/src/util-linux/libmount/src/tab_parse.c

Source (jump to first uncovered line)
/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * This file is part of libmount from util-linux project.
 *
 * Copyright (C) 2009-2018 Karel Zak <kzak@redhat.com>
 *
 * libmount 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.
 */
#ifdef HAVE_SCANDIRAT
#ifndef __USE_GNU
#define __USE_GNU
#endif  /* !__USE_GNU */
#endif  /* HAVE_SCANDIRAT */

#include <ctype.h>
#include <limits.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

#include "fileutils.h"
#include "mangle.h"
#include "mountP.h"
#include "pathnames.h"
#include "strutils.h"

struct libmnt_parser {
  FILE  *f;   /* fstab, swaps or mountinfo ... */
  const char *filename; /* file name or NULL */
  char  *buf;   /* buffer (the current line content) */
  size_t  bufsiz;   /* size of the buffer */
  size_t  line;   /* current line */
  int     sysroot_rc; /* rc from mnt_guess_system_root() */
  char  *sysroot; /* guess from mmnt_guess_system_root() */
};

static void parser_cleanup(struct libmnt_parser *pa)
{
  if (!pa)
    return;
  free(pa->buf);
  free(pa->sysroot);
  memset(pa, 0, sizeof(*pa));
}

static const char *next_s32(const char *s, int *num, int *rc)
{
  char *end = NULL;

  if (!s || !*s)
    return s;

  errno = 0;
  *rc = -EINVAL;
  *num = strtol(s, &end, 10);
  if (end == NULL || s == end)
         return s;
  if (errno == 0 && (*end == ' ' || *end == '\t' || *end == '\0'))
    *rc = 0;
  return end;
}

static const char *next_u64(const char *s, uint64_t *num, int *rc)
{
  char *end = NULL;

  if (!s || !*s)
    return s;

  errno = 0;
  *rc = -EINVAL;
  *num = (uint64_t) strtoumax(s, &end, 10);
  if (end == NULL || s == end)
         return s;
  if (errno == 0 && (*end == ' ' || *end == '\t' || *end == '\0'))
    *rc = 0;
  return end;
}

static inline const char *skip_separator(const char *p)
{
  while (p && (*p == ' ' || *p == '\t'))
    ++p;
  return p;
}

static inline const char *skip_nonspearator(const char *p)
{
  while (p && *p && !(*p == ' ' || *p == '\t'))
    p++;
  return p;
}

/*
 * Parses one line from {fs,m}tab
 */
static int mnt_parse_table_line(struct libmnt_fs *fs, const char *s)
{
  int rc = 0;
  char *p = NULL;

  fs->passno = fs->freq = 0;

  /* (1) source */
  p = unmangle(s, &s);
  if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
    DBG(TAB, ul_debug("tab parse error: [source]"));
    free(p);
    goto fail;
  }

  s = skip_separator(s);

  /* (2) target */
  fs->target = unmangle(s, &s);
  if (!fs->target) {
    DBG(TAB, ul_debug("tab parse error: [target]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (3) FS type */
  p = unmangle(s, &s);
  if (!p || (rc = __mnt_fs_set_fstype_ptr(fs, p))) {
    DBG(TAB, ul_debug("tab parse error: [fstype]"));
    free(p);
    goto fail;
  }

  s = skip_separator(s);

  /* (4) options (optional) */
  p = unmangle(s, &s);
  if (p && (rc = mnt_fs_set_options(fs, p))) {
    DBG(TAB, ul_debug("tab parse error: [options]"));
    free(p);
    goto fail;
  }
  if (!p)
    goto done;
  free(p);

  s = skip_separator(s);
  if (!s || !*s)
    goto done;

  /* (5) freq (optional) */
  s = next_s32(s, &fs->freq, &rc);
  if (s && *s && rc) {
    DBG(TAB, ul_debug("tab parse error: [freq]"));
    goto fail;
  }

  s = skip_separator(s);
  if (!s || !*s)
    goto done;

  /* (6) passno (optional) */
  s = next_s32(s, &fs->passno, &rc);
  if (s && *s && rc) {
    DBG(TAB, ul_debug("tab parse error: [passno]"));
    goto fail;
  }

done:
  return 0;
fail:
  if (rc == 0)
    rc = -EINVAL;
  DBG(TAB, ul_debug("tab parse error on: '%s' [rc=%d]", s, rc));
  return rc;
}


/*
 * Parses one line from a mountinfo file
 */
static int mnt_parse_mountinfo_line(struct libmnt_fs *fs, const char *s)
{
  int rc = 0;
  unsigned int maj, min;
  char *p;

  fs->flags |= MNT_FS_KERNEL;

