/*
 * VIM - Vi IMproved	by Bram Moolenaar
 *
 * Do ":help uganda"  in Vim to read copying and usage conditions.
 * Do ":help credits" in Vim to see a list of people who contributed.
 * See README.txt for an overview of the Vim source code.
 */

/*
 * os_unix.c -- code for all flavors of Unix (BSD, SYSV, SVR4, POSIX, ...)
 *
 * A lot of this file was originally written by Juergen Weigert and later
 * changed beyond recognition.
 */

#include <assert.h>
#include <errno.h>
#include <inttypes.h>
#include <stdbool.h>
#include <string.h>

#include "nvim/api/private/handle.h"
#include "nvim/vim.h"
#include "nvim/ascii.h"
#include "nvim/os_unix.h"
#include "nvim/buffer.h"
#include "nvim/charset.h"
#include "nvim/eval.h"
#include "nvim/ex_cmds.h"
#include "nvim/fileio.h"
#include "nvim/getchar.h"
#include "nvim/main.h"
#include "nvim/mbyte.h"
#include "nvim/memline.h"
#include "nvim/memory.h"
#include "nvim/message.h"
#include "nvim/misc1.h"
#include "nvim/misc2.h"
#include "nvim/mouse.h"
#include "nvim/garray.h"
#include "nvim/path.h"
#include "nvim/screen.h"
#include "nvim/strings.h"
#include "nvim/syntax.h"
#include "nvim/tempfile.h"
#include "nvim/ui.h"
#include "nvim/types.h"
#include "nvim/os/os.h"
#include "nvim/os/time.h"
#include "nvim/os/input.h"
#include "nvim/os/shell.h"
#include "nvim/os/signal.h"
#include "nvim/os/job.h"
#include "nvim/msgpack_rpc/helpers.h"

#ifdef HAVE_STROPTS_H
# include <stropts.h>
#endif

#ifdef HAVE_SELINUX
# include <selinux/selinux.h>
static int selinux_enabled = -1;
#endif


#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "os_unix.c.generated.h"
#endif

#if defined(HAVE_ACL)
# ifdef HAVE_SYS_ACL_H
#  include <sys/acl.h>
# endif
# ifdef HAVE_SYS_ACCESS_H
#  include <sys/access.h>
# endif


#if defined(HAVE_SELINUX)
/*
 * Copy security info from "from_file" to "to_file".
 */
void mch_copy_sec(char_u *from_file, char_u *to_file)
{
  if (from_file == NULL)
    return;

  if (selinux_enabled == -1)
    selinux_enabled = is_selinux_enabled();

  if (selinux_enabled > 0) {
    security_context_t from_context = NULL;
    security_context_t to_context = NULL;

    if (getfilecon((char *)from_file, &from_context) < 0) {
      /* If the filesystem doesn't support extended attributes,
         the original had no special security context and the
         target cannot have one either.  */
      if (errno == EOPNOTSUPP)
        return;

      MSG_PUTS(_("\nCould not get security context for "));
      msg_outtrans(from_file);
      msg_putchar('\n');
      return;
    }
    if (getfilecon((char *)to_file, &to_context) < 0) {
      MSG_PUTS(_("\nCould not get security context for "));
      msg_outtrans(to_file);
      msg_putchar('\n');
      freecon (from_context);
      return;
    }
    if (strcmp(from_context, to_context) != 0) {
      if (setfilecon((char *)to_file, from_context) < 0) {
        MSG_PUTS(_("\nCould not set security context for "));
        msg_outtrans(to_file);
        msg_putchar('\n');
      }
    }
    freecon(to_context);
    freecon(from_context);
  }
}
#endif /* HAVE_SELINUX */

/*
 * Return a pointer to the ACL of file "fname" in allocated memory.
 * Return NULL if the ACL is not available for whatever reason.
 */
vim_acl_T mch_get_acl(char_u *fname)
{
  vim_acl_T ret = NULL;
  return ret;
}

