threads / patch / 46776

patch, 4 partst1502: demonstrate rev-parse --parseopt option mis-parsing

Subject: [PATCH 1/4] t1502: demonstrate rev-parse --parseopt option mis-parsing

## tl;dr

4 messages between Sep 17, 2017 and Sep 17, 2017. Diffs are folded; open one to read it.

replies: 3people: 1as markdown or json

Brandon Casey· Sep 17, 2017, 22:28 UTC · lore

Since commit 2d893df rev-parse will scan forward from the beginning of the option string looking for a flag character. If there are no flag characters then the scan will spill over into the help text and will interpret the characters preceding the "flag" as part of the option-spec i.e. the long option name.

For example, the following option spec:
    exclame this does something!
will produce this 'set' expression when --exclame is specified:
    set -- --exclame this does something --

which will be interpreted as four separate parameters by the shell. And will produce a help string that looks like:

    --exclame this does something
                          this does something!

git-rebase.sh has such an option (--autosquash), and so will add extra parameters to the 'set' expression when --autosquash is used. git-rebase continues to work correctly though because when it parses the arguments, it ignores ones that it does not recognize.

Also, rev-parse --parseopt does not currently interpret a tab character as a delimiter between the option spec and the help text. If a tab is used at the end of the option spec, before the help text, and before a space has been specified, then rev-parse will interpret the tab as part of the preceding component (either the long name or the arg hint).

For example, the following option spec (note: there is a <tab> between "frotz" and "enable"):

    frotz	enable frotzing
will produce this 'set' expression when --frotz is specified:
    set -- --frotz  enable --
which will be interpreted as 2 separate arguments by the shell.

git-rebase.sh has one of these too (--keep-empty). In this case the tab is immediately followed by spaces so there are no additional parameters produced on the command line. The only side-effect is misalignment in the help text.

Signed-off-by: Brandon Casey <drafnel@gmail.com>
---
 t/t1502-rev-parse-parseopt.sh | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)
Show changes to t/t1502-rev-parse-parseopt.sh +12 −6
diff --git a/t/t1502-rev-parse-parseopt.sh b/t/t1502-rev-parse-parseopt.sh
index 310f93f..910fc56 100755
--- a/t/t1502-rev-parse-parseopt.sh
+++ b/t/t1502-rev-parse-parseopt.sh
@@ -28,6 +28,9 @@ test_expect_success 'setup optionspec' '
 |g,fluf?path     short and long option optional argument
 |longest=very-long-argument-hint  a very long argument hint
 |pair=key=value  with an equals sign in the hint
+|aswitch help te=t contains? fl*g characters!`
+|bswitch=hint	 hint has trailing tab character
+|cswitch	 switch has trailing tab character
 |short-hint=a    with a one symbol hint
 |
 |Extras
@@ -35,7 +38,7 @@ test_expect_success 'setup optionspec' '
 EOF
 '
 
-test_expect_success 'test --parseopt help output' '
+test_expect_failure 'test --parseopt help output' '
 	sed -e "s/^|//" >expect <<\END_EXPECT &&
 |cat <<\EOF
 |usage: some-command [options] <args>...
@@ -62,6 +65,9 @@ test_expect_success 'test --parseopt help output' '
 |    --longest <very-long-argument-hint>
 |                          a very long argument hint
 |    --pair <key=value>    with an equals sign in the hint
+|    --aswitch             help te=t contains? fl*g characters!`
+|    --bswitch <hint>      hint has trailing tab character
+|    --cswitch             switch has trailing tab character
 |    --short-hint <a>      with a one symbol hint
 |
 |Extras
@@ -75,17 +81,17 @@ END_EXPECT
 
 test_expect_success 'setup expect.1' "
 	cat > expect <<EOF
-set -- --foo --bar 'ham' -b -- 'arg'
+set -- --foo --bar 'ham' -b --aswitch -- 'arg'
 EOF
 "
 
-test_expect_success 'test --parseopt' '
-	git rev-parse --parseopt -- --foo --bar=ham --baz arg < optionspec > output &&
+test_expect_failure 'test --parseopt' '
+	git rev-parse --parseopt -- --foo --bar=ham --baz --aswitch arg < optionspec > output &&
 	test_cmp expect output
 '
 
-test_expect_success 'test --parseopt with mixed options and arguments' '
-	git rev-parse --parseopt -- --foo arg --bar=ham --baz < optionspec > output &&
+test_expect_failure 'test --parseopt with mixed options and arguments' '
+	git rev-parse --parseopt -- --foo arg --bar=ham --baz --aswitch < optionspec > output &&
 	test_cmp expect output
 '
 

-- 
2.2.0.rc3
Brandon Casey· Sep 17, 2017, 22:28 UTC · re: Brandon Casey · lore

[PATCH 2/4] rev-parse parseopt: do not search help text for flag chars

When searching for flag characters in the option spec, we should ensure the search stays within the bounds of the option spec and does not enter the help text portion of the spec. So when we find the boundary white space marking the start of the help text, let's mark it with a nul character. Then when we search for flag characters starting from the beginning of the string we'll stop at the nul and won't enter the help text.

