/* Unwinding of frames like gstack/pstack.
 Copyright (C) 2013-2014 Red Hat, Inc.
 This file is part of elfutils.

 This file is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 3 of the License, or
 (at your option) any later version.

 elfutils is distributed in the hope that it will be useful, but
 WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 GNU General Public License for more details.

 You should have received a copy of the GNU General Public License
 along with this program. If not, see <http://www.gnu.org/licenses/>. */

#include <config.h>
#include <assert.h>
#include <argp.h>
#include <stdlib.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdio_ext.h>
#include <string.h>
#include <locale.h>
#include <fcntl.h>
#include ELFUTILS_HEADER(dwfl)

#include <dwarf.h>
#include <system.h>
#include <printversion.h>

/* Name and version of program. */
ARGP_PROGRAM_VERSION_HOOK_DEF = print_version;

/* Bug report address. */
ARGP_PROGRAM_BUG_ADDRESS_DEF = PACKAGE_BUGREPORT;

/* non-printable argp options. */
#define OPT_DEBUGINFO	0x100
#define OPT_COREFILE	0x101

static bool show_activation = false;
static bool show_module = false;
static bool show_build_id = false;
static bool show_source = false;
static bool show_one_tid = false;
static bool show_quiet = false;
static bool show_raw = false;
static bool show_modules = false;
static bool show_debugname = false;
static bool show_inlines = false;

static int maxframes = 256;

struct frame
{
 Dwarf_Addr pc;
 bool isactivation;
};

struct frames
{
 int frames;
 int allocated;
 struct frame *frame;
};

static Dwfl *dwfl = NULL;
static pid_t pid = 0;
static int core_fd = -1;
static Elf *core = NULL;
static const char *exec = NULL;
static char *debuginfo_path = NULL;

static const Dwfl_Callbacks proc_callbacks =
 {
 .find_elf = dwfl_linux_proc_find_elf,
 .find_debuginfo = dwfl_standard_find_debuginfo,
 .debuginfo_path = &debuginfo_path,
 };

static const Dwfl_Callbacks core_callbacks =
 {
 .find_elf = dwfl_build_id_find_elf,
 .find_debuginfo = dwfl_standard_find_debuginfo,
 .debuginfo_path = &debuginfo_path,
 };

#ifdef USE_DEMANGLE
static size_t demangle_buffer_len = 0;
static char *demangle_buffer = NULL;
#endif

/* Whether any frames have been shown at all. Determines exit status. */
static bool frames_shown = false;

/* Program exit codes. All frames shown without any errors is GOOD.
 Some frames shown with some non-fatal errors is an ERROR. A fatal
 error or no frames shown at all is BAD. A command line USAGE exit
 is generated by argp_error. */
#define EXIT_OK 0
#define EXIT_ERROR 1
#define EXIT_BAD 2
#define EXIT_USAGE 64

static int
get_addr_width (Dwfl_Module *mod)
{
 // Try to find the address wide if possible.
 static int width = 0;
 if (width == 0 && mod)
 {
 Dwarf_Addr bias;
 Elf *elf = dwfl_module_getelf (mod, &bias);
 if (elf)
 {
	 GElf_Ehdr ehdr_mem;
	 GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
	 if (ehdr)
	 width = ehdr->e_ident[EI_CLASS] == ELFCLASS32 ? 8 : 16;
	}
 }
 if (width == 0)
 width = 16;

 return width;
}

static int
module_callback (Dwfl_Module *mod, void **userdata __attribute__((unused)),
		 const char *name, Dwarf_Addr start,
		 void *arg __attribute__((unused)))
{
 /* Forces resolving of main elf and debug files. */
 Dwarf_Addr bias;
 Elf *elf = dwfl_module_getelf (mod, &bias);
 Dwarf *dwarf = dwfl_module_getdwarf (mod, &bias);

