376 lines
8.9 KiB
C
376 lines
8.9 KiB
C
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#include <string.h>
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#include <debug.h>
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/* Copies SIZE bytes from SRC to DST, which must not overlap.
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Returns DST. */
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void *
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memcpy (void *dst_, const void *src_, size_t size)
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{
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unsigned char *dst = dst_;
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const unsigned char *src = src_;
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ASSERT (dst != NULL || size == 0);
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ASSERT (src != NULL || size == 0);
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while (size-- > 0)
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*dst++ = *src++;
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return dst_;
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}
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/* Copies SIZE bytes from SRC to DST, which are allowed to
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overlap. Returns DST. */
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void *
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memmove (void *dst_, const void *src_, size_t size)
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{
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unsigned char *dst = dst_;
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const unsigned char *src = src_;
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ASSERT (dst != NULL || size == 0);
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ASSERT (src != NULL || size == 0);
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if (dst < src)
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{
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while (size-- > 0)
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*dst++ = *src++;
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}
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else
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{
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dst += size;
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src += size;
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while (size-- > 0)
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*--dst = *--src;
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}
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return dst;
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}
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/* Find the first differing byte in the two blocks of SIZE bytes
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at A and B. Returns a positive value if the byte in A is
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greater, a negative value if the byte in B is greater, or zero
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if blocks A and B are equal. */
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int
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memcmp (const void *a_, const void *b_, size_t size)
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{
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const unsigned char *a = a_;
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const unsigned char *b = b_;
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ASSERT (a != NULL || size == 0);
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ASSERT (b != NULL || size == 0);
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for (; size-- > 0; a++, b++)
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if (*a != *b)
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return *a > *b ? +1 : -1;
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return 0;
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}
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/* Finds the first differing characters in strings A and B.
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Returns a positive value if the character in A (as an unsigned
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char) is greater, a negative value if the character in B (as
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an unsigned char) is greater, or zero if strings A and B are
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equal. */
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int
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strcmp (const char *a_, const char *b_)
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{
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const unsigned char *a = (const unsigned char *) a_;
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const unsigned char *b = (const unsigned char *) b_;
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ASSERT (a != NULL);
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ASSERT (b != NULL);
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while (*a != '\0' && *a == *b)
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{
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a++;
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b++;
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}
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return *a < *b ? -1 : *a > *b;
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}
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/* Returns a pointer to the first occurrence of CH in the first
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SIZE bytes starting at BLOCK. Returns a null pointer if CH
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does not occur in BLOCK. */
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void *
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memchr (const void *block_, int ch_, size_t size)
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{
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const unsigned char *block = block_;
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unsigned char ch = ch_;
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ASSERT (block != NULL || size == 0);
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for (; size-- > 0; block++)
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if (*block == ch)
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return (void *) block;
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return NULL;
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}
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/* Finds and returns the first occurrence of C in STRING, or a
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null pointer if C does not appear in STRING. If C == '\0'
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then returns a pointer to the null terminator at the end of
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STRING. */
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char *
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strchr (const char *string, int c_)
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{
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char c = c_;
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ASSERT (string != NULL);
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for (;;)
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if (*string == c)
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return (char *) string;
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else if (*string == '\0')
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return NULL;
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else
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string++;
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}
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/* Returns the length of the initial substring of STRING that
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consists of characters that are not in STOP. */
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size_t
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strcspn (const char *string, const char *stop)
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{
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size_t length;
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for (length = 0; string[length] != '\0'; length++)
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if (strchr (stop, string[length]) != NULL)
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break;
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return length;
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}
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/* Returns a pointer to the first character in STRING that is
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also in STOP. If no character in STRING is in STOP, returns a
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null pointer. */
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char *
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strpbrk (const char *string, const char *stop)
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{
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for (; *string != '\0'; string++)
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if (strchr (stop, *string) != NULL)
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return (char *) string;
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return NULL;
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}
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/* Returns a pointer to the last occurrence of C in STRING.
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Returns a null pointer if C does not occur in STRING. */
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char *
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strrchr (const char *string, int c_)
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{
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char c = c_;
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const char *p = NULL;
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for (; *string != '\0'; string++)
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if (*string == c)
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p = string;
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return (char *) p;
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}
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/* Returns the length of the initial substring of STRING that
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consists of characters in SKIP. */
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size_t
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strspn (const char *string, const char *skip)
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{
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size_t length;
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for (length = 0; string[length] != '\0'; length++)
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if (strchr (skip, string[length]) == NULL)
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break;
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return length;
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}
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/* Returns a pointer to the first occurrence of NEEDLE within
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HAYSTACK. Returns a null pointer if NEEDLE does not exist
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within HAYSTACK. */
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char *
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strstr (const char *haystack, const char *needle)
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{
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size_t haystack_len = strlen (haystack);
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size_t needle_len = strlen (needle);
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if (haystack_len >= needle_len)
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{
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size_t i;
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for (i = 0; i <= haystack_len - needle_len; i++)
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if (!memcmp (haystack + i, needle, needle_len))
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return (char *) haystack + i;
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}
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return NULL;
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}
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/* Breaks a string into tokens separated by DELIMITERS. The
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first time this function is called, S should be the string to
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tokenize, and in subsequent calls it must be a null pointer.
