如何使用 OpenSSL 编译 .c 文件？
我正在尝试编译一个小的 .c 文件，其中包含以下内容：
#include <openssl/ssl.h>
#include <openssl/rsa.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
在包含 .c 文件的同一文件夹中，我有一个包含所有这些文件（以及更多文件）的 /openssl，也在突触包管理器中我看到安装了 OpenSSL ，我试图用这个进行编译：
gcc -o Opentest Opentest.c -lcrypto
但我总是收到错误：
error: openssl/ssl.h: No such file or directory
error: openssl/rsa.h: No such file or directory
error: openssl/x509.h: No such file or directory
error: openssl/evp.h: No such file or directory
我想要编译的文件只是一个 .c 文件，没有 Makefile 或 ./configure。
我已经尝试过：
env CFLAGS=-I/path/to/openssl/
并尝试再次编译，但出现相同的错误。
我应该怎么做才能使用 OpenSSL 进行编译？
I am trying to compile a small .c file that has the following includes:
#include <openssl/ssl.h>
#include <openssl/rsa.h>
#include <openssl/x509.h>
#include <openssl/evp.h>
In the same folder where I have the .c file I have a /openssl with all those files (and more), also in synaptic package manager I see OpenSSL installed, I am trying to compile with this:
gcc -o Opentest Opentest.c -lcrypto
but I always get the errors:
error: openssl/ssl.h: No such file or directory
error: openssl/rsa.h: No such file or directory
error: openssl/x509.h: No such file or directory
error: openssl/evp.h: No such file or directory
The file I want to compile is only a .c file, doesn't have Makefile or ./configure.
I already tried:
env CFLAGS=-I/path/to/openssl/
and tried to compile again but I get the same errors.
What should I do in order to compile with OpenSSL includes?
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评论（7）
您的包含路径表明您应该针对系统的 OpenSSL 安装进行编译。您的包目录中不应该有
.h文件 - 它应该从/usr/include/openssl中获取它们。普通 OpenSSL 包 (
libssl) 不包含.h文件 - 您还需要安装开发包。在 Debian、Ubuntu 和类似发行版上，其名称为libssl-dev；在 CentOS、Fedora、Red Hat 及类似发行版上，名称为openssl-devel。Your include paths indicate that you should be compiling against the system's OpenSSL installation. You shouldn't have the
.hfiles in your package directory - it should be picking them up from/usr/include/openssl.The plain OpenSSL package (
libssl) doesn't include the.hfiles - you need to install the development package as well. This is namedlibssl-devon Debian, Ubuntu and similar distributions, andopenssl-develon CentOS, Fedora, Red Hat and similar.正确使用 gcc 的
-I标志。gcc -I/path/to/openssl/ -o Opentest -lcrypto Opentest.c-I应指向包含openssl的目录文件夹。Use the
-Iflag to gcc properly.gcc -I/path/to/openssl/ -o Opentest -lcrypto Opentest.cThe
-Ishould point to the directory containing theopensslfolder.使用下面的代码片段作为所引用挑战的解决方案；
在 CentOS 5.4 版和 keepalived 1.2.7 版上测试并证明有效。
Use the snippet below as a solution for the cited challenge;
Tested and proved effective on CentOS version 5.4 with keepalived version 1.2.7.
您需要包含库路径（-L/usr/local/lib/）
gcc -o Opentest Opentest.c -L/usr/local/lib/ -lssl -lcrypto它对我有用。
You need to include the library path (-L/usr/local/lib/)
gcc -o Opentest Opentest.c -L/usr/local/lib/ -lssl -lcryptoIt works for me.
如果 OpenSSL 标头位于当前目录的
openssl子目录中，请使用：预处理器会创建一个名称，例如“
./openssl/ssl.h”来自-I选项中的“.”以及尖括号中指定的名称。如果您在双引号中指定了名称 (#include "openssl/ssl.h")，您可能永远不需要提出这个问题； Unix 上的编译器通常会自动在当前目录中搜索用双引号括起来的标头，但它不会搜索用尖括号括起来的标头 (#include)。这是实现定义的行为。您没有说明 OpenSSL 库的位置 - 您可能需要添加适当的选项和参数来指定它，例如“
-L /opt/openssl/lib”。If the OpenSSL headers are in the
opensslsub-directory of the current directory, use:The pre-processor looks to create a name such as "
./openssl/ssl.h" from the "." in the-Ioption and the name specified in angle brackets. If you had specified the names in double quotes (#include "openssl/ssl.h"), you might never have needed to ask the question; the compiler on Unix usually searches for headers enclosed in double quotes in the current directory automatically, but it does not do so for headers enclosed in angle brackets (#include <openssl/ssl.h>). It is implementation defined behaviour.You don't say where the OpenSSL libraries are - you might need to add an appropriate option and argument to specify that, such as '
-L /opt/openssl/lib'.从 openssl.pc 文件中
您可以从中记下 Include 目录路径和 Libs 路径。现在，包含文件的前缀是
/home/username/Programming。因此，您的包含文件选项应该是
-I//home/username/Programming。（是的，我从上面的评论中得到它）
这只是为了删除有关标题的日志。您还可以提供
-L选项来链接-lcrypto库。From the openssl.pc file
You can note the Include directory path and the Libs path from this. Now your prefix for the include files is
/home/username/Programming.Hence your include file option should be
-I//home/username/Programming.(Yes i got it from the comments above)
This is just to remove logs regarding the headers. You may as well provide
-L<Lib path>option for linking with the-lcryptolibrary.对于这个gcc错误，您应该参考关于搜索路径的gcc文档。
简而言之：
1）如果你在#include中使用尖括号（<>），gcc将首先从系统路径中搜索头文件，例如/usr/local/include和/usr /include 等
2) -Ldir 命令行选项指定的路径，将在默认目录之前搜索。
3)如果使用引号("")和#include作为#include“文件”，则首先搜索包含当前文件的目录。
所以，你的问题的答案如下：
1）如果你想使用源代码文件夹中的头文件，请将 <> 替换为#include 指令中带有“”。
2）如果你想使用-I命令行选项，请将其添加到你的编译命令行中。（如果在环境变量中设置CFLAGS，它将不会自动引用）
3）关于包配置（openssl.pc），我不认为它将被引用而无需在构建配置中显式声明。
For this gcc error, you should reference to to the gcc document about Search Path.
In short:
1) If you use angle brackets(<>) with #include, gcc will search header file firstly from system path such as /usr/local/include and /usr/include, etc.
2) The path specified by -Ldir command-line option, will be searched before the default directories.
3)If you use quotation("") with #include as #include "file", the directory containing the current file will be searched firstly.
so, the answer to your question is as following:
1) If you want to use header files in your source code folder, replace <> with "" in #include directive.
2) if you want to use -I command line option, add it to your compile command line.(if set CFLAGS in environment variables, It will not referenced automatically)
3) About package configuration(openssl.pc), I do not think it will be referenced without explicitly declared in build configuration.