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man: make width selection more thorough; explain how to override it

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Fedora's "man CMD >file" still uses terminal width, not 80 (but disables formatting),
this change mimics that.

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2016-10-31 01:52:18 +01:00
parent a92a74961d
commit 7c3c92c533
2 changed files with 44 additions and 16 deletions
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47
libbb/xfuncs.c
View File

@ -237,16 +237,27 @@ ssize_t FAST_FUNC full_write2_str(const char *str)
static int wh_helper(int value, int def_val, const char *env_name, int *err)
{
if (value == 0) {
char *s = getenv(env_name);
if (s) {
value = atoi(s);
/* If LINES/COLUMNS are set, pretend that there is
* no error getting w/h, this prevents some ugly
* cursor tricks by our callers */
*err = 0;
}
/* Envvars override even if "value" from ioctl is valid (>0).
* Rationale: it's impossible to guess what user wants.
* For example: "man CMD | ...": should "man" format output
* to stdout's width? stdin's width? /dev/tty's width? 80 chars?
* We _cant_ know it. If "..." saves text for e.g. email,
* then it's probably 80 chars.
* If "..." is, say, "grep -v DISCARD | $PAGER", then user
* would prefer his tty's width to be used!
*
* Since we don't know, at least allow user to do this:
* "COLUMNS=80 man CMD | ..."
*/
char *s = getenv(env_name);
if (s) {
value = atoi(s);
/* If LINES/COLUMNS are set, pretend that there is
* no error getting w/h, this prevents some ugly
* cursor tricks by our callers */
*err = 0;
}
if (value <= 1 || value >= 30000)
value = def_val;
return value;
@ -258,6 +269,20 @@ int FAST_FUNC get_terminal_width_height(int fd, unsigned *width, unsigned *heigh
{
struct winsize win;
int err;
int close_me = -1;
if (fd == -1) {
if (isatty(STDOUT_FILENO))
fd = STDOUT_FILENO;
else
if (isatty(STDERR_FILENO))
fd = STDERR_FILENO;
else
if (isatty(STDIN_FILENO))
fd = STDIN_FILENO;
else
close_me = fd = open("/dev/tty", O_RDONLY);
}
win.ws_row = 0;
win.ws_col = 0;
@ -268,6 +293,10 @@ int FAST_FUNC get_terminal_width_height(int fd, unsigned *width, unsigned *heigh
*height = wh_helper(win.ws_row, 24, "LINES", &err);
if (width)
*width = wh_helper(win.ws_col, 80, "COLUMNS", &err);
if (close_me >= 0)
close(close_me);
return err;
}
int FAST_FUNC get_terminal_width(int fd)

13
miscutils/man.c
View File

@ -9,6 +9,8 @@
//usage: "Format and display manual page\n"
//usage: "\n -a Display all pages"
//usage: "\n -w Show page locations"
//usage: "\n"
//usage: "\n$COLUMNS overrides output width"
#include "libbb.h"
#include "common_bufsiz.h"
@ -53,7 +55,7 @@ struct globals {
setup_common_bufsiz(); \
G.col = "col"; \
G.tbl = "tbl"; \
/* replaced -Tlatin1 with -Tascii for non-UTF8 displays */; \
/* replaced -Tlatin1 with -Tascii for non-UTF8 displays */ \
G.nroff = "nroff -mandoc -Tascii"; \
G.pager = ENABLE_LESS ? "less" : "more"; \
} while (0)
@ -132,15 +134,12 @@ static int run_pipe(char *man_filename, int man, int level)
close(STDIN_FILENO);
open_zipped(man_filename, /*fail_if_not_compressed:*/ 0); /* guaranteed to use fd 0 (STDIN_FILENO) */
if (man) {
/* "man man" formats to screen width.
* "man man >file" formats to default 80 columns.
* "man man | cat" formats to default 80 columns.
*/
int w = get_terminal_width(STDOUT_FILENO);
int w = get_terminal_width(-1);
if (w > 10)
w -= 2;
/* "2>&1" is added so that nroff errors are shown in pager too.
* Otherwise it may show just empty screen */
* Otherwise it may show just empty screen.
*/
cmd = xasprintf("%s | %s -rLL=%un -rLT=%un 2>&1 | %s",
G.tbl, G.nroff, w, w,
G.pager);