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- How to use /dev/random or urandom in C? 5 answers
如何在C中使用/ dev / random或urandom? 5个答案
I'm new to Linux system programming.
How can I fill some file with 100 mb of any data (but not zeros)?
The only way I see is to use /dev/urandom, but how to do this?
I know there's dd command in Shell, but I'm writing a C program
我是Linux系统编程的新手。如何用100 mb的任何数据(但不是零)填充一些文件?我看到的唯一方法是使用/ dev / urandom,但是如何做到这一点?我知道Shell中有dd命令,但我正在写一个C程序
1 个解决方案
#1
1
read(2) system call will fill a buffer buf with at most count bytes, and return the actual size that was filled. So what you need to do is just:
read(2)系统调用将填充最多count个字节的缓冲区buf,并返回填充的实际大小。所以你需要做的只是:
- 3 = open() /dev/urandom
- 4 = open() target file
- read() in a buffer from 3 and write into 4 until written size equals 100*1024*1024
- close(3)
- close(4)
3 = open()/ dev / urandom
4 = open()目标文件
read()在3的缓冲区中写入4,直到写入的大小等于100 * 1024 * 1024
and you're done. You can also optimize using mmap() for instance, but it may not worth it.
你已经完成了您也可以使用mmap()进行优化,但它可能不值得。
#1
1
read(2) system call will fill a buffer buf with at most count bytes, and return the actual size that was filled. So what you need to do is just:
read(2)系统调用将填充最多count个字节的缓冲区buf,并返回填充的实际大小。所以你需要做的只是:
- 3 = open() /dev/urandom
- 4 = open() target file
- read() in a buffer from 3 and write into 4 until written size equals 100*1024*1024
- close(3)
- close(4)
3 = open()/ dev / urandom
4 = open()目标文件
read()在3的缓冲区中写入4,直到写入的大小等于100 * 1024 * 1024
and you're done. You can also optimize using mmap() for instance, but it may not worth it.
你已经完成了您也可以使用mmap()进行优化,但它可能不值得。