threads / patch / 62462

patchtrace2: prevent segfault on config collection where no value specified

Subject: [PATCH] trace2: prevent segfault on config collection where no value specified

## tl;dr

11 messages between Nov 7, 2024 and Jan 23, 2025. Diffs are folded; open one to read it.

replies: 10people: 5as markdown or json

Adam Murray via GitGitGadget· Nov 7, 2024, 00:04 UTC · lore
From: Adam Murray <ad@canva.com>

When TRACE2 analytics is enabled, a git config option that has no value causes a segfault.

Steps to Reproduce GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.* git -c status.relativePaths version Expected Result git version 2.46.0 Actual Result zsh: segmentation fault GIT_TRACE2=true

This adds a null check to prevent the segfault and instead return the "empty config value" error.

Signed-off-by: Adam Murray <ad@canva.com>
---
    trace2: prevent segfault on config collection where no value specified
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1814%2Fad-murray%2Ffix-trace2-segfault-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1814/ad-murray/fix-trace2-segfault-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1814
 t/t0210-trace2-normal.sh | 8 ++++++++
 trace2.c                 | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)
Show changes to 2 files +9 −1

t/t0210-trace2-normal.sh, trace2.c

diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
index b9adc94aab4..4047ab562a4 100755
--- a/t/t0210-trace2-normal.sh
+++ b/t/t0210-trace2-normal.sh
@@ -244,6 +244,14 @@ test_expect_success 'bug messages followed by BUG() are written to trace2' '
 	test_cmp expect actual
 '
 
+test_expect_success 'empty configuration values are handled' '
+  test_when_finished "rm trace2.normal actual expect" &&
+  echo >expect &&
+  GIT_TRACE2="$(pwd)/trace2.normal"  GIT_TRACE2_CONFIG_PARAMS=foo.empty \
+	  git -c foo.empty config foo.empty >actual &&
+	test_cmp expect actual
+'
+
 sane_unset GIT_TRACE2_BRIEF
 
 # Now test without environment variables and get all Trace2 settings
diff --git a/trace2.c b/trace2.c
index f894532d053..5df43478b8f 100644
--- a/trace2.c
+++ b/trace2.c
@@ -759,7 +759,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
 	int j;
 	const char *redacted;
 
-	if (!trace2_enabled)
+	if (!trace2_enabled || !value)
 		return;
 
 	redacted = redact_arg(value);

base-commit: 8f8d6eee531b3fa1a8ef14f169b0cb5035f7a772

-- 
gitgitgadget
Jeff King· Nov 7, 2024, 02:01 UTC · re: Adam Murray via GitGitGadget · lore

Re: [PATCH] trace2: prevent segfault on config collection where no value specified

On Thu, Nov 07, 2024 at 12:04:48AM +0000, Adam Murray via GitGitGadget wrote:
Show 13 quoted lines
> When TRACE2 analytics is enabled, a git config option that has no value
> causes a segfault.
> 
> Steps to Reproduce
> GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.*
> git -c status.relativePaths version
> Expected Result
> git version 2.46.0
> Actual Result
> zsh: segmentation fault GIT_TRACE2=true
> 
> This adds a null check to prevent the segfault and instead return
> the "empty config value" error.

We definitely should deal with the NULL here, but I'm not sure that returning an error is correct. A value-less config like this is a synonym for "true". If the point of this code is to dump a trace of config settings, then by returning without printing anything, we're misleading the user.

I.e., doing this, with an explicit value for the config option:
  GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.* git -c status.relativePaths=true version
should (and does) show:
  20:48:11.662470 trace2.c:437                      def_param scope:command status.relativepaths=true

If we swap that our for "-c status.relativePaths", then the outcome is the same: we've turned on that config option. But with your patch, the trace won't mention it at all.

Show 13 quoted lines
> diff --git a/trace2.c b/trace2.c
> index f894532d053..5df43478b8f 100644
> --- a/trace2.c
> +++ b/trace2.c
> @@ -759,7 +759,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
>  	int j;
>  	const char *redacted;
>  
> -	if (!trace2_enabled)
> +	if (!trace2_enabled || !value)
>  		return;
>  
>  	redacted = redact_arg(value);
So here I think we need to either:
  1. Just quietly substitute "true" for the value. For a bool, the two
     are equivalent, and this is probably an acceptable fiction for a
     trace to show. For a non-bool (e.g., something like "author.name"),
     though, it's an error, and the trace is somewhat misleading.
  2. Put in some special marker for the NULL value. Something like
     "(null)" works, but it's ambiguous with a config of the same value
     (which obviously you wouldn't expect in normal use, but since the
     point of tracing is often to debug, I could see it being
     misleading).

