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DWARF_GET_RELOCATION_INFO(3) FreeBSD Library Functions Manual
NAME
dwarf_get_relocation_info - retrieve generated relocation arrays
LIBRARY
DWARF Access Library (libdwarf, -ldwarf)
SYNOPSIS
#include <libdwarf.h>
int
dwarf_get_relocation_info(Dwarf_P_Debug dbg,
Dwarf_Signed *elf_section_index, Dwarf_Signed *elf_section_link,
Dwarf_Unsigned *reloc_entry_count, Dwarf_Relocation_Data *reloc_buf,
Dwarf_Error *err);
DESCRIPTION
The function dwarf_get_relocation_info() is used to retrieve the
relocation arrays generated by a prior call to
dwarf_transform_to_disk_form(3).
Each call to this function retrieves the next available relocation array.
Application code should call this function repeatly to retrieve all the
relocation arrays. The total number of generated relocation arrays
retrievable by this function may be obtained by calling function
dwarf_get_relocation_info_count(3).
Argument dbg should reference a DWARF producer instance allocated using
dwarf_producer_init(3) in sequence. or dwarf_producer_init_b(3). The
DW_DLC_SYMBOLIC_RELOCATIONS flag should have been set on the DWARF
producer instance.
Argument elf_section_index should point to a location which will be set
to the ELF section index of the relocation section to which the retrieved
relocation array belongs.
Argument elf_section_link should point to a location which will be set to
the section index of the ELF section to which the retrieved relocation
array applies.
Argument reloc_entry_count should point to a location which will be set
to the total number of relocation entries contained in the relocation
array.
Argument reloc_buf should point to a location which will be set to a
pointer to the retrieved array of relocation entries.
If argument err is not NULL, it will be used to store error information
in case of an error.
The retrieved relocation entries are described using structure
Dwarf_Relocation_Data_s, defined in the header file <libdwarf.h>:
typedef struct Dwarf_Relocation_Data_s {
unsigned char drd_type;
unsigned char drd_length;
Dwarf_Unsigned drd_offset;
Dwarf_Unsigned drd_symbol_index;
drd_length The size in bytes of the field to be relocated.
drd_offset The section-relative offset of the field to be
relocated.
drd_symbol_index The symbol index associated with the relocation
entry.
Memory Management
The memory area used for the relocation arrays is managed by the DWARF
Access Library (libdwarf, -ldwarf). The function dwarf_producer_finish()
may be used to release it, along with other resources associated with the
producer instance.
RETURN VALUES
On success, function dwarf_get_relocation_info() returns DW_DLV_OK. It
returns DW_DLV_NO_ENTRY if there were no more relocation arrays to
retrieve, or if the flag DW_DLC_SYMBOLIC_RELOCATIONS was not set on the
producer instance. In case of an error, function
dwarf_get_relocation_info() returns DW_DLV_ERROR and sets the argument
err.
EXAMPLES
To generate relocation entries and retrieve them, use:
Dwarf_P_Debug dbg;
Dwarf_Relocation_Data buf;
Dwarf_Signed count, index, link;
Dwarf_Unsigned reloc_cnt, entry_cnt;
Dwarf_Error de;
int version, i, j;
/*
* Assume that dbg refers to a DWARF producer instance created
* created with DW_DLC_SYMBOLIC_RELOCATIONS flag set 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;
}
/* ... process generated section byte streams ... */
if (dwarf_get_relocation_info_count(dbg, &reloc_cnt, &version, &de) !=
DW_DLV_OK) {
warnx("dwarf_get_relocation_info_count failed: %s",
dwarf_errmsg(-1));
return;
}
for (i = 0; (Dwarf_Unsigned) i < reloc_cnt; i++) {
if (dwarf_get_relocation_info(dbg, &index, &link, &entry_cnt,
&buf, &de) != DW_DLV_OK) {
warnx("dwarf_get_relocation_info failed: %s",
dwarf_errmsg(-1));
continue;
}
for (j = 0; (Dwarf_Unsigned) j < entry_cnt; j++) {
Function dwarf_get_relocation_info() can fail with:
[DW_DLE_ARGUMENT] One of the arguments dbg, elf_section_index,
elf_section_link, reloc_entry_count or reloc_buf was
NULL.
[DW_DLE_NO_ENTRY] There were no more ELF relocation arrays to retrieve.
[DW_DLE_NO_ENTRY] The flag DW_DLC_SYMBOLIC_RELOCATIONS was not set on
the producer instance.
[DW_DLE_NO_ENTRY] Function dwarf_transform_to_disk_form(3) was not
called prior to calling function
dwarf_get_relocation_info().
SEE ALSO
dwarf(3), dwarf_get_relocation_info_count(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)
FreeBSD 14.0-RELEASE-p11 September 3, 2011 FreeBSD 14.0-RELEASE-p11