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SAVE_PTR is the address of a `char *' variable used to keep
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track of the tokenizer's position. The return value each time
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is the next token in the string, or a null pointer if no
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tokens remain.
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This function treats multiple adjacent delimiters as a single
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delimiter. The returned tokens will never be length 0.
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DELIMITERS may change from one call to the next within a
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single string.
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strtok_r() modifies the string S, changing delimiters to null
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bytes. Thus, S must be a modifiable string. String literals,
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in particular, are *not* modifiable in C, even though for
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backward compatibility they are not `const'.
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Example usage:
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char s[] = " String to tokenize. ";
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char *token, *save_ptr;
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for (token = strtok_r (s, " ", &save_ptr); token != NULL;
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token = strtok_r (NULL, " ", &save_ptr))
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printf ("'%s'\n", token);
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outputs:
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'String'
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'to'
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'tokenize.'
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*/
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char *
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strtok_r (char *s, const char *delimiters, char **save_ptr)
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{
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char *token;
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ASSERT (delimiters != NULL);
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ASSERT (save_ptr != NULL);
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/* If S is nonnull, start from it.
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If S is null, start from saved position. */
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if (s == NULL)
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s = *save_ptr;
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ASSERT (s != NULL);
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/* Skip any DELIMITERS at our current position. */
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while (strchr (delimiters, *s) != NULL)
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{
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/* strchr() will always return nonnull if we're searching
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for a null byte, because every string contains a null
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byte (at the end). */
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if (*s == '\0')
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{
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*save_ptr = s;
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return NULL;
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}
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s++;
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}
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/* Skip any non-DELIMITERS up to the end of the string. */
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token = s;
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while (strchr (delimiters, *s) == NULL)
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s++;
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if (*s != '\0')
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{
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*s = '\0';
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*save_ptr = s + 1;
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}
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else
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*save_ptr = s;
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return token;
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}
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/* Sets the SIZE bytes in DST to VALUE. */
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void *
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memset (void *dst_, int value, size_t size)
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{
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unsigned char *dst = dst_;
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ASSERT (dst != NULL || size == 0);
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while (size-- > 0)
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*dst++ = value;
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return dst_;
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}
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/* Returns the length of STRING. */
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size_t
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strlen (const char *string)
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{
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const char *p;
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ASSERT (string != NULL);
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for (p = string; *p != '\0'; p++)
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continue;
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return p - string;
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}
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/* If STRING is less than MAXLEN characters in length, returns
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its actual length. Otherwise, returns MAXLEN. */
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size_t
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strnlen (const char *string, size_t maxlen)
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{
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size_t length;
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for (length = 0; string[length] != '\0' && length < maxlen; length++)
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continue;
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return length;
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}
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/* Copies string SRC to DST. If SRC is longer than SIZE - 1
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characters, only SIZE - 1 characters are copied. A null
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terminator is always written to DST, unless SIZE is 0.
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Returns the length of SRC, not including the null terminator.
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strlcpy() is not in the standard C library, but it is an
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increasingly popular extension. See
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http://www.courtesan.com/todd/papers/strlcpy.html for
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information on strlcpy(). */
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size_t
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strlcpy (char *dst, const char *src, size_t size)
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{
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size_t src_len;
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ASSERT (dst != NULL);
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ASSERT (src != NULL);
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src_len = strlen (src);
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if (size > 0)
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{
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size_t dst_len = size - 1;
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if (src_len < dst_len)
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dst_len = src_len;
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memcpy (dst, src, dst_len);
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dst[dst_len] = '\0';
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}
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return src_len;
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}
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/* Concatenates string SRC to DST. The concatenated string is
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limited to SIZE - 1 characters. A null terminator is always
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written to DST, unless SIZE is 0. Returns the length that the
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concatenated string would have assuming that there was
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sufficient space, not including a null terminator.
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strlcat() is not in the standard C library, but it is an
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increasingly popular extension. See
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http://www.courtesan.com/todd/papers/strlcpy.html for
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information on strlcpy(). */
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size_t
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strlcat (char *dst, const char *src, size_t size)
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{
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size_t src_len, dst_len;
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ASSERT (dst != NULL);
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ASSERT (src != NULL);
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src_len = strlen (src);
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dst_len = strlen (dst);
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if (size > 0 && dst_len < size)
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{
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size_t copy_cnt = size - dst_len - 1;
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if (src_len < copy_cnt)
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copy_cnt = src_len;
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memcpy (dst + dst_len, src, copy_cnt);
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dst[dst_len + copy_cnt] = '\0';
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}
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return src_len + dst_len;
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}
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