All of this is made harder by the fact that there are multiple output targets. So you'd have to pass the NULL down to them and let them handle it. Something like:

Show changes to 2 files +5 −5

trace2.c, trace2/tr2_tgt_normal.c

diff --git a/trace2.c b/trace2.c
index 5df43478b8..e67edf4b1b 100644
--- a/trace2.c
+++ b/trace2.c
@@ -759,10 +759,10 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
 	int j;
 	const char *redacted;
 
-	if (!trace2_enabled || !value)
+	if (!trace2_enabled)
 		return;
 
-	redacted = redact_arg(value);
+	redacted = value ? redact_arg(value) : NULL;
 
 	for_each_wanted_builtin (j, tgt_j)
 		if (tgt_j->pfn_param_fl)
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index baef48aa69..924736ab36 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -307,8 +307,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
 	enum config_scope scope = kvi->scope;
 	const char *scope_name = config_scope_name(scope);
 
-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
-		    value);
+	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
+	if (value)
+		strbuf_addf(&buf_payload, "=%s", value);
 	normal_io_write_fl(file, line, &buf_payload);
 	strbuf_release(&buf_payload);
 }

but you'd need to do the same for each target implementation.

-Peff
Junio C Hamano· Nov 7, 2024, 03:02 UTC · re: Jeff King · lore

Re: [PATCH] trace2: prevent segfault on config collection where no value specified

Jeff King <peff@peff.net> writes:
Show 11 quoted lines
> I.e., doing this, with an explicit value for the config option:
>
>   GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.* git -c status.relativePaths=true version
>
> should (and does) show:
>
>   20:48:11.662470 trace2.c:437                      def_param scope:command status.relativepaths=true
>
> If we swap that our for "-c status.relativePaths", then the outcome is
> the same: we've turned on that config option. But with your patch, the
> trace won't mention it at all.

which may be improvement, but ideally, the "valueless truth" case should be given differently, perhaps like 

   20:48:11.662470 trace2.c:437                      def_param scope:command status.relativepaths

to allow showing what exactly the system has seen. After all, trace output is often used for debugging, and it is not unusual for a buggy code path to behave on explicit truth and valueless truth differently.

Show 30 quoted lines
> So here I think we need to either:
>
>   1. Just quietly substitute "true" for the value. For a bool, the two
>      are equivalent, and this is probably an acceptable fiction for a
>      trace to show. For a non-bool (e.g., something like "author.name"),
>      though, it's an error, and the trace is somewhat misleading.
>
>   2. Put in some special marker for the NULL value. Something like
>      "(null)" works, but it's ambiguous with a config of the same value
>      (which obviously you wouldn't expect in normal use, but since the
>      point of tracing is often to debug, I could see it being
>      misleading).
>
> All of this is made harder by the fact that there are multiple output
> targets. So you'd have to pass the NULL down to them and let them handle
> it. Something like:
> ...
> diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
> index baef48aa69..924736ab36 100644
> --- a/trace2/tr2_tgt_normal.c
> +++ b/trace2/tr2_tgt_normal.c
> @@ -307,8 +307,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	enum config_scope scope = kvi->scope;
>  	const char *scope_name = config_scope_name(scope);
>  
> -	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
> -		    value);
> +	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, "=%s", value);
Yes, exactly.
Show 5 quoted lines
>  	normal_io_write_fl(file, line, &buf_payload);
>  	strbuf_release(&buf_payload);
>  }
>
> but you'd need to do the same for each target implementation.
Thanks.
Adam Murray via GitGitGadget· Jan 10, 2025, 07:28 UTC · re: Adam Murray via GitGitGadget · lore

[PATCH v2] trace2: prevent segfault on config collection where no value specified

From: Adam Murray <ad@canva.com>

When TRACE2 analytics is enabled, a git config option that has no value causes a segfault.

Steps to Reproduce GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.* git -c status.relativePaths version Expected Result git version 2.46.0 Actual Result zsh: segmentation fault GIT_TRACE2=true

This adds checks to prevent the segfault and instead return an empty value.

