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75 lines
1.7 KiB
75 lines
1.7 KiB
#undef NDEBUG
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#include "dbg.h"
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#include <stdio.h>
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#include <assert.h>
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/*
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* naive copy that assumes all inputs are always valid
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* taken from K&R C and cleaned up a bit;
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*/
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void copy(char to[], char from[])
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{
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int i = 0;
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// while loop will not end if from isn't '\0' terminated
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while((to[i] = from[i]) != '\0') {
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++i;
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}
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}
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/*
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* A safer version that checks for many common errors using the
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* length of each string to control the loops and termination.
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*/
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int safercopy(int from_len, char *from, int to_len, char *to)
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{
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assert(from != NULL && to != NULL && "from and to can't be NULL");
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int i = 0;
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int max = from_len > to_len - 1 ? to_len - 1 : from_len;
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// to_len must have at least 1 byte
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if(from_len < 0 || to_len <= 0) return -1;
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for(i = 0; i < max; i++) {
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to[i] = from[i];
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}
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to[to_len - 1] = '\0';
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return i;
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}
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int main(int argc, char *argv[])
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{
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// careful to understand why we can get these sizes
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char from[] = "0123456789";
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int from_len = sizeof(from);
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// notice that it's 7 chars + \0
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char to[] = "0123456";
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int to_len = sizeof(to);
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debug("Copying '%s':%d to '%s':%d", from, from_len, to, to_len);
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int rc = safercopy(from_len, from, to_len, to);
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check(rc > 0, "Failed to safercopy.");
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check(to[to_len - 1] == '\0', "String not terminated.");
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debug("Result is '%s':%d", to, to_len);
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// now try to break it
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rc = safercopy(from_len * -1, from, to_len, to);
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check(rc == -1, "safercopy should fail #1");
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check(to[to_len - 1] == '\0', "String not terminated.");
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rc = safercopy(from_len, from, 0, to);
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check(rc == -1, "safercopy should fail #2");
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check(to[to_len - 1] == '\0', "String not terminated.");
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return 0;
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error:
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return 1;
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}
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