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qubes-restore: fix race condition in allocating VM IDs

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This commit is contained in:
Vincent Penquerc'h 2013-12-30 09:17:01 -05:00 committed by Marek Marczykowski-Górecki
parent 2cf4ad18eb
commit ed24d8bc75
1 changed files with 6 additions and 0 deletions
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6
dispvm/qubes-restore.c
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@ -9,6 +9,7 @@
#include <unistd.h> #include <unistd.h>
#include <sys/time.h> #include <sys/time.h>
#include <sys/wait.h> #include <sys/wait.h>
#include <sys/file.h>
#include <syslog.h> #include <syslog.h>
#include <xs.h> #include <xs.h>
@ -415,6 +416,10 @@ int get_next_disposable_id()
perror("open dispVM.seq"); perror("open dispVM.seq");
exit(1); exit(1);
} }
if (flock(fd, LOCK_EX) < 0) {
perror("lock dispVM.seq");
exit(1);
}
if (read(fd, &seq, sizeof(seq)) != sizeof(seq)) { if (read(fd, &seq, sizeof(seq)) != sizeof(seq)) {
perror("read dispVM.seq"); perror("read dispVM.seq");
exit(1); exit(1);
@ -428,6 +433,7 @@ int get_next_disposable_id()
perror("write dispVM.seq"); perror("write dispVM.seq");
exit(1); exit(1);
} }
flock(fd, LOCK_UN);
close(fd); close(fd);
return seq; return seq;
} }