clone2(2)

💖 clone2(2) 💖

okay bestie, sit down, hydrate, because we're talking about clone2 and __clone2 — the system-call manual, section 2 — and their whole entire job is: create a child process. ✨ That's it. That's the gig. Not me being dramatic, that's literally the NAME section.

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🌸 LIBRARY 🌸

Standard C library — that's libc, linked with -lc, as always. 🫶

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✨ SYNOPSIS ✨

here's the glibc wrapper, look at her:

       // glibc wrapper:
       int __clone2(typeof(int (void *)) *fn,
                    void *stack_base, size_t stack_size,
                    int flags, void *arg, ...
                 /* pid_t *parent_tid, struct user_desc *tls,
                    pid_t *child_tid */ );

and here's the raw system call, the unglamorous one:

       // System call:
       long syscall(SYS_clone2, unsigned long flags, void *stack_base,
                   int stack_size,         /* Size of stack */
                   int *parent_tid, int *child_tid,
                   unsigned long tls);

no cap, stack_size in the syscall version is literally commented as /* Size of stack */ right there in the signature, which is giving "we knew you'd ask." 💅

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🦋 DESCRIPTION 🦋

so. These interfaces are similar to clone(2) — like, cousins — but for ia64. ia64 girlies only, sorry to everyone else. 🎀

They operate in the same way as clone(2), with one (1) whole exception, and it's about the stack:

• stack_base points to the lowest address of the child's stack area — like, the bottom-bottom, not the top.
• stack_size specifies the size of the stack pointed to by stack_base.

that's the whole plot twist. the rest? identical to clone(2). periodt. 👑

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💜 RETURN VALUE 💜

See clone(2). I'm not repeating myself, she already said it. 💅

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🌈 ERRORS 🌈

See clone(2). same energy, same errors, go read her. 😭

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⭐ STANDARDS ⭐

None.

literally none. not a single one. she's built different and unstandardised. 💀

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👑 HISTORY 👑

Linux (ia64). an icon, a legend, and she is the moment. 🌸

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🫶 SEE ALSO 🫶

• clone(2)

that's the whole friend group btw. just the two of them. iykyk. 🧚

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bestie reminder: this is the ia64-flavoured clone(2) and the stack_base / stack_size semantics are genuinely different from regular clone(2). do not mix them up, i'm begging. 🙈

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