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45 lines
1.0 KiB
C
45 lines
1.0 KiB
C
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#include <errno.h>
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#include <fcntl.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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/* This assumes that a check for the
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template size has already been made */
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static char * __randname(char * template)
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{
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int i;
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struct timespec ts;
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unsigned long r;
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clock_gettime(CLOCK_REALTIME, &ts);
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r = (ts.tv_nsec * 65537) ^ ((((intptr_t)(&ts)) / 16) + ((intptr_t)template));
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for (i = 0; i < 6; i++, r >>= 5)
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template[i] = 'A' + (r & 15) + (r & 16) * 2;
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return template;
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}
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int mkstemps(char * template, int len)
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{
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size_t l = strlen(template);
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if (l < 6 || len > l - 6 || memcmp(template + l - len - 6, "XXXXXX", 6))
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{
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errno = EINVAL;
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return -1;
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}
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int fd, retries = 100;
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do
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{
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__randname(template + l - len - 6);
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if ((fd = open(template, O_RDWR | O_CREAT | O_EXCL, 0600)) >= 0)
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return fd;
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} while (--retries && errno == EEXIST);
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memcpy(template + l - len - 6, "XXXXXX", 6);
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return -1;
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}
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