1 .\" Copyright (c) 2011 Joseph Koshy
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25 .\" $Id: dwarf_object_init.3 2074 2011-10-27 03:34:33Z jkoshy $
27 .Dd September 29, 2011
29 .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"
50 function allocates and returns a
52 instance that uses application-supplied access methods to read file
57 should point to a populated
58 .Vt Dwarf_Obj_Access_Interface
61 .Vt Dwarf_Obj_Access_Interface
62 structure are described in the section
63 .Sx "Object Access Functions"
68 should point to a function to be called in case of an error.
71 then a default error handling scheme is used.
74 for a description of the error handling schemes available.
78 will be passed to the error handler function pointed to by argument
83 should point to a memory location that will be set to a reference to
90 will be used to return a
92 descriptor in case of an error.
93 .Ss Object Access Functions
94 The data structures used to specify object access methods are defined
97 .Bl -tag -width indent
98 .It Vt "Dwarf_Obj_Access_Interface"
99 This structure bundles together a set of file access methods along
100 with a pointer to application-private state.
101 .Bd -literal -offset indent
104 const Dwarf_Obj_Access_Methods *methods;
105 } Dwarf_Obj_Access_Interface;
108 .Bl -tag -width ".Ar methods" -compact
110 This field points to application-specific state that will be passed as
111 the first parameter to the actual access object methods.
113 This structure contains pointers to the functions implementing the
114 access methods, as described below.
116 .It Vt Dwarf_Obj_Access_Methods
117 This structure specifies the functions implementing low-level access.
118 .Bd -literal -offset indent
120 int (*get_section_info)(void *obj, Dwarf_Half index,
121 Dwarf_Obj_Access_Section *ret, int *error);
122 Dwarf_Endianness (*get_byte_order)(void *obj);
123 Dwarf_Small (*get_length_size)(void *obj);
124 Dwarf_Small (*get_pointer_size)(void *obj);
125 Dwarf_Unsigned (*get_section_count)(void *obj);
126 int (*load_section)(void *obj, Dwarf_Half ndx,
127 Dwarf_Small **ret_data, int *error);
128 } Dwarf_Obj_Access_Methods;
131 .Bl -tag -width ".Ar get_section_count" -compact
132 .It Ar get_byte_order
133 This function should return the endianness of the DWARF object by
134 returning one of the constants
138 .It Ar get_length_size
139 This function should return the number of bytes needed to represent a
140 DWARF offset in the object being debugged.
141 .It Ar get_pointer_size
142 This function should return the size in bytes, in the object being
143 debugged, of a memory address.
144 .It Ar get_section_count
145 This function should return the number of sections in the object being
147 .It Ar get_section_info
148 This function should return information about the section at the
151 by filling in the structure of type
152 .Vt Dwarf_Obj_Access_Section
153 pointed to by argument
156 .Vt Dwarf_Obj_Access_Section
157 structure is described below.
159 This function should load the section specified by argument
161 into memory and place a pointer to the section's data into
162 the location pointed to by argument
168 passed to these functions will be set to the pointer value in the
170 field of the associated
171 .Vt Dwarf_Obj_Access_Interface
176 is used to return an error code in case of an error.
177 .It Vt Dwarf_Obj_Access_Section
178 This structure describes the layout of a section in the DWARF object.
179 .Bd -literal -offset indent
184 } Dwarf_Obj_Access_Section;
187 .Bl -tag -width ".Ar name" -compact
189 A pointer to the start of the section's data.
191 The size of the section in bytes.
193 A pointer to a NUL-terminated string containing the name of the
199 .Fn dwarf_object_init
202 In case of an error, the function returns
204 and sets the argument
208 .Fn dwarf_object_init
209 function may fail with the following errors:
210 .Bl -tag -width ".Bq Er DW_DLE_DEBUG_INFO_NULL"
211 .It Bq Er DW_DLE_ARGUMENT
217 .It Bq Er DW_DLE_DEBUG_INFO_NULL
218 The underlying object did not contain debugging information.
219 .It Bq Er DW_DLE_MEMORY
220 An out of memory condition was encountered during the execution of the
226 .Xr dwarf_init_elf 3 ,
227 .Xr dwarf_object_finish 3