Signed-off-by: Adam Murray <ad@canva.com>
---
    trace2: prevent segfault on config collection where no value specified
    
    cc: Jeff King peff@peff.net
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1814%2Fad-murray%2Ffix-trace2-segfault-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1814/ad-murray/fix-trace2-segfault-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1814
Range-diff vs v1:
 1:  24ba9db7aa1 ! 1:  fd7bed52dda trace2: prevent segfault on config collection where no value specified
     @@ Commit message
          Actual Result
          zsh: segmentation fault GIT_TRACE2=true
      
     -    This adds a null check to prevent the segfault and instead return
     -    the "empty config value" error.
     +    This adds checks to prevent the segfault and instead return
     +    an empty value.
      
          Signed-off-by: Adam Murray <ad@canva.com>
      
     @@ t/t0210-trace2-normal.sh: test_expect_success 'bug messages followed by BUG() ar
      
       ## trace2.c ##
      @@ trace2.c: void trace2_def_param_fl(const char *file, int line, const char *param,
     - 	int j;
     - 	const char *redacted;
     - 
     --	if (!trace2_enabled)
     -+	if (!trace2_enabled || !value)
     + 	if (!trace2_enabled)
       		return;
       
     - 	redacted = redact_arg(value);
     +-	redacted = redact_arg(value);
     ++	redacted = value ? redact_arg(value): NULL;
     + 
     + 	for_each_wanted_builtin (j, tgt_j)
     + 		if (tgt_j->pfn_param_fl)
     +
     + ## trace2/tr2_tgt_event.c ##
     +@@ trace2/tr2_tgt_event.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	event_fmt_prepare(event_name, file, line, NULL, &jw);
     + 	jw_object_string(&jw, "scope", scope_name);
     + 	jw_object_string(&jw, "param", param);
     +-	jw_object_string(&jw, "value", value);
     ++	if (value)
     ++		jw_object_string(&jw, "value", value);
     + 	jw_end(&jw);
     + 
     + 	tr2_dst_write_line(&tr2dst_event, &jw.json);
     +
     + ## trace2/tr2_tgt_normal.c ##
     +@@ trace2/tr2_tgt_normal.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	enum config_scope scope = kvi->scope;
     + 	const char *scope_name = config_scope_name(scope);
     + 
     +-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
     +-		    value);
     ++	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
     ++	if (value)
     ++		strbuf_addf(&buf_payload, "=%s", value);
     + 	normal_io_write_fl(file, line, &buf_payload);
     + 	strbuf_release(&buf_payload);
     + }
     +
     + ## trace2/tr2_tgt_perf.c ##
     +@@ trace2/tr2_tgt_perf.c: static void fn_param_fl(const char *file, int line, const char *param,
     + 	struct strbuf scope_payload = STRBUF_INIT;
     + 	enum config_scope scope = kvi->scope;
     + 	const char *scope_name = config_scope_name(scope);
     +-
     +-	strbuf_addf(&buf_payload, "%s:%s", param, value);
     ++	strbuf_addstr(&buf_payload, param);
     ++	if (value)
     ++		strbuf_addf(&buf_payload, ":%s", value);
     + 	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
     + 
     + 	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,
 t/t0210-trace2-normal.sh | 8 ++++++++
 trace2.c                 | 2 +-
 trace2/tr2_tgt_event.c   | 3 ++-
 trace2/tr2_tgt_normal.c  | 5 +++--
 trace2/tr2_tgt_perf.c    | 5 +++--
 5 files changed, 17 insertions(+), 6 deletions(-)
Show changes to 5 files +17 −6

t/t0210-trace2-normal.sh, trace2.c, trace2/tr2_tgt_event.c, trace2/tr2_tgt_normal.c, trace2/tr2_tgt_perf.c

diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
index b9adc94aab4..4047ab562a4 100755
--- a/t/t0210-trace2-normal.sh
+++ b/t/t0210-trace2-normal.sh
@@ -244,6 +244,14 @@ test_expect_success 'bug messages followed by BUG() are written to trace2' '
 	test_cmp expect actual
 '
 
+test_expect_success 'empty configuration values are handled' '
+  test_when_finished "rm trace2.normal actual expect" &&
+  echo >expect &&
+  GIT_TRACE2="$(pwd)/trace2.normal"  GIT_TRACE2_CONFIG_PARAMS=foo.empty \
+	  git -c foo.empty config foo.empty >actual &&
+	test_cmp expect actual
+'
+
 sane_unset GIT_TRACE2_BRIEF
 
