51 lines
1.4 KiB
C
51 lines
1.4 KiB
C
#include <string.h>
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/*
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** The strcat() function appends the src string to the dest string,
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** overwriting the terminating null byte ('\0') at the end of dest, and then
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** adds a terminating null byte. The strings may not overlap, and the dest
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** string must have enough space for the result. If dest is not large enough,
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** program behavior is unpredictable; buffer overruns are a favorite avenue for
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** attacking secure programs.
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**
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** TODO: use the DMA !
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** TODO: look at the DSP ?
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*/
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char *strcat(char *dest, char const *src)
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{
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size_t i;
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size_t start;
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if (src == NULL || dest == NULL)
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return (0);
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i = -1;
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start = -1;
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while (dest[++start] != '\0') ;
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while (src[++i] != '\0')
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dest[start + i] = src[i];
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dest[i + start] = '\0';
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return (dest);
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}
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/*
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** The strncat() function is similar, except that:
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** * it will use at most n bytes from src; and
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** * src does not need to be null-terminated if it contains n or more bytes.
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**
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** As with strcat(), the resulting string in dest is always null-terminated.
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**
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** If src contains n or more bytes, strncat() writes n+1 bytes to dest (n from
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** src plus the terminating null byte). Therefore, the size of dest must be at
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** least strlen(dest)+n+1.
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*/
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char *strncat(char *dest, const char *src, size_t n)
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{
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size_t dest_len = strlen(dest);
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size_t i;
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for (i = 0; i < n && src[i] != '\0'; i++)
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dest[dest_len + i] = src[i];
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dest[dest_len + i] = '\0';
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return (dest);
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}
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