  /* (1) id */
  s = next_s32(s, &fs->id, &rc);
  if (!s || !*s || rc) {
    DBG(TAB, ul_debug("tab parse error: [id]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (2) parent */
  s = next_s32(s, &fs->parent, &rc);
  if (!s || !*s || rc) {
    DBG(TAB, ul_debug("tab parse error: [parent]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (3) maj:min */
  if (sscanf(s, "%u:%u", &maj, &min) != 2) {
    DBG(TAB, ul_debug("tab parse error: [maj:min]"));
    goto fail;
  }
  fs->devno = makedev(maj, min);
  s = skip_nonspearator(s);
  s = skip_separator(s);

  /* (4) mountroot */
  fs->root = unmangle(s, &s);
  if (!fs->root) {
    DBG(TAB, ul_debug("tab parse error: [mountroot]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (5) target */
  fs->target = unmangle(s, &s);
  if (!fs->target) {
    DBG(TAB, ul_debug("tab parse error: [target]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (6) vfs options (fs-independent) */
  fs->vfs_optstr = unmangle(s, &s);
  if (!fs->vfs_optstr) {
    DBG(TAB, ul_debug("tab parse error: [VFS options]"));
    goto fail;
  }

  /* (7) optional fields, terminated by " - " */
  p = strstr(s, " - ");
  if (!p) {
    DBG(TAB, ul_debug("mountinfo parse error: separator not found"));
    return -EINVAL;
  }
  if (p > s + 1)
    fs->opt_fields = strndup(s + 1, p - s - 1);

  s = skip_separator(p + 3);

  /* (8) FS type */
  p = unmangle(s, &s);
  if (!p || (rc = __mnt_fs_set_fstype_ptr(fs, p))) {
    DBG(TAB, ul_debug("tab parse error: [fstype]"));
    free(p);
    goto fail;
  }

  /* (9) source -- maybe empty string */
  if (!s || !*s) {
    DBG(TAB, ul_debug("tab parse error: [source]"));
    goto fail;
  } else if (*s == ' ' && *(s+1) == ' ') {
    if ((rc = mnt_fs_set_source(fs, ""))) {
      DBG(TAB, ul_debug("tab parse error: [empty source]"));
      goto fail;
    }
  } else {
    s = skip_separator(s);
    p = unmangle(s, &s);
    if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
      DBG(TAB, ul_debug("tab parse error: [regular source]"));
      free(p);
      goto fail;
    }
  }

  s = skip_separator(s);

  /* (10) fs options (fs specific) */
  fs->fs_optstr = unmangle(s, &s);
  if (!fs->fs_optstr) {
    DBG(TAB, ul_debug("tab parse error: [FS options]"));
    goto fail;
  }

  /* merge VFS and FS options to one string */
  fs->optstr = mnt_fs_strdup_options(fs);
  if (!fs->optstr) {
    rc = -ENOMEM;
    DBG(TAB, ul_debug("tab parse error: [merge VFS and FS options]"));
    goto fail;
  }

  return 0;
fail:
  if (rc == 0)
    rc = -EINVAL;
  DBG(TAB, ul_debug("tab parse error on: '%s' [rc=%d]", s, rc));
  return rc;
}

/*
 * Parses one line from utab file
 */
static int mnt_parse_utab_line(struct libmnt_fs *fs, const char *s)
{
  const char *p = s;

  assert(fs);
  assert(s);
  assert(!fs->source);
  assert(!fs->target);

  while (p && *p) {
    const char *end = NULL;

    while (*p == ' ') p++;
    if (!*p)
      break;

    if (!fs->id && !strncmp(p, "ID=", 3)) {
      int rc = 0;

      end = next_s32(p + 3, &fs->id, &rc);
      if (!end || rc)
        return rc;

    } else if (!fs->source && !strncmp(p, "SRC=", 4)) {
      char *v = unmangle(p + 4, &end);
      if (!v)
        goto enomem;
      if (__mnt_fs_set_source_ptr(fs, v))
        free(v);

    } else if (!fs->target && !strncmp(p, "TARGET=", 7)) {
      fs->target = unmangle(p + 7, &end);
      if (!fs->target)
        goto enomem;

    } else if (!fs->root && !strncmp(p, "ROOT=", 5)) {
      fs->root = unmangle(p + 5, &end);
      if (!fs->root)
        goto enomem;

    } else if (!fs->bindsrc && !strncmp(p, "BINDSRC=", 8)) {
      fs->bindsrc = unmangle(p + 8, &end);
      if (!fs->bindsrc)
        goto enomem;

    } else if (!fs->user_optstr && !strncmp(p, "OPTS=", 5)) {
      fs->user_optstr = unmangle(p + 5, &end);
      if (!fs->user_optstr)
        goto enomem;

    } else if (!fs->attrs && !strncmp(p, "ATTRS=", 6)) {
      fs->attrs = unmangle(p + 6, &end);
      if (!fs->attrs)
        goto enomem;