 # Now test without environment variables and get all Trace2 settings
diff --git a/trace2.c b/trace2.c
index f894532d053..49e7d1db88f 100644
--- a/trace2.c
+++ b/trace2.c
@@ -762,7 +762,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
 	if (!trace2_enabled)
 		return;
 
-	redacted = redact_arg(value);
+	redacted = value ? redact_arg(value): NULL;
 
 	for_each_wanted_builtin (j, tgt_j)
 		if (tgt_j->pfn_param_fl)
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index 45b0850a5ec..8e09485c83c 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -491,7 +491,8 @@ static void fn_param_fl(const char *file, int line, const char *param,
 	event_fmt_prepare(event_name, file, line, NULL, &jw);
 	jw_object_string(&jw, "scope", scope_name);
 	jw_object_string(&jw, "param", param);
-	jw_object_string(&jw, "value", value);
+	if (value)
+		jw_object_string(&jw, "value", value);
 	jw_end(&jw);
 
 	tr2_dst_write_line(&tr2dst_event, &jw.json);
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index baef48aa698..924736ab360 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -307,8 +307,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
 	enum config_scope scope = kvi->scope;
 	const char *scope_name = config_scope_name(scope);
 
-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
-		    value);
+	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
+	if (value)
+		strbuf_addf(&buf_payload, "=%s", value);
 	normal_io_write_fl(file, line, &buf_payload);
 	strbuf_release(&buf_payload);
 }
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index a6f9a8a193e..19ae7433ef8 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -446,8 +446,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
 	struct strbuf scope_payload = STRBUF_INIT;
 	enum config_scope scope = kvi->scope;
 	const char *scope_name = config_scope_name(scope);
-
-	strbuf_addf(&buf_payload, "%s:%s", param, value);
+	strbuf_addstr(&buf_payload, param);
+	if (value)
+		strbuf_addf(&buf_payload, ":%s", value);
 	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
 
 	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,

base-commit: 8f8d6eee531b3fa1a8ef14f169b0cb5035f7a772

-- 
gitgitgadget
Junio C Hamano· Jan 10, 2025, 17:10 UTC · re: Adam Murray via GitGitGadget · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

"Adam Murray via GitGitGadget" <gitgitgadget@gmail.com> writes:
> From: Adam Murray <ad@canva.com>
>
> When TRACE2 analytics is enabled, a git config option that has no value
> causes a segfault.

We often call this "valueless true syntax". It may techincally correct to say "has no value", but it is more friendly to readers if you said "a configuration variable that is set to 'true' with the valueless true syntax".

Show 25 quoted lines
> diff --git a/trace2.c b/trace2.c
> index f894532d053..49e7d1db88f 100644
> --- a/trace2.c
> +++ b/trace2.c
> @@ -762,7 +762,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
>  	if (!trace2_enabled)
>  		return;
>  
> -	redacted = redact_arg(value);
> +	redacted = value ? redact_arg(value): NULL;
>  
>  	for_each_wanted_builtin (j, tgt_j)
>  		if (tgt_j->pfn_param_fl)
> diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
> index 45b0850a5ec..8e09485c83c 100644
> --- a/trace2/tr2_tgt_event.c
> +++ b/trace2/tr2_tgt_event.c
> @@ -491,7 +491,8 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	event_fmt_prepare(event_name, file, line, NULL, &jw);
>  	jw_object_string(&jw, "scope", scope_name);
>  	jw_object_string(&jw, "param", param);
> -	jw_object_string(&jw, "value", value);
> +	if (value)
> +		jw_object_string(&jw, "value", value);
>  	jw_end(&jw);

OK, so for "valueless true", we do not get the "value" element in the json output, which makes sense. Don't we have documentation that explains what each element in the output means and when they are given? Shouldn't we update it?

Show 5 quoted lines
> -	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
> -		    value);
> +	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, "=%s", value);
OK.

The input did not spell the "=value" part and said "[section] key" to mean that section.key is true, so we report that without "=value" part. This also makes sense.

