Re: [PATCH 2/3] help.c: make term_columns() cached and export it

Conforms to The Single UNIX Specification, Version 2
(http://pubs.opengroup.org/onlinepubs/7908799/xbd/envvar.html#tag_002_003).

Signed-off-by: Zbigniew Jędrzejewski-Szmek <redacted>
---
 help.c  |   37 +++++++++++++++++++++++++++++--------
 help.h  |    2 ++
 pager.c |    5 +++++
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/help.c b/help.c
index bc15066..5d1cb1d 100644
--- a/help.c
+++ b/help.c

@@ -5,26 +5,47 @@

 #include "help.h"
 #include "common-cmds.h"

-/* most GUI terminals set COLUMNS (although some don't export it) */
-static int term_columns(void)
+/*
+ * Cache for term_columns() value. Set on first use or when
+ * installing a pager and replacing stdout.
+ */
+static int term_columns_cache;
+
+/*
+ * Return cached value (if set) or $COLUMNS (if set and positive) or
+ * ioctl(1, TIOCGWINSZ).ws_col (if positive) or 80.
+ *
+ * $COLUMNS even if set, is usually not exported, so
+ * the variable can be used to override autodection.
+ */
+int term_columns(void)
 {
-       char *col_string = getenv("COLUMNS");
+       char *col_string;
       int n_cols;

-       if (col_string && (n_cols = atoi(col_string)) > 0)
-               return n_cols;
+       if (term_columns_cache)
+               return term_columns_cache;
+
+       col_string = getenv("COLUMNS");
+       if (col_string && (n_cols = atoi(col_string)) > 0) {
+               term_columns_cache = n_cols;
+               return term_columns_cache;
+       }

 #ifdef TIOCGWINSZ
       {
               struct winsize ws;
               if (!ioctl(1, TIOCGWINSZ, &ws)) {
-                       if (ws.ws_col)
-                               return ws.ws_col;
+                       if (ws.ws_col) {
+                               term_columns_cache = ws.ws_col;
+                               return term_columns_cache;
+                       }
               }
       }
 #endif

-       return 80;
+       term_columns_cache = 80;
+       return term_columns_cache;
 }

 void add_cmdname(struct cmdnames *cmds, const char *name, int len)

diff --git a/help.h b/help.h
index b6b12d5..880a4b4 100644
--- a/help.h
+++ b/help.h

@@ -29,4 +29,6 @@ extern void list_commands(const char *title,

                         struct cmdnames *main_cmds,
                         struct cmdnames *other_cmds);

+extern int term_columns(void);
+
 #endif /* HELP_H */

diff --git a/pager.c b/pager.c
index 975955b..e7032de 100644
--- a/pager.c
+++ b/pager.c

@@ -1,6 +1,7 @@

 #include "cache.h"
 #include "run-command.h"
 #include "sigchain.h"
+#include "help.h"

 #ifndef DEFAULT_PAGER
 #define DEFAULT_PAGER "less"

@@ -76,6 +77,10 @@ void setup_pager(void)

       if (!pager)
               return;

+       /* prime the term_columns() cache before it is too
+        * late and stdout is replaced */
+       (void) term_columns();
+
       setenv("GIT_PAGER_IN_USE", "true", 1);

       /* spawn the pager */
--
1.7.9.263.g4be11.dirty