    } else {
      /* unknown variable */
      while (*p && *p != ' ') p++;
    }
    if (end)
      p = end;
  }

  return 0;
enomem:
  DBG(TAB, ul_debug("utab parse error: ENOMEM"));
  return -ENOMEM;
}

/*
 * Parses one line from /proc/swaps
 */
static int mnt_parse_swaps_line(struct libmnt_fs *fs, const char *s)
{
  uint64_t num;
  int rc = 0;
  char *p;

  /* (1) source */
  p = unmangle(s, &s);
  if (p) {
    char *x = (char *) endswith(p, PATH_DELETED_SUFFIX);
    if (x && *x)
      *x = '\0';
  }
  if (!p || (rc = __mnt_fs_set_source_ptr(fs, p))) {
    DBG(TAB, ul_debug("tab parse error: [source]"));
    free(p);
    goto fail;
  }

  s = skip_separator(s);

  /* (2) type */
  fs->swaptype = unmangle(s, &s);
  if (!fs->swaptype) {
    DBG(TAB, ul_debug("tab parse error: [swaptype]"));
    goto fail;
  }

  s = skip_separator(s);

  /* (3) size */
  s = next_u64(s, &num, &rc);
  if (!s || !*s || rc) {
    DBG(TAB, ul_debug("tab parse error: [size]"));
    goto fail;
  }
  fs->size = num;

  s = skip_separator(s);

  /* (4) size */
  s = next_u64(s, &num, &rc);
  if (!s || !*s || rc) {
    DBG(TAB, ul_debug("tab parse error: [used size]"));
    goto fail;
  }
  fs->usedsize = num;

  s = skip_separator(s);

  /* (5) priority */
  s = next_s32(s, &fs->priority, &rc);
  if (rc) {
    DBG(TAB, ul_debug("tab parse error: [priority]"));
    goto fail;
  }

  mnt_fs_set_fstype(fs, "swap");
  return 0;
fail:
  if (rc == 0)
    rc = -EINVAL;
  DBG(TAB, ul_debug("tab parse error on: '%s' [rc=%d]", s, rc));
  return rc;
}


/*
 * Returns {m,fs}tab or mountinfo file format (MNT_FMT_*)
 *
 * Note that we aren't trying to guess the utab file format, because this file
 * always has to be parsed by private libmount routines with an explicitly defined
 * format.
 *
 * mountinfo: "<number> <number> ... "
 */
static int guess_table_format(const char *line)
{
  unsigned int a, b;

  DBG(TAB, ul_debug("trying to guess table type"));

  if (sscanf(line, "%u %u", &a, &b) == 2)
    return MNT_FMT_MOUNTINFO;

  if (strncmp(line, "Filename\t", 9) == 0)
    return MNT_FMT_SWAPS;

  return MNT_FMT_FSTAB;   /* fstab, or /proc/mounts */
}

static int is_comment_line(const char *line)
{
  const char *p = skip_blank(line);

  if (p && (*p == '#' || *p == '\n'))
    return 1;
  return 0;
}

/* returns 1 if the last line in the @str is blank */
static int is_terminated_by_blank(const char *str)
{
  size_t sz = str ? strlen(str) : 0;
  const char *p = sz ? str + (sz - 1) : NULL;

  if (!sz || !p || *p != '\n')
    return 0;    /* empty or not terminated by '\n' */
  if (p == str)
    return 1;    /* only '\n' */
  p--;
  while (p > str && (*p == ' ' || *p == '\t'))
    p--;
  return *p == '\n' ? 1 : 0;
}

/*
 * Reads the next line from the file.
 *
 * Returns 0 if the line is a comment
 *         1 if the line is not a comment
 *        <0 on error
 */
static int next_comment_line(struct libmnt_parser *pa, char **last)
{
  if (getline(&pa->buf, &pa->bufsiz, pa->f) < 0)
    return feof(pa->f) ? 1 : -errno;

  pa->line++;
  *last = strchr(pa->buf, '\n');

  return is_comment_line(pa->buf) ? 0 : 1;
}

static int append_comment(struct libmnt_table *tb,
        struct libmnt_fs *fs,
        const char *comm,
        int eof)
{
  int rc, intro = mnt_table_get_nents(tb) == 0;

  if (intro && is_terminated_by_blank(mnt_table_get_intro_comment(tb)))
    intro = 0;

  DBG(TAB, ul_debugobj(tb, "appending %s comment",
      intro ? "intro" :
      eof ? "trailing" : "fs"));
  if (intro)
    rc = mnt_table_append_intro_comment(tb, comm);
  else if (eof) {
    rc = mnt_table_set_trailing_comment(tb,
        mnt_fs_get_comment(fs));
    if (!rc)
      rc = mnt_table_append_trailing_comment(tb, comm);
    if (!rc)
      rc = mnt_fs_set_comment(fs, NULL);
  } else
    rc = mnt_fs_append_comment(fs, comm);
  return rc;
}

