dt@ist.UUCP (David Tilbrook) (01/29/85)
I recently found the following bug (feature?) in System 3, 5, OSx Make
in the following shell script:
cat <<'!' >make.tmp
MAIN:
echo *
!
make -f make.tmp
make -f - <make.tmp
The outputs on all my systems (4.1, SysV, OSx) in empty directories were:
echo *
make.tmp
echo *
*
Is this an obscure and useful feature the value of which I
fail to understand or appreciate?
--
David Tilbrook {inset, root44, mcvax, qtlon}!ist!dt
Imperial Software Technology, London Englandwescott@ncrcae.UUCP (Mike Wescott) (02/06/85)
David Tilbrook, Imperial Software Technology, London England in <305@ist.UUCP>
points up a bug in make whereby the shell's filename expansion is suppressed
when make is invoked:
make -f - < descfile
rather than:
make -f descfile
The bug is actually in /bin/sh. In sh/expand.c around line 112 the shell
attemps to open a directory to scan for file name expansions:
if ((dirf = open(*s ? s : ".", 0)) > 0)
{
if (fstat(dirf, &statb) != -1 &&
(statb.st_mode & S_IFMT) == S_IFDIR)
dir++;
else
close(dirf);
}
The asuumption is that open will never return 0; the check should be >= 0.
How is it that stdin is not open? In make, in main.c while parsing the
-f flag, the routine rddescf() is called. rddescf() fopen's the file named
by the argument following the -f flag unless it is "-". The file pointer
retruned by fopen or stdin is then passed to rdd1() which reads and fcloses
the file passed to it; hence when "-f -" is used stdin is closed before
/bin/sh is called. This is also a bug since
make -f - -f -
won't work properly, but then it's kinda silly anyway.
Mike Wescott
NCR Corp.
mcnc!ncsu!ncrcae!wescott
akgua!usceast!ncrcae!wescotted@mtxinu.UUCP (Ed Gould) (02/12/85)
> I recently found the following bug (feature?) in System 3, 5, OSx Make > in the following shell script: > > cat <<'!' >make.tmp > MAIN: > echo * > ! > make -f make.tmp > make -f - <make.tmp > > The outputs on all my systems (4.1, SysV, OSx) in empty directories were: > > echo * > make.tmp > echo * > * > > Is this an obscure and useful feature the value of which I > fail to understand or appreciate? > -- > David Tilbrook {inset, root44, mcvax, qtlon}!ist!dt > Imperial Software Technology, London England I get the following on 4.2bsd, using the 4.2 make and also Doug Gwyn's System V make (/usr/5bin/make). Note that since I generated this with "script" the file "typescript" also appears. (Editing to change the ../xx file is omitted.) (ed) mtxinu> cat ../xx cat <<'!' >make.tmp MAIN: echo * ! make -f make.tmp make -f - <make.tmp (ed) mtxinu> /bin/sh ../xx echo * make.tmp typescript echo * make.tmp typescript (ed) mtxinu> cat ../xx cat <<'!' >make.tmp MAIN: echo * ! /usr/5bin/make SHELL=/bin/sh -f make.tmp /usr/5bin/make SHELL=/bin/sh -f - <make.tmp (ed) mtxinu> /bin/sh ../xx echo * make.tmp typescript echo * make.tmp typescript (ed) mtxinu> I guess it's fixed here! -- Ed Gould mt Xinu, 739 Allston Way, Berkeley, CA 94710 USA {ucbvax,decvax}!mtxinu!ed +1 415 644 0146
guy@rlgvax.UUCP (Guy Harris) (02/15/85)
> > I recently found the following bug (feature?) in System 3, 5, OSx Make > > in the following shell script: ... > I guess it's fixed here! That's probably because you're on a 4.2BSD system; it doesn't occur here either. From an article explaining the bug: > David Tilbrook, Imperial Software Technology, London England in <305@ist.UUCP> > points up a bug in make whereby the shell's filename expansion is suppressed > when make is invoked: > make -f - < descfile > rather than: > make -f descfile > The bug is actually in /bin/sh. In sh/expand.c around line 112 the shell > attemps to open a directory to scan for file name expansions: > if ((dirf = open(*s ? s : ".", 0)) > 0) ... > The asuumption is that open will never return 0; the check should be >= 0. In a 4.2BSD version of the shell (any shell), this would be done with "opendir"; in the process of changing the code to use the directory library, one would almost certainly fix the bug (since the test would be against a null pointer return). Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy