make read!() resize its array argument on EOFError

Make 'read!(::Base.LibuvStream, ::Array{UInt8, 1})' resize its array
argument on EOFError to indicate the number of bytes actually received.

base/stream.jl

@@ -913,13 +913,19 @@ function read!(s::LibuvStream, a::Array{UInt8, 1})
     @assert sbuf.seekable == false
     @assert sbuf.maxsize >= nb
 
-    if nb_available(sbuf) >= nb
+    nba = nb_available(sbuf)
+    if nba >= nb
         return read!(sbuf, a)
     end
 
     if nb <= SZ_UNBUFFERED_IO # Under this limit we are OK with copying the array from the stream's buffer
         wait_readnb(s, nb)
-        read!(sbuf, a)
+        nba = nb_available(sbuf)
+        try
+            read!(sbuf, a)
+        finally
+            nba < nb && resize!(a, nba)
+        end
     else
         try
             stop_reading(s) # Just playing it safe, since we are going to switch buffers.
@@ -929,7 +935,9 @@ function read!(s::LibuvStream, a::Array{UInt8, 1})
             write(newbuf, sbuf)
             wait_readnb(s, nb)
         finally
+            nba = nb_available(s.buffer)
             s.buffer = sbuf
+            nba < nb && resize!(a, nba)
             if !isempty(s.readnotify.waitq)
                 start_reading(s) # resume reading iff there are currently other read clients of the stream
             end

test/choosetests.jl

@@ -33,7 +33,7 @@ function choosetests(choices = [])
         "base64", "serialize", "functors", "misc", "threads",
         "enums", "cmdlineargs", "i18n", "workspace", "libdl", "int",
         "checked", "intset", "floatfuncs", "compile", "parallel", "inline",
-        "boundscheck"
+        "boundscheck", "stream"
     ]
 
     if Base.USE_GPL_LIBS
@@ -79,7 +79,7 @@ function choosetests(choices = [])
         prepend!(tests, linalgtests)
     end
 
-    net_required_for = ["socket", "parallel"]
+    net_required_for = ["socket", "parallel", "stream"]
     net_on = true
     try
         getipaddr()

test/stream.jl

@@ -0,0 +1,57 @@
+# This file is a part of Julia. License is MIT: http://julialang.org/license
+
+
+using Base.Test
+
+
+let
+    # PR#14627
+    Base.connect!(sock::TCPSocket, addr::Base.InetAddr) = Base.connect!(sock, addr.host, addr.port)
+
+    addr = Base.InetAddr(ip"127.0.0.1", 4444)
+    srv = listen(addr)
+
+    function oneshot_accept(_srv::Base.TCPServer, _send::Vector{UInt8})
+        @async try
+            c = accept(_srv)
+            write(c, _send)
+            close(c)
+        end
+        yield()
+        nothing
+    end
+
+    # method 'read!(::Base.LibuvStream, ::Array{UInt8, 1})'
+    # resizes its array argument on EOFError
+    # to indicate the number of bytes actually received
+    send_buf = UInt8[0,1,2]
+    recv_buf = UInt8[5,5,5,5,5]
+    oneshot_accept(srv, send_buf)
+    c = connect(addr)
+    try
+        read!(c, recv_buf)
+    catch x
+        if isa(x,EOFError)
+            @test length(recv_buf) == length(send_buf)  # receive buffer resized
+            @test recv_buf == send_buf  # check up the content
+        else
+            rethrow()
+        end
+    finally
+        close(c)
+    end
+
+    # test a normal (nonexceptional) case
+    send_buf = UInt8[0,1,2,3,4]
+    recv_buf = UInt8[5,5,5]
+    recvbuf_len = length(recv_buf)
+    oneshot_accept(srv, send_buf)
+    c = connect(addr)
+    read!(c, recv_buf)
+    @test length(recv_buf) == recvbuf_len  # receive buffer's length not changed
+    @test recv_buf == send_buf[1:recvbuf_len]  # check up the content
+    close(c)
+
+    close(srv)
+end
+