DWARF_GET_SECTION_BYTES(3)

✨ DWARF_GET_SECTION_BYTES(3) ✨

okay bestie, so this one is from the Library Functions Manual and it's giving “let me hand you the raw ELF section bytes” energy 💅 it lives in the DWARF Access Library (libdwarf, -ldwarf), and honestly? kinda iconic.

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🌸 NAME 🌸

dwarf_get_section_bytes — retrieve ELF section byte streams

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🎀 LIBRARY 🎀

DWARF Access Library (libdwarf, -ldwarf)

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🦋 SYNOPSIS 🦋

#include <libdwarf.h>

Dwarf_Ptr
dwarf_get_section_bytes(Dwarf_P_Debug dbg, Dwarf_Signed dwarf_section,
    Dwarf_Signed *elf_section_index, Dwarf_Unsigned *length,
    Dwarf_Error *err);

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💖 DESCRIPTION 💖

so basically, dwarf_get_section_bytes() returns the ELF section byte streams that were generated by a prior call to dwarf_transform_to_disk_form(3). like, it's the handoff, the moment the bytes become yours 🫶

every single call to dwarf_get_section_bytes() gives you the byte stream for one ELF section. the first call always returns the first ELF section, and then the subsequent calls return the rest of the sections in the order they were generated, all the way until the last one. no skipping, no shuffling, it's a whole orderly vibe ✨

the total number of sections generated is returned by dwarf_transform_to_disk_form(3). that's your count, bestie — remember it.

argument dbg should reference a DWARF producer instance allocated using dwarf_producer_init(3) or dwarf_producer_init_b(3).

argument dwarf_section is currently ignored. yes, literally ignored. not me pointing at it and saying “it's giving placeholder” 😭

argument elf_section_index should point to a location which will be set to the section index value of the returned ELF section.

argument length should point to a location which will hold the length in bytes of the returned ELF section.

if argument err is not NULL, it will be used to store error information in case of an error.

🧚 Memory Management 🧚

the memory areas used for the returned ELF section byte streams should be freed using the function dwarf_producer_finish(). that's the cleanup era, don't ghost it 💀

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⭐ RETURN VALUES ⭐

on success, function dwarf_get_section_bytes() returns a pointer to a ELF section byte stream. slay.

in case of an error, function dwarf_get_section_bytes() will return NULL and set the argument err. so if you get NULL, check err, bestie — it's not being mysterious on purpose 🙈

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🌈 EXAMPLES 🌈

to generate and retrieve ELF section byte streams, use:

      Dwarf_P_Debug dbg;
      Dwarf_Signed count, i, sec_index;
      Dwarf_Unsigned len;
      Dwarf_Ptr bytes;
      Dwarf_Error de;

      /* ... Assume that `dbg' refers to a DWARF producer instance,
       * and that application code has added DWARF debugging
       * information to the producer instance. ...
       */
      if ((count = dwarf_transform_to_disk_form(dbg, &de)) ==
          DW_DLV_NOCOUNT) {
              warnx("dwarf_transform_to_disk_form failed: %s",
                  dwarf_errmsg(-1));
              return;
      }

      /* Retrieve section data. */
      for (i = 0; i < count; i++) {
              bytes = dwarf_get_section_bytes(dbg, i, &sec_index, &len,
                  &de);
              if (bytes == NULL) {
                      warnx("dwarf_get_section_bytes failed: %s",
                          dwarf_errmsg(-1));
                      continue;
              }
              /* ... use the returned byte stream ... */
      }

      /* Release resources. */
      dwarf_producer_finish(dbg, &de);

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🔥 ERRORS 🔥

function dwarf_get_section_bytes() can fail with:

• [DW_DLE_ARGUMENT] — one of the arguments dbg, elf_section_index, or length was NULL.
• [DW_DLE_NO_ENTRY] — there were no more ELF sections to retrieve, or the function was called before a call to dwarf_transform_to_disk_form(3).

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👑 SEE ALSO 👑

dwarf(3), dwarf_producer_finish(3), dwarf_producer_init(3), dwarf_producer_init_b(3), dwarf_reset_section_bytes(3), dwarf_transform_to_disk_form(3)

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and that's the whole page, bestie 💜 cute little sign-off: this was Debian, dated August 26, 2011, for DWARF_GET_SECTION_BYTES(3) — periodt 🎀