Subject: Re: [PATCH] exec_cmd: system_path memory leak fix

From: 0xAX <[email-masked]>
Date: Sun, 23 Nov 2014 20:01:39 +0600

For example some testing with valgrind:

1. pu (952f0aaadff4afca1497450911587a973c8cca02)

valgrind git help
==27034== Memcheck, a memory error detector
==27034== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==27034== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==27034== Command: git help
==27034==
==27034== HERE GIT HELP OUTPUT
==27034==
==27034== HEAP SUMMARY:
==27034==     in use at exit: 65 bytes in 1 blocks
==27034==   total heap usage: 71 allocs, 70 frees, 11,928 bytes allocated
==27034==
==27034== LEAK SUMMARY:
==27034==    definitely lost: 65 bytes in 1 blocks
==27034==    indirectly lost: 0 bytes in 0 blocks
==27034==      possibly lost: 0 bytes in 0 blocks
==27034==    still reachable: 0 bytes in 0 blocks
==27034==         suppressed: 0 bytes in 0 blocks
==27034== Rerun with --leak-check=full to see details of leaked memory
==27034==
==27034== For counts of detected and suppressed errors, rerun with: -v
==27034== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

2. With patch:

valgrind git help
==28945== Memcheck, a memory error detector
==28945== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==28945== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info
==28945== Command: git help
==28945==
==28945== HERE git help OUTPUT
==28945==
==28945== HEAP SUMMARY:
==28945==     in use at exit: 0 bytes in 0 blocks
==28945==   total heap usage: 72 allocs, 72 frees, 11,956 bytes allocated
==28945==
==28945== All heap blocks were freed -- no leaks are possible
==28945==
==28945== For counts of detected and suppressed errors, rerun with: -v
==28945== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Of course it is very small leak, but i just started to deep in git
source code. Hope i will be useful for community.

Thank you.

0xAX <[email-masked]> @ 2014-11-23 19:56 ALMT:

> Signed-off-by: 0xAX <[email-masked]>
> ---
>  exec_cmd.c | 25 ++++++++++++++++---------
>  exec_cmd.h |  4 ++--
>  git.c      | 12 +++++++++---
>  3 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/exec_cmd.c b/exec_cmd.c
> index 698e752..08f8f80 100644
> --- a/exec_cmd.c
> +++ b/exec_cmd.c
> @@ -6,7 +6,7 @@
>  static const char *argv_exec_path;
>  static const char *argv0_path;
>
> -const char *system_path(const char *path)
> +char *system_path(const char *path)
>  {
>  #ifdef RUNTIME_PREFIX
>  	static const char *prefix;
> @@ -14,9 +14,10 @@ const char *system_path(const char *path)
>  	static const char *prefix = PREFIX;
>  #endif
>  	struct strbuf d = STRBUF_INIT;
> +	char *new_path = NULL;
>
>  	if (is_absolute_path(path))
> -		return path;
> +		return strdup(path);
>
>  #ifdef RUNTIME_PREFIX
>  	assert(argv0_path);
> @@ -32,10 +33,13 @@ const char *system_path(const char *path)
>  				"Using static fallback '%s'.\n", prefix);
>  	}
>  #endif
> -
>  	strbuf_addf(&d, "%s/%s", prefix, path);
> -	path = strbuf_detach(&d, NULL);
> -	return path;
> +	new_path = malloc((strlen(prefix) + strlen(path)) + 2);
> +	sprintf(new_path, "%s/%s", prefix, path);
> +
> +	strbuf_release(&d);
> +
> +	return new_path;
>  }
>
>  const char *git_extract_argv0_path(const char *argv0)
> @@ -68,16 +72,16 @@ void git_set_argv_exec_path(const char *exec_path)
>
>
>  /* Returns the highest-priority, location to look for git programs. */
> -const char *git_exec_path(void)
> +char *git_exec_path(void)
>  {
>  	const char *env;
>
>  	if (argv_exec_path)
> -		return argv_exec_path;
> +		return strdup(argv_exec_path);
>
>  	env = getenv(EXEC_PATH_ENVIRONMENT);
>  	if (env && *env) {
> -		return env;
> +		return strdup(env);
>  	}
>
>  	return system_path(GIT_EXEC_PATH);
> @@ -96,7 +100,9 @@ void setup_path(void)
>  	const char *old_path = getenv("PATH");
>  	struct strbuf new_path = STRBUF_INIT;
>
> -	add_path(&new_path, git_exec_path());
> +	char *exec_path = git_exec_path();
> +
> +	add_path(&new_path, exec_path);
>  	add_path(&new_path, argv0_path);
>
>  	if (old_path)
> @@ -107,6 +113,7 @@ void setup_path(void)
>  	setenv("PATH", new_path.buf, 1);
>
>  	strbuf_release(&new_path);
> +	free(exec_path);
>  }
>
>  const char **prepare_git_cmd(const char **argv)
> diff --git a/exec_cmd.h b/exec_cmd.h
> index e4c9702..03c8599 100644
> --- a/exec_cmd.h
> +++ b/exec_cmd.h
> @@ -3,12 +3,12 @@
>
>  extern void git_set_argv_exec_path(const char *exec_path);
>  extern const char *git_extract_argv0_path(const char *path);
> -extern const char *git_exec_path(void);
> +extern char *git_exec_path(void);
>  extern void setup_path(void);
>  extern const char **prepare_git_cmd(const char **argv);
>  extern int execv_git_cmd(const char **argv); /* NULL terminated */
>  LAST_ARG_MUST_BE_NULL
>  extern int execl_git_cmd(const char *cmd, ...);
> -extern const char *system_path(const char *path);
> +extern char *system_path(const char *path);
>
>  #endif /* GIT_EXEC_CMD_H */
> diff --git a/git.c b/git.c
> index 82d7a1c..499dc2a 100644
> --- a/git.c
> +++ b/git.c
> @@ -99,13 +99,19 @@ static int handle_options(const char ***argv, int *argc, int *envchanged)
>  				exit(0);
>  			}
>  		} else if (!strcmp(cmd, "--html-path")) {
> -			puts(system_path(GIT_HTML_PATH));
> +			char *git_html_path = system_path(GIT_HTML_PATH);
> +			puts(git_html_path);
> +			free(git_html_path);
>  			exit(0);
>  		} else if (!strcmp(cmd, "--man-path")) {
> -			puts(system_path(GIT_MAN_PATH));
> +			char *git_man_path = system_path(GIT_MAN_PATH);
> +			puts(git_man_path);
> +			free(git_man_path);
>  			exit(0);
>  		} else if (!strcmp(cmd, "--info-path")) {
> -			puts(system_path(GIT_INFO_PATH));
> +			char *git_info_path = system_path(GIT_INFO_PATH);
> +			puts(git_info_path);
> +			free(git_info_path);
>  			exit(0);
>  		} else if (!strcmp(cmd, "-p") || !strcmp(cmd, "--paginate")) {
>  			use_pager = 1;

--
Best regards.
0xAX