Mac OS X上的标准C库在哪里？

$ otool -L al

al:
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.200.5)

$ clang --version
Apple LLVM version 10.0.0 (clang-1000.11.45.5)
Target: x86_64-apple-darwin18.2.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

其他程序有更多的库，例如，这个Tower of Hanoi程序是用一个自制的GCC 8.2.0和ncurses库构建的：

$ otool -L hanoi

hanoi:
    /usr/lib/libncurses.5.4.dylib (compatibility version 5.4.0, current version 5.4.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.200.5)
    /opt/gcc/v8.2.0/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)

另一个程序使用的更多：

$ otool -L $(which sqlcmd)

/Users/jonathanleffler/bin/sqlcmd:
    /usr/lib/libedit.3.dylib (compatibility version 2.0.0, current version 3.0.0)
    /usr/lib/libncurses.5.4.dylib (compatibility version 5.4.0, current version 5.4.0)
    isqls09b.dylib (compatibility version 0.0.0, current version 0.0.0)
    iasfs09b.dylib (compatibility version 0.0.0, current version 0.0.0)
    igens09a.dylib (compatibility version 0.0.0, current version 0.0.0)
    iosls09a.dylib (compatibility version 0.0.0, current version 0.0.0)
    sobj4/igl4a304.dylib (compatibility version 0.0.0, current version 0.0.0)
    sobj4/iglxa304.dylib (compatibility version 0.0.0, current version 0.0.0)
    /System/Library/Frameworks/DirectoryService.framework/Versions/A/DirectoryService (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.200.5)
    /opt/gcc/v8.2.0/lib/libgcc_s.1.dylib (compatibility version 1.0.0, current version 1.0.0)

并且系统程序可以使用其他库和框架：

$ otool -L $(which passwd)

/usr/bin/passwd:
    /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (compatibility version 150.0.0, current version 1561.0.0)
    /System/Library/Frameworks/OpenDirectory.framework/Versions/A/OpenDirectory (compatibility version 1.0.0, current version 1.0.0)
    /usr/lib/libpam.2.dylib (compatibility version 3.0.0, current version 3.0.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1252.200.5)

$ otool -L /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome

/Applications/Google Chrome.app/Contents/MacOS/Google Chrome:
    /System/Library/Frameworks/Cocoa.framework/Versions/A/Cocoa (compatibility version 1.0.0, current version 22.0.0)
    /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation (compatibility version 300.0.0, current version 1349.63.0)
    /System/Library/Frameworks/IOKit.framework/Versions/A/IOKit (compatibility version 1.0.0, current version 275.0.0)
    /System/Library/Frameworks/Security.framework/Versions/A/Security (compatibility version 1.0.0, current version 57740.51.2)
    /System/Library/Frameworks/SystemConfiguration.framework/Versions/A/SystemConfiguration (compatibility version 1.0.0, current version 888.51.1)
    /usr/lib/libc++.1.dylib (compatibility version 1.0.0, current version 307.5.0)
    /usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 1238.50.2)

还有许多其他工作可以用otool完成-请查看手册页。

赞(0）回复(0）举报 2023-01-25

stszievb3#

回答你的第二个问题：静态库保存在归档文件中，因此.a。因此它们只是一堆文件的容器，就像ZIP、TAR、RAR等，没有任何压缩。ar（代表 archive）实用程序列出的那些文件是打包到归档文件中的原始文件。您可以解包并获得原始文件。
静态库与动态库形成了鲜明的对比。静态库的内容由链接器提取，并在链接时包含到程序中，就好像它们只是程序构建过程中其他编译阶段的结果一样。
另一方面，动态库不仅仅是目标文件的存档，它们本身也是链接的可执行文件，动态链接器将它们Map到链接进程的地址空间，并调整符号表以匹配Map的地址。