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This file was processed as: Mailbox/MIME Entity
(archive/mbox).
| Confidence | Program | Detection | Match Type | Support
|
|---|
| 100%
| dexvert
| Mailbox/MIME Entity (archive/mbox)
| magic
| Supported |
| 100%
| dexvert
| Internet Message Format (text/imf)
| magic
| Supported |
| 1%
| dexvert
| Text File (text/txt)
| fallback
| Supported |
| 100%
| file
| Mailbox text, 1st line "From jsq@cs.utexas.edu Sun Feb 3 12:59:17 1991", ASCII text
| default
| |
| 100%
| TrID
| E-Mail message (Var. 2)
| default
| |
| 100%
| checkBytes
| Printable ASCII
| default
| |
| 100%
| perlTextCheck
| Likely Text (Perl)
| default
| |
| 100%
| siegfried
| x-fmt/111 Plain Text File
| default
| |
| 100%
| detectItEasy
| Format: plain text[LF]
| default (weak)
| |
| 100%
| xdgMime
| application/mbox
| default
|
|
hex view+--------+-------------------------+-------------------------+--------+--------+
|00000000| 46 72 6f 6d 20 6a 73 71 | 40 63 73 2e 75 74 65 78 |From jsq|@cs.utex|
|00000010| 61 73 2e 65 64 75 20 20 | 53 75 6e 20 46 65 62 20 |as.edu |Sun Feb |
|00000020| 20 33 20 31 32 3a 35 39 | 3a 31 37 20 31 39 39 31 | 3 12:59|:17 1991|
|00000030| 0a 52 65 63 65 69 76 65 | 64 3a 20 66 72 6f 6d 20 |.Receive|d: from |
|00000040| 63 73 2e 75 74 65 78 61 | 73 2e 65 64 75 20 62 79 |cs.utexa|s.edu by|
|00000050| 20 75 75 6e 65 74 2e 55 | 55 2e 4e 45 54 20 28 35 | uunet.U|U.NET (5|
|00000060| 2e 36 31 2f 31 2e 31 34 | 29 20 77 69 74 68 20 53 |.61/1.14|) with S|
|00000070| 4d 54 50 20 0a 09 69 64 | 20 41 41 30 39 36 35 31 |MTP ..id| AA09651|
|00000080| 3b 20 53 75 6e 2c 20 33 | 20 46 65 62 20 39 31 20 |; Sun, 3| Feb 91 |
|00000090| 31 32 3a 35 39 3a 31 37 | 20 2d 30 35 30 30 0a 50 |12:59:17| -0500.P|
|000000a0| 6f 73 74 65 64 2d 44 61 | 74 65 3a 20 33 20 46 65 |osted-Da|te: 3 Fe|
|000000b0| 62 20 39 31 20 31 32 3a | 35 34 3a 35 31 20 47 4d |b 91 12:|54:51 GM|
|000000c0| 54 0a 52 65 63 65 69 76 | 65 64 3a 20 62 79 20 63 |T.Receiv|ed: by c|
|000000d0| 73 2e 75 74 65 78 61 73 | 2e 65 64 75 20 28 35 2e |s.utexas|.edu (5.|
|000000e0| 36 34 2f 31 2e 39 33 29 | 20 0a 46 72 6f 6d 3a 20 |64/1.93)| .From: |
|000000f0| 6d 6f 68 74 61 40 6e 65 | 63 6f 6d 38 33 30 2e 63 |mohta@ne|com830.c|
|00000100| 63 2e 74 69 74 65 63 68 | 2e 61 63 2e 6a 70 20 28 |c.titech|.ac.jp (|
|00000110| 4d 61 73 61 74 61 6b 61 | 20 4f 68 74 61 29 0a 4e |Masataka| Ohta).N|
|00000120| 65 77 73 67 72 6f 75 70 | 73 3a 20 63 6f 6d 70 2e |ewsgroup|s: comp.|
