Jakub Narebski <jnareb@xxxxxxxxx> writes:
> Wouldn't it be better to be able to use (or be able to enable, like echo -e
> option) interpretation of the backslash-escaped characters, like
> \t, \n, \0?
I've been thinking about letting the --format to specify
embedding arbitrary byte value in the output.
This option however is mostly to help Porcelain written in
languages other than C (and that is where the language specific
quoting styles come in) to allow a template of a scriptlet to be
specified, as you have probably seen in the examples in the
documentation page, so I think it is more user friendly to leave
backslash as just a literal character.
My current thinking is to allow you to say %XX (a per-cent
followed by exactly two hexadecimal digits) to do embed a
literal byte value. Then a Porcelain written in Perl that does
not want to eval output can do something like this:
my $fmt = 'r%(refname)%00o%(objectname)%00%00';
open R, '-|', 'git-for-each-ref', "--format=$fmt";
my $all = join('', <R>);
close R;
for (split(/\0\0/, $all)) {
/r(.*?)\0o(.*)/ &&
print "ref = $1, obj = $2\n";
}
Another thing is that originally I picked %(name) syntax because
I thought we might want to do fancier "%20(column)d" like Python
does with its string formatting operator. But I now think it
makes more sense to output whatever is asked as string literals
and have host language worry about formatting. So in that
sense, using %() as our formatting specifier will get in the way
for people who writes in Python. Maybe I should change it to
something like %{name} instead (not ${name} -- that would
interfere with the shell and Perl).
Anyhow, on top of the previous one, this will let you say %00 to
embed a NUL in your string.
diff --git a/builtin-for-each-ref.c b/builtin-for-each-ref.c
index f064e7e..698618b 100644
--- a/builtin-for-each-ref.c
+++ b/builtin-for-each-ref.c
@@ -710,12 +710,39 @@ static void print_value(struct refinfo *
}
}
+static int hex1(char ch)
+{
+ if ('0' <= ch && ch <= '9')
+ return ch - '0';
+ else if ('a' <= ch && ch <= 'f')
+ return ch - 'a' + 10;
+ else if ('A' <= ch && ch <= 'F')
+ return ch - 'A' + 10;
+ return -1;
+}
+static int hex2(const char *cp)
+{
+ if (cp[0] && cp[1])
+ return (hex1(cp[0]) << 4) | hex1(cp[1]);
+ else
+ return -1;
+}
+
static void emit(const char *cp, const char *ep)
{
while (*cp && (!ep || cp < ep)) {
- if (*cp == '%')
+ if (*cp == '%') {
if (cp[1] == '%')
cp++;
+ else {
+ int ch = hex2(cp + 1);
+ if (0 <= ch) {
+ putchar(ch);
+ cp += 3;
+ continue;
+ }
+ }
+ }
putchar(*cp);
cp++;
}
@@ -731,8 +758,10 @@ static void show_ref(struct refinfo *inf
emit(cp, sp);
print_value(info, parse_atom(sp + 2, ep), quote_style);
}
- if (*cp)
- fputs(cp, stdout);
+ if (*cp) {
+ sp = cp + strlen(cp);
+ emit(cp, sp);
+ }
putchar('\n');
}
-
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