menuconfig: wrap long help lines

Help text for certain config options is very extensive (the text
includes the names of all  other options the option in question depends
on). Long lines are not wrapped, making it impossible to see the list
without scrolling horizontally.

This patch adds some logic which wraps help screen lines at word
boundaries to prevent truncating.

Tested by running

  ARCH=powerpc make menuconfig O=/tmp/build

which shows that the long lines are now wrapped, and

 ARCH=powerpc make xconfig O=/tmp/build

to demonstrate that it still compiles and operates as expected.

Signed-off-by: Vadim Bendebury <vbendeb@google.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>

scripts/kconfig/expr.c

diff --git a/scripts/kconfig/expr.c b/scripts/kconfig/expr.c
index edd3f39..d83f232 100644
--- a/scripts/kconfig/expr.c
+++ b/scripts/kconfig/expr.c
@@ -1097,9 +1097,32 @@
 
 static void expr_print_gstr_helper(void *data, struct symbol *sym, const char *str)
 {
-	str_append((struct gstr*)data, str);
+	struct gstr *gs = (struct gstr*)data;
+	const char *sym_str = NULL;
+
 	if (sym)
-		str_printf((struct gstr*)data, " [=%s]", sym_get_string_value(sym));
+		sym_str = sym_get_string_value(sym);
+
+	if (gs->max_width) {
+		unsigned extra_length = strlen(str);
+		const char *last_cr = strrchr(gs->s, '\n');
+		unsigned last_line_length;
+
+		if (sym_str)
+			extra_length += 4 + strlen(sym_str);
+
+		if (!last_cr)
+			last_cr = gs->s;
+
+		last_line_length = strlen(gs->s) - (last_cr - gs->s);
+
+		if ((last_line_length + extra_length) > gs->max_width)
+			str_append(gs, "\\\n");
+	}
+
+	str_append(gs, str);
+	if (sym)
+		str_printf(gs, " [=%s]", sym_str);
 }
 
 void expr_gstr_print(struct expr *e, struct gstr *gs)

scripts/kconfig/lkc.h

diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index f379b0b..e59dd0c 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -106,6 +106,11 @@
 struct gstr {
 	size_t len;
 	char  *s;
+	/*
+	* when max_width is not zero long lines in string s (if any) get
+	* wrapped not to exceed the max_width value
+	*/
+	int max_width;
 };
 struct gstr str_new(void);
 struct gstr str_assign(const char *s);

scripts/kconfig/mconf.c

diff --git a/scripts/kconfig/mconf.c b/scripts/kconfig/mconf.c
index 8413cf3..ac1e9da 100644
--- a/scripts/kconfig/mconf.c
+++ b/scripts/kconfig/mconf.c
@@ -638,6 +638,7 @@
 {
 	struct gstr help = str_new();
 
+	help.max_width = getmaxx(stdscr) - 10;
 	menu_get_ext_help(menu, &help);
 
 	show_helptext(_(menu_get_prompt(menu)), str_get(&help));

scripts/kconfig/util.c

diff --git a/scripts/kconfig/util.c b/scripts/kconfig/util.c
index b6b2a46a..81c100d 100644
--- a/scripts/kconfig/util.c
+++ b/scripts/kconfig/util.c
@@ -78,6 +78,7 @@
 	struct gstr gs;
 	gs.s = malloc(sizeof(char) * 64);
 	gs.len = 64;
+	gs.max_width = 0;
 	strcpy(gs.s, "\0");
 	return gs;
 }
@@ -88,6 +89,7 @@
 	struct gstr gs;
 	gs.s = strdup(s);
 	gs.len = strlen(s) + 1;
+	gs.max_width = 0;
 	return gs;
 }