glibc/nss/makedb.c

/* Create simple DB database from textual input.
   Copyright (C) 1996-2020 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1996.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#include <argp.h>
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <inttypes.h>
#include <libintl.h>
#include <locale.h>
#include <search.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include "nss_db/nss_db.h"

/* Get libc version number.  */
#include "../version.h"

/* The hashing function we use.  */
#include "../intl/hash-string.h"

/* SELinux support.  */
#ifdef HAVE_SELINUX
# include <selinux/selinux.h>
#endif

#ifndef MAP_POPULATE
# define MAP_POPULATE 0
#endif

#define PACKAGE _libc_intl_domainname

/* List of data bases.  */
struct database
{
  char dbid;
  bool extra_string;
  struct database *next;
  void *entries;
  size_t nentries;
  size_t nhashentries;
  stridx_t *hashtable;
  size_t keystrlen;
  stridx_t *keyidxtab;
  char *keystrtab;
} *databases;
static size_t ndatabases;
static size_t nhashentries_total;
static size_t valstrlen;
static void *valstrtree;
static char *valstrtab;
static size_t extrastrlen;

/* Database entry.  */
struct dbentry
{
  stridx_t validx;
  uint32_t hashval;
  char str[0];
};

/* Stored string entry.  */
struct valstrentry
{
  stridx_t idx;
  bool extra_string;
  char str[0];
};


/* True if any entry has been added.  */
static bool any_dbentry;

/* If non-zero convert key to lower case.  */
static int to_lowercase;

/* If non-zero print content of input file, one entry per line.  */
static int do_undo;

/* If non-zero do not print informational messages.  */
static int be_quiet;

/* Name of output file.  */
static const char *output_name;

/* Name and version of program.  */
static void print_version (FILE *stream, struct argp_state *state);
void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;

/* Definitions of arguments for argp functions.  */
static const struct argp_option options[] =
{
  { "fold-case", 'f', NULL, 0, N_("Convert key to lower case") },
  { "output", 'o', N_("NAME"), 0, N_("Write output to file NAME") },
  { "quiet", 'q', NULL, 0,
    N_("Do not print messages while building database") },
  { "undo", 'u', NULL, 0,
    N_("Print content of database file, one entry a line") },
  { "generated", 'g', N_("CHAR"), 0,
    N_("Generated line not part of iteration") },
  { NULL, 0, NULL, 0, NULL }
};

/* Short description of program.  */
static const char doc[] = N_("Create simple database from textual input.");

/* Strings for arguments in help texts.  */
static const char args_doc[] = N_("\
INPUT-FILE OUTPUT-FILE\n-o OUTPUT-FILE INPUT-FILE\n-u INPUT-FILE");

/* Prototype for option handler.  */
static error_t parse_opt (int key, char *arg, struct argp_state *state);

/* Function to print some extra text in the help message.  */
static char *more_help (int key, const char *text, void *input);

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


/* List of databases which are not part of the iteration table.  */
static struct db_option
{
  char dbid;
  struct db_option *next;
} *db_options;


/* Prototypes for local functions.  */
static int process_input (FILE *input, const char *inname,
			  int to_lowercase, int be_quiet);
static int print_database (int fd);
static void compute_tables (void);
static int write_output (int fd);

/* SELinux support.  */
#ifdef HAVE_SELINUX
/* Set the SELinux file creation context for the given file. */
static void set_file_creation_context (const char *outname, mode_t mode);
static void reset_file_creation_context (void);
#else
# define set_file_creation_context(_outname,_mode)
# define reset_file_creation_context()
#endif


/* External functions.  */
#include <programs/xmalloc.h>


int
main (int argc, char *argv[])
{
  const char *input_name;
  FILE *input_file;
  int remaining;
  int mode = 0644;

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

  /* Set the text message domain.  */
  textdomain (_libc_intl_domainname);

  /* Initialize local variables.  */
  input_name = NULL;