/*
 * Read and parse the next line from {fs,m}tab or mountinfo
 */
static int mnt_table_parse_next(struct libmnt_parser *pa,
        struct libmnt_table *tb,
        struct libmnt_fs *fs)
{
  char *s;
  int rc;

  assert(tb);
  assert(pa);
  assert(fs);

  /* read the next non-blank non-comment line */
next_line:
  do {
    if (getline(&pa->buf, &pa->bufsiz, pa->f) < 0)
      return -EINVAL;
    pa->line++;
    s = strchr(pa->buf, '\n');
    if (!s) {
      DBG(TAB, ul_debugobj(tb, "%s:%zu: no final newline",
            pa->filename, pa->line));

      /* Missing final newline?  Otherwise an extremely */
      /* long line - assume file was corrupted */
      if (feof(pa->f))
        s = memchr(pa->buf, '\0', pa->bufsiz);

    /* comments parser */
    } else if (tb->comms
        && (tb->fmt == MNT_FMT_GUESS || tb->fmt == MNT_FMT_FSTAB)
        && is_comment_line(pa->buf)) {
      do {
        rc = append_comment(tb, fs, pa->buf, feof(pa->f));
        if (!rc)
          rc = next_comment_line(pa, &s);
      } while (rc == 0);

      if (rc == 1 && feof(pa->f))
        rc = append_comment(tb, fs, NULL, 1);
      if (rc < 0)
        return rc;

    }

    if (!s)
      goto err;
    *s = '\0';
    if (s > pa->buf && *(s - 1)  == '\r')
      *(--s) = '\0';
    s = (char *) skip_blank(pa->buf);
  } while (*s == '\0' || *s == '#');

  if (tb->fmt == MNT_FMT_GUESS) {
    tb->fmt = guess_table_format(s);
    if (tb->fmt == MNT_FMT_SWAPS)
      goto next_line;     /* skip swap header */
  }

  switch (tb->fmt) {
  case MNT_FMT_FSTAB:
    rc = mnt_parse_table_line(fs, s);
    break;
  case MNT_FMT_MOUNTINFO:
    rc = mnt_parse_mountinfo_line(fs, s);
    break;
  case MNT_FMT_UTAB:
    rc = mnt_parse_utab_line(fs, s);
    break;
  case MNT_FMT_SWAPS:
    if (strncmp(s, "Filename\t", 9) == 0)
      goto next_line;      /* skip swap header */
    rc = mnt_parse_swaps_line(fs, s);
    break;
  default:
    rc = -1;  /* unknown format */
    break;
  }

  if (rc == 0)
    return 0;
err:
  DBG(TAB, ul_debugobj(tb, "%s:%zu: %s parse error", pa->filename, pa->line,
        tb->fmt == MNT_FMT_MOUNTINFO ? "mountinfo" :
        tb->fmt == MNT_FMT_SWAPS ? "swaps" :
        tb->fmt == MNT_FMT_FSTAB ? "tab" : "utab"));

  /* by default all errors are recoverable, otherwise behavior depends on
   * the errcb() function. See mnt_table_set_parser_errcb().
   */
  return tb->errcb ? tb->errcb(tb, pa->filename, pa->line) : 1;
}

static pid_t path_to_tid(const char *filename)
{
  char *path = mnt_resolve_path(filename, NULL);
  char *p, *end = NULL;
  pid_t tid = 0;

  if (!path)
    goto done;
  p = strrchr(path, '/');
  if (!p)
    goto done;
  *p = '\0';
  p = strrchr(path, '/');
  if (!p)
    goto done;
  p++;

  errno = 0;
  tid = strtol(p, &end, 10);
  if (errno || p == end || (end && *end)) {
    tid = 0;
    goto done;
  }
  DBG(TAB, ul_debug("TID for %s is %d", filename, tid));
done:
  free(path);
  return tid;
}

static int kernel_fs_postparse(struct libmnt_parser *pa,
             struct libmnt_table *tb,
             struct libmnt_fs *fs, pid_t *tid)
{
  int rc = 0;
  const char *src = mnt_fs_get_srcpath(fs);

  /* This is a filesystem description from /proc, so we're in some process
   * namespace. Let's remember the process PID.
   */
  if (pa->filename && *tid == -1)
    *tid = path_to_tid(pa->filename);

  fs->tid = *tid;

  /*
   * Convert obscure /dev/root to something more usable
   */
  if (src && strcmp(src, "/dev/root") == 0) {

    /* We will only call mnt_guess_system_root() if it has not
     * been called before. Inside a container, mountinfo can contain
     * many lines with /dev/root.
     */
    if (pa->sysroot_rc == 0 && pa->sysroot == NULL)
      pa->sysroot_rc = mnt_guess_system_root(fs->devno,
            tb->cache, &pa->sysroot);

    rc = pa->sysroot_rc;
    if (rc < 0)
      return rc;

