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+This file is help.def, from which is created help.c.
+It implements the builtin "help" in Bash.
+
+Copyright (C) 1987-2021 Free Software Foundation, Inc.
+
+This file is part of GNU Bash, the Bourne Again SHell.
+
+Bash 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.
+
+Bash 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 a copy of the GNU General Public License
+along with Bash. If not, see <http://www.gnu.org/licenses/>.
+
+$PRODUCES help.c
+
+$BUILTIN help
+$FUNCTION help_builtin
+$DEPENDS_ON HELP_BUILTIN
+$SHORT_DOC help [-dms] [pattern ...]
+Display information about builtin commands.
+
+Displays brief summaries of builtin commands. If PATTERN is
+specified, gives detailed help on all commands matching PATTERN,
+otherwise the list of help topics is printed.
+
+Options:
+ -d output short description for each topic
+ -m display usage in pseudo-manpage format
+ -s output only a short usage synopsis for each topic matching
+ PATTERN
+
+Arguments:
+ PATTERN Pattern specifying a help topic
+
+Exit Status:
+Returns success unless PATTERN is not found or an invalid option is given.
+$END
+
+#include <config.h>
+
+#if defined (HELP_BUILTIN)
+#include <stdio.h>
+
+#if defined (HAVE_UNISTD_H)
+# ifdef _MINIX
+# include <sys/types.h>
+# endif
+# include <unistd.h>
+#endif
+
+#include <errno.h>
+
+#include <filecntl.h>
+#include <stddef.h>
+
+#include "../bashintl.h"
+
+#include "../shell.h"
+#include "../builtins.h"
+#include "../execute_cmd.h"
+#include "../pathexp.h"
+#include "common.h"
+#include "bashgetopt.h"
+
+#include <glob/strmatch.h>
+#include <glob/glob.h>
+
+#ifndef errno
+extern int errno;
+#endif
+
+extern const char * const bash_copyright;
+extern const char * const bash_license;
+
+static void show_builtin_command_help PARAMS((void));
+static int open_helpfile PARAMS((char *));
+static void show_desc PARAMS((char *, int));
+static void show_manpage PARAMS((char *, int));
+static void show_longdoc PARAMS((int));
+
+/* Print out a list of the known functions in the shell, and what they do.
+ If LIST is supplied, print out the list which matches for each pattern
+ specified. */
+int
+help_builtin (list)
+ WORD_LIST *list;
+{
+ register int i;
+ char *pattern, *name;
+ int plen, match_found, sflag, dflag, mflag, m, pass, this_found;
+
+ dflag = sflag = mflag = 0;
+ reset_internal_getopt ();
+ while ((i = internal_getopt (list, "dms")) != -1)
+ {
+ switch (i)
+ {
+ case 'd':
+ dflag = 1;
+ break;
+ case 'm':
+ mflag = 1;
+ break;
+ case 's':
+ sflag = 1;
+ break;
+ CASE_HELPOPT;
+ default:
+ builtin_usage ();
+ return (EX_USAGE);
+ }
+ }
+ list = loptend;
+
+ if (list == 0)
+ {
+ show_shell_version (0);
+ show_builtin_command_help ();
+ return (EXECUTION_SUCCESS);
+ }
+
+ /* We should consider making `help bash' do something. */
+
+ if (glob_pattern_p (list->word->word) == 1)
+ {
+ printf ("%s", ngettext ("Shell commands matching keyword `", "Shell commands matching keywords `", (list->next ? 2 : 1)));
+ print_word_list (list, ", ");
+ printf ("%s", _("'\n\n"));
+ }
+
+ for (match_found = 0, pattern = ""; list; list = list->next)
+ {
+ pattern = list->word->word;
+ plen = strlen (pattern);
+
+ for (pass = 1, this_found = 0; pass < 3; pass++)
+ {
+ for (i = 0; name = shell_builtins[i].name; i++)
+ {
+ QUIT;
+
+ /* First pass: look for exact string or pattern matches.