  /* Parse and process arguments.  */
  argp_parse (&argp, argc, argv, 0, &remaining, NULL);

  /* Determine file names.  */
  if (do_undo || output_name != NULL)
    {
      if (remaining + 1 != argc)
	{
	wrong_arguments:
	  error (0, 0, gettext ("wrong number of arguments"));
	  argp_help (&argp, stdout, ARGP_HELP_SEE,
		     program_invocation_short_name);
	  exit (1);
	}
      input_name = argv[remaining];
    }
  else
    {
      if (remaining + 2 != argc)
	goto wrong_arguments;

      input_name = argv[remaining++];
      output_name = argv[remaining];
    }

  /* Special handling if we are asked to print the database.  */
  if (do_undo)
    {
      int fd = open (input_name, O_RDONLY);
      if (fd == -1)
	error (EXIT_FAILURE, errno, gettext ("cannot open database file `%s'"),
	       input_name);

      int status = print_database (fd);

      close (fd);

      return status;
    }

  /* Open input file.  */
  if (strcmp (input_name, "-") == 0 || strcmp (input_name, "/dev/stdin") == 0)
    input_file = stdin;
  else
    {
      struct stat64 st;

      input_file = fopen64 (input_name, "r");
      if (input_file == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot open input file `%s'"),
	       input_name);

      /* Get the access rights from the source file.  The output file should
	 have the same.  */
      if (fstat64 (fileno (input_file), &st) >= 0)
	mode = st.st_mode & ACCESSPERMS;
    }

  /* Start the real work.  */
  int status = process_input (input_file, input_name, to_lowercase, be_quiet);

  /* Close files.  */
  if (input_file != stdin)
    fclose (input_file);

  /* No need to continue when we did not read the file successfully.  */
  if (status != EXIT_SUCCESS)
    return status;

  /* Bail out if nothing is to be done.  */
  if (!any_dbentry)
    {
      if (be_quiet)
	return EXIT_SUCCESS;
      else
	error (EXIT_SUCCESS, 0, gettext ("no entries to be processed"));
    }

  /* Compute hash and string tables.  */
  compute_tables ();

  /* Open output file.  This must not be standard output so we don't
     handle "-" and "/dev/stdout" special.  */
  char *tmp_output_name;
  if (asprintf (&tmp_output_name, "%s.XXXXXX", output_name) == -1)
    error (EXIT_FAILURE, errno, gettext ("cannot create temporary file name"));

  set_file_creation_context (output_name, mode);
  int fd = mkstemp (tmp_output_name);
  reset_file_creation_context ();
  if (fd == -1)
    error (EXIT_FAILURE, errno, gettext ("cannot create temporary file"));

  status = write_output (fd);

  if (status == EXIT_SUCCESS)
    {
      struct stat64 st;

      if (fstat64 (fd, &st) == 0)
	{
	  if ((st.st_mode & ACCESSPERMS) != mode)
	    /* We ignore problems with changing the mode.  */
	    fchmod (fd, mode);
	}
      else
	{
	  error (0, errno, gettext ("cannot stat newly created file"));
	  status = EXIT_FAILURE;
	}
    }

  close (fd);

  if (status == EXIT_SUCCESS)
    {
      if (rename (tmp_output_name, output_name) != 0)
	{
	  error (0, errno, gettext ("cannot rename temporary file"));
	  status = EXIT_FAILURE;
	  goto do_unlink;
	}
    }
  else
  do_unlink:
    unlink (tmp_output_name);

  return status;
}


/* Handle program arguments.  */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
  struct db_option *newp;

  switch (key)
    {
    case 'f':
      to_lowercase = 1;
      break;
    case 'o':
      output_name = arg;
      break;
    case 'q':
      be_quiet = 1;
      break;
    case 'u':
      do_undo = 1;
      break;
    case 'g':
      newp = xmalloc (sizeof (*newp));
      newp->dbid = arg[0];
      newp->next = db_options;
      db_options = newp;
      break;
    default:
      return ARGP_ERR_UNKNOWN;
    }
  return 0;
}


