DWARF_FORMREF(3)

💅 DWARF_FORMREF(3) — ok so bestie, it's a libdwarf manpage from the Library Functions Manual 🌸

No cap, this one's a little niche but it slaps once you get it. We're talking about dwarf_formref and dwarf_global_formref — the two functions that pull offsets out of REFERENCE class attributes. Pull up a chair, we're doing this. 🪑

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✨ NAME ✨

dwarf_formref, dwarf_global_formref — retrieve offsets for REFERENCE class attributes 🎯

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📚 LIBRARY 📚

DWARF Access Library — that's libdwarf, and you link it with -ldwarf. Iconic. 💜

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🧚 SYNOPSIS 🧚

Like, just copy it exactly, don't come for me:

#include <libdwarf.h>

int
dwarf_formref(Dwarf_Attribute attr, Dwarf_Off *retoffset,
    Dwarf_Error *err);

int
dwarf_global_formref(Dwarf_Attribute attr, Dwarf_Off *retoffset,
    Dwarf_Error *err);

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🦋 DESCRIPTION 🦋

Okay so both of these functions return the offsets associated with a DWARF attribute descriptor. Same energy, different scope — and the scope thing is the whole plot twist, so listen up. 👀

💖 dwarf_formref()

This one returns the compilation unit relative offset of the descriptor referenced by argument attr, and it puts it in the location pointed to by argument retoffset. 🫶

Heads up: argument attr must be a reference that is local to a compilation unit. That's not a suggestion, bestie, that's the requirement.

The permitted forms for argument attr are:

• DW_FORM_ref1
• DW_FORM_ref2
• DW_FORM_ref4
• DW_FORM_ref8
• DW_FORM_ref_udata

🌈 dwarf_global_formref()

This one returns the section-relative offset of the descriptor referenced by argument attr, dropped into the location pointed to by argument retoffset. ✨

Argument attr should be a legal REFERENCE class form. The permitted forms for argument attr are:

• DW_FORM_ref_addr
• DW_FORM_ref_udata
• DW_FORM_ref1
• DW_FORM_ref2
• DW_FORM_ref4
• DW_FORM_ref8
• DW_FORM_sec_offset

And the returned offset is relative to the start of the .debug_info ELF section. That's the whole vibe — .debug_info, always. 💀

🎀 the err situation

If argument err is not NULL, it will be used to return an error descriptor in case of an error. If it is NULL, well — you do you, but don't say nobody warned you. 🙈

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👑 RETURN VALUES 👑

These functions return DW_DLV_OK on success. Slay. 🎉

In case of an error, these functions return DW_DLV_ERROR and sets argument err. So yeah, check that err, bestie. 😭

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💀 ERRORS 💀

These functions may fail with the following errors:

• [DW_DLE_ARGUMENT] — Either of arguments attr or retoffset was NULL. Classic.
• [DW_DLE_ATTR_FORM_BAD] — The attribute referenced by argument attr was not of a permitted kind. You gave it the wrong form and it's giving "not today". 🚫

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🔥 SEE ALSO 🔥

Go read these next, iykyk — the whole friend group:

• dwarf(3)
• dwarf_attr(3)
• dwarf_formblock(3)
• dwarf_formflag(3)
• dwarf_formsdata(3)
• dwarf_formsig8(3)
• dwarf_formstring(3)
• dwarf_formudata(3)
• dwarf_hasattr(3)

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okay that's the whole page, mwah 💋 This one's from Debian, dated June 21, 2010 — vintage, honestly, but still serving. Go be a main character with your offsets, bestie 🎀🦋⭐