構建本地yum源之rpmbuild問題彙總

- check-rpaths的問題

　　今天在編譯varnish的時候，遇到幾個問題，其中一個就是出現如下錯誤：

...
+ /usr/lib/rpm/check-rpaths /usr/lib/rpm/check-buildroot

*******************************************************************************
*
* WARNING: 'check-rpaths' detected a broken RPATH and will cause 'rpmbuild'
*          to fail. To ignore these errors, you can set the '$QA_RPATHS'
*          environment variable which is a bitmask allowing the values
*          below. The current value of QA_RPATHS is 0x0000.
*
*    0x0001 ... standard RPATHs (e.g. /usr/lib); such RPATHs are a minor
*               issue but are introducing redundant searchpaths without
*               providing a benefit. They can also cause errors in multilib
*               environments.
*    0x0002 ... invalid RPATHs; these are RPATHs which are neither absolute
*               nor relative filenames and can therefore be a SECURITY risk
*    0x0004 ... insecure RPATHs; these are relative RPATHs which are a
*               SECURITY risk
*    0x0008 ... the special '$ORIGIN' RPATHs are appearing after other
*               RPATHs; this is just a minor issue but usually unwanted
*    0x0010 ... the RPATH is empty; there is no reason for such RPATHs
*               and they cause unneeded work while loading libraries
*    0x0020 ... an RPATH references '..' of an absolute path; this will break
*               the functionality when the path before '..' is a symlink
*          
*
* Examples:
* - to ignore standard and empty RPATHs, execute 'rpmbuild' like
*   $ QA_RPATHS=$[ 0x0001|0x0010 ] rpmbuild my-package.src.rpm
* - to check existing files, set $RPM_BUILD_ROOT and execute check-rpaths like
*   $ RPM_BUILD_ROOT=<top-dir> /usr/lib/rpm/check-rpaths
*  
*******************************************************************************

ERROR   0002: file 'xxx.so' contains an invalid rpath 'xxx' in [xxx]
...

　　參考 https://fedoraproject.org/wiki/Packaging:Guidelines， 其中說道：

Sometimes, code will hardcode specific library paths when linking binaries (using the -rpath or -R flag). This is commonly referred to as an rpath. Normally, the dynamic linker and loader (ld.so) resolve the executable's dependencies on shared libraries and load what is required. However, when -rpath or -R is used, the location information is then hardcoded into the binary and is examined by ld.so in the beginning of the execution. Since the Linux dynamic linker is usually smarter than a hardcoded path, we usually do not permit the use of rpath in Fedora.
There is a tool called check-rpaths which is included in the rpmdevtools package. It is a good idea to add it to the %__arch_install_post macro in your ~/.rpmmacros config file:

　　由此可知，這一步只是一種檢測是不是代碼中使用了rpath，那我們可以簡單的註釋掉rpath檢測就可以了，具體做法就是：

　　vi ~/.rpmmacros

%_topdir      %(echo $HOME)/rpmbuild
%_smp_mflags  -j3
#%__arch_install_post   /usr/lib/rpm/check-rpaths   /usr/lib/rpm/check-buildroot

　　後面就能順利編譯了

- pkgconfig跟ldconfig， ldd的問題

　　先看下麵的說明：

1. The pkgconfig package contains tools for passing the include path and/or library paths to build tools during the make file execution.
pkg-config is a function that returns meta information for the specified library.
The default setting for PKG_CONFIG_PATH is /usr/lib/pkgconfig because of the prefix we use to install pkgconfig. You may add to PKG_CONFIG_PATH by exporting additional paths on your system where pkgconfig files are installed. Note that PKG_CONFIG_PATH is only needed when compiling packages, not during run-time.
上面的解釋夠清楚了，pkg-config是用來在執行makefile時指定頭文件和庫文件的路徑。它到由環境變數PKG_CONFIG_PATH指定的路徑下(預設為/usr/lib/config)去找對應庫的*.pc文件，*.pc文件記錄了包之間的倚賴關係、頭文件和庫文件包含路徑、版本等信息。

2. /etc/ld.so.conf.d/* 或/etc/ld.so.conf和ldconfig. 
/etc/ld.so.conf.d/*目錄下的文件和/etc/ld.so.conf記錄了動態鏈接庫的路徑，系統預設搜索/lib和 /usr/lib，在其他路徑下的庫文件就需在這些文件中指定。或者，還有個方法，就是設置LD_LIBRARY_PATH環境變數，添加其他路徑，多個 中間用：分隔開。
ldconfig是一個用來將/etc/ld.so.conf.d/*h 和/etc/ld.so.conf中列出的庫緩存到/etc/ld.so.cache文件中以供使用，因此在裝完一些庫或更新/etc/ld.so.conf文件時，需運行/sbin/ldconfig命令一下。

　　當運行 ./configure 產生Makefile的過程中出現, pkg-config有問題，或是不能找到對應的lib文件的時候。

　　不妨重新設置下pkgconfig的兩個變數：

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig:/usr/share/pkgconfig:$PKG_CONFIG_PATH
export PKG_CONFIG=/usr/bin/pkg-config

　　並且重新載入下動態鏈接庫

ldconfig

　　另外一個非常實用的調試腳本就是ldd: 

[root@xx pcre-8.34]# ldd /bin/ls
    linux-vdso.so.1 =>  (0x00007fff2a5ff000)
    libselinux.so.1 => /lib64/libselinux.so.1 (0x00007fec45edf000)
    librt.so.1 => /lib64/librt.so.1 (0x00007fec45cd7000)
    libcap.so.2 => /lib64/libcap.so.2 (0x00007fec45ad2000)
    libacl.so.1 => /lib64/libacl.so.1 (0x00007fec458ca000)
    libc.so.6 => /lib64/libc.so.6 (0x00007fec45536000)
    libdl.so.2 => /lib64/libdl.so.2 (0x00007fec45331000)
    /lib64/ld-linux-x86-64.so.2 (0x00007fec46105000)
    libpthread.so.0 => /lib64/libpthread.so.0 (0x00007fec45114000)
    libattr.so.1 => /lib64/libattr.so.1 (0x00007fec44f0f000)
[root@xx pcre-8.34]# 

　　其本質也就是設置諸如LD_DEBUG等環境變數，在程式運行時，列印出調用的動態鏈接庫。