Hi, I've tested this bug myself, and here's what I found. Doing an strace after a ulimit -v, I get:
[snipped lots of brk()'s] brk(0x889d000) = 0x889d000 read(3, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 8192) = 8192 brk(0x889f000) = 0x889d000 old_mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = -1 ENOMEM (Cannot allocate memory) old_mmap(NULL, 2097152, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory) old_mmap(NULL, 1048576, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory) old_mmap(NULL, 2097152, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory) old_mmap(NULL, 1048576, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS|MAP_NORESERVE, -1, 0) = -1 ENOMEM (Cannot allocate memory) --- SIGSEGV (Segmentation fault) --- +++ killed by SIGSEGV +++ It looks like somewhere in libc, it's not catching/handling ENOMEM properly. But the original bug seems to be more of an issue: shouldn't it be a bug that tail chews up infinite amounts of memory when it can't find an end-of-line char? IMHO, tail should just bail out when it finds a line which is more than, say 10MB long (I'm being generous about limits here). I mean, when there is no newline for 10MB's worth of data, is there even any usefulness to tail anymore? I just can't imagine any scenario where it'd actually do anything *useful*. I think there is no reason to let tail grow without bounds and chew up the entire machine's memory. Tail should be patched to bail out after reaching a (very high) limit. (Or perhaps, just in case, we can add an option to tail to allow it to go past the limit... but I seriously doubt it's worth the effort.) W.r.t. to tailing /dev/zero, bug #162257 should already take care of it. Nevertheless, I still think tail should impose a finite limit on line length. Just because chewing up the entire machine's memory without producing any meaningful output just seems unacceptable to me. T -- Roasting my brains over a slow fire. Please do not interrupt this process.
