DWARF_GET_ABBREV(3)

💅 NAME 💅

dwarf_get_abbrev — retrieve abbreviation information

Okay bestie, welcome to the DWARF_GET_ABBREV(3) page from the Library Functions Manual. This is where we grab abbreviation info and make it make sense. 💖

📚 LIBRARY 📚

DWARF Access Library (libdwarf, -ldwarf)

✨ SYNOPSIS ✨

#include <libdwarf.h>

int
dwarf_get_abbrev(Dwarf_Debug dbg, Dwarf_Unsigned offset,
    Dwarf_Abbrev *ret_abbrev, Dwarf_Unsigned *length,
    Dwarf_Unsigned *attr_count, Dwarf_Error *err);

🫶 DESCRIPTION 🫶

Function dwarf_get_abbrev() retrieves information about an abbreviation from the DWARF abbreviations section, .debug_abbrev. The abbreviation info comes back using an opaque descriptor of type Dwarf_Abbrev. You can then pass that returned Dwarf_Abbrev descriptor to the other abbreviation-related APIs in the DWARF(3) API to get the specific info about the abbreviation. 💫

Argument dbg should reference a DWARF debug context allocated using dwarf_init(3).

Argument offset should be an offset, relative to the .debug_abbrev section, to the start of an abbreviation entry.

Argument ret_abbrev should point to a location that will hold a pointer to the returned Dwarf_Abbrev descriptor.

Argument length should point to a location that will hold the number of bytes used by the abbrevation in the DWARF .debug_abbrev section.

Argument attr_count should point to a location that will hold the number of attributes in the abbrevation.

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

🧠 Memory Management 🧠

The memory area used for the Dwarf_Abbrev descriptor returned in argument ret_abbrev is allocated by the DWARF Access Library (libdwarf, -ldwarf). Application code should use function dwarf_dealloc() with the allocation type DW_DLA_ABBREV to free the memory area when the Dwarf_Abbrev descriptor is no longer needed. Do not ghost that cleanup, bestie. 🫶

📝 Application Programming Notes 📝

The last abbreviation entry in a standard DWARF abbreviation section will have a special length value of 1. That’s the little “we’re done here” signal. 💅

🔁 RETURN VALUES 🔁

Function dwarf_get_abbrev() returns DW_DLV_OK when it succeeds. It returns DW_DLV_NO_ENTRY if there is no abbreviation information at offset offset. In case of an error, it returns DW_DLV_ERROR and sets the argument err. 🚨

🌈 EXAMPLES 🌈

To loop through all the abbreviation information associated with a DWARF debug context, use:

             Dwarf_Debug dbg;
             Dwarf_Abbrev ab;
             Dwarf_Off aboff;
             Dwarf_Unsigned length, attr_count;
             Dwarf_Half tag;
             Dwarf_Error de;
             int ret;

             while ((ret = dwarf_next_cu_header(dbg, NULL, NULL, &aboff,
                 NULL, NULL, &de)) ==  DW_DLV_OK) {
                     while ((ret = dwarf_get_abbrev(re->dbg, aboff, &ab, &length,
                         &attr_count, &de)) == DW_DLV_OK) {
                             if (length == 1)        /* Last entry. */
                                     break;
                             aboff += length;
                             if (dwarf_get_abbrev_tag(ab, &tag, &de) != DW_DLV_OK) {
                                     warnx("dwarf_get_abbrev_tag failed: %s",
                                         dwarf_errmsg(de));
                                     continue;
                             }
                     if (ret != DW_DLV_OK)
                             warnx("dwarf_get_abbrev: %s", dwarf_errmsg(de));
             }
             if (ret == DW_DLV_ERROR)
                     warnx("dwarf_next_cu_header: %s", dwarf_errmsg(de));

💀 ERRORS 💀

Function dwarf_get_abbrev() can fail with:

• [DW_DLE_ARGUMENT] — One of the arguments dbg, ret_abbrev, length or attr_count was NULL.
• [DW_DLE_NO_ENTRY] — There is no abbreviation information at offset offset.

👀 SEE ALSO 👀

• dwarf(3)
• dwarf_dealloc(3)
• dwarf_get_abbrev_children_flag(3)
• dwarf_get_abbrev_code(3)
• dwarf_get_abbrev_entry(3)
• dwarf_get_abbrev_tag(3)

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xoxo, this page is from the Debian edition, dated March 27, 2011, and it’s literally DWARF_GET_ABBREV(3) 💅🎀