mirror of
https://github.com/cirosantilli/linux-kernel-module-cheat.git
synced 2026-01-13 20:12:26 +00:00
0d5c7f5c4c
And pass niters as a thread argument to all threading implementations... otherwise every loop has to do a memory load from the global!
59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
/* https://cirosantilli.com/linux-kernel-module-cheat#c
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*
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* Like `sprintf`, but writes at most n bytes, so it is safer,
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* because it may not be possible or easy to calculate the resulting
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* size of a formated string.
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*
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* The size given includes the null terminator. */
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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int main(void) {
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#if __STDC_VERSION__ >= 199901L
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/* Common usage when string fits.
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*
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* Ensures that there will be no out or bounds access on out. */
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{
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int in = 1234;
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char out[1024];
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int snprintf_return;
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snprintf_return = snprintf(out, sizeof(out), "ab%dcd", in);
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/* The usual error checking. */
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if (snprintf_return < 0) {
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perror("snprintf");
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exit(EXIT_FAILURE);
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}
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assert((size_t)snprintf_return < sizeof(out));
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/* Assert because we know the return here. */
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assert(snprintf_return == 8);
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/* What it actually copied. */
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assert(strcmp(out, "ab1234cd") == 0);
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}
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/* Less common case where string does not fit. Error handling would
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* normally follow in a real program. */
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{
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/* The return here is the same as before.
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*
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* Because it is >= than the imposed limit of 6, we know that
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* the write failed to fully complete. */
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#if 0
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/* GCC 8.3.0 with -O3 actually detects this and breaks the build.
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* error: ‘cd’ directive output truncated writing 2 bytes into a region of size 0 [-Werror=format-truncation=] */
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int in = 1234;
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char out[6];
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assert(snprintf(out, sizeof(out), "ab%dcd", in) == 8);
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assert(strcmp(out, "ab123") == 0);
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#endif
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}
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#endif
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return EXIT_SUCCESS;
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}
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