在二进制数据中搜索文本 [英] Searching text in binary data

问题描述

我有一个包含文本的二进制数据.文字是已知的.搜索该文本的快速方法是什么:

I've a binary data which contains a text. The text is known. What could be a fast method to search for that text:

作为一个例子.

这是文字 1---!@##$%%#^%&!%^$!<= 假设这一行是 3 MB 的二进制数据现在，这是文本 2 ---!@##$%%#^%&!%^$!<= 假设这一行是 2.5 MB 的二进制数据这是文字 3 ---

This is text 1---
!@##$%%#^%&!%^$! <= Assume this line is 3 MB of binary data
Now, This is text 2 ---
!@##$%%#^%&!%^$! <= Assume this line is 2.5 MB of binary data
This is text 3 ---

如何搜索文本这是文本2.
目前我正在做:
size_t count = 0;
size_t s_len = strlen("This is text 2");

//Assume data_len is length of the data from which text is to be found and data is pointer (char*) to the start of it.
for(; count < data_len; ++count)
{
    if(!memcmp("This is text 2", data + count, s_len)
    {
         printf("%s\n", "Hurray found you...");
    }
}

有没有其他更有效的方法来做到这一点
将用 memchr('T') logic 替换 ++count 逻辑 help <= 如果此语句不清楚，请忽略
memchr 的一般情况下 big-O 复杂度应该是多少

推荐答案
标准 C 中没有任何东西可以帮助您，但有一个 GNU 扩展 memmem() 这样做:
There's nothing in standard C to help you, but there is a GNU extension memmem() that does this:
#define TEXT2 "This is text 2"

char *pos = memmem(data, data_len, TEXT2, sizeof(TEXT2));

if (pos != NULL)
    /* Found it. */

如果您需要可移植到没有此功能的系统，您可以采用 memmem() 的 glibc 实现并将其合并到您的程序中.
If you need to be portable to systems that don't have this, you could take the glibc implementation of memmem() and incorporate it into your program.

                        
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