Mac OS X安裝libevent庫報Install libevent bufferevent_openssl.c:60:10: fatal error: 'openssl/bio.h' file

編譯 libevent（源檔案在/Users/carl/Downloads/libevent-2.1.8-stable），執行make命令是，報

Install libevent bufferevent_openssl.c:60:10: fatal error: 'openssl/bio.h' file

第一反應，感覺是不是 openssl版本太低了。

1. 查看openssl版本，發現版本比較低

$ openssl versionOpenSSL 0.9.8zh 14 Jan 2016

2. 升級spenssl，執行

brew install openssl

輸出（前面的輸出忽略）如下：

==> Downloading https://homebrew.bintray.com/bottles/openssl-1.0.2l.sierra.bottle.tar.gz
######################################################################## 100.0%
==> Pouring openssl-1.0.2l.sierra.bottle.tar.gz
==> Caveats
A CA file has been bootstrapped using certificates from the SystemRoots
keychain. To add additional certificates (e.g. the certificates added in
the System keychain), place .pem files in
  /usr/local/etc/openssl/certs

and run
  /usr/local/opt/openssl/bin/c_rehash

This formula is keg-only, which means it was not symlinked into /usr/local,
because Apple has deprecated use of OpenSSL in favor of its own TLS and crypto libraries.

If you need to have this software first in your PATH run:
  echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.zshrc

For compilers to find this software you may need to set:
    LDFLAGS:  -L/usr/local/opt/openssl/lib
    CPPFLAGS: -I/usr/local/opt/openssl/include

==> Summary
�  /usr/local/Cellar/openssl/1.0.2l: 1,709 files, 12.2MB

輸出以上資訊，說明安裝成功，安裝目錄在（/usr/local/Cellar/openssl/1.0.2l）

3. 配置openssl環境變數，指向新安裝的openssl

a. 執行 whereis openssl

輸出 /usr/bin/openssl

b. 備份原openssl，執行 mv /usr/bin/openssl /usr/bin/openssl_old

c. 建立openssl命令軟串連，執行 ln -s /usr/local/Cellar/openssl/1.0.2l/bin/openssl /usr/bin/openssl

d.再執行 openssl version

輸出 OpenSSL 1.0.2l  25 May 2017

說明升級成功。

openssl升級成功後，重新編譯libevent，執行make名了，還是報Install libevent bufferevent_openssl.c:60:10: fatal error: 'openssl/bio.h' file錯誤，

於是把新安裝的openssl目錄的下的標頭檔 拷貝到libevent源檔案目錄下，

執行 cp -R /usr/local/Cellar/openssl/1.0.2l/bin/openssl/include    /Users/carl/Downloads/libevent-2.1.8-stable

重新make，編譯成功。

參考資料 ：

http://blog.csdn.net/hackcoder/article/details/52442350

http://blog.csdn.net/pz0605/article/details/51954868