Hi, More details about this: > 3) On MacOS X, SIGSTOP and SIGCONT make not only read() fail with EINTR, but > fread() as well. > > Test case: [3]. Run it, type Hello<Return> then Ctrl-Z then fg. Result is: > > $ ./a.out > Hello > ^Z > [1]+ Stopped ./a.out > $ fg > ./a.out > fread: Interrupted system call > Hello > > $ ./a.out --unbuffered > Hello > Hello > ^Z > [1]+ Stopped ./a.out --unbuffered > $ fg > ./a.out --unbuffered > fread: Interrupted system call > > This was also reported in [4]. > > I would expect that EINTR also occurs in write() and fwrite() when writing > to a pipe that is temporarily full, but I can't easily reproduce this.
Looking at the MacOS X 10.5 kernel, EINTR appears to be generated in these situations: - read, write, ioctl only on tty devices, - select, poll, - sleep, - pthread_cond_*, - connect. This explaing why I cannot reproduce a malfunction with input from a pipe, only from a tty. Let me try a couple of coreutils programs that use fread(): 1) base64: affected $ ./base64 Hello ^Z [1]+ Stopped ./base64 $ fg ./base64 SGVsbG8K ./base64: read error: Interrupted system call 2) cksum: affected $ ./cksum Hello ^Z [1]+ Stopped ./cksum $ fg ./cksum World ./cksum: -: Interrupted system call 3) sha1sum: affected $ ./sha1sum Hello ^Z [1]+ Stopped ./sha1sum $ fg ./sha1sum ./sha1sum: -: Interrupted system call 4) od: affected $ ./od -x Hello ^Z [1]+ Stopped ./od -x $ fg ./od -x ./od: standard input: read error: Interrupted system call 0000000 6548 6c6c 0a6f 0000006 5) sort: affected $ sort Hello ^Z [1]+ Stopped sort $ fg sort sort: read failed: -: Interrupted system call So indeed, many programs are affected. I think an fread() wrapper would be appropriate. Shall we call it safe_fread or fread? Bruno
