From 54b77bb078333ecf576a6b59ba9b26354d855d09 Mon Sep 17 00:00:00 2001 From: Laurent Bercot Date: Wed, 18 Jan 2023 22:35:59 +0000 Subject: Add bytestr.h doc Signed-off-by: Laurent Bercot --- doc/libstddjb/bytestr.html | 237 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 236 insertions(+), 1 deletion(-) (limited to 'doc') diff --git a/doc/libstddjb/bytestr.html b/doc/libstddjb/bytestr.html index 8ae68aa..951712b 100644 --- a/doc/libstddjb/bytestr.html +++ b/doc/libstddjb/bytestr.html @@ -21,7 +21,242 @@

The skalibs/bytestr.h header

- TODO: write this documentation page. (Sorry!) + The following functions are declared in the skalibs/bytestr.h header +and implemented in the libskarnet.a or libskarnet.so library. +

+ +

Purpose

+ +

+ These functions handle arrays of bytes (strings). They are similar to their +counterparts from the standard + string.h +header, but they return indices instead of pointers. +

+ +

+ byte_* functions and macros work with strings that are not +necessarily null-terminated, but require sizes of the strings to be passed. +On the contary, str_* family accepts null-terminated strings. +case_* functions and macros are like their str_* counterparts, +but are case-insensitive. +

+ +

Functions

+ +

+ size_t byte_chr (char const *s, size_t n, int c)
+Looks for the first occurrence of byte c in array s of size +n. Returns its index, or n if there is no such byte in +s. +

+ +

+ size_t byte_rchr (char const *s, size_t n, int c)
+Looks for the last occurrence of byte c in array s of size +n. Returns its index, or n if there is no such byte in +s. +

+ +

+ size_t byte_in (char const *s, size_t n, char const *sep, size_t len)
+Looks for the first occurrence of any byte from array sep of size +len in array s of size n. Returns the index of such +an occurrence, or n if there are no bytes from sep in s. +

+ +

+ size_t byte_count (char const *s, size_t len, char b)
+Returns the amount of occurrences of byte b in string s of +size len. +

+ +

+ size_t byte_search (char const *haystack, size_t hlen, char const *needle, size_t nlen)
+Looks for the first occurrence of string needle of size nlen in +string haystack of size hlen. Returns the index of the first +byte of that occurrence, or hlen + 1 - nlen if needle cannot +be found in haystack. +

+ +

+ void byte_zzero (char *s, size_t n)
+Zeroes n bytes of memory beginning with address s. Special +measures are taken to prevent the compiler from optimizing out the call: +

+This is useful for erasing sensitive data before returning from some +function, typically in cryptography settings. Compilers usually remove +memset calls since these have no observable effect for the rest of the code. +

+ +

+ size_t str_chr (char const *s, int c)
+Looks for the first occurrence of byte c in null-terminated string +s. Returns the index of this occurrence, or the length of the string +if there is no such byte in s. +

+ +

+ size_t str_rchr (char const *s, int c)
+Looks for the last occurrence of byte c in null-terminated string +s. Returns the index of this occurrence, or the length of the string +if there is no such byte in s. +

+ +

+ int str_start (char const *s, char const *t)
+Returns 1 if (null-terminated) string s begins with (null-terminated) +string t, and 0 otherwise. +

+ +

+ size_t str_strn (char const *haystack, size_t hlen, char const *needle, size_t nlen)
+Looks for the first occurrence of string needle of size nlen in +string haystack of size hlen. Returns the index of the first +character in this occurrence, or hlen if needle is not present +in haystack. +

+ +

+ void case_lowers (char *s)
+Turns all capital letters in null-terminated string s into lowercase +letters. This function only works with ASCII symbols. +

+ +

+ void case_lowerb (char *s, size_t len)
+Turns all capital letters in string s of size len into +lowercase letters. This function only works with ASCII symbols. +

+ +

+ void case_uppers (char *s)
+Turns all lowercase letters in null-terminated string s into capital +letters. This function only works with ASCII symbols. +

+ +

+ void case_upperb (char *s, size_t len)
+Turns all lowercase letters in string s of size len into +capital letters. This function only works with ASCII symbols. +

+ +

+ int case_startb (char const *s, size_t slen, char const *t)
+Returns 1 if string s of size slen begins with +null-terminated string t, ignoring case, and 0 otherwise. +

+ +

+ size_t case_str (char const *haystack, char const *needle)
+Looks for the first occurrence of null-terminated string needle in +null-terminated string haystack, ignoring case while comparing +bytes. Returns the index of the first byte of this occurrence or the length of +haystack if needle is not presented in haystack. +

+ +

Macros

+ +

+These macros are either wrappers around functions described above or C standard +library functions. They only exist for compatibility purposes. Programmers are +expected to use the standard functions directly: in the rare case where a +standard function interface is good, it is best to use it. +

+ +

+ byte_copy(to, n, from)
+ byte_copyr(to, n, from)
+Same as memmove(to, from, n). +

+ +

+ byte_diff(a, n, b)
+Same as memcmp(a, b, n). +

+ +

+ byte_zero(p, n)
+Same as memset(p, 0 ,n). There is a caveat in zeroing memory range with +memset — compiler may omit the call to memset if it is +called in the end of function. If you need to destroy sensitive data, use +byte_zzero instead. +

+ +

+ str_len(s)
+Same as strlen(s). +

+ +

+ str_nlen(s)
+Same as strnlen(s). +

+ +

+ str_diff(s1, s2)
+Same as strcmp(s1, s2). +

+ +

+ str_diffn(s1, s2, n)
+Same as strncmp(s1, s2, n). +

+ +

+ str_copy(to, from)
+Copies null-terminated string from, including null terminator, to +buffer to. Returns the length of the string. +

+ +

+ case_diffs(s1, s2)
+Same as strcasecmp(s1, s2). +

+ +

+ case_diffn(s1, s2, n)
+Same as strcasecmp(s1, s2, n). +

+ +

+ byte_equal(s, n, t)
+Same as !memcmp(s, t, n). +

+ +

+ str_diffb(a, n, b)
+Same as strncmp(a, b, n). +

+ +

+ str_equal(s, t)
+Same as !strcmp(s, t). +

+ +

+ case_diffb(a, n, b)
+Same as strncasecmp(a, b, n). +

+ +

+ case_equals(a, b)
+Same as !strcasecmp(a, b). +

+ +

+ case_equalb(a, n, b)
+Same as !strncasecmp(a, b, n). +

+ +

+ case_starts(s, t)
+Same as case_startb(s, strlen(s), t).

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