From 05df9d0879317816dcee00282eea3a06b0310c3b Mon Sep 17 00:00:00 2001
From: Dan Fandrich <dan@coneharvesters.com>
Date: Sat, 3 Dec 2011 11:13:10 -0800
Subject: [PATCH] Declare many structures const (closes #3552)

Many structs used in mutt are actually constant but are defined
without the 'const' keyword. This can slow initialization (slightly)
in some environments due to extra copying and increases the amount of
writable RAM required at run-time, which can be significant on non-MMU
systems. Using const can also increase the opportunities for compiler
optimization.

The attached patch marks many such structures as const. On my test x86
build, this reduces the size of .data by over 50%.
---
 addrbook.c     |  2 +-
 browser.c      |  2 +-
 charset.c      |  6 +++---
 color.c        |  6 +++---
 compose.c      |  4 ++--
 crypt-gpgme.c  |  4 ++--
 curs_lib.c     |  4 ++--
 curs_main.c    |  2 +-
 date.c         |  4 ++--
 enter.c        |  2 +-
 functions.h    | 26 +++++++++++++-------------
 globals.h      | 12 ++++++------
 handler.c      |  6 +++---
 help.c         | 14 +++++++-------
 imap/auth.c    |  4 ++--
 imap/command.c |  2 +-
 imap/message.c |  2 +-
 imap/utf7.c    |  4 ++--
 imap/util.c    |  3 ++-
 init.c         | 17 +++++++++--------
 init.h         |  2 +-
 keymap.c       | 24 ++++++++++++------------
 keymap.h       | 31 +++++++++++++++----------------
 lib.c          |  6 +++---
 mapping.h      |  6 +++---
 mime.h         |  6 +++---
 mutt_ssl.c     |  2 +-
 pager.c        |  4 ++--
 parse.c        |  2 +-
 pattern.c      |  6 +++---
 pgpkey.c       |  2 +-
 pgpmicalg.c    |  2 +-
 pop_auth.c     |  4 ++--
 postpone.c     |  2 +-
 protos.h       |  2 +-
 query.c        |  2 +-
 recvattach.c   |  2 +-
 remailer.c     |  2 +-
 rfc2047.c      |  2 +-
 rfc822.c       |  2 +-
 rfc822.h       |  2 +-
 sendlib.c      |  2 +-
 url.c          |  2 +-
 43 files changed, 122 insertions(+), 121 deletions(-)

diff --git a/addrbook.c b/addrbook.c
index 7d82cf57..8767a00f 100644
--- a/addrbook.c
+++ b/addrbook.c
@@ -33,7 +33,7 @@
 
 #define RSORT(x) (SortAlias & SORT_REVERSE) ? -x : x
 
-static struct mapping_t AliasHelp[] = {
+static const struct mapping_t AliasHelp[] = {
   { N_("Exit"),   OP_EXIT },
   { N_("Del"),    OP_DELETE },
   { N_("Undel"),  OP_UNDELETE },
diff --git a/browser.c b/browser.c
index 3cc24939..cda4900a 100644
--- a/browser.c
+++ b/browser.c
@@ -42,7 +42,7 @@
 #include <errno.h>
 #include <locale.h>
 
-static struct mapping_t FolderHelp[] = {
+static const struct mapping_t FolderHelp[] = {
   { N_("Exit"),  OP_EXIT },
   { N_("Chdir"), OP_CHANGE_DIRECTORY },
   { N_("Mask"),  OP_ENTER_MASK },
diff --git a/charset.c b/charset.c
index fd011a49..9dd278ee 100644
--- a/charset.c
+++ b/charset.c
@@ -50,10 +50,10 @@
  * a preferred MIME name is given.
  */
 
-static struct 
+static const const struct 
 {
-  char *key;
-  char *pref;
+  const char *key;
+  const char *pref;
 }
 PreferredMIMENames[] = 
 {
diff --git a/color.c b/color.c
index b39957f0..db8266d0 100644
--- a/color.c
+++ b/color.c
@@ -55,7 +55,7 @@ typedef struct color_list
 static COLOR_LIST *ColorList = NULL;
 static int UserColors = 0;
 
-static struct mapping_t Colors[] =
+static const struct mapping_t Colors[] =
 {
   { "black",	COLOR_BLACK },
   { "blue",	COLOR_BLUE },
@@ -73,7 +73,7 @@ static struct mapping_t Colors[] =
 
 #endif /* HAVE_COLOR */
 
-static struct mapping_t Fields[] =
+static const struct mapping_t Fields[] =
 {
   { "hdrdefault",	MT_COLOR_HDEFAULT },
   { "quoted",		MT_COLOR_QUOTED },
@@ -159,7 +159,7 @@ void ci_start_color (void)
 #ifdef USE_SLANG_CURSES
 static char *get_color_name (char *dest, size_t destlen, int val)
 {
-  static char * missing[3] = {"brown", "lightgray", "default"};
+  static const char * const missing[3] = {"brown", "lightgray", "default"};
   int i;
 
   switch (val)
diff --git a/compose.c b/compose.c
index 3b7cb173..edda021d 100644
--- a/compose.c
+++ b/compose.c
@@ -74,7 +74,7 @@ enum
 #define TITLE_FMT "%10s" /* Used for Prompts, which are ASCII */
 #define W (COLS - HDR_XOFFSET)
 
-static char *Prompts[] =
+static const char * const Prompts[] =
 {
   "From: ",
   "To: ",
@@ -85,7 +85,7 @@ static char *Prompts[] =
   "Fcc: "
 };
 
