blob: c57aa8977a45726c1aa88639d28b89dc56cd43d9 [file] [log] [blame]
/*
* include/common/ist.h
* Very simple indirect string manipulation functions.
*
* Copyright (C) 2014-2017 Willy Tarreau - w@1wt.eu
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#ifndef _COMMON_IST_H
#define _COMMON_IST_H
#include <string.h>
#include <common/config.h>
/* This string definition will most often be used to represent a read-only
* string returned from a function, based on the starting point and its length
* in bytes. No storage is provided, only a pointer and a length. The types
* here are important as we only want to have 2 native machine words there so
* that on modern architectures the compiler is capable of efficiently
* returning a register pair without having to allocate stack room from the
* caller. This is done with -freg-struct which is often enabled by default.
*/
struct ist {
char *ptr;
size_t len;
};
/* makes a constant ist from a constant string, for use in array declarations */
#define IST(str) { .ptr = str "", .len = (sizeof str "") - 1 }
/* makes an ist from a regular zero terminated string. Null has length 0.
* Constants are detected and replaced with constant initializers. Other values
* are measured by hand without strlen() as it's much cheaper and inlinable on
* small strings. The construct is complex because we must never call
* __builtin_strlen() with an expression otherwise it involves a real
* measurement.
*/
#if __GNUC__ >= 4
// gcc >= 4 detects constant propagation of str through __x and resolves the
// length of constant strings easily.
#define ist(str) ({ \
char *__x = (void *)(str); \
(struct ist){ \
.ptr = __x, \
.len = __builtin_constant_p(str) ? \
((void *)str == (void *)0) ? 0 : \
__builtin_strlen(__x) : \
({ \
size_t __l = 0; \
if (__x) for (__l--; __x[++__l]; ) ; \
__l; \
}) \
}; \
})
#else
// gcc < 4 can't do this, and the side effect is a warning each time a NULL is
// passed to ist() due to the check on __builtin_strlen(). It doesn't have the
// ability to know that this code is never called.
#define ist(str) ({ \
char *__x = (void *)(str); \
(struct ist){ \
.ptr = __x, \
.len = __builtin_constant_p(str) ? \
((void *)str == (void *)0) ? 0 : \
__builtin_strlen(str) : \
({ \
size_t __l = 0; \
if (__x) for (__l--; __x[++__l]; ) ; \
__l; \
}) \
}; \
})
#endif
/* makes an ist struct from a string and a length */
static inline struct ist ist2(const void *ptr, size_t len)
{
return (struct ist){ .ptr = (char *)ptr, .len = len };
}
/* returns the length of the string */
static inline size_t istlen(const struct ist ist)
{
return ist.len;
}
/* skips to next character in the string, always stops at the end */
static inline struct ist istnext(const struct ist ist)
{
struct ist ret = ist;
if (ret.len) {
ret.len--;
ret.ptr++;
}
return ret;
}
/* copies the contents from string <ist> to buffer <buf> and adds a trailing
* zero. The caller must ensure <buf> is large enough.
*/
static inline struct ist istpad(void *buf, const struct ist ist)
{
struct ist ret = { .ptr = buf, .len = ist.len };
for (ret.len = 0; ret.len < ist.len; ret.len++)
ret.ptr[ret.len] = ist.ptr[ret.len];
ret.ptr[ret.len] = 0;
return ret;
}
/* trims string <ist> to no more than <size> characters. The string is
* returned.
*/
static inline struct ist isttrim(const struct ist ist, size_t size)
{
struct ist ret = ist;
if (ret.len > size)
ret.len = size;
return ret;
}
/* trims string <ist> to no more than <size>-1 characters and ensures that a
* zero is placed after <ist.len> (possibly reduced by one) and before <size>,
* unless <size> is already zero. The string is returned. This is mostly aimed
* at building printable strings that need to be zero-terminated.
*/
static inline struct ist istzero(const struct ist ist, size_t size)
{
struct ist ret = ist;
if (!size)
ret.len = 0;
else {
if (ret.len > size - 1)
ret.len = size - 1;
ret.ptr[ret.len] = 0;
}
return ret;
}
/* returns the ordinal difference between two strings :
* < 0 if ist1 < ist2
* = 0 if ist1 == ist2
* > 0 if ist1 > ist2
*/
static inline int istdiff(const struct ist ist1, const struct ist ist2)
{
struct ist l = ist1;
struct ist r = ist2;
do {
if (!l.len--)
return -r.len;
if (!r.len--)
return 1;
} while (*l.ptr++ == *r.ptr++);
return *(unsigned char *)(l.ptr - 1) - *(unsigned char *)(r.ptr - 1);
}
/* returns non-zero if <ist1> starts like <ist2> (empty strings do match) */
static inline int istmatch(const struct ist ist1, const struct ist ist2)
{
struct ist l = ist1;
struct ist r = ist2;
if (l.len < r.len)
return 0;
while (r.len--) {
if (*l.ptr++ != *r.ptr++)
return 0;
}
return 1;
}
/* returns non-zero if <ist1> starts like <ist2> on the first <count>
* characters (empty strings do match).