 Dwarf_Addr end;
 const char *mainfile;
 const char *debugfile;
 const char *modname = dwfl_module_info (mod, NULL, NULL, &end, NULL,
 NULL, &mainfile, &debugfile);
 assert (strcmp (modname, name) == 0);

 int width = get_addr_width (mod);
 printf ("0x%0*" PRIx64 "-0x%0*" PRIx64 " %s\n",
	 width, start, width, end, basename (name));

 const unsigned char *id;
 GElf_Addr id_vaddr;
 int id_len = dwfl_module_build_id (mod, &id, &id_vaddr);
 if (id_len > 0)
 {
 printf (" [");
 do
	printf ("%02" PRIx8, *id++);
 while (--id_len > 0);
 printf ("]\n");
 }

 if (elf != NULL)
 printf (" %s\n", mainfile != NULL ? mainfile : "-");
 if (dwarf != NULL)
 printf (" %s\n", debugfile != NULL ? debugfile : "-");

 return DWARF_CB_OK;
}

static int
frame_callback (Dwfl_Frame *state, void *arg)
{
 struct frames *frames = (struct frames *) arg;
 int nr = frames->frames;
 if (! dwfl_frame_pc (state, &frames->frame[nr].pc,
		 &frames->frame[nr].isactivation))
 return -1;

 frames->frames++;
 if (frames->frames == maxframes)
 return DWARF_CB_ABORT;

 if (frames->frames == frames->allocated)
 {
 frames->allocated *= 2;
 frames->frame = realloc (frames->frame,
			 sizeof (struct frame) * frames->allocated);
 if (frames->frame == NULL)
	error (EXIT_BAD, errno, "realloc frames.frame");
 }

 return DWARF_CB_OK;
}

static const char*
die_name (Dwarf_Die *die)
{
 Dwarf_Attribute attr;
 const char *name;
 name = dwarf_formstring (dwarf_attr_integrate (die,
						 DW_AT_MIPS_linkage_name,
						 &attr)
			 ?: dwarf_attr_integrate (die,
						 DW_AT_linkage_name,
						 &attr));
 if (name == NULL)
 name = dwarf_diename (die);

 return name;
}

static void
print_frame (int nr, Dwarf_Addr pc, bool isactivation,
	 Dwarf_Addr pc_adjusted, Dwfl_Module *mod,
	 const char *symname, Dwarf_Die *cudie,
	 Dwarf_Die *die)
{
 int width = get_addr_width (mod);
 printf ("#%-2u 0x%0*" PRIx64, nr, width, (uint64_t) pc);

 if (show_activation)
 printf ("%4s", ! isactivation ? "- 1" : "");

 if (symname != NULL)
 {
#ifdef USE_DEMANGLE
 // Require GNU v3 ABI by the "_Z" prefix.
 if (! show_raw && symname[0] == '_' && symname[1] == 'Z')
	{
	 int status = -1;
	 char *dsymname = __cxa_demangle (symname, demangle_buffer,
					 &demangle_buffer_len, &status);
	 if (status == 0)
	 symname = demangle_buffer = dsymname;
	}
#endif
 printf (" %s", symname);
 }

 const char* fname;
 Dwarf_Addr start;
 fname = dwfl_module_info(mod, NULL, &start,
			 NULL, NULL, NULL, NULL, NULL);
 if (show_module)
 {
 if (fname != NULL)
	printf (" - %s", fname);
 }

 if (show_build_id)
 {
 const unsigned char *id;
 GElf_Addr id_vaddr;
 int id_len = dwfl_module_build_id (mod, &id, &id_vaddr);
 if (id_len > 0)
	{
	 printf ("\n [");
	 do
	 printf ("%02" PRIx8, *id++);
	 while (--id_len > 0);
	 printf ("]@0x%0" PRIx64 "+0x%" PRIx64,
		 start, pc_adjusted - start);
	}
 }

