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DWARF_GET_RELOCATION_INFO(3)                          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;
           } *Dwarf_Relocation_Data;

     Struct Dwarf_Relocation_Data_s consists of following fields:
           drd_type              The type code of the relocation entry.  The
                                 Dwarf_Rel_Type enumeration defined in the
                                 header file <libdwarf.h> specifies legal
                                 values for this field.
           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.

ERRORS
     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().

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++) {
                           /* ...use each reloc data in buf[j]... */
                   }
           }

           dwarf_producer_finish(dbg, &de);

SEE ALSO
     dwarf(3), dwarf_get_relocation_info_count(3),
     dwarf_reset_section_bytes(3), dwarf_producer_finish(3),
     dwarf_producer_init(3), dwarf_producer_init_b(3),
     dwarf_transform_to_disk_form(3)

NetBSD 7.1.2                   September 3, 2011                  NetBSD 7.1.2