-static struct mapping_t ComposeHelp[] = {
+static const struct mapping_t ComposeHelp[] = {
   { N_("Send"),    OP_COMPOSE_SEND_MESSAGE },
   { N_("Abort"),   OP_EXIT },
   { "To",      OP_COMPOSE_EDIT_TO },
diff --git a/crypt-gpgme.c b/crypt-gpgme.c
index b1da88bf..3ef629db 100644
--- a/crypt-gpgme.c
+++ b/crypt-gpgme.c
@@ -129,7 +129,7 @@ static char *current_sender = NULL;
  * General helper functions.
  */
 
-/* return true when S pints to a didgit or letter. */
+/* return true when s points to a digit or letter. */
 static int
 digit_or_letter (const unsigned char *s)
 {
@@ -2923,7 +2923,7 @@ print_dn_part (FILE *fp, struct dn_array_s *dn, const char *key)
 static void
 print_dn_parts (FILE *fp, struct dn_array_s *dn)
 {
-  const char *stdpart[] = {
+  static const char * const stdpart[] = {
     "CN", "OU", "O", "STREET", "L", "ST", "C", NULL 
   };
   int any=0, any2=0, i;
diff --git a/curs_lib.c b/curs_lib.c
index 7f88cc93..29114906 100644
--- a/curs_lib.c
+++ b/curs_lib.c
@@ -129,7 +129,7 @@ event_t mutt_getch (void)
   return (ch == ctrl ('G') ? err : ret);
 }
 
-int _mutt_get_field (/* const */ char *field, char *buf, size_t buflen, int complete, int multiple, char ***files, int *numfiles)
+int _mutt_get_field (const char *field, char *buf, size_t buflen, int complete, int multiple, char ***files, int *numfiles)
 {
   int ret;
   int x, y;
@@ -139,7 +139,7 @@ int _mutt_get_field (/* const */ char *field, char *buf, size_t buflen, int comp
   do
   {
     CLEARLINE (LINES-1);
-    addstr (field);
+    addstr ((char *)field); /* cast to get around bad prototypes */
     mutt_refresh ();
     getyx (stdscr, y, x);
     ret = _mutt_enter_string (buf, buflen, y, x, complete, multiple, files, numfiles, es);
diff --git a/curs_main.c b/curs_main.c
index dd2ac398..302082b4 100644
--- a/curs_main.c
+++ b/curs_main.c
@@ -401,7 +401,7 @@ static void resort_index (MUTTMENU *menu)
   menu->redraw = REDRAW_INDEX | REDRAW_STATUS;
 }
 
-static struct mapping_t IndexHelp[] = {
+static const struct mapping_t IndexHelp[] = {
   { N_("Quit"),  OP_QUIT },
   { N_("Del"),   OP_DELETE },
   { N_("Undel"), OP_UNDELETE },
diff --git a/date.c b/date.c
index a2f00048..0cd83122 100644
--- a/date.c
+++ b/date.c
@@ -69,7 +69,7 @@ time_t mutt_mktime (struct tm *t, int local)
 {
   time_t g;
 
-  static int AccumDaysPerMonth[12] = {
+  static const int AccumDaysPerMonth[12] = {
     0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
   };
 
@@ -118,7 +118,7 @@ static int isLeapYearFeb (struct tm *tm)
 
 void mutt_normalize_time (struct tm *tm)
 {
-  static char DaysPerMonth[12] = {
+  static const char DaysPerMonth[12] = {
     31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
   };
   int nLeap;
diff --git a/enter.c b/enter.c
index 9f8a45e6..ac083f5c 100644
--- a/enter.c
+++ b/enter.c
@@ -191,7 +191,7 @@ static void replace_part (ENTER_STATE *state, size_t from, char *buf)
  */
 static inline int is_shell_char(wchar_t ch)
 {
-  static wchar_t shell_chars[] = L"<>&()$?*;{}| "; /* ! not included because it can be part of a pathname in Mutt */
+  static const wchar_t shell_chars[] = L"<>&()$?*;{}| "; /* ! not included because it can be part of a pathname in Mutt */
   return wcschr(shell_chars, ch) != NULL;
 }
 
diff --git a/functions.h b/functions.h
index e8beacb4..7a1c5a9f 100644
--- a/functions.h
+++ b/functions.h
@@ -38,7 +38,7 @@
 # include "doc/makedoc-defs.h"
 #endif
 
-struct binding_t OpGeneric[] = { /* map: generic */
+const struct binding_t OpGeneric[] = { /* map: generic */
   /*
   ** <para>
   ** The <emphasis>generic</emphasis> menu is not a real menu, but specifies common functions
@@ -82,7 +82,7 @@ struct binding_t OpGeneric[] = { /* map: generic */
   { NULL,		0,			NULL }
 };
 
-struct binding_t OpMain[] = { /* map: index */
+const struct binding_t OpMain[] = { /* map: index */
   { "create-alias",		OP_CREATE_ALIAS,		"a" },
   { "bounce-message",		OP_BOUNCE_MESSAGE,		"b" },
   { "break-thread",		OP_MAIN_BREAK_THREAD,		"#" },
@@ -172,7 +172,7 @@ struct binding_t OpMain[] = { /* map: index */
   { NULL,			0,				NULL }
 };
 
-struct binding_t OpPager[] = { /* map: pager */
+const struct binding_t OpPager[] = { /* map: pager */
   { "break-thread",	OP_MAIN_BREAK_THREAD,		"#" },
   { "create-alias",	OP_CREATE_ALIAS,		"a" },
   { "bounce-message",	OP_BOUNCE_MESSAGE,		"b" },
@@ -275,7 +275,7 @@ struct binding_t OpPager[] = { /* map: pager */
   { NULL,		0,				NULL }
 };
 