*/
static inline int istnmatch(const struct ist ist1, const struct ist ist2, size_t count)
{
struct ist l = ist1;
struct ist r = ist2;
if (l.len > count)
l.len = count;
if (r.len > count)
r.len = count;
return istmatch(l, r);
}
/* returns non-zero if <ist1> equals <ist2> (empty strings are equal) */
static inline int isteq(const struct ist ist1, const struct ist ist2)
{
struct ist l = ist1;
struct ist r = ist2;
if (l.len != r.len)
return 0;
while (l.len--) {
if (*l.ptr++ != *r.ptr++)
return 0;
}
return 1;
}
/* returns non-zero if <ist1> equals <ist2> on the first <count> characters
* (empty strings are equal).
*/
static inline int istneq(const struct ist ist1, const struct ist ist2, size_t count)
{
struct ist l = ist1;
struct ist r = ist2;
if (l.len > count)
l.len = count;
if (r.len > count)
r.len = count;
return isteq(l, r);
}
/* copies <src> over <dst> for a maximum of <count> bytes. Returns the number
* of characters copied (src.len), or -1 if it does not fit. In all cases, the
* contents are copied prior to reporting an error, so that the destination
* at least contains a valid but truncated string.
*/
static inline ssize_t istcpy(struct ist *dst, const struct ist src, size_t count)
{
dst->len = 0;
if (count > src.len)
count = src.len;
while (dst->len < count) {
dst->ptr[dst->len] = src.ptr[dst->len];
dst->len++;
}
if (dst->len == src.len)
return src.len;
return -1;
}
/* copies <src> over <dst> for a maximum of <count> bytes. Returns the number
* of characters copied, or -1 if it does not fit. A (possibly truncated) valid
* copy of <src> is always left into <dst>, and a trailing \0 is appended as
* long as <count> is not null, even if that results in reducing the string by
* one character.
*/
static inline ssize_t istscpy(struct ist *dst, const struct ist src, size_t count)
{
dst->len = 0;
if (!count)
goto fail;
if (count > src.len)
count = src.len + 1;
while (dst->len < count - 1) {
dst->ptr[dst->len] = src.ptr[dst->len];
dst->len++;
}
dst->ptr[dst->len] = 0;
if (dst->len == src.len)
return src.len;
fail:
return -1;
}
/* appends <src> after <dst> for a maximum of <count> total bytes in <dst> after
* the copy. <dst> is assumed to be <count> or less before the call. The new
* string's length is returned, or -1 if a truncation happened. In all cases,
* the contents are copied prior to reporting an error, so that the destination
* at least contains a valid but truncated string.
*/
static inline ssize_t istcat(struct ist *dst, const struct ist src, size_t count)
{
const char *s = src.ptr;
while (dst->len < count && s != src.ptr + src.len)
dst->ptr[dst->len++] = *s++;
if (s == src.ptr + src.len)
return dst->len;
return -1;
}
/* appends <src> after <dst> for a maximum of <count> total bytes in <dst> after
* the copy. <dst> is assumed to be <count> or less before the call. The new
* string's length is returned, or -1 if a truncation happened. In all cases,
* the contents are copied prior to reporting an error, so that the destination
* at least contains a valid but truncated string.
*/
static inline ssize_t istscat(struct ist *dst, const struct ist src, size_t count)
{
const char *s = src.ptr;
if (!count)
goto fail;
while (dst->len < count - 1 && s != src.ptr + src.len) {
dst->ptr[dst->len++] = *s++;
}
dst->ptr[dst->len] = 0;
if (s == src.ptr + src.len)
return dst->len;
fail:
return -1;
}
/* looks for first occurrence of character <chr> in string <ist>. Returns the
* pointer if found, or NULL if not found.
*/
static inline char *istchr(const struct ist ist, char chr)
{
char *s = ist.ptr;
do {
if (s >= ist.ptr + ist.len)
return NULL;
} while (*s++ != chr);
return s - 1;
}
/* looks for first occurrence of character <chr> in string <ist> and returns
* the tail of the string starting with this character, or (ist.end,0) if not
* found.
*/
static inline struct ist istfind(const struct ist ist, char chr)
{
struct ist ret = ist;
while (ret.len--) {
if (*ret.ptr++ == chr)
return ist2(ret.ptr - 1, ret.len + 1);
}
return ist2(ret.ptr, 0);
}
/* looks for first occurrence of character different from <chr> in string <ist>
* and returns the tail of the string starting at this character, or (ist_end,0)
* if not found.
*/
static inline struct ist istskip(const struct ist ist, char chr)
{
struct ist ret = ist;
while (ret.len--) {
if (*ret.ptr++ != chr)
return ist2(ret.ptr - 1, ret.len + 1);
}
return ist2(ret.ptr, 0);
}
/* looks for first occurrence of string <pat> in string <ist> and returns the
* tail of the string starting at this position, or (NULL,0) if not found. The
* empty pattern is found everywhere.
*/
static inline struct ist istist(const struct ist ist, const struct ist pat)
{
struct ist ret = ist;
size_t pos;
if (!pat.len)
return ret;
while (1) {
loop:
ret = istfind(ret, *pat.ptr);
if (ret.len < pat.len)
break;
/* ret.len >= 1, pat.len >= 1 and *ret.ptr == *pat.ptr */
ret = istnext(ret);
for (pos = 0; pos < pat.len - 1; ) {
++pos;
if (ret.ptr[pos - 1] != pat.ptr[pos])
goto loop;
}
return ist2(ret.ptr - 1, ret.len + 1);
}
return ist2(NULL, 0);
}
#endif