Expose who is using a board when it's blocked #79
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Allow it to be accessed outside cdba-server.c Signed-off-by: Caleb Connolly <[email protected]>
Keep track of who is using a board by writing $CDBA_USER to the lockfile and display it when the board is blocked. Signed-off-by: Caleb Connolly <[email protected]>
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| err(1, "failed to truncate lockfile %s", lock); | ||
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| lseek(fd, 0, SEEK_SET); | ||
| if (write(fd, user, n) < 0) |
Check warning
Code scanning / CodeQL
Exposure of system data to an unauthorized control sphere Medium
| if (fd < 0) | ||
| err(1, "failed to open lockfile %s", lock); | ||
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| /* Read current user out of the lockfile if there is one */ | ||
| n = read(fd, user, sizeof(user)-1); |
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This should happen under the read-lock (so that reading doesn't collide with unfinished write call). But then we don't want to give away exclusive lock on the file. Maybe it's better to have two files: one for the lock and another one for the username.
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| warnx("board is in use, waiting..."); | ||
| warnx("board is in use by %s, waiting...", user); |
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User is not a constant, it needs to be re-read constantly when printing the message. Consider userB "stealing" the board while you are waiting for it to be freed by userA. The message will still print userA, while you should be pinging userB.
| if (write(fd, user, n) < 0) | ||
| err(1, "failed to write lockfile %s", lock); | ||
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| warnx("board locked by %s", cdba_user); |
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| sleep(3); | ||
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| /* check that connection isn't gone */ | ||
| if (read(STDIN_FILENO, &c, 1) == 0) | ||
| errx(1, "connection is gone"); | ||
| } | ||
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| /* Write our username to the lockfile */ | ||
| n = snprintf(user, sizeof(user), "%s\n", cdba_user); |
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I think skipping \n might be a better choice, it saves the code on both read and write sides.
For peace of mind, the ability to pester said user, and to catch deadlocks.