|00000130| 73 74 64 2e 75 6e 69 78 | 0a 53 75 62 6a 65 63 74 |std.unix|.Subject|
|00000140| 3a 20 52 65 3a 20 71 66 | 6f 72 6b 28 29 0a 4d 65 |: Re: qf|ork().Me|
|00000150| 73 73 61 67 65 2d 49 64 | 3a 20 3c 31 37 35 39 39 |ssage-Id|: <17599|
|00000160| 40 63 73 2e 75 74 65 78 | 61 73 2e 65 64 75 3e 0a |@cs.utex|as.edu>.|
|00000170| 52 65 66 65 72 65 6e 63 | 65 73 3a 20 3c 31 36 32 |Referenc|es: <162|
|00000180| 31 33 40 63 73 2e 75 74 | 65 78 61 73 2e 65 64 75 |13@cs.ut|exas.edu|
|00000190| 3e 20 3c 31 36 34 38 33 | 40 63 73 2e 75 74 65 78 |> <16483|@cs.utex|
|000001a0| 61 73 2e 65 64 75 3e 20 | 3c 31 36 35 32 32 40 63 |as.edu> |<16522@c|
|000001b0| 73 2e 75 74 65 78 61 73 | 2e 65 64 75 3e 20 3c 31 |s.utexas|.edu> <1|
|000001c0| 36 38 37 33 40 63 73 2e | 75 74 65 78 61 73 2e 65 |6873@cs.|utexas.e|
|000001d0| 64 75 3e 20 3c 31 36 38 | 39 35 40 63 73 2e 75 74 |du> <168|95@cs.ut|
|000001e0| 65 78 61 73 2e 65 64 75 | 3e 20 3c 31 36 39 39 34 |exas.edu|> <16994|
|000001f0| 40 63 73 2e 75 74 65 78 | 61 73 2e 65 64 75 3e 0a |@cs.utex|as.edu>.|
|00000200| 53 65 6e 64 65 72 3a 20 | 6a 73 71 40 63 73 2e 75 |Sender: |jsq@cs.u|
|00000210| 74 65 78 61 73 2e 65 64 | 75 0a 4f 72 67 61 6e 69 |texas.ed|u.Organi|
|00000220| 7a 61 74 69 6f 6e 3a 20 | 54 6f 6b 79 6f 20 49 6e |zation: |Tokyo In|
|00000230| 73 74 69 74 75 74 65 20 | 6f 66 20 54 65 63 68 6e |stitute |of Techn|
|00000240| 6f 6c 6f 67 79 0a 58 2d | 53 75 62 6d 69 73 73 69 |ology.X-|Submissi|
|00000250| 6f 6e 73 3a 20 73 74 64 | 2d 75 6e 69 78 40 75 75 |ons: std|-unix@uu|
|00000260| 6e 65 74 2e 75 75 2e 6e | 65 74 0a 44 61 74 65 3a |net.uu.n|et.Date:|
|00000270| 20 33 20 46 65 62 20 39 | 31 20 31 32 3a 35 34 3a | 3 Feb 9|1 12:54:|
|00000280| 35 31 20 47 4d 54 0a 52 | 65 70 6c 79 2d 54 6f 3a |51 GMT.R|eply-To:|
|00000290| 20 73 74 64 2d 75 6e 69 | 78 40 75 75 6e 65 74 2e | std-uni|x@uunet.|
|000002a0| 55 55 2e 4e 45 54 0a 54 | 6f 3a 20 73 74 64 2d 75 |UU.NET.T|o: std-u|
|000002b0| 6e 69 78 40 75 75 6e 65 | 74 2e 55 55 2e 4e 45 54 |nix@uune|t.UU.NET|
|000002c0| 0a 0a 53 75 62 6d 69 74 | 74 65 64 2d 62 79 3a 20 |..Submit|ted-by: |
|000002d0| 6d 6f 68 74 61 40 6e 65 | 63 6f 6d 38 33 30 2e 63 |mohta@ne|com830.c|
|000002e0| 63 2e 74 69 74 65 63 68 | 2e 61 63 2e 6a 70 20 28 |c.titech|.ac.jp (|
|000002f0| 4d 61 73 61 74 61 6b 61 | 20 4f 68 74 61 29 0a 0a |Masataka| Ohta)..|
|00000300| 49 6e 20 61 72 74 69 63 | 6c 65 20 3c 31 36 39 39 |In artic|le <1699|
|00000310| 34 40 63 73 2e 75 74 65 | 78 61 73 2e 65 64 75 3e |4@cs.ute|xas.edu>|