Now, the following option spec:
    exclame this does something!
will produce this 'set' expression when --exclame is specified:
    set -- --exclame --
instead of this one:
    set -- --exclame this does something --
Mark t1502.4 and t1502.5 as fixed.
Signed-off-by: Brandon Casey <drafnel@gmail.com>
---
 builtin/rev-parse.c           | 6 ++++--
 t/t1502-rev-parse-parseopt.sh | 4 ++--
 2 files changed, 6 insertions(+), 4 deletions(-)
Show changes to 2 files +6 −4

builtin/rev-parse.c, t/t1502-rev-parse-parseopt.sh

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index 2bd28d3..b19f677 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -434,7 +434,7 @@ static int cmd_parseopt(int argc, const char **argv, const char *prefix)
 	/* parse: (<short>|<short>,<long>|<long>)[*=?!]*<arghint>? SP+ <help> */
 	while (strbuf_getline(&sb, stdin) != EOF) {
 		const char *s;
-		const char *help;
+		char *help;
 		struct option *o;
 
 		if (!sb.len)
@@ -451,8 +451,10 @@ static int cmd_parseopt(int argc, const char **argv, const char *prefix)
 			continue;
 		}
 
+		*help = '\0';
+
 		o->type = OPTION_CALLBACK;
-		o->help = xstrdup(skipspaces(help));
+		o->help = xstrdup(skipspaces(help+1));
 		o->value = &parsed;
 		o->flags = PARSE_OPT_NOARG;
 		o->callback = &parseopt_dump;
diff --git a/t/t1502-rev-parse-parseopt.sh b/t/t1502-rev-parse-parseopt.sh
index 910fc56..3d895e0 100755
--- a/t/t1502-rev-parse-parseopt.sh
+++ b/t/t1502-rev-parse-parseopt.sh
@@ -85,12 +85,12 @@ set -- --foo --bar 'ham' -b --aswitch -- 'arg'
 EOF
 "
 
-test_expect_failure 'test --parseopt' '
+test_expect_success 'test --parseopt' '
 	git rev-parse --parseopt -- --foo --bar=ham --baz --aswitch arg < optionspec > output &&
 	test_cmp expect output
 '
 
-test_expect_failure 'test --parseopt with mixed options and arguments' '
+test_expect_success 'test --parseopt with mixed options and arguments' '
 	git rev-parse --parseopt -- --foo arg --bar=ham --baz --aswitch < optionspec > output &&
 	test_cmp expect output
 '

-- 
2.2.0.rc3
Brandon Casey· Sep 17, 2017, 22:28 UTC · re: Brandon Casey · lore

[PATCH 3/4] rev-parse parseopt: interpret any whitespace as start of help text

Currently, rev-parse only interprets a space ' ' character as the delimiter between the option spec and the help text. So if a tab character is placed between the option spec and the help text, it will be interpreted as part of the long option name or as part of the arg hint. If it is interpreted as part of the long option name, then rev-parse will produce what will be interpreted as multiple arguments on the command line.

For example, the following option spec (note: there is a <tab> between "frotz" and "enable"):

    frotz	enable frotzing
will produce the following set expression when --frotz is used:
    set -- --frotz --
instead of this:
    set -- --frotz  enable --
Mark t1502.2 as fixed.
Signed-off-by: Brandon Casey <drafnel@gmail.com>
---
 builtin/rev-parse.c           | 12 ++++++++++--
 t/t1502-rev-parse-parseopt.sh |  2 +-
 2 files changed, 11 insertions(+), 3 deletions(-)
Show changes to 2 files +11 −3

builtin/rev-parse.c, t/t1502-rev-parse-parseopt.sh

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index b19f677..351b1a3 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -387,6 +387,14 @@ static const char *skipspaces(const char *s)
 	return s;
 }
 
+static char *findspace(const char *s)
+{
+	for (; *s; s++)
+		if (isspace(*s))
+			return (char*)s;
+	return NULL;
+}
+
 static int cmd_parseopt(int argc, const char **argv, const char *prefix)
 {
 	static int keep_dashdash = 0, stop_at_non_option = 0;
@@ -444,8 +452,8 @@ static int cmd_parseopt(int argc, const char **argv, const char *prefix)
 		memset(opts + onb, 0, sizeof(opts[onb]));
 
 		o = &opts[onb++];
-		help = strchr(sb.buf, ' ');
-		if (!help || *sb.buf == ' ') {
+		help = findspace(sb.buf);
+		if (!help || sb.buf == help) {
 			o->type = OPTION_GROUP;
 			o->help = xstrdup(skipspaces(sb.buf));
 			continue;
diff --git a/t/t1502-rev-parse-parseopt.sh b/t/t1502-rev-parse-parseopt.sh
index 3d895e0..6e1b45f 100755
--- a/t/t1502-rev-parse-parseopt.sh
+++ b/t/t1502-rev-parse-parseopt.sh
@@ -38,7 +38,7 @@ test_expect_success 'setup optionspec' '
 EOF
 '
 
-test_expect_failure 'test --parseopt help output' '
+test_expect_success 'test --parseopt help output' '
 	sed -e "s/^|//" >expect <<\END_EXPECT &&
 |cat <<\EOF
 |usage: some-command [options] <args>...

-- 
2.2.0.rc3
Brandon Casey· Sep 17, 2017, 22:28 UTC · re: Brandon Casey · lore

[PATCH 4/4] git-rebase: don't ignore unexpected command line arguments

Currently, git-rebase will silently ignore any unexpected command-line switches and arguments (the command-line produced by git rev-parse). This allowed the rev-parse bug, fixed in the preceding commits, to go unnoticed. Let's make sure that doesn't happen again. We shouldn't be ignoring unexpected arguments. Let's not.

Signed-off-by: Brandon Casey <drafnel@gmail.com>
---
 git-rebase.sh | 3 +++
 1 file changed, 3 insertions(+)
Show changes to git-rebase.sh +3 −0
diff --git a/git-rebase.sh b/git-rebase.sh
index ad8415e..6344e8d 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -350,6 +350,9 @@ do
 		shift
 		break
 		;;
+	*)
+		usage
+		;;
 	esac
 	shift
 done

-- 
2.2.0.rc3

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