 if (show_source)
 {
 int line, col;
 const char* sname;
 line = col = -1;
 sname = NULL;
 if (die != NULL)
	{
	 Dwarf_Files *files;
	 if (dwarf_getsrcfiles (cudie, &files, NULL) == 0)
	 {
	 Dwarf_Attribute attr;
	 Dwarf_Word val;
	 if (dwarf_formudata (dwarf_attr (die, DW_AT_call_file, &attr),
				 &val) == 0)
		{
		 sname = dwarf_filesrc (files, val, NULL, NULL);
		 if (dwarf_formudata (dwarf_attr (die, DW_AT_call_line,
						 &attr), &val) == 0)
		 {
		 line = val;
		 if (dwarf_formudata (dwarf_attr (die, DW_AT_call_column,
						 &attr), &val) == 0)
			col = val;
		 }
		}
	 }
	}
 else
	{
	 Dwfl_Line *lineobj = dwfl_module_getsrc(mod, pc_adjusted);
	 if (lineobj)
	 sname = dwfl_lineinfo (lineobj, NULL, &line, &col, NULL, NULL);
	}

 if (sname != NULL)
	{
	 printf ("\n %s", sname);
	 if (line > 0)
	 {
	 printf (":%d", line);
	 if (col > 0)
		printf (":%d", col);
	 }
	}
 }
 printf ("\n");
}

static void
print_inline_frames (int *nr, Dwarf_Addr pc, bool isactivation,
		 Dwarf_Addr pc_adjusted, Dwfl_Module *mod,
		 const char *symname, Dwarf_Die *cudie, Dwarf_Die *die)
{
 Dwarf_Die *scopes = NULL;
 int nscopes = dwarf_getscopes_die (die, &scopes);
 if (nscopes > 0)
 {
 /* scopes[0] == die, the lowest level, for which we already have
	 the name. This is the actual source location where it
	 happened. */
 print_frame ((*nr)++, pc, isactivation, pc_adjusted, mod, symname,
		 NULL, NULL);

 /* last_scope is the source location where the next frame/function
	 call was done. */
 Dwarf_Die *last_scope = &scopes[0];
 for (int i = 1; i < nscopes && (maxframes == 0 || *nr < maxframes); i++)
	{
	 Dwarf_Die *scope = &scopes[i];
	 int tag = dwarf_tag (scope);
	 if (tag != DW_TAG_inlined_subroutine
	 && tag != DW_TAG_entry_point
	 && tag != DW_TAG_subprogram)
	 continue;

	 symname = die_name (scope);
	 print_frame ((*nr)++, pc, isactivation, pc_adjusted, mod, symname,
		 cudie, last_scope);

	 /* Found the "top-level" in which everything was inlined? */
	 if (tag == DW_TAG_subprogram)
	 break;

	 last_scope = scope;
	}
 }
 free (scopes);
}

static void
print_frames (struct frames *frames, pid_t tid, int dwflerr, const char *what)
{
 if (frames->frames > 0)
 frames_shown = true;

 printf ("TID %lld:\n", (long long) tid);
 int frame_nr = 0;
 for (int nr = 0; nr < frames->frames && (maxframes == 0
					 || frame_nr < maxframes); nr++)
 {
 Dwarf_Addr pc = frames->frame[nr].pc;
 bool isactivation = frames->frame[nr].isactivation;
 Dwarf_Addr pc_adjusted = pc - (isactivation ? 0 : 1);

 /* Get PC->SYMNAME. */
 Dwfl_Module *mod = dwfl_addrmodule (dwfl, pc_adjusted);
 const char *symname = NULL;
 Dwarf_Die die_mem;
 Dwarf_Die *die = NULL;
 Dwarf_Die *cudie = NULL;
 if (mod && ! show_quiet)
	{
	 if (show_debugname)
	 {
	 Dwarf_Addr bias = 0;
	 Dwarf_Die *scopes = NULL;
	 cudie = dwfl_module_addrdie (mod, pc_adjusted, &bias);
	 int nscopes = dwarf_getscopes (cudie, pc_adjusted - bias,
					 &scopes);