|00000320| 0a 09 72 69 63 68 61 72 | 64 40 61 69 61 69 2e 65 |..richar|d@aiai.e|
|00000330| 64 2e 61 63 2e 75 6b 20 | 28 52 69 63 68 61 72 64 |d.ac.uk |(Richard|
|00000340| 20 54 6f 62 69 6e 29 20 | 77 72 69 74 65 73 3a 0a | Tobin) |writes:.|
|00000350| 0a 3e 4f 66 20 63 6f 75 | 72 73 65 2c 20 74 68 65 |.>Of cou|rse, the|
|00000360| 73 65 20 70 72 6f 67 72 | 61 6d 73 20 64 6f 6e 27 |se progr|ams don'|
|00000370| 74 20 75 73 75 61 6c 6c | 79 20 63 68 61 6e 67 65 |t usuall|y change|
|00000380| 20 6d 61 6e 79 20 76 61 | 72 69 61 62 6c 65 73 2c | many va|riables,|
|00000390| 20 73 6f 20 61 0a 3e 63 | 6f 70 79 2d 6f 6e 2d 77 | so a.>c|opy-on-w|
|000003a0| 72 69 74 65 20 66 6f 72 | 6b 28 29 20 77 6f 6e 27 |rite for|k() won'|
|000003b0| 74 20 6e 65 65 64 20 6d | 61 6e 79 20 70 61 67 65 |t need m|any page|
|000003c0| 73 20 69 6e 20 74 68 69 | 73 20 63 61 73 65 2e 20 |s in thi|s case. |
|000003d0| 20 41 20 63 2d 6f 2d 77 | 09 0a 3e 66 6f 72 6b 28 | A c-o-w|..>fork(|
|000003e0| 29 20 77 69 74 68 20 6c | 61 74 65 20 61 6c 6c 6f |) with l|ate allo|
|000003f0| 63 61 74 69 6f 6e 20 6f | 66 20 70 61 67 65 73 20 |cation o|f pages |
|00000400| 63 6f 75 6c 64 20 63 6f | 75 6c 64 20 62 65 20 61 |could co|uld be a|
|00000410| 73 20 72 6f 62 75 73 74 | 20 61 73 0a 3e 76 66 6f |s robust| as.>vfo|
|00000420| 72 6b 28 29 20 61 6c 6d | 6f 73 74 20 61 6c 77 61 |rk() alm|ost alwa|
|00000430| 79 73 20 62 79 20 70 72 | 65 2d 61 6c 6c 6f 63 61 |ys by pr|e-alloca|
|00000440| 74 69 6e 67 20 61 20 66 | 65 77 20 70 61 67 65 73 |ting a f|ew pages|
|00000450| 2e 0a 0a 54 68 61 74 20 | 69 73 20 74 68 65 20 63 |...That |is the c|
|00000460| 61 73 65 20 77 68 65 72 | 65 20 43 4f 57 20 66 6f |ase wher|e COW fo|
|00000470| 72 6b 28 29 20 77 69 74 | 68 20 6c 61 74 65 20 61 |rk() wit|h late a|
|00000480| 6c 6c 6f 63 61 74 69 6f | 6e 20 6f 66 20 70 61 67 |llocatio|n of pag|
|00000490| 65 73 20 6f 72 0a 76 66 | 6f 72 6b 28 29 20 6d 75 |es or.vf|ork() mu|
|000004a0| 73 74 20 62 65 20 75 73 | 65 64 2e 0a 0a 3e 53 75 |st be us|ed...>Su|
|000004b0| 72 65 6c 79 20 74 68 65 | 20 70 72 6f 62 6c 65 6d |rely the| problem|
|000004c0| 20 69 73 20 77 68 65 6e | 20 69 74 27 73 20 62 65 | is when| it's be|
|000004d0| 69 6e 67 20 75 73 65 64 | 20 61 73 20 61 20 2a 72 |ing used| as a *r|
|000004e0| 65 61 6c 2a 20 66 6f 72 | 6b 28 29 2c 20 61 6e 64 |eal* for|k(), and|
|000004f0| 20 74 68 65 0a 3e 70 72 | 6f 67 72 61 6d 20 66 61 | the.>pr|ogram fa|
|00000500| 69 6c 73 20 6d 75 63 68 | 20 6c 61 74 65 72 20 77 |ils much| later w|
