ELF_NEXT(3)

💅 ELF_NEXT(3) — the libelf glow-up page

okay bestie, welcome to the Libelf Programmer's Manual, section 3. this is the one about elf_next, and honestly? it's giving "small function, big main character energy" ✨

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🌸 NAME

elf_next — advance an ELF descriptor to the next archive member 🦋

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🎀 SYNOPSIS

#include <libelf.h>

Elf_Cmd elf_next(Elf *elf);

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✨ DESCRIPTION

so what it does: it advances an ELF descriptor that's associated with an archive file, and moves it along to the next available archive member. literally just "next bestie pls" 🫶

here's the vibe: ELF descriptors that got initialized from an archive file can be used to grab ELF descriptors for archive members, one at a time, using elf_begin(3). and elf_next(3) is the thing that updates the archive descriptor so that elf_begin(3) hands you the ELF descriptor of the next member of the archive. see the EXAMPLES section below, it's all laid out for u 💖

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👑 RETURN VALUE

if elf refers to an archive member: it updates the state of the parent archive ELF descriptor associated with elf, so that the next archive member can be retrieved with elf_begin(3). then it returns the Elf_Cmd that was used with elf_begin(3) to initialize elf. slay 💅

if elf was not initialized from an archive file, or there are no more archive members left? then elf_next(3) returns ELF_C_NULL. that's the "nothing left, we're done here" signal, no cap 😭

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🌈 EXAMPLES

okay this is the part where it all clicks, i promise. read it slowly, it's iconic:

  /* Open the archive.  */
  fd = open (archive_name, O_RDONLY);
  if (fd == -1)
    {
      printf ("cannot open archive file `%s'", fname);
      exit (1);
    }

  /* Set the ELF version.  */
  elf_version (EV_CURRENT);

  /* Create an ELF descriptor for the archive.  */
  cmd = ELF_C_READ;
  elf = elf_begin (fd, cmd, NULL);
  if (elf == NULL)
    {
      printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
      exit (1);
    }

  /* Verify this is a descriptor for an archive.  */
  if (elf_kind (elf) != ELF_K_AR)
    {
      printf ("`%s' is not an archive\n", fname);
      exit (1);
    }

  /* Get the members of the archive one after the other.  */
  while ((subelf = elf_begin (fd, cmd, elf)) != NULL)
    {
      /* Process subelf here */
      [...]

      /* elf_next updates elf, the parent archive, so that the next call
         to elf_begin returns the next archive member.  */
      cmd = elf_next (subelf);
      if (elf_end (subelf) != 0)
        {
          printf ("error while freeing sub-ELF descriptor: %s\n",
                  elf_errmsg (-1));
          exit (1);
        }
    }

  elf_end (elf);
  close (fd);

see how cmd gets recycled back into elf_begin? that's the loop. that's the whole trick. obsessed 🔥

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💜 SEE ALSO

• elf_begin(3)
• elf_rand(3)
• libelf(3)
• elf(5)

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🧚 ATTRIBUTES

• Interface: elf_next()
• Attribute: Thread safety
• Value: MT-Safe

(translation: she's thread safe, she can hang with the whole group chat at once 💖)

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🍓 REPORTING BUGS

found a bug? spill it, respectfully 🙈 report bugs to <elfutils-devel@sourceware.org> or at https://sourceware.org/bugzilla/.

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that's the page, bestie. go forth and iterate over archives like the icon you are 🌟

— from the Libelf manual, dated 2025-06-06, and yes she ate 💅👑