33 lines
574 B
C
33 lines
574 B
C
#include <unistd.h>
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#include <fcntl.h>
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#include <errno.h>
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int lockf(int fd, int op, off_t size)
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{
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struct flock l = {
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.l_type = F_WRLCK,
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.l_whence = SEEK_CUR,
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.l_len = size,
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};
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switch (op) {
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case F_TEST:
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l.l_type = F_RDLCK;
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if (fcntl(fd, F_GETLK, &l) < 0)
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return -1;
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if (l.l_type == F_UNLCK || l.l_pid == getpid())
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return 0;
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errno = EACCES;
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return -1;
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case F_ULOCK:
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l.l_type = F_UNLCK;
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case F_TLOCK:
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return fcntl(fd, F_SETLK, &l);
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case F_LOCK:
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return fcntl(fd, F_SETLKW, &l);
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}
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errno = EINVAL;
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return -1;
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}
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weak_alias(lockf, lockf64);
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