/*
 * Set the ACL of file "fname" to "acl" (unless it's NULL).
 */
void mch_set_acl(char_u *fname, vim_acl_T aclent)
{
  if (aclent == NULL)
    return;
}

void mch_free_acl(vim_acl_T aclent)
{
  if (aclent == NULL)
    return;
}
#endif

/*
 * Check what "name" is:
 * NODE_NORMAL: file or directory (or doesn't exist)
 * NODE_WRITABLE: writable device, socket, fifo, etc.
 * NODE_OTHER: non-writable things
 */
int mch_nodetype(char_u *name)
{
  struct stat st;

  if (stat((char *)name, &st))
    return NODE_NORMAL;
  if (S_ISREG(st.st_mode) || S_ISDIR(st.st_mode))
    return NODE_NORMAL;
  if (S_ISBLK(st.st_mode))      /* block device isn't writable */
    return NODE_OTHER;
  /* Everything else is writable? */
  return NODE_WRITABLE;
}

void mch_exit(int r)
{
  exiting = TRUE;

  ui_builtin_stop();
  ui_flush();
  ml_close_all(TRUE);           /* remove all memfiles */

  event_teardown();
  stream_set_blocking(input_global_fd(), true);  // normalize stream (#2598)

#ifdef EXITFREE
  free_all_mem();
#endif

  exit(r);
}

#ifndef SEEK_SET
# define SEEK_SET 0
#endif
#ifndef SEEK_END
# define SEEK_END 2
#endif

#define SHELL_SPECIAL (char_u *)"\t \"&'$;<>()\\|"

/// Does wildcard pattern matching using the shell.
///
/// @param      num_pat  is the number of input patterns.
/// @param      pat      is an array of pointers to input patterns.
/// @param[out] num_file is pointer to number of matched file names.
///                      Set to the number of pointers in *file.
/// @param[out] file     is pointer to array of pointers to matched file names.
///                      Memory pointed to by the initial value of *file will
///                      not be freed.
///                      Set to NULL if FAIL is returned. Otherwise points to
///                      allocated memory.
/// @param      flags    is a combination of EW_* flags used in
///                      expand_wildcards().
///                      If matching fails but EW_NOTFOUND is set in flags or
///                      there are no wildcards, the patterns from pat are
///                      copied into *file.
///
/// @returns             OK for success or FAIL for error.
int mch_expand_wildcards(int num_pat, char_u **pat, int *num_file,
                         char_u ***file, int flags) FUNC_ATTR_NONNULL_ARG(3)
    FUNC_ATTR_NONNULL_ARG(4)
{
  int i;
  size_t len;
  char_u      *p;
  bool dir;
  char_u *extra_shell_arg = NULL;
  ShellOpts shellopts = kShellOptExpand | kShellOptSilent;
  int j;
  char_u      *tempname;
  char_u      *command;
  FILE        *fd;
  char_u      *buffer;
#define STYLE_ECHO      0       /* use "echo", the default */
#define STYLE_GLOB      1       /* use "glob", for csh */
#define STYLE_VIMGLOB   2       /* use "vimglob", for Posix sh */
#define STYLE_PRINT     3       /* use "print -N", for zsh */
#define STYLE_BT        4       /* `cmd` expansion, execute the pattern
                                 * directly */
  int shell_style = STYLE_ECHO;
  int check_spaces;
  static int did_find_nul = FALSE;
  int ampersent = FALSE;
  /* vimglob() function to define for Posix shell */
  static char *sh_vimglob_func =
    "vimglob() { while [ $# -ge 1 ]; do echo \"$1\"; shift; done }; vimglob >";

  *num_file = 0;        /* default: no files found */
  *file = NULL;

  /*
   * If there are no wildcards, just copy the names to allocated memory.
   * Saves a lot of time, because we don't have to start a new shell.
   */
  if (!have_wildcard(num_pat, pat)) {
    save_patterns(num_pat, pat, num_file, file);
    return OK;
  }

  // Don't allow any shell command in the sandbox.
  if (sandbox != 0 && check_secure()) {
    return FAIL;
  }

  /*
   * Don't allow the use of backticks in secure and restricted mode.
   */
  if (secure || restricted)
    for (i = 0; i < num_pat; ++i)
      if (vim_strchr(pat[i], '`') != NULL
          && (check_restricted() || check_secure()))
        return FAIL;

  /*
   * get a name for the temp file
   */
  if ((tempname = vim_tempname()) == NULL) {
    EMSG(_(e_notmp));
    return FAIL;
  }

