[systemd-devel] [PATCH] core: avoid needless strdup by working with strings directly

[Colin Guthrie]

'Twas brillig, and Shawn Landden at 16/08/12 02:13 did gyre and gimble:
> ---
>  src/core/main.c |   51 ++++++++++++++++++++++-----------------------------
>  1 file changed, 22 insertions(+), 29 deletions(-)
> 
> diff --git a/src/core/main.c b/src/core/main.c
> index cdd77c1..e9b656b 100644
> --- a/src/core/main.c
> +++ b/src/core/main.c
> @@ -339,12 +339,11 @@ static int parse_proc_cmdline_word(const char *word) {
>                  else
>                          arg_default_std_error = r;
>          } else if (startswith(word, "systemd.setenv=")) {
> -                char *cenv, *eq;
> +                const char *cenv;
> +                char *eq;
>                  int r;
>  
> -                cenv = strdup(word + 15);
> -                if (!cenv)
> -                        return -ENOMEM;
> +                cenv = word + 15;
>  
>                  eq = strchr(cenv, '=');
>                  if (!eq) {
> @@ -352,12 +351,12 @@ static int parse_proc_cmdline_word(const char *word) {
>                          if (r < 0)
>                                  log_warning("unsetenv failed %m. Ignoring.");
>                  } else {
> -                        *eq = 0;
> +                        *eq = '\0';

If I am reading this correctly, you're modifying eq's value here, which
means you're modifying word, which is a const char *. I know you change
it back later, but if the complier puts this data in a read only page,
you'll still get a segv so you simply cannot do this.

I've not looked through the rest of the patch, but it might be subject
to the same issues.

Col





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Colin Guthrie
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http://colin.guthr.ie/

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