-struct binding_t OpAttach[] = { /* map: attachment */
+const struct binding_t OpAttach[] = { /* map: attachment */
   { "bounce-message",	OP_BOUNCE_MESSAGE,		"b" },
   { "display-toggle-weed",	OP_DISPLAY_HEADERS,	"h" },
   { "edit-type",	OP_EDIT_TYPE,			"\005" },
@@ -301,7 +301,7 @@ struct binding_t OpAttach[] = { /* map: attachment */
   { NULL,		0,				NULL }
 };
 
-struct binding_t OpCompose[] = { /* map: compose */
+const struct binding_t OpCompose[] = { /* map: compose */
   { "attach-file",	OP_COMPOSE_ATTACH_FILE,		"a" },
   { "attach-message",	OP_COMPOSE_ATTACH_MESSAGE,	"A" },
   { "edit-bcc",		OP_COMPOSE_EDIT_BCC,		"b" },
@@ -351,13 +351,13 @@ struct binding_t OpCompose[] = { /* map: compose */
   { NULL,		0,				NULL }
 };
 
-struct binding_t OpPost[] = { /* map: postpone */
+const struct binding_t OpPost[] = { /* map: postpone */
   { "delete-entry",	OP_DELETE,	"d" },
   { "undelete-entry",	OP_UNDELETE,	"u" },
   { NULL,		0,		NULL }
 };
 
-struct binding_t OpAlias[] = { /* map: alias */
+const struct binding_t OpAlias[] = { /* map: alias */
   { "delete-entry",	OP_DELETE,	"d" },
   { "undelete-entry",	OP_UNDELETE,	"u" },
   { NULL,		0,		NULL }
@@ -365,7 +365,7 @@ struct binding_t OpAlias[] = { /* map: alias */
   
 
 /* The file browser */
-struct binding_t OpBrowser[] = { /* map: browser */
+const struct binding_t OpBrowser[] = { /* map: browser */
   { "change-dir",	OP_CHANGE_DIRECTORY,	"c" },
   { "display-filename",	OP_BROWSER_TELL,	"@" },
   { "enter-mask",	OP_ENTER_MASK,		"m" },
@@ -388,7 +388,7 @@ struct binding_t OpBrowser[] = { /* map: browser */
 };
 
 /* External Query Menu */
-struct binding_t OpQuery[] = { /* map: query */
+const struct binding_t OpQuery[] = { /* map: query */
   { "create-alias",	OP_CREATE_ALIAS,	"a" },
   { "mail",		OP_MAIL,		"m" },
   { "query",		OP_QUERY,		"Q" },
@@ -396,7 +396,7 @@ struct binding_t OpQuery[] = { /* map: query */
   { NULL,		0,			NULL }
 };
 
-struct binding_t OpEditor[] = { /* map: editor */
+const struct binding_t OpEditor[] = { /* map: editor */
   { "bol",		OP_EDITOR_BOL,			"\001" },
   { "backward-char",	OP_EDITOR_BACKWARD_CHAR,	"\002" },
   { "backward-word",	OP_EDITOR_BACKWARD_WORD,	"\033b"},
@@ -424,7 +424,7 @@ struct binding_t OpEditor[] = { /* map: editor */
 
 
 
-struct binding_t OpPgp[] = { /* map: pgp */
+const struct binding_t OpPgp[] = { /* map: pgp */
   { "verify-key",	OP_VERIFY_KEY,		"c" },
   { "view-name",	OP_VIEW_ID,		"%" },
   { NULL,		0,				NULL }
@@ -434,7 +434,7 @@ struct binding_t OpPgp[] = { /* map: pgp */
 
 /* When using the GPGME based backend we have some useful functions
    for the SMIME menu.  */
-struct binding_t OpSmime[] = { /* map: smime */
+const struct binding_t OpSmime[] = { /* map: smime */
 #ifdef CRYPT_BACKEND_GPGME
   { "verify-key",    OP_VERIFY_KEY,             "c" },
   { "view-name",     OP_VIEW_ID,	        "%" },
@@ -445,7 +445,7 @@ struct binding_t OpSmime[] = { /* map: smime */
 
 
 #ifdef MIXMASTER
-struct binding_t OpMix[] = { /* map: mixmaster */
+const struct binding_t OpMix[] = { /* map: mixmaster */
   { "accept",		OP_MIX_USE,	M_ENTER_S },
   { "append",		OP_MIX_APPEND,	"a"       },
   { "insert",		OP_MIX_INSERT,	"i"       },
diff --git a/globals.h b/globals.h
index 5aec5300..6fefe5b0 100644
--- a/globals.h
+++ b/globals.h
@@ -266,14 +266,14 @@ WHERE char *SmimeGetCertEmailCommand;
 
 
 #ifdef MAIN_C
-const char *Weekdays[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
-const char *Months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "ERR" };
+const char * const Weekdays[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
+const char * const Months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec", "ERR" };
 
-const char *BodyTypes[] = { "x-unknown", "audio", "application", "image", "message", "model", "multipart", "text", "video" };
-const char *BodyEncodings[] = { "x-unknown", "7bit", "8bit", "quoted-printable", "base64", "binary", "x-uuencoded" };
+const char * const BodyTypes[] = { "x-unknown", "audio", "application", "image", "message", "model", "multipart", "text", "video" };
+const char * const BodyEncodings[] = { "x-unknown", "7bit", "8bit", "quoted-printable", "base64", "binary", "x-uuencoded" };
 #else
-extern const char *Weekdays[];
-extern const char *Months[];
+extern const char * const Weekdays[];
+extern const char * const Months[];
 #endif
 
 #ifdef MAIN_C
diff --git a/handler.c b/handler.c
index 39b7979b..13c89ecc 100644
--- a/handler.c
+++ b/handler.c
@@ -43,7 +43,7 @@
 
 typedef int (*handler_t) (BODY *, STATE *);
 
