DWARF_GET_SECTION_BYTES(3) Library Functions Manual DWARF_GET_SECTION_BYTES(3)

dwarf_get_section_bytes — retrieve ELF section byte streams

DWARF Access Library (libdwarf, -ldwarf)

#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);

Function () returns the ELF section byte streams generated by a prior call to function dwarf_transform_to_disk_form(3).

Each call to function () will return the byte stream for one ELF section. The first call to this function will always return the first ELF section, and the subsequent calls will return the rest of sections in the order when they were generated, until the last one. The total number of sections generated is returned by the function dwarf_transform_to_disk_form(3).

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

Argument dwarf_section is currently ignored.

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.

The memory areas used for the returned ELF section byte streams should be freed using the function ().

On success, function dwarf_get_section_bytes() returns a pointer to a ELF section byte stream. In case of an error, function dwarf_get_section_bytes() will return NULL and set the argument err.

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);

Function dwarf_get_section_bytes() can fail with:

[]
One of the arguments dbg, elf_section_index, or length was NULL.
[]
There were no more ELF sections to retrieve, or the function was called before a call to dwarf_transform_to_disk_form(3).

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)

August 26, 2011 NetBSD 11.0