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Fix command substitutions in here-docs (rhbz#994241, rhbz#1036802)

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When ksh was compiled with SHOPT_SPAWN (the default), any command
substitution embedded in a here-document returned an empty string.
The bug was also present in 93u+ 2012-08-01 (although not in every
case as some systems compile it without SHOPT_SPAWN).

This fixes it by applying a slightly edited combination of two Red
Hat patches (the second containing a fix for the first), which
backport a new command substitution mechanism from the abandoned
ksh 93v- beta version. The originals are:

642af4d6/f/ksh-20120801-macro.patch
642af4d6/f/ksh-20120801-fd2lost.patch

src/cmd/ksh93/include/io.h:
- The iopipe() function from xec.c is now needed in sh_subshell()
  (subshell.c), so rename it to sh_iounpipe() and declare it as an
  extern here. The 93v- beta did it as well. (The Red Hat patch did
  this without renaming it.)

src/cmd/ksh93/sh/xec.c:
- Backport new versions of iousepipe() and sh_iounpipe() from ksh
  93v-. New 'type' flaggery is introduced to distinguish between
  different command substitution conditions. What all that means
  remains to be determined.
- sh_exec(): I made one change to the Red Hat patch myself: if in a
  subshell and the type flags FAMP (for "ampersand" as in '&' as in
  background job) and TFORK are set, continue to call sh_subfork()
  to fork the subshell unconditionally, instead of only if we're in
  a command substitution connected to an unseekable file. Maybe the
  latter works for the 93v- code, but on 93u+(m) it causes a couple
  of regressions, which are fixed by my change:
  signal.sh[273]: subshell ignoring signal does not send signal to parent
  signal.sh[276]: subshell catching signal does not send signal to parent
  Details: https://github.com/ksh93/ksh/issues/104#issuecomment-696341902

src/cmd/ksh93/sh/macro.c,
src/cmd/ksh93/sh/subshell.c:
- Updates that go with those new functions.

Fixes:   https://github.com/ksh93/ksh/issues/104
Affects: https://github.com/ksh93/ksh/issues/124
This commit is contained in:
Martijn Dekker 2020-09-21 23:02:08 +02:00
parent 0d3bedd67d
commit 970069a6fe
6 changed files with 111 additions and 30 deletions
Download patch file Download diff file Expand all files Collapse all files

4
src/cmd/ksh93/sh/macro.c
View file

@ -385,7 +385,7 @@ void sh_machere(Shell_t *shp,Sfio_t *infile, Sfio_t *outfile, char *string)
break;
}
case S_PAR:
comsubst(mp,(Shnode_t*)0,1);
comsubst(mp,(Shnode_t*)0,3);
break;
case S_EOF:
if((c=fcfill()) > 0)
@ -1150,7 +1150,7 @@ retry1:
case S_PAR:
if(type)
goto nosub;
comsubst(mp,(Shnode_t*)0,1);
comsubst(mp,(Shnode_t*)0,3);
return(1);
case S_DIG:
var = 0;

19
src/cmd/ksh93/sh/subshell.c
View file

@ -123,7 +123,8 @@ void sh_subtmpfile(Shell_t *shp)
else if(errno!=EBADF)
errormsg(SH_DICT,ERROR_system(1),e_toomany);
/* popping a discipline forces a /tmp file create */
sfdisc(sfstdout,SF_POPDISC);
if(shp->comsub != 1)
sfdisc(sfstdout,SF_POPDISC);
if((fd=sffileno(sfstdout))<0)
{
/* unable to create the /tmp file so use a pipe */
@ -173,6 +174,7 @@ void sh_subfork(void)
register struct subshell *sp = subshell_data;
Shell_t *shp = sp->shp;
unsigned int curenv = shp->curenv;
char comsub = shp->comsub;
pid_t pid;
char *trap = shp->st.trapcom[0];
if(trap)
@ -204,7 +206,7 @@ void sh_subfork(void)
shp->subshell = 0;
shp->comsub = 0;
sp->subpid=0;
shp->st.trapcom[0] = trap;
shp->st.trapcom[0] = (comsub==2 ? NULL : trap);
shp->savesig = 0;
/* sh_fork() increases ${.sh.subshell} but we forked an existing virtual subshell, so undo */
SH_SUBSHELLNOD->nvalue.s--;
@ -653,6 +655,13 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
}
else
{
if(comsub!=1 && shp->spid)
{
job_wait(shp->spid);
if(shp->pipepid==shp->spid)
shp->spid = 0;
shp->pipepid = 0;
}
/* move tmp file to iop and restore sfstdout */
iop = sfswap(sfstdout,NIL(Sfio_t*));
if(!iop)
@ -761,7 +770,6 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
shp->coutpipe = sp->coutpipe;
}
shp->subshare = sp->subshare;
shp->comsub = sp->comsub;
shp->subdup = sp->subdup;
if(shp->subshell)
{
@ -790,7 +798,12 @@ Sfio_t *sh_subshell(Shell_t *shp,Shnode_t *t, volatile int flags, int comsub)
if(nsig>0)
kill(getpid(),nsig);
if(sp->subpid)
{
job_wait(sp->subpid);
if(comsub>1)
sh_iounpipe(shp);
}
shp->comsub = sp->comsub;
if(comsub && iop && sp->pipefd<0)
sfseek(iop,(off_t)0,SEEK_SET);
if(shp->trapnote)