	 /* Find the first function-like DIE with a name in scope. */
	 for (int i = 0; symname == NULL && i < nscopes; i++)
		{
		 Dwarf_Die *scope = &scopes[i];
		 int tag = dwarf_tag (scope);
		 if (tag == DW_TAG_subprogram
		 || tag == DW_TAG_inlined_subroutine
		 || tag == DW_TAG_entry_point)
		 symname = die_name (scope);

		 if (symname != NULL)
		 {
		 die_mem = *scope;
		 die = &die_mem;
		 }
		}
	 free (scopes);
	 }

	 if (symname == NULL)
	 symname = dwfl_module_addrname (mod, pc_adjusted);
	}

 if (show_inlines && die != NULL)
	print_inline_frames (&frame_nr, pc, isactivation, pc_adjusted, mod,
			 symname, cudie, die);
 else
	print_frame (frame_nr++, pc, isactivation, pc_adjusted, mod, symname,
		 NULL, NULL);
 }

 if (frames->frames > 0 && frame_nr == maxframes)
 error (0, 0, "tid %lld: shown max number of frames "
	 "(%d, use -n 0 for unlimited)", (long long) tid, maxframes);
 else if (dwflerr != 0)
 {
 if (frames->frames > 0)
	{
	 unsigned nr = frames->frames - 1;
	 Dwarf_Addr pc = frames->frame[nr].pc;
	 bool isactivation = frames->frame[nr].isactivation;
	 Dwarf_Addr pc_adjusted = pc - (isactivation ? 0 : 1);
	 Dwfl_Module *mod = dwfl_addrmodule (dwfl, pc_adjusted);
	 const char *mainfile = NULL;
	 const char *modname = dwfl_module_info (mod, NULL, NULL, NULL, NULL,
						 NULL, &mainfile, NULL);
	 if (modname == NULL || modname[0] == '0円')
	 {
	 if (mainfile != NULL)
		modname = mainfile;
	 else
		modname = "<unknown>";
	 }
	 error (0, 0, "%s tid %lld at 0x%" PRIx64 " in %s: %s", what,
		 (long long) tid, pc_adjusted, modname, dwfl_errmsg (dwflerr));
	}
 else
	error (0, 0, "%s tid %lld: %s", what, (long long) tid,
	 dwfl_errmsg (dwflerr));
 }
}

static int
thread_callback (Dwfl_Thread *thread, void *thread_arg)
{
 struct frames *frames = (struct frames *) thread_arg;
 pid_t tid = dwfl_thread_tid (thread);
 int err = 0;
 frames->frames = 0;
 switch (dwfl_thread_getframes (thread, frame_callback, thread_arg))
 {
 case DWARF_CB_OK:
 case DWARF_CB_ABORT:
 break;
 case -1:
 err = dwfl_errno ();
 break;
 default:
 abort ();
 }
 print_frames (frames, tid, err, "dwfl_thread_getframes");
 return DWARF_CB_OK;
}

static error_t
parse_opt (int key, char *arg __attribute__ ((unused)),
	 struct argp_state *state)
{
 switch (key)
 {
 case 'p':
 pid = atoi (arg);
 if (pid == 0)
	argp_error (state, N_("-p PID should be a positive process id."));
 break;

 case OPT_COREFILE:
 core_fd = open (arg, O_RDONLY);
 if (core_fd < 0)
	error (EXIT_BAD, errno, N_("Cannot open core file '%s'"), arg);
 elf_version (EV_CURRENT);
 core = elf_begin (core_fd, ELF_C_READ_MMAP, NULL);
 if (core == NULL)
	error (EXIT_BAD, 0, "core '%s' elf_begin: %s", arg, elf_errmsg(-1));
 break;

 case 'e':
 exec = arg;
 break;

 case OPT_DEBUGINFO:
 debuginfo_path = arg;
 break;

 case 'm':
 show_module = true;
 break;

 case 's':
 show_source = true;
 break;

 case 'a':
 show_activation = true;
 break;

 case 'd':
 show_debugname = true;
 break;

 case 'i':
 show_inlines = show_debugname = true;
 break;

 case 'v':
 show_activation = show_source = show_module = show_debugname = true;
 show_inlines = true;
 break;

 case 'b':
 show_build_id = true;
 break;

 case 'q':
 show_quiet = true;
 break;

 case 'r':
 show_raw = true;
 break;

 case '1':
 show_one_tid = true;
 break;

