cache terminal size, add SIGWINCH handler to reset

Refactoring getcols, yet again. We do the following:

1) Introduce a static global in src/pacman/util.c
2) getcols always prefers this cached value, but will derive it from
the COLUMNS environment var, the characteristics of stdout, or a sane
default (in that order).
3) Introduce a SIGWINCH signal handler to reset the cached value,
meaning we only call ioctl when we don't know the value.

On my machine, pacman -Syy goes from ~4300 ioctl calls to 3.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/pacman/package.c b/src/pacman/package.c
index 3be996db..1ac0fcae 100644
--- a/src/pacman/package.c
+++ b/src/pacman/package.c
@@ -140,7 +140,7 @@ void dump_pkg_full(alpm_pkg_t *pkg, int extra)
 		optionalfor = alpm_pkg_compute_optionalfor(pkg);
 	}
 
-	cols = getcols(fileno(stdout));
+	cols = getcols();
 
 	/* actual output */
 	if(from == ALPM_PKG_FROM_SYNCDB) {
@@ -404,7 +404,7 @@ int dump_pkg_search(alpm_db_t *db, alpm_list_t *targets, int show_status)
 		return 1;
 	}
 
-	cols = getcols(fileno(stdout));
+	cols = getcols();
 	for(i = searchlist; i; i = alpm_list_next(i)) {
 		alpm_list_t *grp;
 		alpm_pkg_t *pkg = i->data;