-int Index_hex[128] = {
+const int Index_hex[128] = {
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
@@ -54,7 +54,7 @@ int Index_hex[128] = {
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1
 };
 
-int Index_64[128] = {
+const int Index_64[128] = {
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, -1,-1,-1,63,
@@ -434,7 +434,7 @@ enum { RICH_PARAM=0, RICH_BOLD, RICH_UNDERLINE, RICH_ITALIC, RICH_NOFILL,
   RICH_INDENT, RICH_INDENT_RIGHT, RICH_EXCERPT, RICH_CENTER, RICH_FLUSHLEFT,
   RICH_FLUSHRIGHT, RICH_COLOR, RICH_LAST_TAG };
 
-static struct {
+static const struct {
   const wchar_t *tag_name;
   int index;
 } EnrichedTags[] = {
diff --git a/help.c b/help.c
index 6d54059f..c1d2d0c6 100644
--- a/help.c
+++ b/help.c
@@ -31,10 +31,10 @@
 #include <ctype.h>
 #include <string.h>
 
-static struct binding_t *help_lookupFunction (int op, int menu)
+static const struct binding_t *help_lookupFunction (int op, int menu)
 {
   int i;
-  struct binding_t *map;
+  const struct binding_t *map;
 
   if (menu != MENU_PAGER)
   {
@@ -66,7 +66,7 @@ void mutt_make_help (char *d, size_t dlen, char *txt, int menu, int op)
 }
 
 char *
-mutt_compile_help (char *buf, size_t buflen, int menu, struct mapping_t *items)
+mutt_compile_help (char *buf, size_t buflen, int menu, const struct mapping_t *items)
 {
   int i;
   size_t len;
@@ -282,7 +282,7 @@ static void format_line (FILE *f, int ismacro,
 static void dump_menu (FILE *f, int menu)
 {
   struct keymap_t *map;
-  struct binding_t *b;
+  const struct binding_t *b;
   char buf[SHORT_STRING];
 
   /* browse through the keymap table */
@@ -318,7 +318,7 @@ static int is_bound (struct keymap_t *map, int op)
 }
 
 static void dump_unbound (FILE *f,
-			  struct binding_t *funcs,
+			  const struct binding_t *funcs,
 			  struct keymap_t *map,
 			  struct keymap_t *aux)
 {
@@ -336,9 +336,9 @@ void mutt_help (int menu)
 {
   char t[_POSIX_PATH_MAX];
   char buf[SHORT_STRING];
-  char *desc;
+  const char *desc;
   FILE *f;
-  struct binding_t *funcs;
+  const struct binding_t *funcs;
 
   mutt_mktemp (t, sizeof (t));
 
diff --git a/imap/auth.c b/imap/auth.c
index 6ac29251..8a7f0789 100644
--- a/imap/auth.c
+++ b/imap/auth.c
@@ -28,7 +28,7 @@
 #include "imap_private.h"
 #include "auth.h"
 
-static imap_auth_t imap_authenticators[] = {
+static const imap_auth_t imap_authenticators[] = {
 #ifdef USE_SASL
   { imap_auth_sasl, NULL },
 #else
@@ -50,7 +50,7 @@ static imap_auth_t imap_authenticators[] = {
  *   authentication method if specified, or any. */
 int imap_authenticate (IMAP_DATA* idata)
 {
-  imap_auth_t* authenticator;
+  const imap_auth_t* authenticator;
   char* methods;
   char* method;
   char* delim;
diff --git a/imap/command.c b/imap/command.c
index 18e1a57c..70e7d481 100644
--- a/imap/command.c
+++ b/imap/command.c
@@ -53,7 +53,7 @@ static void cmd_parse_myrights (IMAP_DATA* idata, const char* s);
 static void cmd_parse_search (IMAP_DATA* idata, const char* s);
 static void cmd_parse_status (IMAP_DATA* idata, char* s);
 
-static char *Capabilities[] = {
+static const char * const Capabilities[] = {
   "IMAP4",
   "IMAP4rev1",
   "STATUS",
diff --git a/imap/message.c b/imap/message.c
index 3c7a38e8..d318b693 100644
--- a/imap/message.c
+++ b/imap/message.c
@@ -71,7 +71,7 @@ int imap_read_headers (IMAP_DATA* idata, int msgbegin, int msgend)
   int rc, mfhrc, oldmsgcount;
   int fetchlast = 0;
   int maxuid = 0;
-  const char *want_headers = "DATE FROM SUBJECT TO CC MESSAGE-ID REFERENCES CONTENT-TYPE CONTENT-DESCRIPTION IN-REPLY-TO REPLY-TO LINES LIST-POST X-LABEL";
+  static const char * const want_headers = "DATE FROM SUBJECT TO CC MESSAGE-ID REFERENCES CONTENT-TYPE CONTENT-DESCRIPTION IN-REPLY-TO REPLY-TO LINES LIST-POST X-LABEL";
   progress_t progress;
   int retval = -1;
 
diff --git a/imap/utf7.c b/imap/utf7.c
index cf2ecb4e..a433971c 100644
--- a/imap/utf7.c
+++ b/imap/utf7.c
@@ -24,7 +24,7 @@
 #include "charset.h"
 #include "imap_private.h"
 
-static int Index_64[128] = {
+static const int Index_64[128] = {
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,-1,
     -1,-1,-1,-1, -1,-1,-1,-1, -1,-1,-1,62, 63,-1,-1,-1,
@@ -35,7 +35,7 @@ static int Index_64[128] = {
     41,42,43,44, 45,46,47,48, 49,50,51,-1, -1,-1,-1,-1
 };
 