 case 'n':
 maxframes = atoi (arg);
 if (maxframes < 0)
	{
	 argp_error (state, N_("-n MAXFRAMES should be 0 or higher."));
	 return EINVAL;
	}
 break;

 case 'l':
 show_modules = true;
 break;

 case ARGP_KEY_END:
 if (core == NULL && exec != NULL)
	argp_error (state,
		 N_("-e EXEC needs a core given by --core."));

 if (pid == 0 && show_one_tid == true)
	argp_error (state,
		 N_("-1 needs a thread id given by -p."));

 if ((pid == 0 && core == NULL) || (pid != 0 && core != NULL))
	argp_error (state,
		 N_("One of -p PID or --core COREFILE should be given."));

 if (pid != 0)
	{
	 dwfl = dwfl_begin (&proc_callbacks);
	 if (dwfl == NULL)
	 error (EXIT_BAD, 0, "dwfl_begin: %s", dwfl_errmsg (-1));

	 int err = dwfl_linux_proc_report (dwfl, pid);
	 if (err < 0)
	 error (EXIT_BAD, 0, "dwfl_linux_proc_report pid %lld: %s",
		 (long long) pid, dwfl_errmsg (-1));
	 else if (err > 0)
	 error (EXIT_BAD, err, "dwfl_linux_proc_report pid %lld",
		 (long long) pid);
	}

 if (core != NULL)
	{
	 dwfl = dwfl_begin (&core_callbacks);
	 if (dwfl == NULL)
	 error (EXIT_BAD, 0, "dwfl_begin: %s", dwfl_errmsg (-1));
	 if (dwfl_core_file_report (dwfl, core, exec) < 0)
	 error (EXIT_BAD, 0, "dwfl_core_file_report: %s", dwfl_errmsg (-1));
	}

 if (dwfl_report_end (dwfl, NULL, NULL) != 0)
	error (EXIT_BAD, 0, "dwfl_report_end: %s", dwfl_errmsg (-1));

 if (pid != 0)
	{
	 int err = dwfl_linux_proc_attach (dwfl, pid, false);
	 if (err < 0)
	 error (EXIT_BAD, 0, "dwfl_linux_proc_attach pid %lld: %s",
		 (long long) pid, dwfl_errmsg (-1));
	 else if (err > 0)
	 error (EXIT_BAD, err, "dwfl_linux_proc_attach pid %lld",
		 (long long) pid);
	}

 if (core != NULL)
	{
	 if (dwfl_core_file_attach (dwfl, core) < 0)
	 error (EXIT_BAD, 0, "dwfl_core_file_report: %s", dwfl_errmsg (-1));
	}

 /* Makes sure we are properly attached. */
 if (dwfl_pid (dwfl) < 0)
	error (EXIT_BAD, 0, "dwfl_pid: %s\n", dwfl_errmsg (-1));
 break;

 default:
 return ARGP_ERR_UNKNOWN;
 }
 return 0;
}

int
main (int argc, char **argv)
{
 /* We use no threads here which can interfere with handling a stream. */
 __fsetlocking (stdin, FSETLOCKING_BYCALLER);
 __fsetlocking (stdout, FSETLOCKING_BYCALLER);
 __fsetlocking (stderr, FSETLOCKING_BYCALLER);

 /* Set locale. */
 (void) setlocale (LC_ALL, "");

 const struct argp_option options[] =
 {
 { NULL, 0, NULL, 0, N_("Input selection options:"), 0 },
 { "pid", 'p', "PID", 0,
	N_("Show stack of process PID"), 0 },
 { "core", OPT_COREFILE, "COREFILE", 0,
	N_("Show stack found in COREFILE"), 0 },
 { "executable", 'e', "EXEC", 0, N_("(optional) EXECUTABLE that produced COREFILE"), 0 },
 { "debuginfo-path", OPT_DEBUGINFO, "PATH", 0,
	N_("Search path for separate debuginfo files"), 0 },

