path: root/src/nvim/help.c

// This is an open source non-commercial project. Dear PVS-Studio, please check
// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

// help.c: functions for Vim help

#include <stdio.h>
#include <stdlib.h>

#include "nvim/buffer.h"
#include "nvim/charset.h"
#include "nvim/ex_cmds.h"
#include "nvim/ex_docmd.h"
#include "nvim/ex_getln.h"
#include "nvim/fileio.h"
#include "nvim/garray.h"
#include "nvim/globals.h"
#include "nvim/help.h"
#include "nvim/memory.h"
#include "nvim/option.h"
#include "nvim/os/input.h"
#include "nvim/path.h"
#include "nvim/strings.h"
#include "nvim/syntax.h"
#include "nvim/tag.h"
#include "nvim/vim.h"
#include "nvim/window.h"

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

/// ":help": open a read-only window on a help file
void ex_help(exarg_T *eap)
{
  char *arg;
  char *tag;
  FILE *helpfd;          // file descriptor of help file
  int n;
  int i;
  win_T *wp;
  int num_matches;
  char **matches;
  char *p;
  int empty_fnum = 0;
  int alt_fnum = 0;
  buf_T *buf;
  int len;
  char *lang;
  const bool old_KeyTyped = KeyTyped;

  if (eap != NULL) {
    // A ":help" command ends at the first LF, or at a '|' that is
    // followed by some text.  Set nextcmd to the following command.
    for (arg = eap->arg; *arg; arg++) {
      if (*arg == '\n' || *arg == '\r'
          || (*arg == '|' && arg[1] != NUL && arg[1] != '|')) {
        *arg++ = NUL;
        eap->nextcmd = arg;
        break;
      }
    }
    arg = eap->arg;

    if (eap->forceit && *arg == NUL && !curbuf->b_help) {
      emsg(_("E478: Don't panic!"));
      return;
    }

    if (eap->skip) {        // not executing commands
      return;
    }
  } else {
    arg = "";
  }

  // remove trailing blanks
  p = arg + STRLEN(arg) - 1;
  while (p > arg && ascii_iswhite(*p) && p[-1] != '\\') {
    *p-- = NUL;
  }

  // Check for a specified language
  lang = check_help_lang(arg);

  // When no argument given go to the index.
  if (*arg == NUL) {
    arg = "help.txt";
  }

  // Check if there is a match for the argument.
  n = find_help_tags(arg, &num_matches, &matches, eap != NULL && eap->forceit);

  i = 0;
  if (n != FAIL && lang != NULL) {
    // Find first item with the requested language.
    for (i = 0; i < num_matches; i++) {
      len = (int)STRLEN(matches[i]);
      if (len > 3 && matches[i][len - 3] == '@'
          && STRICMP(matches[i] + len - 2, lang) == 0) {
        break;
      }
    }
  }
  if (i >= num_matches || n == FAIL) {
    if (lang != NULL) {
      semsg(_("E661: Sorry, no '%s' help for %s"), lang, arg);
    } else {
      semsg(_("E149: Sorry, no help for %s"), arg);
    }
    if (n != FAIL) {
      FreeWild(num_matches, matches);
    }
    return;
  }

  // The first match (in the requested language) is the best match.
  tag = xstrdup(matches[i]);
  FreeWild(num_matches, matches);

  // Re-use an existing help window or open a new one.
  // Always open a new one for ":tab help".
  if (!bt_help(curwin->w_buffer) || cmdmod.cmod_tab != 0) {
    if (cmdmod.cmod_tab != 0) {
      wp = NULL;
    } else {
      wp = NULL;
      FOR_ALL_WINDOWS_IN_TAB(wp2, curtab) {
        if (bt_help(wp2->w_buffer)) {
          wp = wp2;
          break;
        }
      }
    }
    if (wp != NULL && wp->w_buffer->b_nwindows > 0) {
      win_enter(wp, true);
    } else {
      // There is no help window yet.
      // Try to open the file specified by the "helpfile" option.
      if ((helpfd = os_fopen((char *)p_hf, READBIN)) == NULL) {
        smsg(_("Sorry, help file \"%s\" not found"), p_hf);
        goto erret;
      }
      fclose(helpfd);

      // Split off help window; put it at far top if no position
      // specified, the current window is vertically split and
      // narrow.
      n = WSP_HELP;
      if (cmdmod.cmod_split == 0 && curwin->w_width != Columns
          && curwin->w_width < 80) {
        n |= WSP_TOP;
      }
      if (win_split(0, n) == FAIL) {
        goto erret;
      }

      if (curwin->w_height < p_hh) {
        win_setheight((int)p_hh);
      }

      // Open help file (do_ecmd() will set b_help flag, readfile() will
      // set b_p_ro flag).
      // Set the alternate file to the previously edited file.
      alt_fnum = curbuf->b_fnum;
      (void)do_ecmd(0, NULL, NULL, NULL, ECMD_LASTL,
                    ECMD_HIDE + ECMD_SET_HELP,
                    NULL);  // buffer is still open, don't store info

      if ((cmdmod.cmod_flags & CMOD_KEEPALT) == 0) {
        curwin->w_alt_fnum = alt_fnum;
      }
      empty_fnum = curbuf->b_fnum;
    }
  }

  restart_edit = 0;               // don't want insert mode in help file

  // Restore KeyTyped, setting 'filetype=help' may reset it.
  // It is needed for do_tag top open folds under the cursor.
  KeyTyped = old_KeyTyped;

  do_tag((char_u *)tag, DT_HELP, 1, false, true);

  // Delete the empty buffer if we're not using it.  Careful: autocommands
  // may have jumped to another window, check that the buffer is not in a
  // window.
  if (empty_fnum != 0 && curbuf->b_fnum != empty_fnum) {
    buf = buflist_findnr(empty_fnum);
    if (buf != NULL