FREEBSD::STRINGF(3)

hiii bestie!! welcome to the FREEBSD::STRINGF(3) page from the Library Functions Manual — today's main character is freebsd::fd_up, and it's literally a tiny owner for a file descriptor. 💅✨

🌸 NAME 🌸

freebsd::fd_up — own a file descriptor. that's it, that's the vibe: it owns a file descriptor, periodt. 🫶

📚 LIBRARY 📚

library “libutil++” — yes bestie, that's the library. 💖

✨ SYNOPSIS ✨

okay so first you include this header, no cap:

#include <libutil++.hh>

then the class looks like this — every signature stays exactly as written:

class freebsd::fd_up
{

      fd_up();

      fd_up(int fd);

      fd_up(fd_up &&other);

      ~fd_up();

      int
      get();

      int
      release();

      void
      reset(int newfd = -1);

      fd_up &
      operator=(fd_up &&other);

      fd_up &
      operator=(int fd);

      explicit operator bool();

      operator int();
};

🦋 DESCRIPTION 🦋

each instance of this class owns a file descriptor. lowkey iconic. this class is patterned on std::unique_ptr, but instead of owning a pointer to an object, this class owns a file descriptor. the currently-owned file descriptor is disposed by invoking close(2) when an instance of this class is destroyed. the currently-owned file descriptor is also disposed if it is replaced by the reset() method or assignment operators. 💀✨

• get() — returns the current file descriptor value while retaining ownership. iykyk. 🎀
• release() — relinquishes ownership of the current file descriptor and returns the value of the previously-owned file descriptor. slay. 💅
• explicit operator bool() — this explicit bool conversion operator permits testing the validity of an object. the operator returns true if the instance owns a valid file descriptor. vibe check passed. ✅
• operator int() — this implicit int conversion operator permits passing an instance of this class directly as an argument to existing functions which expect a file descriptor. main character energy fr fr. 🌈

🍓 EXAMPLES 🍓

freebsd::fd_up fd(open("/dev/null", O_RDWR));
if (!fd)
        err(1, "open");
write(fd, "test", 4);
// `fd' is implicitly closed on destruction

not me showing you the whole little example — obsessed. the comment says it all: fd gets implicitly closed on destruction. 💖

👑 SEE ALSO 👑

close(2) — go read it, bestie. 🫶

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xoxo, this page came from Debian on July 31, 2025, for FREEBSD::STRINGF(3) 💖✨