  /*
   * Let the shell expand the patterns and write the result into the temp
   * file.
   * STYLE_BT:	NL separated
   *	    If expanding `cmd` execute it directly.
   * STYLE_GLOB:	NUL separated
   *	    If we use *csh, "glob" will work better than "echo".
   * STYLE_PRINT:	NL or NUL separated
   *	    If we use *zsh, "print -N" will work better than "glob".
   * STYLE_VIMGLOB:	NL separated
   *	    If we use *sh*, we define "vimglob()".
   * STYLE_ECHO:	space separated.
   *	    A shell we don't know, stay safe and use "echo".
   */
  if (num_pat == 1 && *pat[0] == '`'
      && (len = STRLEN(pat[0])) > 2
      && *(pat[0] + len - 1) == '`')
    shell_style = STYLE_BT;
  else if ((len = STRLEN(p_sh)) >= 3) {
    if (STRCMP(p_sh + len - 3, "csh") == 0)
      shell_style = STYLE_GLOB;
    else if (STRCMP(p_sh + len - 3, "zsh") == 0)
      shell_style = STYLE_PRINT;
  }
  if (shell_style == STYLE_ECHO && strstr((char *)path_tail(p_sh),
          "sh") != NULL)
    shell_style = STYLE_VIMGLOB;

  /* Compute the length of the command.  We need 2 extra bytes: for the
   * optional '&' and for the NUL.
   * Worst case: "unset nonomatch; print -N >" plus two is 29 */
  len = STRLEN(tempname) + 29;
  if (shell_style == STYLE_VIMGLOB)
    len += STRLEN(sh_vimglob_func);

  for (i = 0; i < num_pat; ++i) {
    /* Count the length of the patterns in the same way as they are put in
     * "command" below. */
    ++len;                              /* add space */
    for (j = 0; pat[i][j] != NUL; ++j) {
      if (vim_strchr(SHELL_SPECIAL, pat[i][j]) != NULL)
        ++len;                  /* may add a backslash */
      ++len;
    }
  }
  command = xmalloc(len);

  /*
   * Build the shell command:
   * - Set $nonomatch depending on EW_NOTFOUND (hopefully the shell
   *	 recognizes this).
   * - Add the shell command to print the expanded names.
   * - Add the temp file name.
   * - Add the file name patterns.
   */
  if (shell_style == STYLE_BT) {
    /* change `command; command& ` to (command; command ) */
    STRCPY(command, "(");
    STRCAT(command, pat[0] + 1);                /* exclude first backtick */
    p = command + STRLEN(command) - 1;
    *p-- = ')';                                 /* remove last backtick */
    while (p > command && ascii_iswhite(*p))
      --p;
    if (*p == '&') {                            /* remove trailing '&' */
      ampersent = TRUE;
      *p = ' ';
    }
    STRCAT(command, ">");
  } else {
    if (flags & EW_NOTFOUND)
      STRCPY(command, "set nonomatch; ");
    else
      STRCPY(command, "unset nonomatch; ");
    if (shell_style == STYLE_GLOB)
      STRCAT(command, "glob >");
    else if (shell_style == STYLE_PRINT)
      STRCAT(command, "print -N >");
    else if (shell_style == STYLE_VIMGLOB)
      STRCAT(command, sh_vimglob_func);
    else
      STRCAT(command, "echo >");
  }

  STRCAT(command, tempname);

  if (shell_style != STYLE_BT)
    for (i = 0; i < num_pat; ++i) {
      /* Put a backslash before special
       * characters, except inside ``. */
      int intick = FALSE;

      p = command + STRLEN(command);
      *p++ = ' ';
      for (j = 0; pat[i][j] != NUL; ++j) {
        if (pat[i][j] == '`')
          intick = !intick;
        else if (pat[i][j] == '\\' && pat[i][j + 1] != NUL) {
          /* Remove a backslash, take char literally.  But keep
           * backslash inside backticks, before a special character
           * and before a backtick. */
          if (intick
              || vim_strchr(SHELL_SPECIAL, pat[i][j + 1]) != NULL
              || pat[i][j + 1] == '`')
            *p++ = '\\';
          ++j;
        } else if (!intick
            && ((flags & EW_KEEPDOLLAR) == 0 || pat[i][j] != '$')
            && vim_strchr(SHELL_SPECIAL, pat[i][j]) != NULL)
          /* Put a backslash before a special character, but not
           * when inside ``. And not for $var when EW_KEEPDOLLAR is
           * set. */
          *p++ = '\\';

        /* Copy one character. */
        *p++ = pat[i][j];
      }
      *p = NUL;
    }

  if (flags & EW_SILENT) {
    shellopts |= kShellOptHideMess;
  }

  if (ampersent)
    STRCAT(command, "&");               /* put the '&' after the redirection */