+ Second pass: look for prefix matches like bash-4.2 */
+ if (pass == 1)
+ m = (strcmp (pattern, name) == 0) ||
+ (strmatch (pattern, name, FNMATCH_EXTFLAG) != FNM_NOMATCH);
+ else
+ m = strncmp (pattern, name, plen) == 0;
+
+ if (m)
+ {
+ this_found = 1;
+ match_found++;
+ if (dflag)
+ {
+ show_desc (name, i);
+ continue;
+ }
+ else if (mflag)
+ {
+ show_manpage (name, i);
+ continue;
+ }
+
+ printf ("%s: %s\n", name, _(shell_builtins[i].short_doc));
+
+ if (sflag == 0)
+ show_longdoc (i);
+ }
+ }
+ if (pass == 1 && this_found == 1)
+ break;
+ }
+ }
+
+ if (match_found == 0)
+ {
+ builtin_error (_("no help topics match `%s'. Try `help help' or `man -k %s' or `info %s'."), pattern, pattern, pattern);
+ return (EXECUTION_FAILURE);
+ }
+
+ return (sh_chkwrite (EXECUTION_SUCCESS));
+}
+
+void
+builtin_help ()
+{
+ int ind;
+ ptrdiff_t d;
+
+ current_builtin = builtin_address_internal (this_command_name, 0);
+ if (current_builtin == 0)
+ return;
+
+ d = current_builtin - shell_builtins;
+
+#if defined (__STDC__)
+ ind = (int)d;
+#else
+ ind = (int)d / sizeof (struct builtin);
+#endif
+
+ printf ("%s: %s\n", this_command_name, _(shell_builtins[ind].short_doc));
+ show_longdoc (ind);
+}
+
+static int
+open_helpfile (name)
+ char *name;
+{
+ int fd;
+
+ fd = open (name, O_RDONLY);
+ if (fd == -1)
+ {
+ builtin_error (_("%s: cannot open: %s"), name, strerror (errno));
+ return -1;
+ }
+ return fd;
+}
+
+/* By convention, enforced by mkbuiltins.c, if separate help files are being
+ used, the long_doc array contains one string -- the full pathname of the
+ help file for this builtin. */
+static void
+show_longdoc (i)
+ int i;
+{
+ register int j;
+ char * const *doc;
+ int fd;
+
+ doc = shell_builtins[i].long_doc;
+
+ if (doc && doc[0] && *doc[0] == '/' && doc[1] == (char *)NULL)
+ {
+ fd = open_helpfile (doc[0]);
+ if (fd < 0)
+ return;
+ zcatfd (fd, 1, doc[0]);
+ close (fd);
+ }
+ else if (doc)
+ for (j = 0; doc[j]; j++)
+ printf ("%*s%s\n", BASE_INDENT, " ", _(doc[j]));
+}
+
+static void
+show_desc (name, i)
+ char *name;
+ int i;
+{
+ register int j, r;
+ char **doc, *line;
+ int fd, usefile;
+
+ doc = (char **)shell_builtins[i].long_doc;
+
+ usefile = (doc && doc[0] && *doc[0] == '/' && doc[1] == (char *)NULL);
+ if (usefile)
+ {
+ fd = open_helpfile (doc[0]);
+ if (fd < 0)
+ return;
+ r = zmapfd (fd, &line, doc[0]);
+ close (fd);
+ /* XXX - handle errors if zmapfd returns < 0 */
+ }
+ else
+ line = doc ? doc[0] : (char *)NULL;
+
+ printf ("%s - ", name);
+ for (j = 0; line && line[j]; j++)
+ {
+ putchar (line[j]);
+ if (line[j] == '\n')
+ break;
+ }
+
+ fflush (stdout);
+
+ if (usefile)
+ free (line);
+}
+
+/* Print builtin help in pseudo-manpage format. */
+static void
+show_manpage (name, i)
+ char *name;
+ int i;
+{
+ register int j;
+ char **doc, *line;
+ int fd, usefile;
+
+ doc = (char **)shell_builtins[i].long_doc;
+
+ usefile = (doc && doc[0] && *doc[0] == '/' && doc[1] == (char *)NULL);
+ if (usefile)
+ {
+ fd = open_helpfile (doc[0]);
