I was going through the learnuv project and looking at uv_fs_read. The method signature here differs from the actual method signature in uv.h

libuv-dox

int uv_fs_read(uv_loop_t* loop,
               uv_fs_t* req,
               uv_file file,
               void* buf,
               size_t length,
               int64_t offset,
               uv_fs_cb cb);

uv.h

int uv_fs_read(uv_loop_t* loop,
               uv_fs_t* req,
               uv_file file,
               const uv_buf_t bufs[],
               unsigned int nbufs,
               int64_t offset,
               uv_fs_cb cb);

The same goes for uv_fs_write. I'm new to libuv, so am I missing something?

Hello there,
I am trying to compile libuv examples, and i get undefined reference errors in all of them. In particular in 05-tcp-echo-server i get the following output:

find . -name ".gc" -exec rm {} ;
rm -rf find . -name "*.dSYM" -print
rm -f main main.o
cc -g -O2 -Wall -I/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/../libuv/include/ /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/../libuv/out/Debug/libuv.a main.c -o main
main.c: In function ‘read_cb’:
main.c:47:8: warning: unused variable ‘readp’ [-Wunused-variable]
/tmp/ccEhPGtr.o: In function read_cb': /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:66: undefined reference touv_buf_init'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:55: undefined reference to uv_close' /tmp/ccEhPGtr.o: In functionwrite_cb':
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:78: undefined reference to uv_strerror' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:78: undefined reference touv_err_name'
/tmp/ccEhPGtr.o: In function alloc_cb': /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:41: undefined reference touv_buf_init'
/tmp/ccEhPGtr.o: In function connection_cb': /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:29: undefined reference touv_tcp_init'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:31: undefined reference to uv_accept' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:26: undefined reference touv_strerror'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:26: undefined reference to uv_err_name' /tmp/ccEhPGtr.o: In functionread_cb':
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:67: undefined reference to uv_write' /tmp/ccEhPGtr.o: In functionconnection_cb':
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:36: undefined reference to uv_read_start' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:34: undefined reference touv_close'
/tmp/ccEhPGtr.o: In function main': /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:89: undefined reference touv_default_loop'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:92: undefined reference to uv_tcp_init' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:95: undefined reference touv_ip4_addr'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:97: undefined reference to uv_tcp_bind' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:99: undefined reference touv_listen'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:104: undefined reference to uv_run' /home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:100: undefined reference touv_strerror'
/home/pgirao/Projects/Libraries/libuv-dox/examples/05-tcp-echo-server/main.c:100: undefined reference to `uv_err_name'
collect2: ld returned 1 exit status
make: *** [main] Error 1

I followed the instructions in the README.md.

Can someone help me?

Thank you!

I'm not entirely sure if this is correct so please bear with me.

On line 64, a write request is queued and sent, passing in a pointer to the buffer received from the read callback. However, on line 68, the same buffer can be freed if the callback is invoked with nread = 0.

This means that if a write request is queued, and while the write is pending on the libuv event loop, the read callback is invoked again with nread = 0, then the buffer which you are trying to write will be freed. This may result in a use-after-free, or at least a double free (since the same buffer later gets freed in the write callback).

Am I correct with my analysis?

There is no reference to uv_now in the tree, although it is present in the text.

Not sure if it can be considered an issue, but if you really follow correctness, it looks to me like the uv_walk method is more about a loop than a handle.

related #9

Hi!

https://github.com/thlorenz/libuv-dox/blob/master/types.md#signal doesn't state any inheritance from uv_handle_t.