Show 13 quoted lines
> diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
> index a6f9a8a193e..19ae7433ef8 100644
> --- a/trace2/tr2_tgt_perf.c
> +++ b/trace2/tr2_tgt_perf.c
> @@ -446,8 +446,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	struct strbuf scope_payload = STRBUF_INIT;
>  	enum config_scope scope = kvi->scope;
>  	const char *scope_name = config_scope_name(scope);
> -
> -	strbuf_addf(&buf_payload, "%s:%s", param, value);
> +	strbuf_addstr(&buf_payload, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, ":%s", value);

I am not versed well enough in tgt-parf output format to tell if this makes sense. We'd need somebody else to review this part.

Thanks.
Johannes Schindelin· Jan 22, 2025, 10:11 UTC · re: Adam Murray via GitGitGadget · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

Hi Adam,
On Fri, 10 Jan 2025, Adam Murray via GitGitGadget wrote:
Show 17 quoted lines
> From: Adam Murray <ad@canva.com>
>
> When TRACE2 analytics is enabled, a git config option that has no value
> causes a segfault.
>
> Steps to Reproduce
> GIT_TRACE2=true GIT_TRACE2_CONFIG_PARAMS=status.*
> git -c status.relativePaths version
> Expected Result
> git version 2.46.0
> Actual Result
> zsh: segmentation fault GIT_TRACE2=true
>
> This adds checks to prevent the segfault and instead return
> an empty value.
>
> Signed-off-by: Adam Murray <ad@canva.com>
This patch looks good to me!

