dwarf_get_macro_details(3)

NAME

dwarf_get_macro_details – retrieve macro information

LIBRARY

library “libdwarf”

SYNOPSIS

#include <libdwarf.h>

int

dwarf_get_macro_details(Dwarf_Debug dbg, Dwarf_Off offset, Dwarf_Unsigned max_count, Dwarf_Signed *entry_cnt, Dwarf_Macro_Details **details, Dwarf_Error *err);

DESCRIPTION

Function dwarf_get_macro_details() retrieves information about macros associated with a DWARF debug context. Information about macro entries are returned as an array of descriptors of type Dwarf_Macro_Details, with each Dwarf_Macro_Details descriptor describing one macro information entry.

Argument dbg should reference a DWARF debug context allocated using dwarf_init(3). Argument offset is an offset, relative to the “.debug_macinfo” section, to the start of the desired macro information. Argument max_count specifies the maximum number of macro information entries to be returned, or 0 if all entries are to be returned. Argument entry_cnt should point to a location that will be set to the number of entries actually returned. Argument details should point to a location that will be set to a pointer to an array of Dwarf_Macro_Details descriptors. If argument err is not NULL, it will be used to store error information in case of an error.

Dwarf_Macro_Details descriptors are defined in the header file ⟨libdwarf.h⟩, and consist of the following fields:

dmd_offset

The section-relative offset within the “.debug_macinfo” section of the macro information entry being described.

dmd_type

The type code of this macro information entry; one of the DW_MACINFO_* constants defined by the DWARF specification.

dmd_lineno

The line number associated with the macro information entry, or 0 if there is no applicable line number.

dmd_fileindex

The source file index for the macro information entry. This field is only meaningful when dmd_type field is set to DW_MACINFO_start_file.

dmd_macro

The contents of this field is a pointer to a NUL-terminated string whose meaning depends on the value of the dmd_type field:

DW_MACINFO_define

The returned string contains the macro name and value.

DW_MACINFO_undef

The string holds the macro name.

DW_MACINFO_vendor_ext

The dmd_macro field points to a vendor defined string.

The field is NULL for other values of dmd_type.

Memory Management

The memory area used for the array of Dwarf_Macro_Details descriptors returned in argument details is owned by the library “libdwarf”. The application should not attempt to directly free this pointer. Portable code should instead use dwarf_dealloc() with the allocation type DW_DLA_STRING to indicate that the memory may be freed.

RETURN VALUES

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

EXAMPLES

To loop through all the macro information entries associated with a DWARF debug context:

Dwarf_Debug dbg;
Dwarf_Unsigned offset;
Dwarf_Signed cnt;
Dwarf_Macro_Details *md;
Dwarf_Error de;
offset = 0;
while (dwarf_get_macro_details(dbg, offset, 0,
    &cnt, &md, &de) == DW_DLV_OK) {
	for (i = 0; i < cnt; i++) {
		/* Access fields of md[i] ... */
	}
	offset = md[cnt - 1].dmd_offset + 1;
}

ERRORS

Function dwarf_get_macro_details() can fail with:

[DW_DLE_ARGUMENT]: One of the arguments dbg, entry_cnt or details was NULL.
[DW_DLE_NO_ENTRY]: There is no more macro information at the specified offset offset.