  /*
   * Using zsh -G: If a pattern has no matches, it is just deleted from
   * the argument list, otherwise zsh gives an error message and doesn't
   * expand any other pattern.
   */
  if (shell_style == STYLE_PRINT)
    extra_shell_arg = (char_u *)"-G";       /* Use zsh NULL_GLOB option */

  /*
   * If we use -f then shell variables set in .cshrc won't get expanded.
   * vi can do it, so we will too, but it is only necessary if there is a "$"
   * in one of the patterns, otherwise we can still use the fast option.
   */
  else if (shell_style == STYLE_GLOB && !have_dollars(num_pat, pat))
    extra_shell_arg = (char_u *)"-f";           /* Use csh fast option */

  /*
   * execute the shell command
   */
  i = call_shell(
      command,
      shellopts,
      extra_shell_arg
      );

  /* When running in the background, give it some time to create the temp
   * file, but don't wait for it to finish. */
  if (ampersent)
    os_delay(10L, true);

  xfree(command);

  if (i) {                         /* os_call_shell() failed */
    os_remove((char *)tempname);
    xfree(tempname);
    /*
     * With interactive completion, the error message is not printed.
     */
    if (!(flags & EW_SILENT))
    {
      redraw_later_clear();             /* probably messed up screen */
      msg_putchar('\n');                /* clear bottom line quickly */
#if SIZEOF_LONG > SIZEOF_INT
      assert(Rows <= (long)INT_MAX + 1);
#endif
      cmdline_row = (int)(Rows - 1);           /* continue on last line */
      MSG(_(e_wildexpand));
      msg_start();                    /* don't overwrite this message */
    }

    /* If a `cmd` expansion failed, don't list `cmd` as a match, even when
     * EW_NOTFOUND is given */
    if (shell_style == STYLE_BT)
      return FAIL;
    goto notfound;
  }

  /*
   * read the names from the file into memory
   */
  fd = fopen((char *)tempname, READBIN);
  if (fd == NULL) {
    /* Something went wrong, perhaps a file name with a special char. */
    if (!(flags & EW_SILENT)) {
      MSG(_(e_wildexpand));
      msg_start();                      /* don't overwrite this message */
    }
    xfree(tempname);
    goto notfound;
  }
  int fseek_res = fseek(fd, 0L, SEEK_END);
  if (fseek_res < 0) {
    xfree(tempname);
    fclose(fd);
    return FAIL;
  }
  long long templen = ftell(fd);        /* get size of temp file */
  if (templen < 0) {
    xfree(tempname);
    fclose(fd);
    return FAIL;
  }
#if SIZEOF_LONG_LONG > SIZEOF_SIZE_T
  assert(templen <= (long long)SIZE_MAX);
#endif
  len = (size_t)templen;
  fseek(fd, 0L, SEEK_SET);
  buffer = xmalloc(len + 1);
  // fread() doesn't terminate buffer with NUL;
  // appropiate termination (not always NUL) is done below.
  size_t readlen = fread((char *)buffer, 1, len, fd);
  fclose(fd);
  os_remove((char *)tempname);
  if (readlen != len) {
    /* unexpected read error */
    EMSG2(_(e_notread), tempname);
    xfree(tempname);
    xfree(buffer);
    return FAIL;
  }
  xfree(tempname);

  /* file names are separated with Space */
  if (shell_style == STYLE_ECHO) {
    buffer[len] = '\n';                 /* make sure the buffer ends in NL */
    p = buffer;
    for (i = 0; *p != '\n'; ++i) {      /* count number of entries */
      while (*p != ' ' && *p != '\n')
        ++p;
      p = skipwhite(p);                 /* skip to next entry */
    }
  }
  /* file names are separated with NL */
  else if (shell_style == STYLE_BT || shell_style == STYLE_VIMGLOB) {
    buffer[len] = NUL;                  /* make sure the buffer ends in NUL */
    p = buffer;
    for (i = 0; *p != NUL; ++i) {       /* count number of entries */
      while (*p != '\n' && *p != NUL)
        ++p;
      if (*p != NUL)
        ++p;
      p = skipwhite(p);                 /* skip leading white space */
    }
  }
  /* file names are separated with NUL */
  else {
    /*
     * Some versions of zsh use spaces instead of NULs to separate
     * results.  Only do this when there is no NUL before the end of the
     * buffer, otherwise we would never be able to use file names with
     * embedded spaces when zsh does use NULs.
     * When we found a NUL once, we know zsh is OK, set did_find_nul and
     * don't check for spaces again.
     */
    check_spaces = FALSE;
    if (shell_style == STYLE_PRINT && !did_find_nul) {
      /* If there is a NUL, set did_find_nul, else set check_spaces */
      buffer[len] = NUL;
      if (len && (int)STRLEN(buffer) < (int)len)
        did_find_nul = TRUE;
      else
        check_spaces = TRUE;
    }

