Generating random UUIDs in Linux

Question

I am stuck in a strange predicament. I need to generate UUIDs in my Linux program (which I distribute using RPMs). I do not want to add another dependency to my application by requiring the user to install libuuid (seems like libuuid isn't included in most Linux distros, like CentOS).

Isn't there a standard Linux system call which generates UUIDs (like say, in Windows there CoCreateGuid)? What does the command uuidgen use?

Answer 1

Thanks for all your comments!

I went through each one, and here's what suited my requirement the best:

What I needed was just plain time-based UUIDs which were generated from random numbers once for every user who installed the application. UUID version 4 as specified in RFC 4122 was exactly it. I went through a the algorithm suggested, and came up with a pretty simple solution which would work in Linux as well as Windows (Maybe its too simplistic, but it does satisfy the need!):

srand(time(NULL));

sprintf(strUuid, "%x%x-%x-%x-%x-%x%x%x", 
    rand(), rand(),                 // Generates a 64-bit Hex number
    rand(),                         // Generates a 32-bit Hex number
    ((rand() & 0x0fff) | 0x4000),   // Generates a 32-bit Hex number of the form 4xxx (4 indicates the UUID version)
    rand() % 0x3fff + 0x8000,       // Generates a 32-bit Hex number in the range [0x8000, 0xbfff]
    rand(), rand(), rand());        // Generates a 96-bit Hex number