static char *
more_help (int key, const char *text, void *input)
{
  char *tp = NULL;
  switch (key)
    {
    case ARGP_KEY_HELP_EXTRA:
      /* We print some extra information.  */
      if (asprintf (&tp, gettext ("\
For bug reporting instructions, please see:\n\
%s.\n"), REPORT_BUGS_TO) < 0)
	return NULL;
      return tp;
    default:
      break;
    }
  return (char *) text;
}

/* Print the version information.  */
static void
print_version (FILE *stream, struct argp_state *state)
{
  fprintf (stream, "makedb %s%s\n", PKGVERSION, VERSION);
  fprintf (stream, gettext ("\
Copyright (C) %s Free Software Foundation, Inc.\n\
This is free software; see the source for copying conditions.  There is NO\n\
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
"), "2020");
  fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
}


static int
dbentry_compare (const void *p1, const void *p2)
{
  const struct dbentry *d1 = (const struct dbentry *) p1;
  const struct dbentry *d2 = (const struct dbentry *) p2;

  if (d1->hashval != d2->hashval)
    return d1->hashval < d2->hashval ? -1 : 1;

  return strcmp (d1->str, d2->str);
}


static int
valstr_compare (const void *p1, const void *p2)
{
  const struct valstrentry *d1 = (const struct valstrentry *) p1;
  const struct valstrentry *d2 = (const struct valstrentry *) p2;

  return strcmp (d1->str, d2->str);
}


static int
process_input (FILE *input, const char *inname, int to_lowercase, int be_quiet)
{
  char *line;
  size_t linelen;
  int status;
  size_t linenr;

  line = NULL;
  linelen = 0;
  status = EXIT_SUCCESS;
  linenr = 0;

  struct database *last_database = NULL;

  while (!feof_unlocked (input))
    {
      ssize_t n = getline (&line, &linelen, input);
      if (n < 0)
	/* This means end of file or some bug.  */
	break;
      if (n == 0)
	/* Short read.  Probably interrupted system call. */
	continue;

      ++linenr;

      if (line[n - 1] == '\n')
	/* Remove trailing newline.  */
	line[--n] = '\0';

      char *cp = line;
      while (isspace (*cp))
	++cp;

      if (*cp == '#' || *cp == '\0')
	/* First non-space character in line '#': it's a comment.
	   Also go to the next line if it is empty except for whitespaces. */
	continue;

      /* Skip over the character indicating the database so that it is not
	 affected by TO_LOWERCASE.  */
      char *key = cp++;
      while (*cp != '\0' && !isspace (*cp))
	{
	  if (to_lowercase)
	    *cp = tolower (*cp);
	  ++cp;
	}

      if (*cp == '\0')
	/* It's a line without a value field.  */
	continue;

      *cp++ = '\0';
      size_t keylen = cp - key;

      while (isspace (*cp))
	++cp;

      char *data = cp;
      size_t datalen = (&line[n] - cp) + 1;

      /* Find the database.  */
      if (last_database == NULL || last_database->dbid != key[0])
	{
	  last_database = databases;
	  while (last_database != NULL && last_database->dbid != key[0])
	    last_database = last_database->next;

	  if (last_database == NULL)
	    {
	      last_database = xmalloc (sizeof (*last_database));
	      last_database->dbid = key[0];
	      last_database->extra_string = false;
	      last_database->next = databases;
	      last_database->entries = NULL;
	      last_database->nentries = 0;
	      last_database->keystrlen = 0;
	      databases = last_database;

	      struct db_option *runp = db_options;
	      while (runp != NULL)
		if (runp->dbid == key[0])
		  {
		    last_database->extra_string = true;
		    break;
		  }
		else
		  runp = runp->next;
	    }
	}

