/* Command-line frontend for retrieving ELF / DWARF / source files
   from the debuginfod.
   Copyright (C) 2019-2020 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 copies of the GNU General Public License and
   the GNU Lesser General Public License along with this program.  If
   not, see <http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "printversion.h"
#include "debuginfod.h"
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <argp.h>
#include <unistd.h>
#include <fcntl.h>
#include <gelf.h>
#include <libdwelf.h>


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

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

/* Short description of program.  */
static const char doc[] = N_("Request debuginfo-related content "
                             "from debuginfods listed in $" DEBUGINFOD_URLS_ENV_VAR ".");

/* Strings for arguments in help texts.  */
static const char args_doc[] = N_("debuginfo BUILDID\n"
                                  "debuginfo PATH\n"
                                  "executable BUILDID\n"
                                  "executable PATH\n"
                                  "source BUILDID /FILENAME\n"
                                  "source PATH /FILENAME\n");


/* Definitions of arguments for argp functions.  */
static const struct argp_option options[] =
  {
   { "verbose", 'v', NULL, 0, "Increase verbosity.", 0 },
   { NULL, 0, NULL, 0, NULL, 0 }
  };

/* debuginfod connection handle.  */
static debuginfod_client *client;
static int verbose;

int progressfn(debuginfod_client *c __attribute__((__unused__)),
	       long a, long b)
{
  fprintf (stderr, "Progress %ld / %ld\n", a, b);
  return 0;
}


static error_t parse_opt (int key, char *arg, struct argp_state *state)
{
  (void) arg;
  (void) state;
  switch (key)
    {
    case 'v': verbose++;
      debuginfod_set_progressfn (client, & progressfn); break;
    default: return ARGP_ERR_UNKNOWN;
    }
  return 0;
}


/* Data structure to communicate with argp functions.  */
static struct argp argp =
  {
   options, parse_opt, args_doc, doc, NULL, NULL, NULL
  };



int
main(int argc, char** argv)
{
  elf_version (EV_CURRENT);

  client = debuginfod_begin ();
  if (client == NULL)
    {
      fprintf(stderr, "Couldn't create debuginfod client context\n");
      return 1;
    }

  /* Exercise user data pointer, to support testing only. */
  debuginfod_set_user_data (client, (void *)"Progress");

  int remaining;
  (void) argp_parse (&argp, argc, argv, ARGP_IN_ORDER|ARGP_NO_ARGS, &remaining, NULL);

  if (argc < 2 || remaining+1 == argc) /* no arguments or at least two non-option words */
    {
      argp_help (&argp, stderr, ARGP_HELP_USAGE, argv[0]);
      return 1;
    }

  /* If we were passed an ELF file name in the BUILDID slot, look in there. */
  unsigned char* build_id = (unsigned char*) argv[remaining+1];
  int build_id_len = 0; /* assume text */

  int any_non_hex = 0;
  int i;
  for (i = 0; build_id[i] != '\0'; i++)
    if ((build_id[i] >= '0' && build_id[i] <= '9') ||
        (build_id[i] >= 'a' && build_id[i] <= 'f'))
      ;
    else
      any_non_hex = 1;

  int fd = -1;
  Elf* elf = NULL;
  if (any_non_hex) /* raw build-id */
    {
      fd = open ((char*) build_id, O_RDONLY);
      if (fd < 0)
        fprintf (stderr, "Cannot open %s: %s\n", build_id, strerror(errno));
    }
  if (fd >= 0)
    {
      elf = elf_begin (fd, ELF_C_READ_MMAP_PRIVATE, NULL);
      if (elf == NULL)
        fprintf (stderr, "Cannot elf_begin %s: %s\n", build_id, elf_errmsg(-1));
    }
  if (elf != NULL)
    {
      const void *extracted_build_id;
      ssize_t s = dwelf_elf_gnu_build_id(elf, &extracted_build_id);
      if (s > 0)
        {
          /* Success: replace the build_id pointer/len with the binary blob
             that elfutils is keeping for us.  It'll remain valid until elf_end(). */
          build_id = (unsigned char*) extracted_build_id;
          build_id_len = s;
        }
      else
        fprintf (stderr, "Cannot extract build-id from %s: %s\n", build_id, elf_errmsg(-1));
    }

  char *cache_name;
  int rc = 0;

  /* Check whether FILETYPE is valid and call the appropriate
     debuginfod_find_* function. If FILETYPE is "source"
     then ensure a FILENAME was also supplied as an argument.  */
  if (strcmp(argv[remaining], "debuginfo") == 0)
    rc = debuginfod_find_debuginfo(client,
				   build_id, build_id_len,
				   &cache_name);
  else if (strcmp(argv[remaining], "executable") == 0)
    rc = debuginfod_find_executable(client,
                                    build_id, build_id_len,
				    &cache_name);
  else if (strcmp(argv[remaining], "source") == 0)
    {
      if (remaining+2 == argc || argv[remaining+2][0] != '/')
        {
          fprintf(stderr, "If FILETYPE is \"source\" then absolute /FILENAME must be given\n");
          return 1;
        }
      rc = debuginfod_find_source(client,
                                  build_id, build_id_len,
				  argv[remaining+2], &cache_name);
    }
  else
    {
      argp_help (&argp, stderr, ARGP_HELP_USAGE, argv[0]);
      return 1;
    }

  if (verbose)
    {
      const char* url = debuginfod_get_url (client);
      if (url != NULL)
        fprintf(stderr, "Downloaded from %s\n", url);
    }

  debuginfod_end (client);
  if (elf)
    elf_end(elf);
  if (fd >= 0)
    close (fd);

  if (rc < 0)
    {
      fprintf(stderr, "Server query failed: %s\n", strerror(-rc));
      return 1;
    }

  printf("%s\n", cache_name);
  free (cache_name);

  return 0;
}