    /* This means that we already have run the mnt_guess_system_root()
     * and that we want to reuse the result.
     */
    if (rc == 0 && pa->sysroot != NULL) {
      char *real = strdup(pa->sysroot);

      if (!real)
        return -ENOMEM;

      DBG(TAB, ul_debugobj(tb, "canonical root FS: %s", real));
      rc = __mnt_fs_set_source_ptr(fs, real);

    } else if (rc == 1) {
      /* mnt_guess_system_root() returns 1 if not able to convert to
       * the real devname; ignore this problem */
      rc = 0;
    }
  }

  return rc;
}

/**
 * mnt_table_parse_stream:
 * @tb: tab pointer
 * @f: file stream
 * @filename: filename used for debug and error messages
 *
 * Returns: 0 on success, negative number in case of error.
 */
int mnt_table_parse_stream(struct libmnt_table *tb, FILE *f, const char *filename)
{
  int rc = -1;
  int flags = 0;
  pid_t tid = -1;
  struct libmnt_parser pa = { .line = 0 };

  assert(tb);
  assert(f);
  assert(filename);

  DBG(TAB, ul_debugobj(tb, "%s: start parsing [entries=%d, filter=%s]",
        filename, mnt_table_get_nents(tb),
        tb->fltrcb ? "yes" : "not"));

  pa.filename = filename;
  pa.f = f;

  /* necessary for /proc/mounts only, the /proc/self/mountinfo
   * parser sets the flag properly
   */
  if (tb->fmt == MNT_FMT_SWAPS)
    flags = MNT_FS_SWAP;
  else if (filename && strcmp(filename, _PATH_PROC_MOUNTS) == 0)
    flags = MNT_FS_KERNEL;

  do {
    struct libmnt_fs *fs;

    if (feof(f)) {
      DBG(TAB, ul_debugobj(tb, "end-of-file"));
      break;
    }
    fs = mnt_new_fs();
    if (!fs)
      goto err;

    /* parse */
    rc = mnt_table_parse_next(&pa, tb, fs);

    if (rc == 0 && tb->fltrcb && tb->fltrcb(fs, tb->fltrcb_data))
      rc = 1; /* filtered out by callback... */

    if (rc == 0 && mnt_table_is_noautofs(tb)) {
      const char *fstype = mnt_fs_get_fstype(fs);

      if (fstype && strcmp(fstype, "autofs") == 0 &&
          mnt_fs_get_option(fs, "ignore", NULL, NULL) == 0)
        rc = 1; /* Skip "ignore" autofs entry */
    }

    /* add to the table */
    if (rc == 0) {
      rc = mnt_table_add_fs(tb, fs);
      fs->flags |= flags;

      if (rc == 0 && tb->fmt == MNT_FMT_MOUNTINFO) {
        rc = kernel_fs_postparse(&pa, tb, fs, &tid);
        if (rc)
          mnt_table_remove_fs(tb, fs);
      }
    }

    /* remove reference (or deallocate on error) */
    mnt_unref_fs(fs);

    /* recoverable error */
    if (rc > 0) {
      DBG(TAB, ul_debugobj(tb, "recoverable error (continue)"));
      continue;
    }

    /* fatal errors */
    if (rc < 0 && !feof(f)) {
      DBG(TAB, ul_debugobj(tb, "fatal error"));
      goto err;
    }
  } while (1);

  DBG(TAB, ul_debugobj(tb, "%s: stop parsing (%d entries)",
        filename, mnt_table_get_nents(tb)));
  parser_cleanup(&pa);
  return 0;
err:
  DBG(TAB, ul_debugobj(tb, "%s: parse error (rc=%d)", filename, rc));
  parser_cleanup(&pa);
  return rc;
}

/**
 * mnt_table_parse_file:
 * @tb: tab pointer
 * @filename: file
 *
 * Parses the whole table (e.g. /etc/fstab) and appends new records to the @tab.
 *
 * The libmount parser ignores broken (syntax error) lines, these lines are
 * reported to the caller by the errcb() function (see mnt_table_set_parser_errcb()).
 *
 * Returns: 0 on success, negative number in case of error.
 */
int mnt_table_parse_file(struct libmnt_table *tb, const char *filename)
{
  FILE *f;
  int rc;

  if (!filename || !tb)
    return -EINVAL;

  f = fopen(filename, "r" UL_CLOEXECSTR);
  if (f) {
    rc = mnt_table_parse_stream(tb, f, filename);
    fclose(f);
  } else
    rc = -errno;

  DBG(TAB, ul_debugobj(tb, "parsing done [filename=%s, rc=%d]", filename, rc));
  return rc;
}

static int mnt_table_parse_dir_filter(const struct dirent *d)
{
  size_t namesz;

#ifdef _DIRENT_HAVE_D_TYPE
  if (d->d_type != DT_UNKNOWN && d->d_type != DT_REG &&
      d->d_type != DT_LNK)
    return 0;
#endif
  if (*d->d_name == '.')
    return 0;

