strace 分析 Linux 版的 getaddrinfo

最新推荐文章于 2024-09-19 10:17:35 发布

素炒瓢儿白

最新推荐文章于 2024-09-19 10:17:35 发布

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CC 4.0 BY-SA版权

分类专栏： Linux

本文链接：https://blog.youkuaiyun.com/q1075355798/article/details/86665445

本文通过strace工具分析了Linux环境下getaddrinfo系统调用的过程，包括查找C库如libc.so.6、nss_files.so.2等，读取网络配置文件resolv.conf和hosts，以及处理找不到库文件时的错误情况。通过这个过程，读者可以了解getaddrinfo在Linux系统下的工作原理。

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为啥说是 Linux 版的 getaddrinfo，因为这世界上还有一个安卓的。而且这一不注意就搅混了。毕竟Linux版本使用的是 glibc 库，而安卓版本用的是 bionic 库。两个不同的 C 库，两个不同的实现，原理相似，基因相似，实质不同。

/ # strace /data/getaddinfo localhost
execve("/data/getaddinfo", ["/data/getaddinfo", "localhost"], [/* 24 vars */]) = 0
brk(0) = 0xb74000
uname({sys="Linux", node="localhost", ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb6f02000
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/v7l/neon/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/v7l/neon/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/v7l/neon/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/v7l/neon", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/v7l/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/v7l/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/v7l/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/v7l", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/neon/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/neon/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/neon/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/neon", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/tls/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/tls", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/v7l/neon/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/v7l/neon/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/v7l/neon/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/v7l/neon", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/v7l/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/v7l/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/v7l/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/v7l", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/neon/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/neon/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/neon/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/neon", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/vendor/lib/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/vendor/lib", {st_mode=S_IFDIR|0755, st_size=2456, ...}) = 0
open("/system/lib/tls/v7l/neon/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/system/lib/tls/v7l/neon/vfp", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/system/lib/tls/v7l/neon/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/system/lib/tls/v7l/neon", 0xbea1b2e0) = -1 ENOENT (No such file or directory)
open("/system/lib/tls/v7l/vfp/libgcc_s.so.1", O_RDONLY) = -1 ENOENT (No such file or directory)
stat64("/system/lib/tls/v7l/vfp", 0