[PATCH 01/16] Move term_columns() to pager.c and save terminal width before pager

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

term_columns() checks for terminal width via ioctl(2). After
redirecting, stdin is no longer terminal to get terminal width.

Check terminal width and save it before redirect stdin in setup_pager()
and let term_columns() reuse the value.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Makefile |    1 +
 column.h |    6 ++++++
 help.c   |   23 +----------------------
 pager.c  |   33 +++++++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+), 22 deletions(-)
 create mode 100644 column.h

diff --git a/Makefile b/Makefile
index 775ee83..ed9e94b 100644
--- a/Makefile
+++ b/Makefile
@@ -1956,6 +1956,7 @@ builtin/prune.o builtin/reflog.o reachable.o: reachable.h
 builtin/commit.o builtin/revert.o wt-status.o: wt-status.h
 builtin/tar-tree.o archive-tar.o: tar.h
 connect.o transport.o http-backend.o: url.h
+pager.o help.o: column.h
 http-fetch.o http-walker.o remote-curl.o transport.o walker.o: walker.h
 http.o http-walker.o http-push.o http-fetch.o remote-curl.o: http.h url.h
 
diff --git a/column.h b/column.h
new file mode 100644
index 0000000..55d8067
--- /dev/null
+++ b/column.h
@@ -0,0 +1,6 @@
+#ifndef COLUMN_H
+#define COLUMN_H
+
+extern int term_columns(void);
+
+#endif
diff --git a/help.c b/help.c
index 7654f1b..768f64c 100644
--- a/help.c
+++ b/help.c
@@ -4,28 +4,7 @@
 #include "levenshtein.h"
 #include "help.h"
 #include "common-cmds.h"
-
-/* most GUI terminals set COLUMNS (although some don't export it) */
-static int term_columns(void)
-{
-	char *col_string = getenv("COLUMNS");
-	int n_cols;
-
-	if (col_string && (n_cols = atoi(col_string)) > 0)
-		return n_cols;
-
-#ifdef TIOCGWINSZ
-	{
-		struct winsize ws;
-		if (!ioctl(1, TIOCGWINSZ, &ws)) {
-			if (ws.ws_col)
-				return ws.ws_col;
-		}
-	}
-#endif
-
-	return 80;
-}
+#include "column.h"
 
 void add_cmdname(struct cmdnames *cmds, const char *name, int len)
 {
diff --git a/pager.c b/pager.c
index dac358f..dad6329 100644
--- a/pager.c
+++ b/pager.c
@@ -12,6 +12,19 @@
  */
 
 static int spawned_pager;
+static int max_columns;
+
+static int retrieve_terminal_width(void)
+{
+#ifdef TIOCGWINSZ
+	struct winsize ws;
+	if (ioctl(1, TIOCGWINSZ, &ws))  /* e.g., ENOSYS */
+		return 0;
+	return ws.ws_col;
+#else
+	return 0;
+#endif
+}
 
 #ifndef WIN32
 static void pager_preexec(void)
@@ -74,12 +87,17 @@ const char *git_pager(int stdout_is_tty)
 void setup_pager(void)
 {
 	const char *pager = git_pager(isatty(1));
+	int width;
 
 	if (!pager)
 		return;
 
 	spawned_pager = 1; /* means we are emitting to terminal */
 
+	width = retrieve_terminal_width();
+	if (width)
+		max_columns = width;
+
 	/* spawn the pager */
 	pager_argv[0] = pager;
 	pager_process.use_shell = 1;
@@ -116,3 +134,18 @@ int pager_in_use(void)
 	env = getenv("GIT_PAGER_IN_USE");
 	return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 }
+
+int term_columns()
+{
+	char *col_string = getenv("COLUMNS");
+	int n_cols;
+
+	if (col_string && (n_cols = atoi(col_string)) > 0)
+		return n_cols;
+
+	if (spawned_pager && max_columns)
+		return max_columns;
+
+	n_cols = retrieve_terminal_width();
+	return n_cols ? n_cols : 80;
+}
-- 
1.7.2.2