P modify in history event

P modify in history event

[Perry Smith]

[-- Attachment #1: Type: text/plain, Size: 563 bytes --]

I’m (slowly) reading through zshexpn and playing with things to learn.  This does not work:

> pedz@MysticSlate my-play-dir % echo /this/is/a/../../path
> /this/is/a/../../path
> pedz@MysticSlate my-play-dir % echo !$:P
> zsh: illegal modifier: P

even if the file specified exists

but this does:

> pedz@MysticSlate my-play-dir % echo /this/is/a/../../path
> /this/is/a/../../path
> pedz@MysticSlate my-play-dir % echo !$:A
> echo /this/path
> /this/path

Is this a documentation bug, code bug, or my misunderstanding?

Thank you,
pedz


[-- Attachment #2: smime.p7s --]
[-- Type: application/pkcs7-signature, Size: 2966 bytes --]

Re: P modify in history event

[Peter Stephenson]

On Sun, 2019-11-17 at 12:42 -0600, Perry Smith wrote:
> I’m (slowly) reading through zshexpn and playing with things to
> learn.  This does not work:
> 
> > 
> > pedz@MysticSlate my-play-dir % echo /this/is/a/../../path
> > /this/is/a/../../path
> > pedz@MysticSlate my-play-dir % echo !$:P
> > zsh: illegal modifier: P
> even if the file specified exists

I think it just got missed out of the history modifiers, which are
handled in a different place from the modifiers in the case of glob
qualifiers and vaariables.

pws

diff --git a/Src/hist.c b/Src/hist.c
index fd5606dc3..e47be8e15 100644
--- a/Src/hist.c
+++ b/Src/hist.c
@@ -920,6 +920,16 @@ histsubchar(int c)
 	    case 'u':
 		sline = casemodify(sline, CASMOD_UPPER);
 		break;
+	    case 'P':
+		if (*sline != '/') {
+		    char *here = zgetcwd();
+		    if (here[strlen(here)-1] != '/')
+			sline = zhtricat(metafy(here, -1, META_HEAPDUP), "/", sline);
+		    else
+			sline = dyncat(here, sline);
+		}
+		sline = xsymlink(sline, 1);
+		break;
 	    default:
 		herrflush();
 		zerr("illegal modifier: %c", c);

Re: P modify in history event

[Daniel Shahaf]

Peter Stephenson wrote on Mon, 18 Nov 2019 09:47 +00:00:
> On Sun, 2019-11-17 at 12:42 -0600, Perry Smith wrote:
> > I’m (slowly) reading through zshexpn and playing with things to
> > learn.  This does not work:
> > 
> > > 
> > > pedz@MysticSlate my-play-dir % echo /this/is/a/../../path
> > > /this/is/a/../../path
> > > pedz@MysticSlate my-play-dir % echo !$:P
> > > zsh: illegal modifier: P
> > even if the file specified exists
> 
> I think it just got missed out of the history modifiers, which are
> handled in a different place from the modifiers in the case of glob
> qualifiers and vaariables.

Thanks for fixing this.  Test added in 030440d5b7bfd2968138836e962f1ef61ea0bae8.

> +++ b/Src/hist.c
> @@ -920,6 +920,16 @@ histsubchar(int c)
> +	    case 'P':
> +		if (*sline != '/') {
> +		    char *here = zgetcwd();
> +		    if (here[strlen(here)-1] != '/')

Can «zgetcwd()» return an empty string?  If that's possible, the
condition will be undefined behaviour («""[-1]»).

> +			sline = zhtricat(metafy(here, -1, META_HEAPDUP), "/", sline);
> +		    else
> +			sline = dyncat(here, sline);
> +		}
> +		sline = xsymlink(sline, 1);
> +		break;

Cheers,

Daniel

Re: P modify in history event

[Peter Stephenson]

On Tue, 2019-11-19 at 18:00 +0000, Daniel Shahaf wrote:
> Can «zgetcwd()» return an empty string?  If that's possible, the
> condition will be undefined behaviour («""[-1]»).

Not in a sane world, but there are cases where we can't work out the
current directory.  I think we return "." then, in fact.  But a bit of
safety probably wouldn't hurt --- applying [-1] to functions arguably
isn't top class style.

pws

Re: P modify in history event

[Daniel Shahaf]

Peter Stephenson wrote on Tue, 19 Nov 2019 18:21 +00:00:
> On Tue, 2019-11-19 at 18:00 +0000, Daniel Shahaf wrote:
> > Can «zgetcwd()» return an empty string?  If that's possible, the
> > condition will be undefined behaviour («""[-1]»).
> 
> Not in a sane world, but there are cases where we can't work out the
> current directory.  I think we return "." then, in fact.  But a bit of
> safety probably wouldn't hurt --- applying [-1] to functions arguably
> isn't top class style.

How about this, then?

diff --git a/Src/compat.c b/Src/compat.c
index 7131d91a4..02b66a780 100644
--- a/Src/compat.c
+++ b/Src/compat.c
@@ -519,7 +519,7 @@ zgetcwd(void)
 #endif /* HAVE_GETCWD */
     if (!ret)
 	ret = unmeta(pwd);
-    if (!ret)
+    if (!ret || *ret == '\0')
 	ret = dupstring(".");
     return ret;
 }

Cheers,

Daniel
(let's continue the discussion on -workers@)