-static char B64Chars[64] = {
+static const char B64Chars[64] = {
   'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
   'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
   'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
diff --git a/imap/util.c b/imap/util.c
index b38268e2..f7e0ef5a 100644
--- a/imap/util.c
+++ b/imap/util.c
@@ -612,7 +612,8 @@ void imap_qualify_path (char *dest, size_t len, IMAP_MBOX *mx, char* path)
  *   surround string with quotes, escape " and \ with \ */
 void imap_quote_string (char *dest, size_t dlen, const char *src)
 {
-  char quote[] = "\"\\", *pt;
+  static const char quote[] = "\"\\";
+  char *pt;
   const char *s;
 
   pt = dest;
diff --git a/init.c b/init.c
index 7773a920..efdba2db 100644
--- a/init.c
+++ b/init.c
@@ -1691,7 +1691,8 @@ static int parse_set (BUFFER *tmp, BUFFER *s, unsigned long data, BUFFER *err)
 {
   int query, unset, inv, reset, r = 0;
   int idx = -1;
-  char *p, scratch[_POSIX_PATH_MAX];
+  const char *p;
+  char scratch[_POSIX_PATH_MAX];
   char* myvar;
 
   while (MoreArgs (s))
@@ -2113,7 +2114,7 @@ static int parse_set (BUFFER *tmp, BUFFER *s, unsigned long data, BUFFER *err)
     {
       if (query)
       {
-	char *vals[] = { "no", "yes", "ask-no", "ask-yes" };
+	static const char * const vals[] = { "no", "yes", "ask-no", "ask-yes" };
 
 	snprintf (err->data, err->dsize, "%s=%s", MuttVars[idx].option,
 		  vals [ quadoption (MuttVars[idx].data) ]);
@@ -2481,7 +2482,7 @@ int mutt_command_complete (char *buffer, size_t len, int pos, int numtabs)
 	   || !mutt_strncmp (buffer, "reset", 5)
 	   || !mutt_strncmp (buffer, "toggle", 6))
   { 		/* complete variables */
-    char *prefixes[] = { "no", "inv", "?", "&", 0 };
+    static const char * const prefixes[] = { "no", "inv", "?", "&", 0 };
     
     pt++;
     /* loop through all the possible prefixes (no, inv, ...) */
@@ -2533,7 +2534,7 @@ int mutt_command_complete (char *buffer, size_t len, int pos, int numtabs)
   }
   else if (!mutt_strncmp (buffer, "exec", 4))
   {
-    struct binding_t *menu = km_get_table (CurrentMenu);
+    const struct binding_t *menu = km_get_table (CurrentMenu);
 
     if (!menu && CurrentMenu != MENU_PAGER)
       menu = OpGeneric;
@@ -2632,7 +2633,7 @@ int mutt_var_value_complete (char *buffer, size_t len, int pos)
 static int var_to_string (int idx, char* val, size_t len)
 {
   char tmp[LONG_STRING];
-  char *vals[] = { "no", "yes", "ask-no", "ask-yes" };
+  static const char * const vals[] = { "no", "yes", "ask-no", "ask-yes" };
 
   tmp[0] = '\0';
 
@@ -2663,7 +2664,7 @@ static int var_to_string (int idx, char* val, size_t len)
   else if (DTYPE (MuttVars[idx].type) == DT_SORT)
   {
     const struct mapping_t *map;
-    char *p;
+    const char *p;
 
     switch (MuttVars[idx].type & DT_SUBTYPE_MASK)
     {
@@ -2789,7 +2790,7 @@ int mutt_dump_variables (void)
   return 0;
 }
 
-char *mutt_getnamebyvalue (int val, const struct mapping_t *map)
+const char *mutt_getnamebyvalue (int val, const struct mapping_t *map)
 {
   int i;
 
@@ -3150,7 +3151,7 @@ void mutt_init (int skip_sys_rc, LIST *commands)
 
 int mutt_get_hook_type (const char *name)
 {
-  struct command_t *c;
+  const struct command_t *c;
 
   for (c = Commands ; c->name ; c++)
     if (c->func == mutt_parse_hook && ascii_strcasecmp (c->name, name) == 0)
diff --git a/init.h b/init.h
index 09dfbf28..360886a1 100644
--- a/init.h
+++ b/init.h
@@ -3488,7 +3488,7 @@ struct command_t
   unsigned long data;
 };
 
-struct command_t Commands[] = {
+const struct command_t Commands[] = {
   { "alternates",	parse_alternates,	0 },
   { "unalternates",	parse_unalternates,	0 },
 #ifdef USE_SOCKET
diff --git a/keymap.c b/keymap.c
index d82310a7..56ec05d3 100644
--- a/keymap.c
+++ b/keymap.c
@@ -36,7 +36,7 @@
 
 #include "functions.h"
 
-struct mapping_t Menus[] = {
+const struct mapping_t Menus[] = {
  { "alias",	MENU_ALIAS },
  { "attach",	MENU_ATTACH },
  { "browser",	MENU_FOLDER },
@@ -298,7 +298,7 @@ void km_bindkey (char *s, int menu, int op)
   km_bind (s, menu, op, NULL, NULL);
 }
 
-static int get_op (struct binding_t *bindings, const char *start, size_t len)
+static int get_op (const struct binding_t *bindings, const char *start, size_t len)
 {
   int i;
 
@@ -312,7 +312,7 @@ static int get_op (struct binding_t *bindings, const char *start, size_t len)
   return OP_NULL;
 }
 
-static char *get_func (struct binding_t *bindings, int op)
+static char *get_func (const struct binding_t *bindings, int op)
 {
   int i;
 
