Author: nanxiao

Build Luajit notice

When uploading Luajit (for example, v2.0.4) from Windows to Linux, you may get the following compile error:

In file included from lj_ffrecord.c:859:0:
lj_recdef.h:224:1: error: ‘recff_rawlen’ undeclared here (not in a function)
 recff_rawlen,
 ^
Makefile:645: recipe for target 'lj_ffrecord.o' failed

The root cause is in src/host/buildvm_lib.c:

void emit_lib(BuildCtx *ctx)
{

    ......
    int ok = 1;
    if (!strcmp(buf, "#if LJ_52\n"))
      ok = LJ_52;
    else if (!strcmp(buf, "#if LJ_HASJIT\n"))
      ok = LJ_HASJIT;
    else if (!strcmp(buf, "#if LJ_HASFFI\n"))
      ok = LJ_HASFFI;
    ......

}

Because in Windows, the EOL(End-of-Line) should be “\r\n“, so the !strcmp(buf, "#if LJ_52\n") will return false (!strcmp(buf, "#if LJ_52\r\n") will return true). The modify method is using the dos2unix tool to convert the whole folder:

# cd LuaJIT-2.0.4
# find . -type f -print0 | xargs -0 dos2unix

Then compile will be OK.

Reference:
(1) The EOL difference in Windows and UNIX may generate compile error;
(2) How can I run dos2unix on an entire directory?.

Set proxy when executing “go get” command

In Windows, if you have configured proxy for connecting Internet, then executing “go get” command may get error, like this:

C:\Users\xiaona>go get -v gopkg.in/fatih/pool.v2
Fetching https://gopkg.in/fatih/pool.v2?go-get=1
https fetch failed.
Fetching http://gopkg.in/fatih/pool.v2?go-get=1
import "gopkg.in/fatih/pool.v2": http/https fetch: Get http://gopkg.in/fatih/poo
l.v2?go-get=1: dial tcp 107.178.216.236:80: ConnectEx tcp: A connection attempt
failed because the connected party did not properly respond after a period of ti
me, or established connection failed because connected host has failed to respon
d.
package gopkg.in/fatih/pool.v2: unrecognized import path "gopkg.in/fatih/pool.v2
"

The solution is set “http_proxy” and/or “https_proxy” environment variables according to your reality need:

C:\Users\xiaona>set https_proxy=https://web-proxy.corp.xx.com:8080/

C:\Users\xiaona>set http_proxy=https://web-proxy.corp.xx.com:8080/

C:\Users\xiaona>go get -v gopkg.in/fatih/pool.v2
Fetching https://gopkg.in/fatih/pool.v2?go-get=1
Parsing meta tags from https://gopkg.in/fatih/pool.v2?go-get=1 (status code 200)

get "gopkg.in/fatih/pool.v2": found meta tag main.metaImport{Prefix:"gopkg.in/fa
tih/pool.v2", VCS:"git", RepoRoot:"https://gopkg.in/fatih/pool.v2"} at https://g
opkg.in/fatih/pool.v2?go-get=1
gopkg.in/fatih/pool.v2 (download)
gopkg.in/fatih/pool.v2

All is OK now!

Fix compile error: “fatal error: ‘libelf.h’ file not found”

Recently, when I try to build an open source project, I meet the following compile error:

fatal error: 'libelf.h' file not found
#include <libelf.h>
     ^
1 error generated.

The solution is installing elfutils-libelf-devel package:

sudo yum install elfutils-libelf-devel

Or:

sudo dnf install elfutils-libelf-devel

(You can also read this post on itechlounge.net)

Install VirtualBox guest additions

To use “Shared Folders” in VirtualBox, the user should install VirtualBox guest additions:

(1) Select Devices -> Insert Guest Additions CD image. If the VirtualBox prompts:

Unable to insert the virtual optical disk C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso into the machine CentOS.

Would you like to try to force insertion of this disk?

Count not mount the media/drive 'C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).

It means the Devices -> CD/DVD DEvices already has ISO file. Please inject it, and try Insert Guest Additions CD image again.

(2) Mount the ISO file:

mount /dev/cdrom /mnt

(3) Install the VirtualBox guest additions (Take Linux as an example):

cd /mnt
./VBoxLinuxAdditions.run

You may also need to install bzip2, gcc and kernel files to install guest additions successfully. When meeting errors, please refer /var/log/vboxadd-install.log for detail info.