Add isnullenv.

charset.c

@@ -331,7 +331,7 @@ set_charset()
  * LESSCHARSET is not defined: try LESSCHARDEF.
  */
  s = lgetenv("LESSCHARDEF");
- if (s != NULL && *s != '\0')
+ if (!isnullenv(s))
  {
  ichardef(s);
  return;

cmdbuf.c

@@ -1398,7 +1398,7 @@ histfile_name()
 
  /* See if filename is explicitly specified by $LESSHISTFILE. */
  name = lgetenv("LESSHISTFILE");
- if (name != NULL && *name != '\0')
+ if (!isnullenv(name))
  {
  if (strcmp(name, "-") == 0 || strcmp(name, "/dev/null") == 0)
  /* $LESSHISTFILE == "-" means don't use a history file. */
@@ -1412,11 +1412,11 @@ histfile_name()
 
  /* Otherwise, file is in $HOME. */
  home = lgetenv("HOME");
- if (home == NULL || *home == '\0')
+ if (isnullenv(home))
  {
 #if OS2
  home = lgetenv("INIT");
- if (home == NULL || *home == '\0')
+ if (isnullenv(home))
 #endif
  return (NULL);
  }

decode.c

@@ -607,6 +607,16 @@ lgetenv(var)
  return (NULL);
 }
 
+/*
+ * Is a string null or empty? 
+ */
+ public int
+isnullenv(s)
+ char* s;
+{
+ return (s == NULL || *s == '\0');
+}
+
 #if USERFILE
 /*
  * Get an "integer" from a lesskey file.

filename.c

@@ -568,7 +568,7 @@ shellcmd(cmd)
  char *shell;
 
  shell = lgetenv("SHELL");
- if (shell != NULL && *shell != '\0')
+ if (!isnullenv(shell))
  {
  char *scmd;
  char *esccmd;
@@ -745,7 +745,7 @@ lglob(filename)
  return (filename);
  }
  lessecho = lgetenv("LESSECHO");
- if (lessecho == NULL || *lessecho == '\0')
+ if (isnullenv(lessecho))
  lessecho = "lessecho";
  /*
  * Invoke lessecho, and read its output (a globbed list of filenames).

less.nro.VER

@@ -942,14 +942,16 @@ will display the contents of that new file.
 Enables mouse input:
 scrolling the mouse wheel down moves forward in the file,
 scrolling the mouse wheel up moves backwards in the file,
-and clicking the mouse will set the "#" mark to the line 
-on which the mouse cursor sits.
+and clicking the mouse sets the "#" mark to the line 
+where the mouse is clicked.
 The number of lines to scroll when the wheel is moved 
 can be set by the \-\-wheel-lines option.
-Mouse input works only on terminals which support X11 mouse reporting
-and on the Windows version.
+Mouse input works only on terminals which support X11 mouse reporting,
+and on the Windows version of 
+.IR less .
 .IP "\-\-MOUSE"
-Like \-\-mouse, except the scrolling direction is reversed.
+Like \-\-mouse, except the direction scrolled 
+on mouse wheel movement is reversed.
 .IP "\-\-no-keypad"
 Disables sending the keypad initialization and deinitialization strings
 to the terminal.

line.c

@@ -75,11 +75,11 @@ static POSITION mbc_pos;
 init_line()
 {
  end_ansi_chars = lgetenv("LESSANSIENDCHARS");
- if (end_ansi_chars == NULL || *end_ansi_chars == '\0')
+ if (isnullenv(end_ansi_chars))
  end_ansi_chars = "m";
 
  mid_ansi_chars = lgetenv("LESSANSIMIDCHARS");
- if (mid_ansi_chars == NULL || *mid_ansi_chars == '\0')
+ if (isnullenv(mid_ansi_chars))
  mid_ansi_chars = "0123456789:;[?!\"'#%()*+ ";
 
  linebuf = (char *) ecalloc(LINEBUF_SIZE, sizeof(char));

main.c

@@ -76,7 +76,7 @@ main(argc, argv)
 
  secure = 0;
  s = lgetenv("LESSSECURE");
- if (s != NULL && *s != '\0')
+ if (!isnullenv(s))
  secure = 1;
 
 #ifdef WIN32
@@ -159,11 +159,11 @@ main(argc, argv)
  if (editor == NULL || *editor == '\0')
  {
  editor = lgetenv("EDITOR");
- if (editor == NULL || *editor == '\0')
+ if (isnullenv(editor))
  editor = EDIT_PGM;
  }
  editproto = lgetenv("LESSEDIT");
- if (editproto == NULL || *editproto == '\0')
+ if (isnullenv(editproto))
  editproto = "%E ?lm+%lm. %g";
 #endif
 

opttbl.c

@@ -500,7 +500,7 @@ init_option()
  char *p;
 
  p = lgetenv("LESS_IS_MORE");
- if (p != NULL && *p != '\0')
+ if (!isnullenv(p))
  less_is_more = 1;
 
  for (o = option; o->oletter != '\0'; o++)

screen.c

@@ -113,7 +113,7 @@ struct keyRecord
 static int keyCount = 0;
 static WORD curr_attr;
 static int pending_scancode = 0;
-static char x11mousebuf[] = "[M???"; /* \e is separate */
+static char x11mousebuf[] = "[M???"; /* Mouse report, after ESC */
 static int x11mousePos, x11mouseCount;
 
 static HANDLE con_out_save = INVALID_HANDLE_VALUE; /* previous console */
@@ -637,7 +637,7 @@ ltget_env(capname)
  char *s;
 
  s = lgetenv("LESS_TERMCAP_DEBUG");
- if (s != NULL && *s != '\0')
+ if (!isnullenv(s))
  {
  struct env { struct env *next; char *name; char *value; };
  static struct env *envs = NULL;
@@ -1141,7 +1141,7 @@ get_term()
  * Make sure the termcap database is available.
  */
  sp = lgetenv("TERMCAP");
- if (sp == NULL || *sp == '\0')
+ if (isnullenv(sp))
  {
  char *termcap;
  if ((sp = homefile("termcap.dat")) != NULL)
@@ -1222,10 +1222,10 @@ get_term()
  kent = ltgetstr("@8", &sp);
 
  sc_s_mousecap = lgetenv("LESS_TERMCAP_MOUSE_START");
- if (sc_s_mousecap == NULL || *sc_s_mousecap == '\0')
+ if (isnullenv(sc_s_mousecap))
  sc_s_mousecap = "\33[?1000h";
  sc_e_mousecap = lgetenv("LESS_TERMCAP_MOUSE_END");
- if (sc_e_mousecap == NULL || *sc_e_mousecap == '\0')
+ if (isnullenv(sc_e_mousecap))
  sc_e_mousecap = "\33[?1000l";
 
  sc_init = ltgetstr("ti", &sp);

tags.c

@@ -522,7 +522,7 @@ findgtag(tag, type)
  char *qtag;
  char *cmd = lgetenv("LESSGLOBALTAGS");
 
- if (cmd == NULL || *cmd == '\0')
+ if (isnullenv(cmd))
  return TAG_NOFILE;
  /* Get suitable flag value for global(1). */
  switch (type)