@@ -366,7 +366,7 @@ static void push_string (char *s)
 	 * skip the '<' and the '>' when comparing */
 	for (i = 0; Menus[i].name; i++)
 	{
-	  struct binding_t *binding = km_get_table (Menus[i].value);
+	  const struct binding_t *binding = km_get_table (Menus[i].value);
 	  if (binding)
 	  {
 	    op = get_op (binding, pp + 1, l - 2);
@@ -465,7 +465,7 @@ int km_dokey (int menu)
     if (tmp.op)
     {
       char *func = NULL;
-      struct binding_t *bindings;
+      const struct binding_t *bindings;
 
       /* is this a valid op for this menu? */
       if ((bindings = km_get_table (menu)) &&
@@ -540,7 +540,7 @@ int km_dokey (int menu)
   /* not reached */
 }
 
-static void create_bindings (struct binding_t *map, int menu)
+static void create_bindings (const struct binding_t *map, int menu)
 {
   int i;
 
@@ -549,10 +549,10 @@ static void create_bindings (struct binding_t *map, int menu)
       km_bindkey (map[i].seq, menu, map[i].op);
 }
 
-char *km_keyname (int c)
+static const char *km_keyname (int c)
 {
   static char buf[10];
-  char *p;
+  const char *p;
 
   if ((p = mutt_getnamebyvalue (c, KeyNames)))
     return p;
@@ -911,7 +911,7 @@ error:
 }
 
 static int
-try_bind (char *key, int menu, char *func, struct binding_t *bindings)
+try_bind (char *key, int menu, char *func, const struct binding_t *bindings)
 {
   int i;
   
@@ -924,7 +924,7 @@ try_bind (char *key, int menu, char *func, struct binding_t *bindings)
   return (-1);
 }
 
-struct binding_t *km_get_table (int menu)
+const struct binding_t *km_get_table (int menu)
 {
   switch (menu)
   {
@@ -971,7 +971,7 @@ struct binding_t *km_get_table (int menu)
 /* bind menu-name '<key_sequence>' function-name */
 int mutt_parse_bind (BUFFER *buf, BUFFER *s, unsigned long data, BUFFER *err)
 {
-  struct binding_t *bindings = NULL;
+  const struct binding_t *bindings = NULL;
   char *key;
   int menu[sizeof(Menus)/sizeof(struct mapping_t)-1], r = 0, nummenus, i;
 
@@ -1072,7 +1072,7 @@ int mutt_parse_exec (BUFFER *buf, BUFFER *s, unsigned long data, BUFFER *err)
 {
   int ops[128]; 
   int nops = 0;
-  struct binding_t *bindings = NULL;
+  const struct binding_t *bindings = NULL;
   char *function;
 
   if (!MoreArgs (s))
diff --git a/keymap.h b/keymap.h
index 20212fd5..e5c85dea 100644
--- a/keymap.h
+++ b/keymap.h
@@ -45,7 +45,6 @@ struct keymap_t
   keycode_t *keys;       /* key sequence */
 };
 
-char *km_keyname (int);
 int km_expand_key (char *, size_t, struct keymap_t *);
 struct keymap_t *km_find_func (int, int);
 void km_init (void);
@@ -89,7 +88,7 @@ extern struct keymap_t *Keymaps[];
 /* dokey() records the last real key pressed  */
 extern int LastKey;
 
-extern struct mapping_t Menus[];
+extern const struct mapping_t Menus[];
 
 struct binding_t
 {
@@ -98,25 +97,25 @@ struct binding_t
   char *seq;	/* default key binding */
 };
 
-struct binding_t *km_get_table (int menu);
+const struct binding_t *km_get_table (int menu);
 
-extern struct binding_t OpGeneric[];
-extern struct binding_t OpPost[];
-extern struct binding_t OpMain[];
-extern struct binding_t OpAttach[];
-extern struct binding_t OpPager[];
-extern struct binding_t OpCompose[];
-extern struct binding_t OpBrowser[];
-extern struct binding_t OpEditor[];
-extern struct binding_t OpQuery[];
-extern struct binding_t OpAlias[];
+extern const struct binding_t OpGeneric[];
+extern const struct binding_t OpPost[];
+extern const struct binding_t OpMain[];
+extern const struct binding_t OpAttach[];
+extern const struct binding_t OpPager[];
+extern const struct binding_t OpCompose[];
+extern const struct binding_t OpBrowser[];
+extern const struct binding_t OpEditor[];
+extern const struct binding_t OpQuery[];
+extern const struct binding_t OpAlias[];
 
-extern struct binding_t OpPgp[];
+extern const struct binding_t OpPgp[];
 
-extern struct binding_t OpSmime[];
+extern const struct binding_t OpSmime[];
 
 #ifdef MIXMASTER
-extern struct binding_t OpMix[];
+extern const struct binding_t OpMix[];
 #endif
 
 #include "keymap_defs.h"
diff --git a/lib.c b/lib.c
index 17cc5160..9662760d 100644
--- a/lib.c
+++ b/lib.c
@@ -53,7 +53,7 @@
 #include "lib.h"
 
 
-static struct sysexits
+static const struct sysexits
 {
   int v;
   const char *str;
@@ -696,7 +696,7 @@ FILE *safe_fopen (const char *path, const char *mode)
     return (fopen (path, mode));
 }
 
-static char safe_chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+@{}._-:%/";
+static const char safe_chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+@{}._-:%/";
 
 void mutt_sanitize_filename (char *f, short slash)
 {
@@ -711,7 +711,7 @@ void mutt_sanitize_filename (char *f, short slash)
 
 /* these characters must be escaped in regular expressions */
 
-static char rx_special_chars[] = "^.[$()|*+?{\\";
+static const char rx_special_chars[] = "^.[$()|*+?{\\";
 
 int mutt_rx_sanitize_string (char *dest, size_t destlen, const char *src)
 {
diff --git a/mapping.h b/mapping.h
index 6f400575..760c33a8 100644
--- a/mapping.h
+++ b/mapping.h
@@ -21,12 +21,12 @@
 
 struct mapping_t
 {
-  char *name;
+  const char *name;
   int value;
 };
 
