[Pam-developers] [PATCH 03/33] Introduce pam_str_skip_prefix_len and pam_str_skip_prefix

Every time I see a code like if (!strncmp(*argv,"user_readenv=",13)) *user_readenv = atoi(13+*argv); my eyes are bleeding. Introduce a new helper inline function pam_str_skip_prefix_len() and a new macro pam_str_skip_prefix() on top of it, to be used in subsequent commits to cleanup the ugliness. * libpam/include/pam_inline.h: Include <string.h>. (pam_str_skip_prefix_len): New function. (pam_str_skip_prefix): New macro. --- libpam/include/pam_inline.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/libpam/include/pam_inline.h b/libpam/include/pam_inline.h index ac7f5c44..e901b332 100644 --- a/libpam/include/pam_inline.h +++ b/libpam/include/pam_inline.h @@ -9,6 +9,7 @@ #define PAM_INLINE_H #include "pam_cc_compat.h" +#include <string.h> /* * Evaluates to @@ -27,4 +28,18 @@ /* Evaluates to the number of elements in the specified array. */ #define PAM_ARRAY_SIZE(a_) (sizeof(a_) / sizeof((a_)[0]) + PAM_MUST_BE_ARRAY(a_)) +/* + * Returns NULL if STR does not start with PREFIX, + * or a pointer to the first char in STR after PREFIX. + * The length of PREFIX is specified by PREFIX_LEN. + */ +static inline const char * +pam_str_skip_prefix_len(const char *str, const char *prefix, size_t prefix_len) +{ + return strncmp(str, prefix, prefix_len) ? NULL : str + prefix_len; +} + +#define pam_str_skip_prefix(str_, prefix_) \ + pam_str_skip_prefix_len((str_), (prefix_), sizeof(prefix_) - 1 + PAM_MUST_BE_ARRAY(prefix_)) + #endif /* PAM_INLINE_H */ -- ldv