      /* Skip the database selector.  */
      ++key;
      --keylen;

      /* Store the data.  */
      struct valstrentry *nentry = xmalloc (sizeof (struct valstrentry)
					    + datalen);
      if (last_database->extra_string)
	nentry->idx = extrastrlen;
      else
	nentry->idx = valstrlen;
      nentry->extra_string = last_database->extra_string;
      memcpy (nentry->str, data, datalen);

      struct valstrentry **fdata = tsearch (nentry, &valstrtree,
					    valstr_compare);
      if (fdata == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot create search tree"));

      if (*fdata != nentry)
	{
	  /* We can reuse a string.  */
	  free (nentry);
	  nentry = *fdata;
	}
      else
	if (last_database->extra_string)
	  extrastrlen += datalen;
	else
	  valstrlen += datalen;

      /* Store the key.  */
      struct dbentry *newp = xmalloc (sizeof (struct dbentry) + keylen);
      newp->validx = nentry->idx;
      newp->hashval = __hash_string (key);
      memcpy (newp->str, key, keylen);

      struct dbentry **found = tsearch (newp, &last_database->entries,
					dbentry_compare);
      if (found == NULL)
	error (EXIT_FAILURE, errno, gettext ("cannot create search tree"));

      if (*found != newp)
	{
	  free (newp);
	  if (!be_quiet)
	    error_at_line (0, 0, inname, linenr, gettext ("duplicate key"));
	  continue;
	}

      ++last_database->nentries;
      last_database->keystrlen += keylen;

      any_dbentry = true;
    }

  if (ferror_unlocked (input))
    {
      error (0, 0, gettext ("problems while reading `%s'"), inname);
      status = EXIT_FAILURE;
    }

  return status;
}


static void
copy_valstr (const void *nodep, const VISIT which, const int depth)
{
  if (which != leaf && which != postorder)
    return;

  const struct valstrentry *p = *(const struct valstrentry **) nodep;

  strcpy (valstrtab + (p->extra_string ? valstrlen : 0) + p->idx, p->str);
}


/* Determine if the candidate is prime by using a modified trial division
   algorithm. The candidate must be both odd and greater than 4.  */
static int
is_prime (size_t candidate)
{
  size_t divn = 3;
  size_t sq = divn * divn;

  assert (candidate > 4 && candidate % 2 != 0);

  while (sq < candidate && candidate % divn != 0)
    {
      ++divn;
      sq += 4 * divn;
      ++divn;
    }

  return candidate % divn != 0;
}


static size_t
next_prime (size_t seed)
{
  /* Make sure that we're always greater than 4.  */
  seed = (seed + 4) | 1;

  while (!is_prime (seed))
    seed += 2;

  return seed;
}


static void
compute_tables (void)
{
  valstrtab = xmalloc (roundup (valstrlen + extrastrlen, sizeof (stridx_t)));
  while ((valstrlen + extrastrlen) % sizeof (stridx_t) != 0)
    valstrtab[valstrlen++] = '\0';
  twalk (valstrtree, copy_valstr);

  static struct database *db;
  for (db = databases; db != NULL; db = db->next)
    if (db->nentries != 0)
      {
	++ndatabases;

	/* We simply use an odd number large than twice the number of
	   elements to store in the hash table for the size.  This gives
	   enough efficiency.  */
#define TEST_RANGE 30
	size_t nhashentries_min = next_prime (db->nentries < TEST_RANGE
					      ? db->nentries
					      : db->nentries * 2 - TEST_RANGE);
	size_t nhashentries_max = MAX (nhashentries_min, db->nentries * 4);
	size_t nhashentries_best = nhashentries_min;
	size_t chainlength_best = db->nentries;

	db->hashtable = xmalloc (2 * nhashentries_max * sizeof (stridx_t)
				 + db->keystrlen);
	db->keyidxtab = db->hashtable + nhashentries_max;
	db->keystrtab = (char *) (db->keyidxtab + nhashentries_max);