-char *mutt_getnamebyvalue (int, const struct mapping_t *);
-char *mutt_compile_help (char *, size_t, int, struct mapping_t *);
+const char *mutt_getnamebyvalue (int, const struct mapping_t *);
+char *mutt_compile_help (char *, size_t, int, const struct mapping_t *);
 
 int mutt_getvaluebyname (const char *, const struct mapping_t *);
 
diff --git a/mime.h b/mime.h
index aec90722..e0239be8 100644
--- a/mime.h
+++ b/mime.h
@@ -55,9 +55,9 @@ enum
 /* MIME encoding/decoding global vars */
 
 #ifndef _SENDLIB_C
-extern int Index_hex[];
-extern int Index_64[];
-extern char B64Chars[];
+extern const int Index_hex[];
+extern const int Index_64[];
+extern const char B64Chars[];
 #endif
 
 #define hexval(c) Index_hex[(unsigned int)(c)]
diff --git a/mutt_ssl.c b/mutt_ssl.c
index 616a0681..d727cc69 100644
--- a/mutt_ssl.c
+++ b/mutt_ssl.c
@@ -911,7 +911,7 @@ static int ssl_check_certificate (CONNECTION *conn, sslsockdata *data)
 
 static int interactive_check_cert (X509 *cert, int idx, int len)
 {
-  char *part[] =
+  static const char * const part[] =
     {"/CN=", "/Email=", "/O=", "/OU=", "/L=", "/ST=", "/C="};
   char helpstr[LONG_STRING];
   char buf[STRING];
diff --git a/pager.c b/pager.c
index e19174cd..ade00c5f 100644
--- a/pager.c
+++ b/pager.c
@@ -1526,13 +1526,13 @@ upNLines (int nlines, struct line_t *info, int cur, int hiding)
   return cur;
 }
 
-static struct mapping_t PagerHelp[] = {
+static const struct mapping_t PagerHelp[] = {
   { N_("Exit"),	OP_EXIT },
   { N_("PrevPg"), OP_PREV_PAGE },
   { N_("NextPg"), OP_NEXT_PAGE },
   { NULL,	0 }
 };
-static struct mapping_t PagerHelpExtra[] = {
+static const struct mapping_t PagerHelpExtra[] = {
   { N_("View Attachm."), OP_VIEW_ATTACHMENTS },
   { N_("Del"), OP_DELETE },
   { N_("Reply"), OP_REPLY },
diff --git a/parse.c b/parse.c
index cba96622..9f227a8c 100644
--- a/parse.c
+++ b/parse.c
@@ -672,7 +672,7 @@ static const char *uncomment_timezone (char *buf, size_t buflen, const char *tz)
   return buf;
 }
 
-static struct tz_t
+static const struct tz_t
 {
   char tzname[5];
   unsigned char zhours;
diff --git a/pattern.c b/pattern.c
index dbd73bda..310d2eed 100644
--- a/pattern.c
+++ b/pattern.c
@@ -47,7 +47,7 @@ static int eat_date (pattern_t *pat, BUFFER *, BUFFER *);
 static int eat_range (pattern_t *pat, BUFFER *, BUFFER *);
 static int patmatch (const pattern_t *pat, const char *buf);
 
-static struct pattern_flags
+static const struct pattern_flags
 {
   int tag;	/* character used to represent this op */
   int op;	/* operation to perform */
@@ -712,7 +712,7 @@ static int patmatch (const pattern_t* pat, const char* buf)
     return regexec (pat->p.rx, buf, 0, NULL, 0);
 }
 
-static struct pattern_flags *lookup_tag (char tag)
+static const struct pattern_flags *lookup_tag (char tag)
 {
   int i;
 
@@ -774,7 +774,7 @@ pattern_t *mutt_pattern_comp (/* const */ char *s, int flags, BUFFER *err)
   int alladdr = 0;
   int or = 0;
   int implicit = 1;	/* used to detect logical AND operator */
-  struct pattern_flags *entry;
+  const struct pattern_flags *entry;
   char *p;
   char *buf;
   BUFFER ps;
diff --git a/pgpkey.c b/pgpkey.c
index 04bca9f7..dad51b0e 100644
--- a/pgpkey.c
+++ b/pgpkey.c
@@ -52,7 +52,7 @@ struct pgp_cache
 
 static struct pgp_cache *id_defaults = NULL;
 
-static char trust_flags[] = "?- +";
+static const char trust_flags[] = "?- +";
 
 static char *pgp_key_abilities (int flags)
 {
diff --git a/pgpmicalg.c b/pgpmicalg.c
index 37519825..c1ec37f5 100644
--- a/pgpmicalg.c
+++ b/pgpmicalg.c
@@ -35,7 +35,7 @@
 #include <string.h>
 #include <ctype.h>
 
-static struct 
+static const struct 
 {
   short id;
   const char *name;
diff --git a/pop_auth.c b/pop_auth.c
index b750533a..62663438 100644
--- a/pop_auth.c
+++ b/pop_auth.c
@@ -277,7 +277,7 @@ static pop_auth_res_t pop_auth_user (POP_DATA *pop_data, const char *method)
   return POP_A_FAILURE;
 }
 
-static pop_auth_t pop_authenticators[] = {
+static const pop_auth_t pop_authenticators[] = {
 #ifdef USE_SASL
   { pop_auth_sasl, NULL },
 #endif
@@ -296,7 +296,7 @@ static pop_auth_t pop_authenticators[] = {
 int pop_authenticate (POP_DATA* pop_data)
 {
   ACCOUNT *acct = &pop_data->conn->account;
-  pop_auth_t* authenticator;
+  const pop_auth_t* authenticator;
   char* methods;
   char* comma;
   char* method;
diff --git a/postpone.c b/postpone.c
index fa3ec64d..4c518200 100644
--- a/postpone.c
+++ b/postpone.c
@@ -37,7 +37,7 @@
 #include <string.h>
 #include <sys/stat.h>
 
