua_toboolean(L, lua_upvalueindex(3))) {  /* generator created file? */
+      int nclose;
       lua_settop(L, 0);  /* clear stack */
       lua_pushvalue(L, lua_upvalueindex(1));  /* push file at index 1 */
-      aux_close(L);  /* close it */
+      nclose = aux_close(L);  /* close it */
+      if (!lua_toboolean(L, -nclose)) {
+         return luaL_error(L, "error closing file during lines iteration");
+      }
     }
     return 0;
   }
-- 
2.39.5 (Apple Git-154)

-- 
You received this message because you are subscribed to the Google Groups "lua-l" group.
To unsubscribe from this group and stop receiving emails from it, send an email to [email protected].
To view this discussion visit https://groups.google.com/d/msgid/lua-l/tencent_3670CEC5ECB28913F330185015D02BFE8907%40qq.com.