+ if (fd < 0)
+ return;
+ zmapfd (fd, &line, doc[0]);
+ close (fd);
+ }
+ else
+ line = doc ? _(doc[0]) : (char *)NULL;
+
+ /* NAME */
+ printf ("NAME\n");
+ printf ("%*s%s - ", BASE_INDENT, " ", name);
+ for (j = 0; line && line[j]; j++)
+ {
+ putchar (line[j]);
+ if (line[j] == '\n')
+ break;
+ }
+ printf ("\n");
+
+ /* SYNOPSIS */
+ printf ("SYNOPSIS\n");
+ printf ("%*s%s\n\n", BASE_INDENT, " ", _(shell_builtins[i].short_doc));
+
+ /* DESCRIPTION */
+ printf ("DESCRIPTION\n");
+ if (usefile == 0)
+ {
+ for (j = 0; doc[j]; j++)
+ printf ("%*s%s\n", BASE_INDENT, " ", _(doc[j]));
+ }
+ else
+ {
+ for (j = 0; line && line[j]; j++)
+ {
+ putchar (line[j]);
+ if (line[j] == '\n')
+ printf ("%*s", BASE_INDENT, " ");
+ }
+ }
+ putchar ('\n');
+
+ /* SEE ALSO */
+ printf ("SEE ALSO\n");
+ printf ("%*sbash(1)\n\n", BASE_INDENT, " ");
+
+ /* IMPLEMENTATION */
+ printf ("IMPLEMENTATION\n");
+ printf ("%*s", BASE_INDENT, " ");
+ show_shell_version (0);
+ printf ("%*s", BASE_INDENT, " ");
+ printf ("%s\n", _(bash_copyright));
+ printf ("%*s", BASE_INDENT, " ");
+ printf ("%s\n", _(bash_license));
+
+ fflush (stdout);
+ if (usefile)
+ free (line);
+}
+
+static void
+dispcolumn (i, buf, bufsize, width, height)
+ int i;
+ char *buf;
+ size_t bufsize;
+ int width, height;
+{
+ int j;
+ int dispcols;
+ char *helpdoc;
+
+ /* first column */
+ helpdoc = _(shell_builtins[i].short_doc);
+
+ buf[0] = (shell_builtins[i].flags & BUILTIN_ENABLED) ? ' ' : '*';
+ strncpy (buf + 1, helpdoc, width - 2);
+ buf[width - 2] = '>'; /* indicate truncation */
+ buf[width - 1] = '\0';
+ printf ("%s", buf);
+ if (((i << 1) >= num_shell_builtins) || (i+height >= num_shell_builtins))
+ {
+ printf ("\n");
+ return;
+ }
+
+ dispcols = strlen (buf);
+ /* two spaces */
+ for (j = dispcols; j < width; j++)
+ putc (' ', stdout);
+
+ /* second column */
+ helpdoc = _(shell_builtins[i+height].short_doc);
+
+ buf[0] = (shell_builtins[i+height].flags & BUILTIN_ENABLED) ? ' ' : '*';
+ strncpy (buf + 1, helpdoc, width - 3);
+ buf[width - 3] = '>'; /* indicate truncation */
+ buf[width - 2] = '\0';
+
+ printf ("%s\n", buf);
+}
+
+#if defined (HANDLE_MULTIBYTE)
+static void
+wdispcolumn (i, buf, bufsize, width, height)
+ int i;
+ char *buf;
+ size_t bufsize;
+ int width, height;
+{
+ int j;
+ int dispcols, dispchars;
+ char *helpdoc;
+ wchar_t *wcstr;
+ size_t slen, n;
+
+ /* first column */
+ helpdoc = _(shell_builtins[i].short_doc);
+
+ wcstr = 0;
+ slen = mbstowcs ((wchar_t *)0, helpdoc, 0);
+ if (slen == -1)
+ {
+ dispcolumn (i, buf, bufsize, width, height);
+ return;
+ }
+
+ /* No bigger than the passed max width */
+ if (slen >= width)
+ slen = width - 2;
+ wcstr = (wchar_t *)xmalloc (sizeof (wchar_t) * (width + 2));
+ n = mbstowcs (wcstr+1, helpdoc, slen + 1);
+ wcstr[n+1] = L'\0';
+
+ /* Turn tabs and newlines into spaces for column display, since wcwidth
+ returns -1 for them */
+ for (j = 1; j < n; j++)
+ if (wcstr[j] == L'\n' || wcstr[j] == L'\t')