 { NULL, 0, NULL, 0, N_("Output selection options:"), 0 },
 { "activation", 'a', NULL, 0,
	N_("Additionally show frame activation"), 0 },
 { "debugname", 'd', NULL, 0,
	N_("Additionally try to lookup DWARF debuginfo name for frame address"),
	0 },
 { "inlines", 'i', NULL, 0,
	N_("Additionally show inlined function frames using DWARF debuginfo if available (implies -d)"), 0 },
 { "module", 'm', NULL, 0,
	N_("Additionally show module file information"), 0 },
 { "source", 's', NULL, 0,
	N_("Additionally show source file information"), 0 },
 { "verbose", 'v', NULL, 0,
	N_("Show all additional information (activation, debugname, inlines, module and source)"), 0 },
 { "quiet", 'q', NULL, 0,
	N_("Do not resolve address to function symbol name"), 0 },
 { "raw", 'r', NULL, 0,
	N_("Show raw function symbol names, do not try to demangle names"), 0 },
 { "build-id", 'b', NULL, 0,
	N_("Show module build-id, load address and pc offset"), 0 },
 { NULL, '1', NULL, 0,
	N_("Show the backtrace of only one thread"), 0 },
 { NULL, 'n', "MAXFRAMES", 0,
	N_("Show at most MAXFRAMES per thread (default 256, use 0 for unlimited)"), 0 },
 { "list-modules", 'l', NULL, 0,
	N_("Show module memory map with build-id, elf and debug files detected"), 0 },
 { NULL, 0, NULL, 0, NULL, 0 }
 };

 const struct argp argp =
 {
 .options = options,
 .parser = parse_opt,
 .doc = N_("Print a stack for each thread in a process or core file.\n\
\n\
Program exits with return code 0 if all frames were shown without \
any errors. If some frames were shown, but there were some non-fatal \
errors, possibly causing an incomplete backtrace, the program exits \
with return code 1. If no frames could be shown, or a fatal error \
occured the program exits with return code 2. If the program was \
invoked with bad or missing arguments it will exit with return code 64.")
 };

 argp_parse (&argp, argc, argv, 0, NULL, NULL);

 if (show_modules)
 {
 printf ("PID %lld - %s module memory map\n", (long long) dwfl_pid (dwfl),
	 pid != 0 ? "process" : "core");
 if (dwfl_getmodules (dwfl, module_callback, NULL, 0) != 0)
	error (EXIT_BAD, 0, "dwfl_getmodules: %s", dwfl_errmsg (-1));
 }

 struct frames frames;
 /* When maxframes is zero, then 2048 is just the initial allocation
 that will be increased using realloc in framecallback (). */
 frames.allocated = maxframes == 0 ? 2048 : maxframes;
 frames.frames = 0;
 frames.frame = malloc (sizeof (struct frame) * frames.allocated);
 if (frames.frame == NULL)
 error (EXIT_BAD, errno, "malloc frames.frame");

 if (show_one_tid)
 {
 int err = 0;
 switch (dwfl_getthread_frames (dwfl, pid, frame_callback, &frames))
	{
	case DWARF_CB_OK:
	case DWARF_CB_ABORT:
	 break;
	case -1:
	 err = dwfl_errno ();
	 break;
	default:
	 abort ();
	}
 print_frames (&frames, pid, err, "dwfl_getthread_frames");
 }
 else
 {
 printf ("PID %lld - %s\n", (long long) dwfl_pid (dwfl),
	 pid != 0 ? "process" : "core");
 switch (dwfl_getthreads (dwfl, thread_callback, &frames))
	{
	case DWARF_CB_OK:
	case DWARF_CB_ABORT:
	 break;
	case -1:
	 error (0, 0, "dwfl_getthreads: %s", dwfl_errmsg (-1));
	 break;
	default:
	 abort ();
	}
 }
 free (frames.frame);
 dwfl_end (dwfl);

 if (core != NULL)
 elf_end (core);

 if (core_fd != -1)
 close (core_fd);

#ifdef USE_DEMANGLE
 free (demangle_buffer);
#endif

 if (! frames_shown)
 error (EXIT_BAD, 0, N_("Couldn't show any frames."));

 return error_message_count != 0 ? EXIT_ERROR : EXIT_OK;
}