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Re: [PATCH 1/2] Save terminal width before setting up pager and export term_columns()

From
Junio C Hamano <gitster@pobox.com>
Date
Feb 13, 2012, 23:00 UTC
Message-ID
<7vlio6baoo.fsf@alter.siamese.dyndns.org>
In-Reply-To
<1329055953-29632-1-git-send-email-zbyszek@in.waw.pl>
Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl> writes:
> term_columns() checks for terminal width via ioctl(2). After
> redirecting, stdin is no longer terminal to get terminal width.
s/stdin/stdout/
Show 7 quoted lines
> Check terminal width and save it before redirecting stdin in
> setup_pager() by calling term_columns().
>
> Move term_columns() to pager.c and export it in cache.h.
>
> Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
> ---
Thanks.

It probably is worth mentioning what the end-user visible effect of this change is somewhere in the log message.

I somehow find "term_columns_cache" a funny name for this variable and does not describe what it does. Unlike a real cache, we cannot discard it and re-read it even if we later wanted to.

I am tempted to rewrite the patch like this to update other minor style issues.

-- >8 --
From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Sun, 12 Feb 2012 15:12:32 +0100
Subject: [PATCH] pager: find out the terminal width before spawning the pager

term_columns() checks for terminal width via ioctl(2) on the standard output, but we spawn the pager too early for this check to be useful.

The effect of this buglet can be observed by opening a wide terminal and running "git -p help --all", which still shows 80-column output, while "git help --all" uses the full terminal width. Run the check before we spawn the pager to fix this.

While at it, move term_columns() to pager.c and export it from cache.h so that callers other than the help subsystem can use it.

Signed-off-by: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 cache.h |    1 +
 help.c  |   22 ----------------------
 pager.c |   43 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 44 insertions(+), 22 deletions(-)
diff --git a/cache.h b/cache.h
index 79c612f..c7e3b4d 100644
--- a/cache.h
+++ b/cache.h
@@ -1172,6 +1172,7 @@ extern void setup_pager(void);
 extern const char *pager_program;
 extern int pager_in_use(void);
 extern int pager_use_color;
+extern int term_columns(void);
 
 extern const char *editor_program;
 extern const char *askpass_program;
diff --git a/help.c b/help.c
index cbbe966..14eefc9 100644
--- a/help.c
+++ b/help.c
@@ -5,28 +5,6 @@
 #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;
-}
-
 void add_cmdname(struct cmdnames *cmds, const char *name, int len)
 {
 	struct cmdname *ent = xmalloc(sizeof(*ent) + len + 1);
diff --git a/pager.c b/pager.c
index 975955b..e06cfa0 100644
--- a/pager.c
+++ b/pager.c
@@ -76,6 +76,12 @@ void setup_pager(void)
 	if (!pager)
 		return;
 
+	/*
+	 * force computing the width of the terminal before we redirect
+	 * the standard output to the pager.
+	 */
+	(void) term_columns();
+
 	setenv("GIT_PAGER_IN_USE", "true", 1);
 
 	/* spawn the pager */
@@ -110,3 +116,40 @@ int pager_in_use(void)
 	env = getenv("GIT_PAGER_IN_USE");
 	return env ? git_config_bool("GIT_PAGER_IN_USE", env) : 0;
 }
+
+/*
+ * 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.
+ * This behaviour conforms to The Single UNIX Specification, Version 2
+ * (http://pubs.opengroup.org/onlinepubs/7908799/xbd/envvar.html#tag_002_003).
+ */
+int term_columns(void)
+{
+	static int term_columns_at_startup;
+
+	char *col_string;
+	int n_cols;
+
+	if (term_columns_at_startup)
+		return term_columns_at_startup;
+
+	term_columns_at_startup = 80;
+
+	col_string = getenv("COLUMNS");
+	if (col_string && (n_cols = atoi(col_string)) > 0)
+		term_columns_at_startup = n_cols;
+#ifdef TIOCGWINSZ
+	else {
+		struct winsize ws;
+		if (!ioctl(1, TIOCGWINSZ, &ws)) {
+			if (ws.ws_col) {
+				term_columns_at_startup = ws.ws_col;
+			}
+		}
+	}
+#endif
+	return term_columns_at_startup;
+}