Thank you for the fix, Johannes

Show 174 quoted lines
> ---
>     trace2: prevent segfault on config collection where no value specified
>
>     cc: Jeff King peff@peff.net
>
> Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1814%2Fad-murray%2Ffix-trace2-segfault-v2
> Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1814/ad-murray/fix-trace2-segfault-v2
> Pull-Request: https://github.com/gitgitgadget/git/pull/1814
>
> Range-diff vs v1:
>
>  1:  24ba9db7aa1 ! 1:  fd7bed52dda trace2: prevent segfault on config collection where no value specified
>      @@ Commit message
>           Actual Result
>           zsh: segmentation fault GIT_TRACE2=true
>
>      -    This adds a null check to prevent the segfault and instead return
>      -    the "empty config value" error.
>      +    This adds checks to prevent the segfault and instead return
>      +    an empty value.
>
>           Signed-off-by: Adam Murray <ad@canva.com>
>
>      @@ t/t0210-trace2-normal.sh: test_expect_success 'bug messages followed by BUG() ar
>
>        ## trace2.c ##
>       @@ trace2.c: void trace2_def_param_fl(const char *file, int line, const char *param,
>      - 	int j;
>      - 	const char *redacted;
>      -
>      --	if (!trace2_enabled)
>      -+	if (!trace2_enabled || !value)
>      + 	if (!trace2_enabled)
>        		return;
>
>      - 	redacted = redact_arg(value);
>      +-	redacted = redact_arg(value);
>      ++	redacted = value ? redact_arg(value): NULL;
>      +
>      + 	for_each_wanted_builtin (j, tgt_j)
>      + 		if (tgt_j->pfn_param_fl)
>      +
>      + ## trace2/tr2_tgt_event.c ##
>      +@@ trace2/tr2_tgt_event.c: static void fn_param_fl(const char *file, int line, const char *param,
>      + 	event_fmt_prepare(event_name, file, line, NULL, &jw);
>      + 	jw_object_string(&jw, "scope", scope_name);
>      + 	jw_object_string(&jw, "param", param);
>      +-	jw_object_string(&jw, "value", value);
>      ++	if (value)
>      ++		jw_object_string(&jw, "value", value);
>      + 	jw_end(&jw);
>      +
>      + 	tr2_dst_write_line(&tr2dst_event, &jw.json);
>      +
>      + ## trace2/tr2_tgt_normal.c ##
>      +@@ trace2/tr2_tgt_normal.c: static void fn_param_fl(const char *file, int line, const char *param,
>      + 	enum config_scope scope = kvi->scope;
>      + 	const char *scope_name = config_scope_name(scope);
>      +
>      +-	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
>      +-		    value);
>      ++	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
>      ++	if (value)
>      ++		strbuf_addf(&buf_payload, "=%s", value);
>      + 	normal_io_write_fl(file, line, &buf_payload);
>      + 	strbuf_release(&buf_payload);
>      + }
>      +
>      + ## trace2/tr2_tgt_perf.c ##
>      +@@ trace2/tr2_tgt_perf.c: static void fn_param_fl(const char *file, int line, const char *param,
>      + 	struct strbuf scope_payload = STRBUF_INIT;
>      + 	enum config_scope scope = kvi->scope;
>      + 	const char *scope_name = config_scope_name(scope);
>      +-
>      +-	strbuf_addf(&buf_payload, "%s:%s", param, value);
>      ++	strbuf_addstr(&buf_payload, param);
>      ++	if (value)
>      ++		strbuf_addf(&buf_payload, ":%s", value);
>      + 	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
>      +
>      + 	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,
>
>
>  t/t0210-trace2-normal.sh | 8 ++++++++
>  trace2.c                 | 2 +-
>  trace2/tr2_tgt_event.c   | 3 ++-
>  trace2/tr2_tgt_normal.c  | 5 +++--
>  trace2/tr2_tgt_perf.c    | 5 +++--
>  5 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/t/t0210-trace2-normal.sh b/t/t0210-trace2-normal.sh
> index b9adc94aab4..4047ab562a4 100755
> --- a/t/t0210-trace2-normal.sh
> +++ b/t/t0210-trace2-normal.sh
> @@ -244,6 +244,14 @@ test_expect_success 'bug messages followed by BUG() are written to trace2' '
>  	test_cmp expect actual
>  '
>
> +test_expect_success 'empty configuration values are handled' '
> +  test_when_finished "rm trace2.normal actual expect" &&
> +  echo >expect &&
> +  GIT_TRACE2="$(pwd)/trace2.normal"  GIT_TRACE2_CONFIG_PARAMS=foo.empty \
> +	  git -c foo.empty config foo.empty >actual &&
> +	test_cmp expect actual
> +'
> +
>  sane_unset GIT_TRACE2_BRIEF
>
>  # Now test without environment variables and get all Trace2 settings
> diff --git a/trace2.c b/trace2.c
> index f894532d053..49e7d1db88f 100644
> --- a/trace2.c
> +++ b/trace2.c
> @@ -762,7 +762,7 @@ void trace2_def_param_fl(const char *file, int line, const char *param,
>  	if (!trace2_enabled)
>  		return;
>
> -	redacted = redact_arg(value);
> +	redacted = value ? redact_arg(value): NULL;
>
>  	for_each_wanted_builtin (j, tgt_j)
>  		if (tgt_j->pfn_param_fl)
> diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
> index 45b0850a5ec..8e09485c83c 100644
> --- a/trace2/tr2_tgt_event.c
> +++ b/trace2/tr2_tgt_event.c
> @@ -491,7 +491,8 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	event_fmt_prepare(event_name, file, line, NULL, &jw);
>  	jw_object_string(&jw, "scope", scope_name);
>  	jw_object_string(&jw, "param", param);
> -	jw_object_string(&jw, "value", value);
> +	if (value)
> +		jw_object_string(&jw, "value", value);
>  	jw_end(&jw);
>
>  	tr2_dst_write_line(&tr2dst_event, &jw.json);
> diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
> index baef48aa698..924736ab360 100644
> --- a/trace2/tr2_tgt_normal.c
> +++ b/trace2/tr2_tgt_normal.c
> @@ -307,8 +307,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	enum config_scope scope = kvi->scope;
>  	const char *scope_name = config_scope_name(scope);
>
> -	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
> -		    value);
> +	strbuf_addf(&buf_payload, "def_param scope:%s %s", scope_name, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, "=%s", value);
>  	normal_io_write_fl(file, line, &buf_payload);
>  	strbuf_release(&buf_payload);
>  }
> diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
> index a6f9a8a193e..19ae7433ef8 100644
> --- a/trace2/tr2_tgt_perf.c
> +++ b/trace2/tr2_tgt_perf.c
> @@ -446,8 +446,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>  	struct strbuf scope_payload = STRBUF_INIT;
>  	enum config_scope scope = kvi->scope;
>  	const char *scope_name = config_scope_name(scope);
> -
> -	strbuf_addf(&buf_payload, "%s:%s", param, value);
> +	strbuf_addstr(&buf_payload, param);
> +	if (value)
> +		strbuf_addf(&buf_payload, ":%s", value);
>  	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
>
>  	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,
>
> base-commit: 8f8d6eee531b3fa1a8ef14f169b0cb5035f7a772
> --
> gitgitgadget
>
>
Junio C Hamano· Jan 22, 2025, 18:12 UTC · re: Johannes Schindelin · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
> This patch looks good to me!

