Subject: Re: [PATCH] remote-testsvn: use internal argv_array of struct child_process in cmd_import()

From: René Scharfe <[email-masked]>
Date: Fri, 18 Jul 2014 21:30:13 +0200

Am 18.07.2014 21:10, schrieb Junio C Hamano:
> René Scharfe <[email-masked]> writes:
> 
>> Use the existing argv_array member instead of providing our own.  This
>> way we don't have to initialize or clean it up explicitly.
>>
>> Signed-off-by: Rene Scharfe <[email-masked]>
>> ---
> 
> The change below looks so trivial and I cannot offhand see why it
> would break t9020 in a reproducible way.
> 
> Puzzled...
> 
>>   remote-testsvn.c | 11 ++++-------
>>   1 file changed, 4 insertions(+), 7 deletions(-)
>>
>> diff --git a/remote-testsvn.c b/remote-testsvn.c
>> index 6be55cb..31415bd 100644
>> --- a/remote-testsvn.c
>> +++ b/remote-testsvn.c
>> @@ -175,7 +175,6 @@ static int cmd_import(const char *line)
>>   	char *note_msg;
>>   	unsigned char head_sha1[20];
>>   	unsigned int startrev;
>> -	struct argv_array svndump_argv = ARGV_ARRAY_INIT;
>>   	struct child_process svndump_proc;
>>   
>>   	if (read_ref(private_ref, head_sha1))
>> @@ -202,11 +201,10 @@ static int cmd_import(const char *line)
>>   	} else {
>>   		memset(&svndump_proc, 0, sizeof(struct child_process));
>>   		svndump_proc.out = -1;
>> -		argv_array_push(&svndump_argv, "svnrdump");
>> -		argv_array_push(&svndump_argv, "dump");
>> -		argv_array_push(&svndump_argv, url);
>> -		argv_array_pushf(&svndump_argv, "-r%u:HEAD", startrev);
>> -		svndump_proc.argv = svndump_argv.argv;
>> +		argv_array_push(&svndump_proc.args, "svnrdump");
>> +		argv_array_push(&svndump_proc.args, "dump");
>> +		argv_array_push(&svndump_proc.args, url);
>> +		argv_array_pushf(&svndump_proc.args, "-r%u:HEAD", startrev);
>>   
>>   		code = start_command(&svndump_proc);
>>   		if (code)
>> @@ -227,7 +225,6 @@ static int cmd_import(const char *line)
>>   		code = finish_command(&svndump_proc);
>>   		if (code)
>>   			warning("%s, returned %d", svndump_proc.argv[0], code);
>> -		argv_array_clear(&svndump_argv);

Unfortunately I don't get a test failure, but I think I see what's
wrong: The warning line above references the argv array after it was
freed by finish_command.  Ouch.  Fixup below:

---
 remote-testsvn.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/remote-testsvn.c b/remote-testsvn.c
index 31415bd..e3ad11b 100644
--- a/remote-testsvn.c
+++ b/remote-testsvn.c
@@ -176,6 +176,7 @@ static int cmd_import(const char *line)
 	unsigned char head_sha1[20];
 	unsigned int startrev;
 	struct child_process svndump_proc;
+	const char *command;
 
 	if (read_ref(private_ref, head_sha1))
 		startrev = 0;
@@ -199,16 +200,17 @@ static int cmd_import(const char *line)
 		if(dumpin_fd < 0)
 			die_errno("Couldn't open svn dump file %s.", url);
 	} else {
+		command = "svnrdump";
 		memset(&svndump_proc, 0, sizeof(struct child_process));
 		svndump_proc.out = -1;
-		argv_array_push(&svndump_proc.args, "svnrdump");
+		argv_array_push(&svndump_proc.args, command);
 		argv_array_push(&svndump_proc.args, "dump");
 		argv_array_push(&svndump_proc.args, url);
 		argv_array_pushf(&svndump_proc.args, "-r%u:HEAD", startrev);
 
 		code = start_command(&svndump_proc);
 		if (code)
-			die("Unable to start %s, code %d", svndump_proc.argv[0], code);
+			die("Unable to start %s, code %d", command, code);
 		dumpin_fd = svndump_proc.out;
 	}
 	/* setup marks file import/export */
@@ -224,7 +226,7 @@ static int cmd_import(const char *line)
 	if (!dump_from_file) {
 		code = finish_command(&svndump_proc);
 		if (code)
-			warning("%s, returned %d", svndump_proc.argv[0], code);
+			warning("%s, returned %d", command, code);
 	}
 
 	return 0;
-- 
2.0.2