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Re: [mapfile]: problem reentrance with normal file


From: Didou Serge
Subject: Re: [mapfile]: problem reentrance with normal file
Date: Mon, 12 Nov 2018 16:48:47 +0100

 Ok, in this case, this should not work either:

mapfile -C xx -c 1 UU  < <( echo -e "Premiere ligne" A{1..45} "\nDeuxieme
ligne" B{1..45} "\nTroisieme ligne" C{1..45})

But, this form work fine.

Le lun. 12 nov. 2018 à 15:44, Chet Ramey <address@hidden> a écrit :

> On 11/11/18 3:32 PM, Didou Serge wrote:
>
> > Bash Version: 4.4
> > Patch Level: 7
> > Release Status: release
> >
> > Description:
> > When use mapfile from normal file that call function that use mapfile,
> the
> > first mapfile lost data.
> >
> > Repeat-By:
> > I create 3 functions:
> > ww(){ echo "$@" | mapfile -C yy -c 1 -t TT ; }
> > xx(){ mapfile -C yy -c 1 -t TT < <(echo "$@") ; }
> > yy(){ echo "$@" ;}
> >
> > I create 1 normal file:
> > echo -e "Premiere ligne" A{1..45} "\nDeuxieme ligne" B{1..45}
> "\nTroisieme
> > ligne" C{1..45} >fic.txt
> >
>         [...]
> > This not work (lost data in second line and after) :
> > mapfile -C xx -c 1 UU <fic.txt
> > 0 0 Premiere ligne A1 A2 A3 A4 A5 A6 A7 A8 A9 A10 A11 A12 A13 A14 A15 A16
> > A17 A18 A19 A20 A21 A22 A23 A24 A25 A26 A27 A28 A29 A30 A31 A32 A33 A34
> A35
> > A36 A37 A38 A39 A40 A41 A42 A43 A44 A45
> > 0 1  B17 B18 B19 B20 B21 B22 B23 B24 B25 B26 B27 B28 B29 B30 B31 B32 B33
> > B34 B35 B36 B37 B38 B39 B40 B41 B42 B43 B44 B45
> > 0 2 ligne C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18
> > C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36
> C37
> > C38 C39 C40 C41 C42 C43 C44 C45
>
> This is a buffering issue caused by nested calls to mapfile in the same
> process. The first call to mapfile reads a bufferful of data from the
> input file, and the second mapfile (the one executed as part of the
> callback) reads data into that same buffer. When the second call finishes,
> and the first mapfile is called again, the remaining characters in the
> buffer have already been discarded. It's not safe to call mapfile as part
> of a callback to a mapfile invocation.
>
> Chet
> --
> ``The lyf so short, the craft so long to lerne.'' - Chaucer
>                  ``Ars longa, vita brevis'' - Hippocrates
> Chet Ramey, UTech, CWRU    address@hidden    http://tiswww.cwru.edu/~chet/
>


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