Trouble understanding how to process C string

Question

I\'m trying to use Mac OS X\'s listxattr C function and turn it into something useful in Python. The man page tells me that the function returns a string buffer, which is a \"si

Answer 1

So you guessed pretty much right.

The listxattr function returns a bunch of null-terminated strings packed in next to each other. Since strings (and arrays) in C are just blobs of memory, they don't carry around any extra information with them (such as their length). The convention in C is to use a null character ('\0') to represent the end of a string.

Here's one way to traverse the list, in this case changing it to a comma-separated list.

int i = 0;
for (; i < res; i++)
   if (buffer[i] == '\0' && i != res -1) //we're in between strings
       buffer[i] = ',';

Of course, you'll want to make these into Python strings rather than just substituting in commas, but that should give you enough to get started.