DWARF_OBJECT_INIT(3) FreeBSD Library Functions Manual DWARF_OBJECT_INIT(3)
NAME
dwarf_object_init - allocate a DWARF debug descriptor with application-
specific file access methods
LIBRARY
DWARF Access Library (libdwarf, -ldwarf)
SYNOPSIS
#include <libdwarf.h>
int
dwarf_object_init(Dwarf_Obj_Access_Interface *iface,
Dwarf_Handler errhand, Dwarf_Ptr errarg, Dwarf_Debug *dbg,
Dwarf_Error *err);
DESCRIPTION
The dwarf_object_init() function allocates and returns a Dwarf_Debug
instance that uses application-supplied access methods to read file
content.
The argument iface should point to a populated Dwarf_Obj_Access_Interface
structure. The contents of the Dwarf_Obj_Access_Interface structure are
described in the section Object Access Functions below.
The argument errhand should point to a function to be called in case of
an error. If this argument is NULL then a default error handling scheme
is used. See dwarf(3) for a description of the error handling schemes
available.
The argument errarg will be passed to the error handler function pointed
to by argument errhand.
The argument dbg should point to a memory location that will be set to a
reference to the returned Dwarf_Debug descriptor.
The argument err will be used to return a Dwarf_Error descriptor in case
of an error.
Object Access Functions
The data structures used to specify object access methods are defined in
<libdwarf.h>.
Dwarf_Obj_Access_Interface
This structure bundles together a set of file access methods
along with a pointer to application-private state.
typedef struct {
void *object;
const Dwarf_Obj_Access_Methods *methods;
} Dwarf_Obj_Access_Interface;
object This field points to application-specific state that
will be passed as the first parameter to the actual
access object methods.
methods This structure contains pointers to the functions
implementing the access methods, as described below.
Dwarf_Obj_Access_Methods
This structure specifies the functions implementing low-level
access.
typedef struct {
int (*get_section_info)(void *obj, Dwarf_Half index,
Dwarf_Obj_Access_Section *ret, int *error);
Dwarf_Endianness (*get_byte_order)(void *obj);
Dwarf_Small (*get_length_size)(void *obj);
Dwarf_Small (*get_pointer_size)(void *obj);
Dwarf_Unsigned (*get_section_count)(void *obj);
int (*load_section)(void *obj, Dwarf_Half ndx,
Dwarf_Small **ret_data, int *error);
} Dwarf_Obj_Access_Methods;
get_byte_order This function should return the endianness of
the DWARF object by returning one of the
constants DW_OBJECT_MSB or DW_OBJECT_LSB.
get_length_size This function should return the number of
bytes needed to represent a DWARF offset in
the object being debugged.
get_pointer_size This function should return the size in bytes,
in the object being debugged, of a memory
address.
get_section_count This function should return the number of
sections in the object being debugged.
get_section_info This function should return information about
the section at the index ndx by filling in the
structure of type Dwarf_Obj_Access_Section
pointed to by argument ret. The
Dwarf_Obj_Access_Section structure is
described below.
load_section This function should load the section
specified by argument ndx into memory and
place a pointer to the section's data into the
location pointed to by argument ret_data.
The argument obj passed to these functions will be set to the
pointer value in the object field of the associated
Dwarf_Obj_Access_Interface structure.
The argument error is used to return an error code in case of an
error.
Dwarf_Obj_Access_Section
This structure describes the layout of a section in the DWARF
object.
typedef struct {
Dwarf_Addr addr;
Dwarf_Unsigned size;
const char *name;
} Dwarf_Obj_Access_Section;
addr A pointer to the start of the section's data.
size The size of the section in bytes.
name A pointer to a NUL-terminated string containing the name of
the section.
RETURN VALUES
On success, the dwarf_object_init() function returns DW_DLV_OK. In case
of an error, the function returns DW_DLV_ERROR and sets the argument err.
ERRORS
The dwarf_object_init() function may fail with the following errors:
[DW_DLE_ARGUMENT] One of the arguments iface or dbg was NULL.
[DW_DLE_DEBUG_INFO_NULL] The underlying object did not contain
debugging information.
[DW_DLE_MEMORY] An out of memory condition was encountered
during the execution of the function.
SEE ALSO
dwarf(3), dwarf_init(3), dwarf_init_elf(3), dwarf_object_finish(3)
FreeBSD 15.1-STABLE-HBSD September 29, 2011 DWARF_OBJECT_INIT(3)