Fix strftime (prompts) before 5.2?

Fix strftime (prompts) before 5.2?

[Bart Schaefer]

Do we want to try to fix users/20859 ?  It shouldn't be that hard for
someone in an environment where it fails (I'm having trouble creating
one).

PATCH: ztrftime: more workarounds for broken strftime interface

[Mikael Magnusson]

On Sun, Nov 22, 2015 at 6:27 PM, Bart Schaefer <schaefer@brasslantern.com> wrote:
> Do we want to try to fix users/20859 ?  It shouldn't be that hard for
> someone in an environment where it fails (I'm having trouble creating
> one).

The problem is that the strftime() function is defined by an idiot. There
is no way to differentiate the success of a zero-length result and any
error. If there is any error then the return result is undefined so we
cannot use it.

I guess we could append some fixed string always, and then discard this
string, for example an x character.

This somehow works and doesn't break the tests, nor my prompt.

---
 Src/utils.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Src/utils.c b/Src/utils.c
index c19cca8..f42b25b 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -3154,8 +3154,9 @@ strftimehandling:
 		{
 		    int size = fmt - fmtstart;
 		    char *tmp, *last;
-		    tmp = zhalloc(size + 1);
+		    tmp = zhalloc(size + 2);
 		    strncpy(tmp, fmtstart, size);
+		    tmp[size] = 'x';
 		    last = fmt-1;
 		    if (*last == Meta) {
 			/*
@@ -3168,7 +3169,7 @@ strftimehandling:
 			 */
 			*last = *++fmt ^ 32;
 		    }
-		    tmp[size] = '\0';
+		    tmp[size+1] = '\0';
 		    *buf = '\1';
 		    if (!strftime(buf, bufsize + 2, tmp, tm))
 		    {
@@ -3178,7 +3179,7 @@ strftimehandling:
 			}
 			return 0;
 		    }
-		    decr = strlen(buf);
+		    decr = strlen(buf) - 1;
 		    buf += decr;
 		    bufsize -= decr - 2;
 		}
-- 
2.6.1

Re: Fix strftime (prompts) before 5.2?

[Peter Stephenson]

On Sun, 22 Nov 2015 09:27:11 -0800
Bart Schaefer <schaefer@brasslantern.com> wrote:
> Do we want to try to fix users/20859 ?  It shouldn't be that hard for
> someone in an environment where it fails (I'm having trouble creating
> one).

Putting it all together, the reported failing case is:

% (LC_ALL=de_CH.UTF-8; print -P "%D{%a %b %d} %D{%I:%M:%S%P}")
Son Nov 22 
5:36% (LC_ALL=de_CH.UTF-8; print -P "%D{%a %b %d} %D{%I:%M:%S}")
Son Nov 22 05:37:02

and that's indeed the feature --- no time if %P is present.

The date component is irrelevant (except that it shosw strftime isn't
completely screwed), so it just reduces to the second %D substitution in
that locale.  Not specific to Switzerland or in fact to German; happens
in de_DE.UTF-8 and fr_CH.UTF-8, too.  Suspected metafication, but it
wasn't.

This suggests the test for a successful expansion isn't safe after all,
but probably there aren't too many expansions like %p and %P.

pws

diff --git a/Src/utils.c b/Src/utils.c
index 0afa8c9..4640970 100644
--- a/Src/utils.c
+++ b/Src/utils.c
@@ -3143,6 +3143,7 @@ strftimehandling:
 		 * in the accounting in bufsize (but nowhere else).
 		 */
 		{
+		    char origchar = fmt[-1];
 		    int size = fmt - fmtstart;
 		    char *tmp, *last;
 		    tmp = zhalloc(size + 1);
@@ -3163,11 +3164,17 @@ strftimehandling:
 		    *buf = '\1';
 		    if (!strftime(buf, bufsize + 2, tmp, tm))
 		    {
-			if (*buf) {
-			    buf[0] = '\0';
-			    return -1;
+			/*
+			 * Some locales don't have strings for
+			 * AM/PM, so empty output is valid.
+			 */
+			if (*buf || (origchar != 'p' && origchar != 'P')) {
+			    if (*buf) {
+				buf[0] = '\0';
+				return -1;
+			    }
+			    return 0;
 			}
-			return 0;
 		    }
 		    decr = strlen(buf);
 		    buf += decr;

Re: Fix strftime (prompts) before 5.2?

[Bart Schaefer]

On Nov 22,  6:06pm, Peter Stephenson wrote:
}
} Putting it all together, the reported failing case is:
} 
} % (LC_ALL=de_CH.UTF-8; print -P "%D{%a %b %d} %D{%I:%M:%S%P}")
} Son Nov 22 

Maybe it's time (ahem) for something like this?  (Equivalent patch would
be needed in elite, elite2, fade, and fire themes.)

The difference is " %p" in most langinfo vs. "%P" in the current themes.


diff --git a/Functions/Prompts/prompt_bigfade_setup b/Functions/Prompts/prompt_bigfade_setup
index 2d95f31..918ac82 100644
--- a/Functions/Prompts/prompt_bigfade_setup
+++ b/Functions/Prompts/prompt_bigfade_setup
@@ -31,7 +31,10 @@ prompt_bigfade_setup () {
   autoload -Uz prompt_special_chars
   prompt_special_chars
 
-  PS1="%B%F{$fadebar}$schars[333]$schars[262]$schars[261]$schars[260]%B%F{$userhost}%K{$fadebar}%n@%m%b%k%f%F{$fadebar}%K{black}$schars[260]$schars[261]$schars[262]$schars[333]%b%f%k%F{$fadebar}%K{black}$schars[333]$schars[262]$schars[261]$schars[260]%B%F{$date}%K{black} %D{%a %b %d} %D{%I:%M:%S%P}$prompt_newline%B%F{$cwd}%K{black}%d>%b%f%k "
+  zmodload zsh/langinfo 2>/dev/null
+  local T_FMT=${${langinfo:+${langinfo[T_FMT_AMPM]}}:-%I:%M:%S%P}
+
+  PS1="%B%F{$fadebar}$schars[333]$schars[262]$schars[261]$schars[260]%B%F{$userhost}%K{$fadebar}%n@%m%b%k%f%F{$fadebar}%K{black}$schars[260]$schars[261]$schars[262]$schars[333]%b%f%k%F{$fadebar}%K{black}$schars[333]$schars[262]$schars[261]$schars[260]%B%F{$date}%K{black} %D{%a %b %d} %D{$T_FMT}$prompt_newline%B%F{$cwd}%K{black}%d>%b%f%k "
   PS2="%B%F{$fadebar}$schars[333]$schars[262]$schars[261]$schars[260]%b%F{$fadebar}%K{black}$schars[260]$schars[261]$schars[262]$schars[333]%F{$fadebar}%K{black}$schars[333]$schars[262]$schars[261]$schars[260]%B%F{$fadebar}>%b%f%k "
 
   prompt_opts=(cr subst percent)