+ wcstr[j] = L' ';
+
+ /* dispchars == number of characters that will be displayed */
+ dispchars = wcsnwidth (wcstr+1, slen, width - 2);
+ /* dispcols == number of columns required to display DISPCHARS */
+ dispcols = wcswidth (wcstr+1, dispchars) + 1; /* +1 for ' ' or '*' */
+
+ wcstr[0] = (shell_builtins[i].flags & BUILTIN_ENABLED) ? L' ' : L'*';
+
+ if (dispcols >= width-2)
+ {
+ wcstr[dispchars] = L'>'; /* indicate truncation */
+ wcstr[dispchars+1] = L'\0';
+ }
+
+ printf ("%ls", wcstr);
+ if (((i << 1) >= num_shell_builtins) || (i+height >= num_shell_builtins))
+ {
+ printf ("\n");
+ free (wcstr);
+ return;
+ }
+
+ /* at least one space */
+ for (j = dispcols; j < width; j++)
+ putc (' ', stdout);
+
+ /* second column */
+ helpdoc = _(shell_builtins[i+height].short_doc);
+ slen = mbstowcs ((wchar_t *)0, helpdoc, 0);
+ if (slen == -1)
+ {
+ /* for now */
+ printf ("%c%s\n", (shell_builtins[i+height].flags & BUILTIN_ENABLED) ? ' ' : '*', helpdoc);
+ free (wcstr);
+ return;
+ }
+
+ /* Reuse wcstr since it is already width wide chars long */
+ if (slen >= width)
+ slen = width - 2;
+ n = mbstowcs (wcstr+1, helpdoc, slen + 1);
+ wcstr[n+1] = L'\0'; /* make sure null-terminated */
+
+ /* Turn tabs and newlines into spaces for column display */
+ for (j = 1; j < n; j++)
+ if (wcstr[j] == L'\n' || wcstr[j] == L'\t')
+ wcstr[j] = L' ';
+
+ /* dispchars == number of characters that will be displayed */
+ dispchars = wcsnwidth (wcstr+1, slen, width - 2);
+ dispcols = wcswidth (wcstr+1, dispchars) + 1; /* +1 for ' ' or '*' */
+
+ wcstr[0] = (shell_builtins[i+height].flags & BUILTIN_ENABLED) ? L' ' : L'*';
+
+ /* The dispchars-1 is there for terminals that behave strangely when you
+ have \n in the nth column for terminal width n; this is what bash-4.3
+ did. */
+ if (dispcols >= width - 2)
+ {
+ wcstr[dispchars-1] = L'>'; /* indicate truncation */
+ wcstr[dispchars] = L'\0';
+ }
+
+ printf ("%ls\n", wcstr);
+
+ free (wcstr);
+}
+#endif /* HANDLE_MULTIBYTE */
+
+static void
+show_builtin_command_help ()
+{
+ int i, j;
+ int height, width;
+ char *t, blurb[128];
+
+ printf (
+_("These shell commands are defined internally. Type `help' to see this list.\n\
+Type `help name' to find out more about the function `name'.\n\
+Use `info bash' to find out more about the shell in general.\n\
+Use `man -k' or `info' to find out more about commands not in this list.\n\
+\n\
+A star (*) next to a name means that the command is disabled.\n\
+\n"));
+
+ width = default_columns ();
+
+ width /= 2;
+ if (width > sizeof (blurb))
+ width = sizeof (blurb);
+ if (width <= 3)
+ width = 40;
+ height = (num_shell_builtins + 1) / 2; /* number of rows */
+
+ for (i = 0; i < height; i++)
+ {
+ QUIT;
+
+#if defined (HANDLE_MULTIBYTE)
+ if (MB_CUR_MAX > 1)
+ wdispcolumn (i, blurb, sizeof (blurb), width, height);
+ else
+#endif
+ dispcolumn (i, blurb, sizeof (blurb), width, height);
+ }
+}
+#endif /* HELP_BUILTIN */
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