ref: 94e26e7576fabcaacd8fa8f75c4f87f9eb6e56f3
dir: /sys/src/cmd/upas/fs/extra/idxtst.c/
#include <u.h> #include <libc.h> #include <bio.h> static char *etab[] = { "not found", "does not exist", "file is locked", "exclusive lock", }; static int bad(int idx) { char buf[ERRMAX]; int i; rerrstr(buf, sizeof buf); for(i = idx; i < nelem(etab); i++) if(strstr(buf, etab[i])) return 0; return 1; } static int exopen(char *s) { int i, fd; for(i = 0; i < 30; i++){ if((fd = open(s, OWRITE|OTRUNC)) >= 0 || bad(0)) return fd; if((fd = create(s, OWRITE|OEXCL, DMEXCL|0600)) >= 0 || bad(2)) return fd; sleep(1000); } werrstr("lock timeout"); return -1; } void main(void) { int fd; Biobuf *b; fd = exopen("testingex"); if(fd == -1) sysfatal("exopen: %r"); b = Bopen("testingex", OREAD); if(b){ free(b); fprint(2, "print both opened at once\n"); }else fprint(2, "bopen: %r\n"); close(fd); exits(""); }