1 .\" Copyright (c) 2011 Joseph Koshy
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25 .\" $Id: dwarf_object_init.3 3644 2018-10-15 19:55:01Z jkoshy $
27 .Dd September 29, 2011
28 .Dt DWARF_OBJECT_INIT 3
32 .Nd allocate a DWARF debug descriptor with application-specific file \
40 .Fa "Dwarf_Obj_Access_Interface *iface"
41 .Fa "Dwarf_Handler errhand"
42 .Fa "Dwarf_Ptr errarg"
43 .Fa "Dwarf_Debug *dbg"
44 .Fa "Dwarf_Error *err"
49 function allocates and returns a
51 instance that uses application-supplied access methods to read file
56 should point to a populated
57 .Vt Dwarf_Obj_Access_Interface
60 .Vt Dwarf_Obj_Access_Interface
61 structure are described in the section
62 .Sx "Object Access Functions"
67 should point to a function to be called in case of an error.
70 then a default error handling scheme is used.
73 for a description of the error handling schemes available.
77 will be passed to the error handler function pointed to by argument
82 should point to a memory location that will be set to a reference to
89 will be used to return a
91 descriptor in case of an error.
92 .Ss Object Access Functions
93 The data structures used to specify object access methods are defined
96 .Bl -tag -width indent
97 .It Vt "Dwarf_Obj_Access_Interface"
98 This structure bundles together a set of file access methods along
99 with a pointer to application-private state.
100 .Bd -literal -offset indent
103 const Dwarf_Obj_Access_Methods *methods;
104 } Dwarf_Obj_Access_Interface;
107 .Bl -tag -width ".Ar methods" -compact
109 This field points to application-specific state that will be passed as
110 the first parameter to the actual access object methods.
112 This structure contains pointers to the functions implementing the
113 access methods, as described below.
115 .It Vt Dwarf_Obj_Access_Methods
116 This structure specifies the functions implementing low-level access.
117 .Bd -literal -offset indent
119 int (*get_section_info)(void *obj, Dwarf_Half index,
120 Dwarf_Obj_Access_Section *ret, int *error);
121 Dwarf_Endianness (*get_byte_order)(void *obj);
122 Dwarf_Small (*get_length_size)(void *obj);
123 Dwarf_Small (*get_pointer_size)(void *obj);
124 Dwarf_Unsigned (*get_section_count)(void *obj);
125 int (*load_section)(void *obj, Dwarf_Half ndx,
126 Dwarf_Small **ret_data, int *error);
127 } Dwarf_Obj_Access_Methods;
130 .Bl -tag -width ".Ar get_section_count" -compact
131 .It Ar get_byte_order
132 This function should return the endianness of the DWARF object by
133 returning one of the constants
137 .It Ar get_length_size
138 This function should return the number of bytes needed to represent a
139 DWARF offset in the object being debugged.
140 .It Ar get_pointer_size
141 This function should return the size in bytes, in the object being
142 debugged, of a memory address.
143 .It Ar get_section_count
144 This function should return the number of sections in the object being
146 .It Ar get_section_info
147 This function should return information about the section at the
150 by filling in the structure of type
151 .Vt Dwarf_Obj_Access_Section
152 pointed to by argument
155 .Vt Dwarf_Obj_Access_Section
156 structure is described below.
158 This function should load the section specified by argument
160 into memory and place a pointer to the section's data into
161 the location pointed to by argument
167 passed to these functions will be set to the pointer value in the
169 field of the associated
170 .Vt Dwarf_Obj_Access_Interface
175 is used to return an error code in case of an error.
176 .It Vt Dwarf_Obj_Access_Section
177 This structure describes the layout of a section in the DWARF object.
178 .Bd -literal -offset indent
183 } Dwarf_Obj_Access_Section;
186 .Bl -tag -width ".Ar name" -compact
188 A pointer to the start of the section's data.
190 The size of the section in bytes.
192 A pointer to a NUL-terminated string containing the name of the
198 .Fn dwarf_object_init
201 In case of an error, the function returns
203 and sets the argument
207 .Fn dwarf_object_init
208 function may fail with the following errors:
209 .Bl -tag -width ".Bq Er DW_DLE_DEBUG_INFO_NULL"
210 .It Bq Er DW_DLE_ARGUMENT
216 .It Bq Er DW_DLE_DEBUG_INFO_NULL
217 The underlying object did not contain debugging information.
218 .It Bq Er DW_DLE_MEMORY
219 An out of memory condition was encountered during the execution of the
225 .Xr dwarf_init_elf 3 ,
226 .Xr dwarf_object_finish 3