Dear York Sun,
In message 1357323245-12455-6-git-send-email-yorksun@freescale.com you wrote:
From: James Yang James.Yang@freescale.com
getenv_f() searches the environment for a variable name and copies the value of the variable to a buffer pointed to by one of the function's parameters. However, this means that the buffer needs to exist and needs to be of sufficient length (passed as another parameter to getenv_f()) to hold the requested variable's value, even if all that is desired is the mere detection of the existence of the variable itself.
This patch removes the requirement that the buffer needs to exist. If the pointer to the buffer is set to NULL and the requested variable is
Hm... this adds a special case and as such increases complexity - and what is the benefit for you?
In your code, you use this feature exactly once, which means all you save is a single buffer on the stack of a function that does not appear to be critical in terms of stack size.
/*
- Look up variable from environment for restricted C runtime env.
- If the variable is found, return the number of bytes copied.
- If buf is NULL, len is ignored, and, if the variable is found, return 1.
- If the variable is not found, return -1.
I think your description is not quite correct, and I dislike the inconsistent behaviour we get though your patch. So far, this function returns the length of the variable value, or -1 in case of errors. This should not change even if we implement the suggested feature, i. e. even when passing NULL as buffer pointer the function should still return the length, and not some unrelated result.
/* found */if (!buf)return 1;
I tend to NAK this part.
Best regards,
Wolfgang Denk