github.com/afumu/libc@v0.0.6/musl/src/internal/procfdname.c (about)

     1  #include "syscall.h"
     2  
     3  void __procfdname(char *buf, unsigned fd)
     4  {
     5  	unsigned i, j;
     6  	for (i=0; (buf[i] = "/proc/self/fd/"[i]); i++);
     7  	if (!fd) {
     8  		buf[i] = '0';
     9  		buf[i+1] = 0;
    10  		return;
    11  	}
    12  	for (j=fd; j; j/=10, i++);
    13  	buf[i] = 0;
    14  	for (; fd; fd/=10) buf[--i] = '0' + fd%10;
    15  }