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FreeBSD 11.0 - man page for dwarf_object_init (freebsd section 3)

DWARF_OBJECT_INIT(3)					   BSD 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 con- tent. The argument iface should point to a populated Dwarf_Obj_Access_Interface structure. The contents of the Dwarf_Obj_Access_Interface struc- ture 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 meth- ods. 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)
BSD
September 29, 2011 BSD