threads / patch / 47477

patchconfig.txt: Document behavior of backslashes in subsections

Subject: [PATCH] config.txt: Document behavior of backslashes in subsections

## tl;dr

2 messages between Dec 21, 2017 and Dec 22, 2017. Diffs are folded; open one to read it.

replies: 1people: 2as markdown or json

Dave Borowitz· Dec 21, 2017, 13:10 UTC · lore

Unrecognized escape sequences are invalid in values:

  $ git config -f - --list <<EOF
  [foo]
    bar = "\t\\\y\"\u"
  EOF
  fatal: bad config line 2 in standard input

But in subsection names, the backslash is simply dropped if the following character does not produce a recognized escape sequence:

  $ git config -f - --list <<EOF
  [foo "\t\\\y\"\u"]
    bar = baz
  EOF
  foo.t\y"u.bar=baz

Although it would be nice for subsection names and values to have consistent behavior, changing the behavior for subsection names is a nonstarter since it would cause existing, valid config files to suddenly be interpreted differently.

Signed-off-by: Dave Borowitz <dborowitz@google.com>
---
 Documentation/config.txt | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

Show changes to Documentation/config.txt +7 −5

diff --git a/Documentation/config.txt b/Documentation/config.txt
index b18c0f97fe..f772186c44 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -41,11 +41,13 @@ in the section header, like in the example below:
 --------
 
 Subsection names are case sensitive and can contain any characters except
-newline (doublequote `"` and backslash can be included by escaping them
-as `\"` and `\\`, respectively).  Section headers cannot span multiple
-lines.  Variables may belong directly to a section or to a given subsection.
-You can have `[section]` if you have `[section "subsection"]`, but you
-don't need to.
+newline and the null byte. Doublequote `"` and backslash can be included
+by escaping them as `\"` and `\\`, respectively. Backslashes preceding
+other characters are dropped when reading; for example, `\t` is read as
+`t` and `\0` is read as `0` Section headers cannot span multiple lines.
+Variables may belong directly to a section or to a given subsection. You
+can have `[section]` if you have `[section "subsection"]`, but you don't
+need to.
 
 There is also a deprecated `[section.subsection]` syntax. With this
 syntax, the subsection name is converted to lower-case and is also

-- 
2.15.1.620.gb9897f4670-goog

Junio C Hamano· Dec 22, 2017, 20:49 UTC · re: Dave Borowitz · lore

Re: [PATCH] config.txt: Document behavior of backslashes in subsections

Dave Borowitz <dborowitz@google.com> writes:

Show 26 quoted lines

> Unrecognized escape sequences are invalid in values:
>
>   $ git config -f - --list <<EOF
>   [foo]
>     bar = "\t\\\y\"\u"
>   EOF
>   fatal: bad config line 2 in standard input
>
> But in subsection names, the backslash is simply dropped if the
> following character does not produce a recognized escape sequence:
>
>   $ git config -f - --list <<EOF
>   [foo "\t\\\y\"\u"]
>     bar = baz
>   EOF
>   foo.t\y"u.bar=baz
>
> Although it would be nice for subsection names and values to have
> consistent behavior, changing the behavior for subsection names is a
> nonstarter since it would cause existing, valid config files to
> suddenly be interpreted differently.
>
> Signed-off-by: Dave Borowitz <dborowitz@google.com>
> ---
>  Documentation/config.txt | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

Thanks.

Show 24 quoted lines

>
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index b18c0f97fe..f772186c44 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -41,11 +41,13 @@ in the section header, like in the example below:
>  --------
>  
>  Subsection names are case sensitive and can contain any characters except
> -newline (doublequote `"` and backslash can be included by escaping them
> -as `\"` and `\\`, respectively).  Section headers cannot span multiple
> -lines.  Variables may belong directly to a section or to a given subsection.
> -You can have `[section]` if you have `[section "subsection"]`, but you
> -don't need to.
> +newline and the null byte. Doublequote `"` and backslash can be included
> +by escaping them as `\"` and `\\`, respectively. Backslashes preceding
> +other characters are dropped when reading; for example, `\t` is read as
> +`t` and `\0` is read as `0` Section headers cannot span multiple lines.
> +Variables may belong directly to a section or to a given subsection. You
> +can have `[section]` if you have `[section "subsection"]`, but you don't
> +need to.
>  
>  There is also a deprecated `[section.subsection]` syntax. With this
>  syntax, the subsection name is converted to lower-case and is also