-- 
1.7.9.300.gd47e4
Previous: Zbigniew Jędrzejewski-SzmekNext: Nguyen Thai Ngoc Duy
Message 19 of 46 in “(unknown)”
  1. Zbigniew Jędrzejewski-SzmekFeb 9, 2012
  2. 1/4 Move git_version_string to help.c in preparation for diff changesZbigniew Jędrzejewski-Szmek, Feb 9, 2012
  3. Junio C HamanoFeb 10, 2012
  4. 2/4 help.c: make term_columns() cached and export itZbigniew Jędrzejewski-Szmek, Feb 9, 2012
  5. Junio C HamanoFeb 10, 2012
  6. 3/4 diff --stat: use the real terminal widthZbigniew Jędrzejewski-Szmek, Feb 9, 2012
  7. Junio C HamanoFeb 10, 2012
  8. Nguyen Thai Ngoc DuyFeb 10, 2012
  9. Zbigniew Jędrzejewski-SzmekFeb 10, 2012
  10. Nguyen Thai Ngoc DuyFeb 10, 2012
  11. 0/3 diff --stat: use the real terminal widthZbigniew Jędrzejewski-Szmek, Feb 10, 2012
  12. 1/3 Move git_version_string to help.c before diff changesZbigniew Jędrzejewski-Szmek, Feb 10, 2012
  13. Junio C HamanoFeb 10, 2012
  14. 2/3 help.c: make term_columns() cached and export itZbigniew Jędrzejewski-Szmek, Feb 10, 2012
  15. Nguyen Thai Ngoc DuyFeb 11, 2012
  16. Zbigniew Jędrzejewski-SzmekFeb 11, 2012
  17. Junio C HamanoFeb 12, 2012
  18. 1/2 Save terminal width before setting up pager and export term_columns()Zbigniew Jędrzejewski-Szmek, Feb 12, 2012
  19. Junio C HamanoFeb 13, 2012
  20. Nguyen Thai Ngoc DuyFeb 14, 2012
  21. Zbigniew Jędrzejewski-SzmekFeb 14, 2012
  22. 2/2 Rename lineno_width to decimal_width and export itZbigniew Jędrzejewski-Szmek, Feb 12, 2012
  23. Junio C HamanoFeb 13, 2012
  24. make lineno_width() from blame reusable for othersZbigniew Jędrzejewski-Szmek, Feb 14, 2012
  25. 3/3 diff --stat: use the real terminal widthZbigniew Jędrzejewski-Szmek, Feb 10, 2012
  26. Junio C HamanoFeb 10, 2012
  27. diff --stat: use the full terminal widthZbigniew Jędrzejewski-Szmek, Feb 12, 2012
  28. Junio C HamanoFeb 14, 2012
  29. 1/3 diff --stat: use the full terminal widthZbigniew Jędrzejewski-Szmek, Feb 14, 2012
  30. 2/3 diff --stat: better alignment for binary filesZbigniew Jędrzejewski-Szmek, Feb 14, 2012
  31. 3/3 Update diff --stat output in tests and tutorialZbigniew Jędrzejewski-Szmek, Feb 14, 2012
  32. Junio C HamanoFeb 15, 2012
  33. 1/3 diff --stat: tests for long filenames and big change countsZbigniew Jędrzejewski-Szmek, Feb 15, 2012
  34. 2/3 diff --stat: use the full terminal widthZbigniew Jędrzejewski-Szmek, Feb 15, 2012
  35. Junio C HamanoFeb 15, 2012
  36. 3/3 diff --stat: use less columns for change countsZbigniew Jędrzejewski-Szmek, Feb 15, 2012
  37. Nguyen Thai Ngoc DuyFeb 15, 2012
  38. Junio C HamanoFeb 15, 2012
  39. Junio C HamanoFeb 15, 2012
  40. Zbigniew Jędrzejewski-SzmekFeb 16, 2012
  41. Junio C HamanoFeb 16, 2012
  42. Junio C HamanoFeb 15, 2012
  43. Junio C HamanoFeb 15, 2012
  44. Johannes SixtFeb 15, 2012
  45. 4/4 diff --stat: use most of the space for file namesZbigniew Jędrzejewski-Szmek, Feb 9, 2012
  46. Junio C HamanoFeb 10, 2012

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