Reimplement flopen(3) using fcntl(2) locks instead of flock(2) locks.
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=184093
@ -46,12 +46,13 @@ The
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function opens or creates a file and acquires an exclusive lock on it.
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It is essentially equivalent with calling
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.Fn open
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with the same parameters followed by
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.Fn flock
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with an
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.Va operation
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argument of
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.Dv LOCK_EX ,
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with the same parameters followed by an
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.Fn fcntl
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.Dv F_SETLK
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or
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.Dv F_SETLKW
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operation with lock type
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.Dv F_WRLCK ,
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except that
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.Fn flopen
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will attempt to detect and handle races that may occur between opening
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@ -86,12 +87,12 @@ returns a valid file descriptor.
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Otherwise, it returns -1, and sets
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.Va errno
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as described in
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.Xr flock 2
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.Xr fcntl 2
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and
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.Xr open 2 .
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.Sh SEE ALSO
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.Xr errno 2 ,
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.Xr flock 2 ,
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.Xr fcntl 2 ,
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.Xr open 2
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.Sh HISTORY
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The
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@ -28,12 +28,12 @@
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/file.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <string.h>
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#include <unistd.h>
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#include <libutil.h>
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@ -42,6 +42,7 @@ int
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flopen(const char *path, int flags, ...)
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{
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int fd, operation, serrno, trunc;
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struct flock flock;
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struct stat sb, fsb;
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mode_t mode;
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@ -58,9 +59,10 @@ flopen(const char *path, int flags, ...)
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va_end(ap);
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}
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operation = LOCK_EX;
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if (flags & O_NONBLOCK)
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operation |= LOCK_NB;
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memset(&flock, 0, sizeof flock);
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flock.l_type = F_WRLCK;
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flock.l_whence = SEEK_SET;
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operation = (flags & O_NONBLOCK) ? F_SETLK : F_SETLKW;
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trunc = (flags & O_TRUNC);
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flags &= ~O_TRUNC;
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@ -69,7 +71,7 @@ flopen(const char *path, int flags, ...)
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if ((fd = open(path, flags, mode)) == -1)
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/* non-existent or no access */
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return (-1);
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if (flock(fd, operation) == -1) {
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if (fcntl(fd, operation, &flock) == -1) {
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/* unsupported or interrupted */
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serrno = errno;
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close(fd);
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