// SPDX-License-Identifier: GPL-2.0
#include "dso.h"
#include "libdw.h"
#include "srcline.h"
#include "symbol.h"
#include "dwarf-aux.h"
#include <fcntl.h>
#include <unistd.h>
#include <elfutils/libdwfl.h>

static const Dwfl_Callbacks offline_callbacks = {
        .find_debuginfo = dwfl_standard_find_debuginfo,
        .section_address = dwfl_offline_section_address,
        .find_elf = dwfl_build_id_find_elf,
};

void dso__free_libdw(struct dso *dso)
{
        Dwfl *dwfl = dso__libdw(dso);

        if (dwfl) {
                dwfl_end(dwfl);
                dso__set_libdw(dso, NULL);
        }
}

struct Dwfl *dso__libdw_dwfl(struct dso *dso)
{
        Dwfl *dwfl = dso__libdw(dso);
        const char *dso_name;
        Dwfl_Module *mod;
        int fd;

        if (dwfl)
                return dwfl;

        dso_name = dso__long_name(dso);
        /*
         * Initialize Dwfl session.
         * We need to open the DSO file to report it to libdw.
         */
        fd = open(dso_name, O_RDONLY);
        if (fd < 0)
                return NULL;

        dwfl = dwfl_begin(&offline_callbacks);
        if (!dwfl) {
                close(fd);
                return NULL;
        }

        /*
         * If the report is successful, the file descriptor fd is consumed
         * and closed by the Dwfl. If not, it is not closed.
         */
        mod = dwfl_report_offline(dwfl, dso_name, dso_name, fd);
        if (!mod) {
                dwfl_end(dwfl);
                close(fd);
                return NULL;
        }

        dwfl_report_end(dwfl, /*removed=*/NULL, /*arg=*/NULL);
        dso__set_libdw(dso, dwfl);

        return dwfl;
}

struct libdw_a2l_cb_args {
        struct dso *dso;
        struct symbol *sym;
        struct inline_node *node;
        char *leaf_srcline;
        bool leaf_srcline_used;
};

static int libdw_a2l_cb(Dwarf_Die *die, void *_args)
{
        struct libdw_a2l_cb_args *args  = _args;
        struct symbol *inline_sym = new_inline_sym(args->dso, args->sym, dwarf_diename(die));
        const char *call_fname = die_get_call_file(die);
        char *call_srcline = srcline__unknown;
        struct inline_list *ilist;

        if (!inline_sym)
                return -ENOMEM;

        /* Assign caller information to the parent. */
        if (call_fname)
                call_srcline = srcline_from_fileline(call_fname, die_get_call_lineno(die));

        list_for_each_entry(ilist, &args->node->val, list) {
                if (args->leaf_srcline == ilist->srcline)
                        args->leaf_srcline_used = false;
                else if (ilist->srcline != srcline__unknown)
                        free(ilist->srcline);
                ilist->srcline =  call_srcline;
                call_srcline = NULL;
                break;
        }
        if (call_srcline && call_srcline != srcline__unknown)
                free(call_srcline);

        /* Add this symbol to the chain as the leaf. */
        if (!args->leaf_srcline_used) {
                inline_list__append_tail(inline_sym, args->leaf_srcline, args->node);
                args->leaf_srcline_used = true;
        } else {
                inline_list__append_tail(inline_sym, strdup(args->leaf_srcline), args->node);
        }
        return 0;
}

int libdw__addr2line(u64 addr, char **file, unsigned int *line_nr,
                     struct dso *dso, bool unwind_inlines,
                     struct inline_node *node, struct symbol *sym)
{
        Dwfl *dwfl = dso__libdw_dwfl(dso);
        Dwfl_Module *mod;
        Dwfl_Line *dwline;
        Dwarf_Addr bias;
        const char *src;
        int lineno = 0;

        if (!dwfl)
                return 0;

        mod = dwfl_addrmodule(dwfl, addr);
        if (!mod)
                return 0;

        /*
         * Get/ignore the dwarf information. Determine the bias, difference
         * between the regular ELF addr2line addresses and those to use with
         * libdw.
         */
        if (!dwfl_module_getdwarf(mod, &bias))
                return 0;

        /* Find source line information for the address. */
        dwline = dwfl_module_getsrc(mod, addr + bias);
        if (!dwline)
                return 0;

        /* Get line information. */
        src = dwfl_lineinfo(dwline, /*addr=*/NULL, &lineno, /*col=*/NULL, /*mtime=*/NULL,
                            /*length=*/NULL);

        if (file)
                *file = src ? strdup(src) : NULL;
        if (line_nr)
                *line_nr = lineno;

        /* Optionally unwind inline function call chain. */
        if (unwind_inlines && node) {
                Dwarf_Addr unused_bias;
                Dwarf_Die *cudie = dwfl_module_addrdie(mod, addr + bias, &unused_bias);
                struct libdw_a2l_cb_args args = {
                        .dso = dso,
                        .sym = sym,
                        .node = node,
                        .leaf_srcline = srcline_from_fileline(src ?: "<unknown>", lineno),
                };

                /* Walk from the parent down to the leaf. */
                cu_walk_functions_at(cudie, addr, libdw_a2l_cb, &args);

                if (!args.leaf_srcline_used)
                        free(args.leaf_srcline);
        }
        return 1;
}