#define MNT_MNTTABDIR_EXTSIZ  (sizeof(MNT_MNTTABDIR_EXT) - 1)

  namesz = strlen(d->d_name);
  if (!namesz || namesz < MNT_MNTTABDIR_EXTSIZ + 1 ||
      strcmp(d->d_name + (namesz - MNT_MNTTABDIR_EXTSIZ),
       MNT_MNTTABDIR_EXT) != 0)
    return 0;

  /* Accept this */
  return 1;
}

#ifdef HAVE_SCANDIRAT
static int __mnt_table_parse_dir(struct libmnt_table *tb, const char *dirname)
{
  int n = 0, i;
  int dd;
  struct dirent **namelist = NULL;

  dd = open(dirname, O_RDONLY|O_CLOEXEC|O_DIRECTORY);
  if (dd < 0)
          return -errno;

  n = scandirat(dd, ".", &namelist, mnt_table_parse_dir_filter, versionsort);
  if (n <= 0) {
          close(dd);
          return 0;
  }

  for (i = 0; i < n; i++) {
    struct dirent *d = namelist[i];
    struct stat st;
    FILE *f;

    if (fstatat(dd, d->d_name, &st, 0) ||
        !S_ISREG(st.st_mode))
      continue;

    f = fopen_at(dd, d->d_name, O_RDONLY|O_CLOEXEC, "r" UL_CLOEXECSTR);
    if (f) {
      mnt_table_parse_stream(tb, f, d->d_name);
      fclose(f);
    }
  }

  for (i = 0; i < n; i++)
    free(namelist[i]);
  free(namelist);
  close(dd);
  return 0;
}
#else
static int __mnt_table_parse_dir(struct libmnt_table *tb, const char *dirname)
{
  int n = 0, i, r = 0;
  DIR *dir = NULL;
  struct dirent **namelist = NULL;

  n = scandir(dirname, &namelist, mnt_table_parse_dir_filter, versionsort);
  if (n <= 0)
    return 0;

  /* let's use "at" functions rather than playing crazy games with paths... */
  dir = opendir(dirname);
  if (!dir) {
    r = -errno;
    goto out;
  }

  for (i = 0; i < n; i++) {
    struct dirent *d = namelist[i];
    struct stat st;
    FILE *f;

    if (fstatat(dirfd(dir), d->d_name, &st, 0) ||
        !S_ISREG(st.st_mode))
      continue;

    f = fopen_at(dirfd(dir), d->d_name,
        O_RDONLY|O_CLOEXEC, "r" UL_CLOEXECSTR);
    if (f) {
      mnt_table_parse_stream(tb, f, d->d_name);
      fclose(f);
    }
  }

out:
  for (i = 0; i < n; i++)
    free(namelist[i]);
  free(namelist);
  if (dir)
    closedir(dir);
  return r;
}
#endif

/**
 * mnt_table_parse_dir:
 * @tb: mount table
 * @dirname: directory
 *
 * The directory:
 *  - files are sorted by strverscmp(3)
 *  - files that start with "." are ignored (e.g. ".10foo.fstab")
 *  - files without the ".fstab" extension are ignored
 *
 * Returns: 0 on success or negative number in case of error.
 */
int mnt_table_parse_dir(struct libmnt_table *tb, const char *dirname)
{
  return __mnt_table_parse_dir(tb, dirname);
}

struct libmnt_table *__mnt_new_table_from_file(const char *filename, int fmt, int empty_for_enoent)
{
  struct libmnt_table *tb;

  if (!filename)
    return NULL;
  if (!mnt_is_path(filename))
    return empty_for_enoent ? mnt_new_table() : NULL;

  tb = mnt_new_table();
  if (tb) {
    DBG(TAB, ul_debugobj(tb, "new tab for file: %s", filename));
    tb->fmt = fmt;
    if (mnt_table_parse_file(tb, filename) != 0) {
      mnt_unref_table(tb);
      tb = NULL;
    }
  }
  return tb;
}

/**
 * mnt_new_table_from_file:
 * @filename: /etc/{m,fs}tab or /proc/self/mountinfo path
 *
 * Same as mnt_new_table() + mnt_table_parse_file(). Use this function for private
 * files only. This function does not allow using the error callback, so you
 * cannot provide any feedback to end-users about broken records in files (e.g.
 * fstab).
 *
 * Returns: newly allocated tab on success and NULL in case of error.
 */
struct libmnt_table *mnt_new_table_from_file(const char *filename)
{
  if (!filename)
    return NULL;

  return __mnt_new_table_from_file(filename, MNT_FMT_GUESS, 0);
}

/**
 * mnt_new_table_from_dir
 * @dirname: directory with *.fstab files
 *
 * Returns: newly allocated tab on success and NULL in case of error.
 */
struct libmnt_table *mnt_new_table_from_dir(const char *dirname)
{
  struct libmnt_table *tb;

  if (!dirname)
    return NULL;
  tb = mnt_new_table();
  if (tb && mnt_table_parse_dir(tb, dirname) != 0) {
    mnt_unref_table(tb);
    tb = NULL;
  }
  return tb;
}