Thanks. As I punted on reviewing the tgt_perf part, it is very good to see somebody else step in to look it over.

Will queue.
Show 22 quoted lines
>> diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
>> index a6f9a8a193e..19ae7433ef8 100644
>> --- a/trace2/tr2_tgt_perf.c
>> +++ b/trace2/tr2_tgt_perf.c
>> @@ -446,8 +446,9 @@ static void fn_param_fl(const char *file, int line, const char *param,
>>  	struct strbuf scope_payload = STRBUF_INIT;
>>  	enum config_scope scope = kvi->scope;
>>  	const char *scope_name = config_scope_name(scope);
>> -
>> -	strbuf_addf(&buf_payload, "%s:%s", param, value);
>> +	strbuf_addstr(&buf_payload, param);
>> +	if (value)
>> +		strbuf_addf(&buf_payload, ":%s", value);
>>  	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
>>
>>  	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,
>>
>> base-commit: 8f8d6eee531b3fa1a8ef14f169b0cb5035f7a772
>> --
>> gitgitgadget
>>
>>
Junio C Hamano· Jan 22, 2025, 18:18 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

Junio C Hamano <gitster@pobox.com> writes:
Show 9 quoted lines
> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
>>
>> This patch looks good to me!
>
> Thanks.  As I punted on reviewing the tgt_perf part, it is very good
> to see somebody else step in to look it over.
>
> Will queue.

The test part used broken indentation and also the use of test_when_finished was careless, so I'll touch it up before queuing.

No need to resend.
Thanks.
D. Ben Knoble· Jan 23, 2025, 17:01 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

On Wed, Jan 22, 2025 at 1:18 PM Junio C Hamano <gitster@pobox.com> wrote:
Show 20 quoted lines
>
> Junio C Hamano <gitster@pobox.com> writes:
>
> > Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> >
> >>
> >> This patch looks good to me!
> >
> > Thanks.  As I punted on reviewing the tgt_perf part, it is very good
> > to see somebody else step in to look it over.
> >
> > Will queue.
>
> The test part used broken indentation and also the use of
> test_when_finished was careless, so I'll touch it up before queuing.
>
> No need to resend.
>
> Thanks.
>

I was curious what changed, so I found 792a3850fa (trace2: prevent segfault on config collection with valueless true, 2025-01-10) and I noticed this:

-       redacted = redact_arg(value);
+       redacted = value ? redact_arg(value): NULL;

I think I expected (based on Documentation/CodingGuidelines) a space before the ternary conditional's colon. Then again, "git grep '?.*[^ ]:' *.[ch]" finds a few other cases with the unspaced style.

-- 
D. Ben Knoble
Junio C Hamano· Jan 23, 2025, 18:02 UTC · re: D. Ben Knoble · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

"D. Ben Knoble" <ben.knoble@gmail.com> writes:
Show 6 quoted lines
> I was curious what changed, so I found 792a3850fa (trace2: prevent
> segfault on config collection with valueless true, 2025-01-10) and I
> noticed this:
>
> -       redacted = redact_arg(value);
> +       redacted = value ? redact_arg(value): NULL;

Oh, I do not think I tweaked any of the code, other than fixing the new test that was not properly formatted. Mostly I touched up the log message.

Will touch it up.  Thanks for a careful reading.
D. Ben Knoble· Jan 23, 2025, 21:15 UTC · re: Junio C Hamano · lore

Re: [PATCH v2] trace2: prevent segfault on config collection where no value specified

On Thu, Jan 23, 2025 at 1:02 PM Junio C Hamano <gitster@pobox.com> wrote:
Show 13 quoted lines
>
> "D. Ben Knoble" <ben.knoble@gmail.com> writes:
>
> > I was curious what changed, so I found 792a3850fa (trace2: prevent
> > segfault on config collection with valueless true, 2025-01-10) and I
> > noticed this:
> >
> > -       redacted = redact_arg(value);
> > +       redacted = value ? redact_arg(value): NULL;
>
> Oh, I do not think I tweaked any of the code, other than fixing the
> new test that was not properly formatted.  Mostly I touched up the
> log message.

I could have been clearer—I think this was in the original. I just happened to notice it because I was curious about what touch-ups you performed :)

-- 
D. Ben Knoble

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