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$Id: dwarf_get_relocation_info.3 2071 2011-10-27 03:20:00Z jkoshy $
.Dd September 3, 2011 .Os .Dt DWARF_GET_RELOCATION_INFO 3 .Sh NAME .Nm dwarf_get_relocation_info .Nd retrieve generated relocation arrays .Sh LIBRARY .Lb libdwarf .Sh SYNOPSIS n libdwarf.h .Ft int .Fo dwarf_get_relocation_info .Fa "Dwarf_P_Debug dbg" .Fa "Dwarf_Signed *elf_section_index" .Fa "Dwarf_Signed *elf_section_link" .Fa "Dwarf_Unsigned *reloc_entry_count" .Fa "Dwarf_Relocation_Data *reloc_buf" .Fa "Dwarf_Error *err" .Fc .Sh DESCRIPTION The function .Fn dwarf_get_relocation_info is used to retrieve the relocation arrays generated by a prior call to .Xr dwarf_transform_to_disk_form 3 .
p 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 .Xr dwarf_get_relocation_info_count 3 .
p Argument .Ar dbg should reference a DWARF producer instance allocated using .Xr dwarf_producer_init 3 in sequence. or .Xr dwarf_producer_init_b 3 . The .Dv DW_DLC_SYMBOLIC_RELOCATIONS flag should have been set on the DWARF producer instance.
p Argument .Ar 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.
p Argument .Ar 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.
p Argument .Ar reloc_entry_count should point to a location which will be set to the total number of relocation entries contained in the relocation array.
p Argument .Ar reloc_buf should point to a location which will be set to a pointer to the retrieved array of relocation entries.
p If argument .Ar err is not NULL, it will be used to store error information in case of an error.
p The retrieved relocation entries are described using structure .Vt Dwarf_Relocation_Data_s , defined in the header file n libdwarf.h : d -literal -offset indent typedef struct Dwarf_Relocation_Data_s { unsigned char drd_type; unsigned char drd_length; Dwarf_Unsigned drd_offset; Dwarf_Unsigned drd_symbol_index; } *Dwarf_Relocation_Data; .Ed
p Struct .Vt Dwarf_Relocation_Data_s consists of following fields: l -tag -width ".Va drd_symbol_index" -compact -offset indent t Va drd_type The type code of the relocation entry. The .Vt Dwarf_Rel_Type enumeration defined in the header file n libdwarf.h specifies legal values for this field. t Va drd_length The size in bytes of the field to be relocated. t Va drd_offset The section-relative offset of the field to be relocated. t Va drd_symbol_index The symbol index associated with the relocation entry. .El .Ss Memory Management The memory area used for the relocation arrays is managed by the .Lb libdwarf . The function .Fn dwarf_producer_finish may be used to release it, along with other resources associated with the producer instance. .Sh RETURN VALUES On success, function .Fn dwarf_get_relocation_info returns .Dv DW_DLV_OK . It returns .Dv DW_DLV_NO_ENTRY if there were no more relocation arrays to retrieve, or if the flag .Dv DW_DLC_SYMBOLIC_RELOCATIONS was not set on the producer instance. In case of an error, function .Fn dwarf_get_relocation_info returns .Dv DW_DLV_ERROR and sets the argument .Ar err . .Sh ERRORS Function .Fn dwarf_get_relocation_info can fail with: l -tag -width ".Bq Er DW_DLE_NO_ENTRY" t Bq Er DW_DLE_ARGUMENT One of the arguments .Ar dbg , .Ar elf_section_index , .Ar elf_section_link , .Ar reloc_entry_count or .Ar reloc_buf was NULL. t Bq Er DW_DLE_NO_ENTRY There were no more ELF relocation arrays to retrieve. t Bq Er DW_DLE_NO_ENTRY The flag .Dv DW_DLC_SYMBOLIC_RELOCATIONS was not set on the producer instance. t Bq Er DW_DLE_NO_ENTRY Function .Xr dwarf_transform_to_disk_form 3 was not called prior to calling function .Fn dwarf_get_relocation_info . .El .Sh EXAMPLES To generate relocation entries and retrieve them, use: d -literal -offset indent 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++) { /* ...use each reloc data in buf[j]... */ } } dwarf_producer_finish(dbg, &de); .Ed .Sh SEE ALSO .Xr dwarf 3 , .Xr dwarf_get_relocation_info_count 3 , .Xr dwarf_reset_section_bytes 3 , .Xr dwarf_producer_finish 3 , .Xr dwarf_producer_init 3 , .Xr dwarf_producer_init_b 3 , .Xr dwarf_transform_to_disk_form 3