/**
 * mnt_table_set_parser_errcb:
 * @tb: pointer to table
 * @cb: pointer to callback function
 *
 * The error callback function is called by table parser (mnt_table_parse_file())
 * in case of a syntax error. The callback function could be used for error
 * evaluation, libmount will continue/stop parsing according to callback return
 * codes:
 *
 *   <0  : fatal error (abort parsing)
 *    0  : success (parsing continues)
 *   >0  : recoverable error (the line is ignored, parsing continues).
 *
 * Returns: 0 on success or negative number in case of error.
 */
int mnt_table_set_parser_errcb(struct libmnt_table *tb,
    int (*cb)(struct libmnt_table *tb, const char *filename, int line))
{
  if (!tb)
    return -EINVAL;
  tb->errcb = cb;
  return 0;
}

/*
 * Filter out entries during tab file parsing. If @cb returns 1, then the entry
 * is ignored.
 */
int mnt_table_set_parser_fltrcb(struct libmnt_table *tb,
    int (*cb)(struct libmnt_fs *, void *),
    void *data)
{
  if (!tb)
    return -EINVAL;

  DBG(TAB, ul_debugobj(tb, "%s table parser filter", cb ? "set" : "unset"));
  tb->fltrcb = cb;
  tb->fltrcb_data = data;
  return 0;
}

/*
 * mnt_table_enable_noautofs:
 * @tb: table
 * @ignore: ignore or don't ignore
 *
 * Enable/disable ignore autofs mount table entries on reading.
 */
int mnt_table_enable_noautofs(struct libmnt_table *tb, int ignore)
{
  if (!tb)
    return -EINVAL;
  tb->noautofs = ignore ? 1 : 0;
  return 0;
}

/*
 * mnt_table_is_noautofs:
 * @tb: table
 *
 * Return the the enabled status of ignore autofs mount table entries.
 */
int mnt_table_is_noautofs(struct libmnt_table *tb)
{
  return tb ? tb->noautofs : 0;
}

/**
 * mnt_table_parse_swaps:
 * @tb: table
 * @filename: overwrites default (/proc/swaps or $LIBMOUNT_SWAPS) or NULL
 *
 * This function parses /proc/swaps and appends new lines to the @tab.
 *
 * See also mnt_table_set_parser_errcb().
 *
 * Returns: 0 on success or negative number in case of error.
 */
int mnt_table_parse_swaps(struct libmnt_table *tb, const char *filename)
{
  if (!tb)
    return -EINVAL;
  if (!filename) {
    filename = mnt_get_swaps_path();
    if (!filename)
      return -EINVAL;
  }

  tb->fmt = MNT_FMT_SWAPS;

  return mnt_table_parse_file(tb, filename);
}

/**
 * mnt_table_parse_fstab:
 * @tb: table
 * @filename: overwrites default (/etc/fstab or $LIBMOUNT_FSTAB) or NULL
 *
 * This function parses /etc/fstab and appends new lines to the @tab. If the
 * @filename is a directory, then mnt_table_parse_dir() is called.
 *
 * See also mnt_table_set_parser_errcb().
 *
 * Returns: 0 on success or negative number in case of error.
 */
int mnt_table_parse_fstab(struct libmnt_table *tb, const char *filename)
{
  struct stat st;
  int rc = 0;

  if (!tb)
    return -EINVAL;
  if (!filename)
    filename = mnt_get_fstab_path();
  if (!filename)
    return -EINVAL;
  if (mnt_safe_stat(filename, &st) != 0)
    return -errno;

  tb->fmt = MNT_FMT_FSTAB;

  if (S_ISREG(st.st_mode))
    rc = mnt_table_parse_file(tb, filename);
  else if (S_ISDIR(st.st_mode))
    rc = mnt_table_parse_dir(tb, filename);
  else
    rc = -EINVAL;

  return rc;
}

/*
 * This function uses @uf to find a corresponding record in @tb, then the record
 * from @tb is updated (user specific mount options are added).
 *
 * Note that @uf must contain only user specific mount options instead of
 * VFS options (note that FS options are ignored).
 *
 * Returns modified filesystem (from @tb) or NULL.
 */
static struct libmnt_fs *mnt_table_merge_user_fs(struct libmnt_table *tb, struct libmnt_fs *uf)
{
  struct libmnt_fs *fs;
  struct libmnt_iter itr;
  const char *optstr, *src, *target, *root, *attrs;
  int id;

  if (!tb || !uf)
    return NULL;