-static struct mapping_t PostponeHelp[] = {
+static const struct mapping_t PostponeHelp[] = {
   { N_("Exit"),  OP_EXIT },
   { N_("Del"),   OP_DELETE },
   { N_("Undel"), OP_UNDELETE },
diff --git a/protos.h b/protos.h
index 140dfc35..95611ed1 100644
--- a/protos.h
+++ b/protos.h
@@ -300,7 +300,7 @@ int _mutt_enter_fname (const char *, char *, size_t, int *, int, int, char ***,
 int  mutt_enter_string (char *buf, size_t buflen, int y, int x, int flags);
 int _mutt_enter_string (char *, size_t, int, int, int, int, char ***, int *, ENTER_STATE *);
 #define mutt_get_field(A,B,C,D) _mutt_get_field(A,B,C,D,0,NULL,NULL)
-int _mutt_get_field (char *, char *, size_t, int, int, char ***, int *);
+int _mutt_get_field (const char *, char *, size_t, int, int, char ***, int *);
 int mutt_get_hook_type (const char *);
 int mutt_get_field_unbuffered (char *, char *, size_t, int);
 #define mutt_get_password(A,B,C) mutt_get_field_unbuffered(A,B,C,M_PASS)
diff --git a/query.c b/query.c
index f2464b95..b3b8f08b 100644
--- a/query.c
+++ b/query.c
@@ -44,7 +44,7 @@ typedef struct entry
   QUERY *data;
 } ENTRY;
 
-static struct mapping_t QueryHelp[] = {
+static const struct mapping_t QueryHelp[] = {
   { N_("Exit"),   OP_EXIT },
   { N_("Mail"),   OP_MAIL },
   { N_("New Query"),  OP_QUERY },
diff --git a/recvattach.c b/recvattach.c
index d9d87bcc..31dfcadd 100644
--- a/recvattach.c
+++ b/recvattach.c
@@ -49,7 +49,7 @@ static const char *Mailbox_is_read_only = N_("Mailbox is read-only.");
     break; \
 }
 
-static struct mapping_t AttachHelp[] = {
+static const struct mapping_t AttachHelp[] = {
   { N_("Exit"),  OP_EXIT },
   { N_("Save"),  OP_SAVE },
   { N_("Pipe"),  OP_PIPE },
diff --git a/remailer.c b/remailer.c
index 3354540f..06eae3e0 100644
--- a/remailer.c
+++ b/remailer.c
@@ -480,7 +480,7 @@ static int mix_chain_add (MIXCHAIN *chain, const char *s,
   return 0;
 }
 
-static struct mapping_t RemailerHelp[] = 
+static const struct mapping_t RemailerHelp[] = 
 {
   { N_("Append"), OP_MIX_APPEND },
   { N_("Insert"), OP_MIX_INSERT },
diff --git a/rfc2047.c b/rfc2047.c
index 2927b6f5..b5e8704d 100644
--- a/rfc2047.c
+++ b/rfc2047.c
@@ -234,7 +234,7 @@ static size_t b_encoder (char *s, ICONV_CONST char *d, size_t dlen,
 static size_t q_encoder (char *s, ICONV_CONST char *d, size_t dlen,
 			 const char *tocode)
 {
-  char hex[] = "0123456789ABCDEF";
+  static const char hex[] = "0123456789ABCDEF";
   char *s0 = s;
 
   memcpy (s, "=?", 2), s += 2;
diff --git a/rfc822.c b/rfc822.c
index 22f9d9bd..fd54a71a 100644
--- a/rfc822.c
+++ b/rfc822.c
@@ -51,7 +51,7 @@ const char RFC822Specials[] = "@.,:;<>[]\\\"()";
 int RFC822Error = 0;
 
 /* these must defined in the same order as the numerated errors given in rfc822.h */
-const char *RFC822Errors[] = {
+const char * const RFC822Errors[] = {
   "out of memory",
   "mismatched parenthesis",
   "mismatched quotes",
diff --git a/rfc822.h b/rfc822.h
index 0c48f75a..ba11801c 100644
--- a/rfc822.h
+++ b/rfc822.h
@@ -61,7 +61,7 @@ int rfc822_valid_msgid (const char *msgid);
 int rfc822_remove_from_adrlist (ADDRESS **a, const char *mailbox);
 
 extern int RFC822Error;
-extern const char *RFC822Errors[];
+extern const char * const RFC822Errors[];
 
 #define rfc822_error(x) RFC822Errors[x]
 #define rfc822_new_address() safe_calloc(1,sizeof(ADDRESS))
diff --git a/sendlib.c b/sendlib.c
index 1ee7fb2b..249d6a1d 100644
--- a/sendlib.c
+++ b/sendlib.c
@@ -65,7 +65,7 @@ extern char RFC822Specials[];
 
 const char MimeSpecials[] = "@.,;:<>[]\\\"()?/= \t";
 
-char B64Chars[64] = {
+const char B64Chars[64] = {
   'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
   'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
   'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
diff --git a/url.c b/url.c
index 347047cd..1b583b50 100644
--- a/url.c
+++ b/url.c
@@ -32,7 +32,7 @@
 
 #include <ctype.h>
 
-static struct mapping_t UrlMap[] =
+static const struct mapping_t UrlMap[] =
 {
   { "file", 	U_FILE },
   { "imap", 	U_IMAP },
-- 
2.40.0