	static size_t max_chainlength;
	static char *wp;
	static size_t nhashentries;
	static bool copy_string;

	void add_key(const void *nodep, const VISIT which, const int depth)
	{
	  if (which != leaf && which != postorder)
	    return;

	  const struct dbentry *dbe = *(const struct dbentry **) nodep;

	  ptrdiff_t stridx;
	  if (copy_string)
	    {
	      stridx = wp - db->keystrtab;
	      wp = stpcpy (wp, dbe->str) + 1;
	    }
	  else
	    stridx = 0;

	  size_t hidx = dbe->hashval % nhashentries;
	  size_t hval2 = 1 + dbe->hashval % (nhashentries - 2);
	  size_t chainlength = 0;

	  while (db->hashtable[hidx] != ~((stridx_t) 0))
	    {
	      ++chainlength;
	      if ((hidx += hval2) >= nhashentries)
		hidx -= nhashentries;
	    }

	  db->hashtable[hidx] = ((db->extra_string ? valstrlen : 0)
				 + dbe->validx);
	  db->keyidxtab[hidx] = stridx;

	  max_chainlength = MAX (max_chainlength, chainlength);
	}

	copy_string = false;
	nhashentries = nhashentries_min;
	for (size_t cnt = 0; cnt < TEST_RANGE; ++cnt)
	  {
	    memset (db->hashtable, '\xff', nhashentries * sizeof (stridx_t));

	    max_chainlength = 0;
	    wp = db->keystrtab;

	    twalk (db->entries, add_key);

	    if (max_chainlength == 0)
	      {
		/* No need to look further, this is as good as it gets.  */
		nhashentries_best = nhashentries;
		break;
	      }

	    if (max_chainlength < chainlength_best)
	      {
		chainlength_best = max_chainlength;
		nhashentries_best = nhashentries;
	      }

	    nhashentries = next_prime (nhashentries + 1);
	    if (nhashentries > nhashentries_max)
	      break;
	  }

	/* Recompute the best table again, this time fill in the strings.  */
	nhashentries = nhashentries_best;
	memset (db->hashtable, '\xff',
		2 * nhashentries_max * sizeof (stridx_t));
	copy_string = true;
	wp = db->keystrtab;

	twalk (db->entries, add_key);

	db->nhashentries = nhashentries_best;
	nhashentries_total += nhashentries_best;
    }
}


static int
write_output (int fd)
{
  struct nss_db_header *header;
  uint64_t file_offset = (sizeof (struct nss_db_header)
			  + (ndatabases * sizeof (header->dbs[0])));
  header = alloca (file_offset);

  header->magic = NSS_DB_MAGIC;
  header->ndbs = ndatabases;
  header->valstroffset = file_offset;
  header->valstrlen = valstrlen;

  size_t filled_dbs = 0;
  struct iovec iov[2 + ndatabases * 3];
  iov[0].iov_base = header;
  iov[0].iov_len = file_offset;

  iov[1].iov_base = valstrtab;
  iov[1].iov_len = valstrlen + extrastrlen;
  file_offset += iov[1].iov_len;

  size_t keydataoffset = file_offset + nhashentries_total * sizeof (stridx_t);
  for (struct database *db = databases; db != NULL; db = db->next)
    if (db->entries != NULL)
      {
	assert (file_offset % sizeof (stridx_t) == 0);
	assert (filled_dbs < ndatabases);

	header->dbs[filled_dbs].id = db->dbid;
	memset (header->dbs[filled_dbs].pad, '\0',
		sizeof (header->dbs[0].pad));
	header->dbs[filled_dbs].hashsize = db->nhashentries;

	iov[2 + filled_dbs].iov_base = db->hashtable;
	iov[2 + filled_dbs].iov_len = db->nhashentries * sizeof (stridx_t);
	header->dbs[filled_dbs].hashoffset = file_offset;
	file_offset += iov[2 + filled_dbs].iov_len;