|00000510| 68 65 6e 20 69 74 20 6d | 6f 64 69 66 69 65 73 20 |hen it m|odifies |
|00000520| 6f 6e 65 20 76 61 72 69 | 61 62 6c 65 20 74 6f 6f |one vari|able too|
|00000530| 20 6d 61 6e 79 2e 0a 0a | 49 66 20 66 6f 72 6b 28 | many...|If fork(|
|00000540| 29 20 69 73 20 75 73 65 | 64 20 61 73 20 61 20 72 |) is use|d as a r|
|00000550| 65 61 6c 20 66 6f 72 6b | 28 29 2c 20 69 74 20 69 |eal fork|(), it i|
|00000560| 73 20 76 65 72 79 20 70 | 72 6f 62 61 62 6c 65 20 |s very p|robable |
|00000570| 74 68 61 74 20 69 74 20 | 6d 6f 64 69 66 69 65 73 |that it |modifies|
|00000580| 0a 69 74 73 20 64 61 74 | 61 20 73 70 61 63 65 20 |.its dat|a space |
|00000590| 6d 61 6e 79 20 74 69 6d | 65 73 2e 0a 0a 54 68 65 |many tim|es...The|
|000005a0| 20 73 65 76 65 72 65 20 | 70 72 6f 62 6c 65 6d 20 | severe |problem |
|000005b0| 69 73 20 74 68 61 74 20 | 74 68 65 20 70 72 6f 67 |is that |the prog|
|000005c0| 72 61 6d 20 63 61 6e 20 | 6e 6f 74 20 63 6f 6e 74 |ram can |not cont|
|000005d0| 72 6f 6c 20 74 68 65 20 | 66 61 69 6c 75 72 65 2e |rol the |failure.|
|000005e0| 0a 49 74 20 69 6d 6d 65 | 64 69 61 74 65 6c 79 20 |.It imme|diately |
|000005f0| 64 69 65 73 2e 0a 0a 57 | 69 74 68 20 6e 6f 6e 2d |dies...W|ith non-|
|00000600| 43 4f 57 20 66 6f 72 6b | 28 29 20 6f 72 20 43 4f |COW fork|() or CO|
|00000610| 57 20 66 6f 72 6b 28 29 | 20 77 69 74 68 20 69 6d |W fork()| with im|
|00000620| 6d 65 64 69 61 74 65 20 | 61 6c 6c 6f 63 61 74 69 |mediate |allocati|
|00000630| 6f 6e 20 6f 66 20 70 61 | 67 65 73 2c 0a 73 75 63 |on of pa|ges,.suc|
|00000640| 68 20 61 20 66 61 69 6c | 75 72 65 20 63 61 6e 20 |h a fail|ure can |
|00000650| 62 65 20 64 65 74 65 63 | 74 65 64 20 61 73 20 65 |be detec|ted as e|
|00000660| 72 72 6f 72 20 72 65 74 | 75 72 6e 20 76 61 6c 75 |rror ret|urn valu|
|00000670| 65 20 6f 66 20 66 6f 72 | 6b 28 29 0a 61 6e 64 20 |e of for|k().and |
|00000680| 6d 61 79 20 62 65 20 70 | 72 6f 63 65 73 73 65 64 |may be p|rocessed|
|00000690| 20 69 6e 20 61 20 63 6f | 6e 74 72 6f 6c 6c 65 64 | in a co|ntrolled|
|000006a0| 20 66 61 73 68 69 6f 6e | 2e 0a 0a 09 09 09 09 09 | fashion|........|
|000006b0| 4d 61 73 61 74 61 6b 61 | 20 4f 68 74 61 0a 0a 56 |Masataka| Ohta..V|
|000006c0| 6f 6c 75 6d 65 2d 4e 75 | 6d 62 65 72 3a 20 56 6f |olume-Nu|mber: Vo|
|000006d0| 6c 75 6d 65 20 32 32 2c | 20 4e 75 6d 62 65 72 20 |lume 22,| Number |
|000006e0| 31 30 31 0a 0a | |101.. | |
+--------+-------------------------+-------------------------+--------+--------+
