DWARF_GET_FDE_LIST(3) | Library Functions Manual | DWARF_GET_FDE_LIST(3)

# NAME

`dwarf_get_fde_list` —
retrieve frame information

# LIBRARY

DWARF Access Library (libdwarf, -ldwarf)

# SYNOPSIS

`#include <libdwarf.h>`

int
`dwarf_get_fde_list`(Dwarf_Debug dbg, Dwarf_Cie **cie_list, Dwarf_Signed *cie_count, Dwarf_Fde **fde_list, Dwarf_Signed *fde_count, Dwarf_Error *err);

int
`dwarf_get_fde_list_eh`(Dwarf_Debug dbg, Dwarf_Cie **cie_list, Dwarf_Signed *cie_count, Dwarf_Fde **fde_list, Dwarf_Signed *fde_count, Dwarf_Error *err);

# DESCRIPTION

These functions retrieve frame related information for the specified DWARF debug context.

Function `dwarf_get_fde_list`() retrieves frame information from the DWARF section named “.debug_frame”. For objects containing GNU style C++ exception handling information, the function `dwarf_get_fde_list_eh`() retrieves frame information from the section named “.eh_frame”.

Frame information is returned using opaque descriptors of type Dwarf_Cie and Dwarf_Fde. Applications need to use the other frame related functions in the DWARF(3) API set to retrieve the information contained in these descriptors.

Argument dbg should reference a DWARF debug context allocated using dwarf_init(3).

Argument cie_list should point to a location that will be set to a pointer to an array of Dwarf_Cie descriptors.

Argument cie_count should point to a location that will be set to the number of Dwarf_Cie descriptors returned.

Argument fde_list should point to a location that will be set to a pointer to an array of Dwarf_Fde descriptors.

Argument fde_count should point to a location that will be set to the number of Dwarf_Fde descriptors returned.

If argument err is not NULL, it will be used to store error information in case of an error.

## Memory Management

The memory areas used for the arrays returned in arguments cie_list and fde_list are owned by the DWARF Access Library (libdwarf, -ldwarf). Application code should not attempt to directly free these areas. Portable applications should instead use the dwarf_fde_cie_list_dealloc(3) function to indicate that these memory areas may be freed.

# RETURN VALUES

On success, these functions returns `DW_DLV_OK`. They return `DW_DLV_NO_ENTRY` if there is no frame information associated with the given DWARF debug context. In case of an error, they return `DW_DLV_ERROR` and set the argument err.

# ERRORS

These functions may fail with the following errors:

[`DW_DLE_ARGUMENT`]
  One of the arguments dbg, cie_list, cie_count, fde_list or fde_count was NULL.
[`DW_DLE_NO_ENTRY`]
  There is no frame information associated with the giving DWARF debug context.

# EXAMPLE

To obtain frame information from the “.debug_frame” section, use:

    Dwarf_Debug dbg;
    Dwarf_Cie *cie_list, cie;
    Dwarf_Fde *fde_list, fde;
    Dwarf_Off fde_offset, cie_offset;
    Dwarf_Unsigned func_len, fde_length, fde_instlen;
    Dwarf_Signed cie_count, fde_count, cie_index;
    Dwarf_Addr low_pc;
    Dwarf_Ptr fde_addr, fde_inst, cie_inst;
    Dwarf_Error de;
    int i;

    if (dwarf_get_fde_list(dbg, &cie_list, &cie_count,
        &fde_list, &fde_count, &de) != DW_DLV_OK) {
    	errx(EXIT_FAILURE, "dwarf_get_fde_list failed: %s",
    	    dwarf_errmsg(de));
    }

    for (i = 0; i < fde_count; i++) {
    	if (dwarf_get_fde_n(fde_list, i, &fde, &de) != DW_DLV_OK) {
    		warnx("dwarf_get_fde_n failed: %s",
    		    dwarf_errmsg(de));
    		continue;
    	}
    	if (dwarf_get_cie_of_fde(fde, &cie, &de) != DW_DLV_OK) {
    		warnx("dwarf_get_fde_n failed: %s",
    		    dwarf_errmsg(de));
    		continue;
    	}
    	if (dwarf_get_fde_range(fde, &low_pc, &func_len, &fde_addr,
    	    &fde_length, &cie_offset, &cie_index, &fde_offset,
    	    &de) != DW_DLV_OK) {
    		warnx("dwarf_get_fde_range failed: %s",
    		    dwarf_errmsg(de));
    		continue;
    	}
    	if (dwarf_get_fde_instr_bytes(fde, &fde_inst, &fde_instlen,
    	    &de) != DW_DLV_OK) {
    		warnx("dwarf_get_fde_instr_bytes failed: %s",
    		    dwarf_errmsg(de));
    		continue;
    	}

    	/* ... Use the retrieved frame information ... */
    }

    /* Indicate that the returned arrays may be freed. */
    dwarf_fde_cie_list_dealloc(dbg, cie_list, cie_count, fde_list,
        fde_count);

# SEE ALSO

dwarf(3), dwarf_get_cie_index(3), dwarf_get_cie_of_fde(3), dwarf_get_fde_at_pc(3), dwarf_get_fde_instr_bytes(3), dwarf_get_fde_n(3), dwarf_get_fde_range(3), dwarf_fde_cie_list_dealloc(3), dwarf_set_frame_cfa_value(3), dwarf_set_frame_rule_table_size(3), dwarf_set_frame_rule_initial_value(3), dwarf_set_frame_same_value(3), dwarf_set_frame_undefined_value(3)

November 9, 2011 | NetBSD 9.4