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/* -*- linux-c -*-
* Symbolic Lookup Functions
* Copyright (C) 2005-2023 Red Hat Inc.
* Copyright (C) 2006 Intel Corporation.
*
* This file is part of systemtap, and is free software. You can
* redistribute it and/or modify it under the terms of the GNU General
* Public License (GPL); either version 2, or (at your option) any
* later version.
*/
#if defined(_STP_SYM_C_) && defined(STP_NEED_LINE_DATA)
// At this point the compiler needs to know the context struct. The context
// struct is emitted by s.up->emit_common_header () within translate.cxx
// The _stp_filename_lookup_5 is declared in runtime/sym.c , but at that point
// the context struct isn't known yet. Here, context struct is known already,
// so here comes the _stp_filename_lookup_5 function body.
static void _stp_filename_lookup_5(struct _stp_module *mod, char ** filename,
uint8_t *dirsecp, uint8_t *enddirsecp,
unsigned int length,
unsigned fileidx, int user, int compat_task,
struct context *c)
{
// Pointer to the .debug_line section
// pointing at just after standard_opcode_lengths
// which is the last header item common to DWARF v4 and v5.
uint8_t *debug_line_p = dirsecp;
// Pointer to the beginning of .debug_line_str section
uint8_t *debug_line_str_p = mod->debug_line_str;
uint8_t *endstrsecp = mod->debug_line_str + mod->debug_line_str_len;
uint8_t directory_entry_format_count = 0, file_name_entry_format_count = 0,
directories_count = 0, file_names_count = 0;
static char fullpath [MAXSTRINGLEN];
// Reusable loop iterators. As the producer records show, the rhel8 kbuild
// system uses -std=gnu90 not allowing initial loop declarations, while the
// rhel9 build system allows that. We need to stay compatible though..
// https://lwn.net/Articles/885941/
int i = 0, j = 0;
// We rely on struct context for c->dw_data.
// That needs to be known at this point.
if (c == NULL)
{
_stp_error("BUG: Unknown context in _stp_filename_lookup_5()\n");
return;
}
// Initialize the *filename
*filename = "unknown";
// Next comes directory_entry_format_count
if (debug_line_str_p + 1 > enddirsecp)
return;
directory_entry_format_count = *debug_line_p++;
if (directory_entry_format_count > STP_MAX_DW_SOURCES)
return;
// Next comes directory_entry_format
for (i = 0; i < directory_entry_format_count; i++)
{
c->dw_data.dir_enc[i].desc = read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user, compat_task);
c->dw_data.dir_enc[i].form = read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user, compat_task);
}
// Next comes directories_count
directories_count = read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user, compat_task);
if (directories_count > STP_MAX_DW_SOURCES)
return;
// Next come directories
// See elfutil's print_form_data() in readelf.c for an analogy of what happens below
for (i=0; i < directories_count; i++)
for (j=0; j < directory_entry_format_count; j++)
switch (c->dw_data.dir_enc[j].form)
{
case DW_FORM_line_strp:
c->dw_data.src_dir[i].offset = (uint32_t) read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_data4, user, compat_task);
if ((uint8_t *) mod->debug_line_str + c->dw_data.src_dir[i].offset > endstrsecp)
return;
c->dw_data.src_dir[i].name = mod->debug_line_str + c->dw_data.src_dir[i].offset;
break;
default:
_stp_error("BUG: Unknown form %d encountered while parsing source dir\n",
c->dw_data.dir_enc[j].form);
return;
}
// Next comes file_name_entry_format_count
if (debug_line_p + 1 > enddirsecp)
return;
file_name_entry_format_count = *debug_line_p++;
if (file_name_entry_format_count > STP_MAX_DW_SOURCES)
return;
// Next comes file_name_entry_format
for (i = 0; i < file_name_entry_format_count; i++)
{
c->dw_data.file_enc[i].desc = read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user,
compat_task);
c->dw_data.file_enc[i].form = read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user,
compat_task);
}
// Next comes the file_names_count
// See elfutil's print_form_data() in readelf.c for an analogy of what happens below
file_names_count = read_pointer ((const uint8_t **) &debug_line_p, enddirsecp,
DW_EH_PE_leb128, user, compat_task);
if (file_names_count > STP_MAX_DW_SOURCES)
return;
// Next come the files
for (i=0; i < file_names_count; i++)
for (j=0; j < file_name_entry_format_count; j++)
switch (c->dw_data.file_enc[j].form)
{
case DW_FORM_line_strp:
c->dw_data.src_file[i].offset = (uint32_t) read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_data4, user,
compat_task);
if ((uint8_t *) mod->debug_line_str + c->dw_data.src_file[i].offset > endstrsecp)
return;
c->dw_data.src_file[i].name = mod->debug_line_str + c->dw_data.src_file[i].offset;
break;
case DW_FORM_data16:
// This is how clang encodes the md5sum, skip it
if (debug_line_p + 16 > enddirsecp)
return;
debug_line_p += 16;
break;
case DW_FORM_udata:
c->dw_data.src_file[i].dirindex = (uint8_t) read_pointer ((const uint8_t **) &debug_line_p,
enddirsecp, DW_EH_PE_leb128, user,
compat_task);
break;
default:
_stp_error("BUG: Unknown form %d encountered while parsing source file\n",
c->dw_data.file_enc[j].form);
return;
}
// Put it together
// - requested file index is fileidx
// (based on the line number program)
// - find directory respective to this file
// - and attach slash and the file name itself
strlcpy(fullpath, c->dw_data.src_dir[c->dw_data.src_file[fileidx].dirindex].name, MAXSTRINGLEN);
strlcat(fullpath, "/", MAXSTRINGLEN);
strlcat(fullpath, c->dw_data.src_file[fileidx].name, MAXSTRINGLEN);
*filename = fullpath;
}
#endif