    /*
     * Make sure the buffer ends with a NUL.  For STYLE_PRINT there
     * already is one, for STYLE_GLOB it needs to be added.
     */
    if (len && buffer[len - 1] == NUL)
      --len;
    else
      buffer[len] = NUL;
    i = 0;
    for (p = buffer; p < buffer + len; ++p)
      if (*p == NUL || (*p == ' ' && check_spaces)) {       /* count entry */
        ++i;
        *p = NUL;
      }
    if (len)
      ++i;                              /* count last entry */
  }
  assert(buffer[len] == NUL || buffer[len] == '\n');

  if (i == 0) {
    /*
     * Can happen when using /bin/sh and typing ":e $NO_SUCH_VAR^I".
     * /bin/sh will happily expand it to nothing rather than returning an
     * error; and hey, it's good to check anyway -- webb.
     */
    xfree(buffer);
    goto notfound;
  }
  *num_file = i;
  *file = xmalloc(sizeof(char_u *) * (size_t)i);

  /*
   * Isolate the individual file names.
   */
  p = buffer;
  for (i = 0; i < *num_file; ++i) {
    (*file)[i] = p;
    /* Space or NL separates */
    if (shell_style == STYLE_ECHO || shell_style == STYLE_BT
        || shell_style == STYLE_VIMGLOB) {
      while (!(shell_style == STYLE_ECHO && *p == ' ')
             && *p != '\n' && *p != NUL)
        ++p;
      if (p == buffer + len)                    /* last entry */
        *p = NUL;
      else {
        *p++ = NUL;
        p = skipwhite(p);                       /* skip to next entry */
      }
    } else {          /* NUL separates */
      while (*p && p < buffer + len)            /* skip entry */
        ++p;
      ++p;                                      /* skip NUL */
    }
  }

  /*
   * Move the file names to allocated memory.
   */
  for (j = 0, i = 0; i < *num_file; ++i) {
    /* Require the files to exist.	Helps when using /bin/sh */
    if (!(flags & EW_NOTFOUND) && !os_file_exists((*file)[i]))
      continue;

    /* check if this entry should be included */
    dir = (os_isdir((*file)[i]));
    if ((dir && !(flags & EW_DIR)) || (!dir && !(flags & EW_FILE)))
      continue;

    /* Skip files that are not executable if we check for that. */
    if (!dir && (flags & EW_EXEC) && !os_can_exe((*file)[i], NULL))
      continue;

    p = xmalloc(STRLEN((*file)[i]) + 1 + dir);
    STRCPY(p, (*file)[i]);
    if (dir)
      add_pathsep((char *)p);             /* add '/' to a directory name */
    (*file)[j++] = p;
  }
  xfree(buffer);
  *num_file = j;

  if (*num_file == 0) {     /* rejected all entries */
    xfree(*file);
    *file = NULL;
    goto notfound;
  }

  return OK;

notfound:
  if (flags & EW_NOTFOUND) {
    save_patterns(num_pat, pat, num_file, file);
    return OK;
  }
  return FAIL;

}


static void save_patterns(int num_pat, char_u **pat, int *num_file,
                          char_u ***file)
{
  int i;
  char_u      *s;

  *file = xmalloc((size_t)num_pat * sizeof(char_u *));

  for (i = 0; i < num_pat; i++) {
    s = vim_strsave(pat[i]);
    /* Be compatible with expand_filename(): halve the number of
     * backslashes. */
    backslash_halve(s);
    (*file)[i] = s;
  }
  *num_file = num_pat;
}

static int have_wildcard(int num, char_u **file)
{
  int i;

  for (i = 0; i < num; i++)
    if (path_has_wildcard(file[i]))
      return 1;
  return 0;
}

static int have_dollars(int num, char_u **file)
{
  int i;

  for (i = 0; i < num; i++)
    if (vim_strchr(file[i], '$') != NULL)
      return TRUE;
  return FALSE;
}