	iov[2 + ndatabases + filled_dbs * 2].iov_base = db->keyidxtab;
	iov[2 + ndatabases + filled_dbs * 2].iov_len
	  = db->nhashentries * sizeof (stridx_t);
	header->dbs[filled_dbs].keyidxoffset = keydataoffset;
	keydataoffset += iov[2 + ndatabases + filled_dbs * 2].iov_len;

	iov[3 + ndatabases + filled_dbs * 2].iov_base = db->keystrtab;
	iov[3 + ndatabases + filled_dbs * 2].iov_len = db->keystrlen;
	header->dbs[filled_dbs].keystroffset = keydataoffset;
	keydataoffset += iov[3 + ndatabases + filled_dbs * 2].iov_len;

	++filled_dbs;
      }

  assert (filled_dbs == ndatabases);
  assert (file_offset == (iov[0].iov_len + iov[1].iov_len
			  + nhashentries_total * sizeof (stridx_t)));
  header->allocate = file_offset;

  if (writev (fd, iov, 2 + ndatabases * 3) != keydataoffset)
    {
      error (0, errno, gettext ("failed to write new database file"));
      return EXIT_FAILURE;
    }

  return EXIT_SUCCESS;
}


static int
print_database (int fd)
{
  struct stat64 st;
  if (fstat64 (fd, &st) != 0)
    error (EXIT_FAILURE, errno, gettext ("cannot stat database file"));

  const struct nss_db_header *header = mmap (NULL, st.st_size, PROT_READ,
					     MAP_PRIVATE|MAP_POPULATE, fd, 0);
  if (header == MAP_FAILED)
    error (EXIT_FAILURE, errno, gettext ("cannot map database file"));

  if (header->magic != NSS_DB_MAGIC)
    error (EXIT_FAILURE, 0, gettext ("file not a database file"));

  const char *valstrtab = (const char *) header + header->valstroffset;

  for (unsigned int dbidx = 0; dbidx < header->ndbs; ++dbidx)
    {
      const stridx_t *stridxtab
	= ((const stridx_t *) ((const char *) header
			       + header->dbs[dbidx].keyidxoffset));
      const char *keystrtab
	= (const char *) header + header->dbs[dbidx].keystroffset;
      const stridx_t *hashtab
	= (const stridx_t *) ((const char *) header
			      + header->dbs[dbidx].hashoffset);

      for (uint32_t hidx = 0; hidx < header->dbs[dbidx].hashsize; ++hidx)
	if (hashtab[hidx] != ~((stridx_t) 0))
	  printf ("%c%s %s\n",
		  header->dbs[dbidx].id,
		  keystrtab + stridxtab[hidx],
		  valstrtab + hashtab[hidx]);
    }

  return EXIT_SUCCESS;
}


#ifdef HAVE_SELINUX
static void
set_file_creation_context (const char *outname, mode_t mode)
{
  static int enabled;
  static int enforcing;
  security_context_t ctx;

  /* Check if SELinux is enabled, and remember. */
  if (enabled == 0)
    enabled = is_selinux_enabled () ? 1 : -1;
  if (enabled < 0)
    return;

  /* Check if SELinux is enforcing, and remember. */
  if (enforcing == 0)
    enforcing = security_getenforce () ? 1 : -1;

  /* Determine the context which the file should have. */
  ctx = NULL;
  if (matchpathcon (outname, S_IFREG | mode, &ctx) == 0 && ctx != NULL)
    {
      if (setfscreatecon (ctx) != 0)
	error (enforcing > 0 ? EXIT_FAILURE : 0, 0,
	       gettext ("cannot set file creation context for `%s'"),
	       outname);

      freecon (ctx);
    }
}

static void
reset_file_creation_context (void)
{
  setfscreatecon (NULL);
}
#endif