[sheepdog] [PATCH] add helper to get a self path

[Liu Yuan]

On Fri, Aug 30, 2013 at 11:05:18PM +0900, MORITA Kazutaka wrote:
> From: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
> 
> Signed-off-by: MORITA Kazutaka <morita.kazutaka at lab.ntt.co.jp>
> ---
>  include/util.h      |    1 +
>  lib/logger.c        |   25 ++++++-------------------
>  lib/util.c          |   14 ++++++++++++++
>  sheep/trace/trace.c |    5 +----
>  4 files changed, 22 insertions(+), 23 deletions(-)
> 
> diff --git a/include/util.h b/include/util.h
> index ace763b..20ec104 100644
> --- a/include/util.h
> +++ b/include/util.h
> @@ -113,6 +113,7 @@ void reraise_crash_signal(int signo, int status);
>  pid_t gettid(void);
>  int tkill(int tid, int sig);
>  bool is_xattr_enabled(const char *path);
> +const char *get_self_path(void);
>  
>  void find_zero_blocks(const void *buf, uint64_t *poffset, uint32_t *plen);
>  void trim_zero_blocks(void *buf, uint64_t *offset, uint32_t *len);
> diff --git a/lib/logger.c b/lib/logger.c
> index 1a31314..9685c8d 100644
> --- a/lib/logger.c
> +++ b/lib/logger.c
> @@ -668,14 +668,6 @@ void get_thread_name(char *name)
>  
>  #define SD_MAX_STACK_DEPTH 1024
>  
> -static int get_my_path(char *path, size_t size)
> -{
> -	/* readlink doesn't append '\0', so initialize here */
> -	memset(path, 0, size);
> -
> -	return readlink("/proc/self/exe", path, size);
> -}
> -
>  static bool check_gdb(void)
>  {
>  	return system("which gdb > /dev/null") == 0;
> @@ -683,7 +675,7 @@ static bool check_gdb(void)
>  
>  static int gdb_cmd(const char *cmd)
>  {
> -	char path[PATH_MAX], time_str[256], cmd_str[ARG_MAX];
> +	char time_str[256], cmd_str[ARG_MAX];
>  	time_t ti;
>  	struct tm tm;
>  
> @@ -692,9 +684,6 @@ static int gdb_cmd(const char *cmd)
>  		return -1;
>  	}
>  
> -	if (get_my_path(path, sizeof(path)) < 0)
> -		return -1;
> -
>  	time(&ti);
>  	localtime_r(&ti, &tm);
>  	strftime(time_str, sizeof(time_str), "%b %2d %H:%M:%S ", &tm);
> @@ -710,7 +699,8 @@ static int gdb_cmd(const char *cmd)
>  		 " -ex 'echo ==\\n'"
>  		 " -ex '%s'"
>  		 " -ex 'set logging off'",
> -		 path, getpid(), time_str, path, cmd, cmd);
> +		 get_self_path(), getpid(), time_str, get_self_path(), cmd,
> +		 cmd);
>  
>  	return system(cmd_str);
>  }
> @@ -737,7 +727,7 @@ void sd_backtrace(void)
>  
>  	for (i = 1; i < n; i++) { /* addrs[0] is here, so skip it */
>  		void *addr = addrs[i];
> -		char cmd[ARG_MAX], path[PATH_MAX], info[256], **str;
> +		char cmd[ARG_MAX], info[256], **str;
>  		FILE *f;
>  
>  		/*
> @@ -747,12 +737,9 @@ void sd_backtrace(void)
>  		addr = (void *)((char *)addr - 1);
>  
>  		/* try to get a line number with addr2line if possible */
> -		if (get_my_path(path, sizeof(path)) < 0)
> -			goto fallback;
> -
>  		snprintf(cmd, sizeof(cmd), "addr2line -s -e %s -f -i %p | "
> -			"perl -e '@a=<>; chomp @a; print \"$a[1]: $a[0]\"'",
> -			path, addr);
> +			 "perl -e '@a=<>; chomp @a; print \"$a[1]: $a[0]\"'",
> +			 get_self_path(), addr);
>  		f = popen(cmd, "r");
>  		if (!f)
>  			goto fallback;
> diff --git a/lib/util.c b/lib/util.c
> index 346b6bd..135c57f 100644
> --- a/lib/util.c
> +++ b/lib/util.c
> @@ -558,6 +558,20 @@ bool is_xattr_enabled(const char *path)
>  	return !(ret == -1 && errno == ENOTSUP);
>  }
>  
> +const char *get_self_path(void)
> +{
> +	static __thread char path[PATH_MAX];
> +	int ret;
> +
> +	if (path[0] == '\0') {
> +		ret = readlink("/proc/self/exe", path, sizeof(path));
> +		if (ret < -1)
> +			panic("%m");
> +	}
> +
> +	return path;
> +}
> +
>  /*
>   * If force_create is true, this function create the file even when the
>   * temporary file exists.
> diff --git a/sheep/trace/trace.c b/sheep/trace/trace.c
> index 1d3007b..9e2e94c 100644
> --- a/sheep/trace/trace.c
> +++ b/sheep/trace/trace.c
> @@ -311,12 +311,9 @@ static unsigned long find_mcount_call(unsigned long entry_addr)
>  
>  static bfd *get_bfd(void)
>  {
> -	char fname[PATH_MAX] = {0};
> +	const char *fname = get_self_path();

my_exe_path() looks better.

Thanks
Yuan