  DBG(TAB, ul_debugobj(tb, "merging user fs"));

  src = mnt_fs_get_srcpath(uf);
  target = mnt_fs_get_target(uf);
  optstr = mnt_fs_get_user_options(uf);
  attrs = mnt_fs_get_attributes(uf);
  root = mnt_fs_get_root(uf);
  id = mnt_fs_get_id(uf);

  if (!src || !target || !root || (!attrs && !optstr))
    return NULL;

  mnt_reset_iter(&itr, MNT_ITER_BACKWARD);

  while(mnt_table_next_fs(tb, &itr, &fs) == 0) {
    const char *r = mnt_fs_get_root(fs);

    if (fs->flags & MNT_FS_MERGED)
      continue;

    if (id > 0 && mnt_fs_get_id(fs)) {
      DBG(TAB, ul_debugobj(tb, " using ID"));
      if (mnt_fs_get_id(fs) == id)
        break;
    } else if (r && strcmp(r, root) == 0
        && mnt_fs_streq_target(fs, target)
        && mnt_fs_streq_srcpath(fs, src))
      break;
  }

  if (fs) {
    DBG(TAB, ul_debugobj(tb, " found"));
    mnt_fs_append_options(fs, optstr);
    mnt_fs_append_attributes(fs, attrs);
    mnt_fs_set_bindsrc(fs, mnt_fs_get_bindsrc(uf));
    fs->flags |= MNT_FS_MERGED;

    DBG(TAB, mnt_fs_print_debug(fs, stderr));
  }
  return fs;
}

/* default filename is /proc/self/mountinfo
 */
int __mnt_table_parse_mountinfo(struct libmnt_table *tb, const char *filename,
         struct libmnt_table *u_tb)
{
  int rc = 0, priv_utab = 0;
  int explicit_file = filename ? 1 : 0;

  assert(tb);

  if (filename)
    DBG(TAB, ul_debugobj(tb, "%s requested as mount table", filename));

  if (!filename || strcmp(filename, _PATH_PROC_MOUNTINFO) == 0) {
    filename = _PATH_PROC_MOUNTINFO;
    tb->fmt = MNT_FMT_MOUNTINFO;
    DBG(TAB, ul_debugobj(tb, "mountinfo parse: #1 read mountinfo"));
  } else
    tb->fmt = MNT_FMT_GUESS;

  rc = mnt_table_parse_file(tb, filename);
  if (rc) {
    if (explicit_file)
      return rc;

    /* hmm, old kernel? ...try /proc/mounts */
    tb->fmt = MNT_FMT_MTAB;
    return mnt_table_parse_file(tb, _PATH_PROC_MOUNTS);
  }

  if (!is_mountinfo(tb))
    return 0;
  DBG(TAB, ul_debugobj(tb, "mountinfo parse: #2 read utab"));

  if (mnt_table_get_nents(tb) == 0)
    return 0;     /* empty, ignore utab */
  /*
   * try to read the user specific information from /run/mount/utabs
   */
  if (!u_tb) {
    const char *utab = mnt_get_utab_path();

    if (!utab || is_file_empty(utab))
      return 0;

    u_tb = mnt_new_table();
    if (!u_tb)
      return -ENOMEM;

    u_tb->fmt = MNT_FMT_UTAB;
    mnt_table_set_parser_fltrcb(u_tb, tb->fltrcb, tb->fltrcb_data);

    rc = mnt_table_parse_file(u_tb, utab);
    priv_utab = 1;
  }

  DBG(TAB, ul_debugobj(tb, "mountinfo parse: #3 merge utab"));

  if (rc == 0) {
    struct libmnt_fs *u_fs;
    struct libmnt_iter itr;

    mnt_reset_iter(&itr, MNT_ITER_BACKWARD);

    /*  merge user options into mountinfo from the kernel */
    while(mnt_table_next_fs(u_tb, &itr, &u_fs) == 0)
      mnt_table_merge_user_fs(tb, u_fs);
  }


  if (priv_utab)
    mnt_unref_table(u_tb);
  return 0;
}
/**
 * mnt_table_parse_mtab:
 * @tb: table
 * @filename: overwrites default or NULL
 *
 * The default filename is /proc/self/mountinfo. If the mount table is a
 * mountinfo file then /run/mount/utabs is parsed too and both files are merged
 * to the one libmnt_table.
 *
 * The file /etc/mtab is no more used. The function uses "mtab" in the name for
 * backward compatibility only.
 *
 * It's strongly recommended to use NULL as a @filename to keep code portable.
 *
 * See also mnt_table_set_parser_errcb().
 *
 * Returns: 0 on success or negative number in case of error.
 */
int mnt_table_parse_mtab(struct libmnt_table *tb, const char *filename)
{
  return __mnt_table_parse_mountinfo(tb, filename, NULL);
}

Coverage Report

Created: 2023-11-19 06:18