66
src/cmd/ksh93/sh/xec.c
View file

@ -151,26 +151,30 @@ static /*inline*/ double timeval_to_double(struct timeval tv)
* temp file.
*/
static int subpipe[3],subdup,tsetio,usepipe;
static void iounpipe(Shell_t*);
static int iousepipe(Shell_t *shp)
{
int i;
int fd=sffileno(sfstdout),i,err=errno;
if(usepipe)
{
usepipe++;
iounpipe(shp);
sh_iounpipe(shp);
}
if(sh_rpipe(subpipe) < 0)
return(0);
usepipe++;
fcntl(subpipe[0],F_SETFD,FD_CLOEXEC);
subpipe[2] = sh_fcntl(1,F_DUPFD,10);
fcntl(subpipe[2],F_SETFD,FD_CLOEXEC);
if(shp->comsub!=1)
{
subpipe[2] = sh_fcntl(subpipe[1],F_DUPFD,10);
sh_close(subpipe[1]);
return(1);
}
subpipe[2] = sh_fcntl(fd,F_dupfd_cloexec,10);
shp->fdstatus[subpipe[2]] = shp->fdstatus[1];
close(1);
fcntl(subpipe[1],F_DUPFD,1);
shp->fdstatus[1] = shp->fdstatus[subpipe[1]];
while(close(fd)<0 && errno==EINTR)
errno = err;
fcntl(subpipe[1],F_DUPFD,fd);
shp->fdstatus[1] = shp->fdstatus[subpipe[1]]&~IOCLEX;
sh_close(subpipe[1]);
if(subdup=shp->subdup) for(i=0; i < 10; i++)
{
@ -184,14 +188,23 @@ static int iousepipe(Shell_t *shp)
return(1);
}
static void iounpipe(Shell_t *shp)
void sh_iounpipe(Shell_t *shp)
{
int n;
int fd=sffileno(sfstdout),n,err=errno;
char buff[SF_BUFSIZE];
close(1);
fcntl(subpipe[2], F_DUPFD, 1);
shp->fdstatus[1] = shp->fdstatus[subpipe[2]];
if(!usepipe)
return;
--usepipe;
if(shp->comsub>1)
{
sh_close(subpipe[2]);
while(read(subpipe[0],buff,sizeof(buff))>0);
goto done;
}
while(close(fd)<0 && errno==EINTR)
errno = err;
fcntl(subpipe[2], F_DUPFD, fd);
shp->fdstatus[1] = shp->fdstatus[subpipe[2]];
if(subdup) for(n=0; n < 10; n++)
{
if(subdup&(1<<n))
@ -223,6 +236,7 @@ static void iounpipe(Shell_t *shp)
else if(errno!=EINTR)
break;
}
done:
sh_close(subpipe[0]);
subpipe[0] = -1;
tsetio = 0;
@ -1514,10 +1528,12 @@ int sh_exec(register const Shnode_t *t, int flags)
if(shp->subshell)
{
sh_subtmpfile(shp);
if(shp->comsub==1 && !(shp->fdstatus[1]&IONOSEEK))
unpipe=iousepipe(shp);
if((type&(FAMP|TFORK))==(FAMP|TFORK))
{
if(shp->comsub && !(shp->fdstatus[1]&IONOSEEK))
unpipe = iousepipe(shp);
sh_subfork();
}
}
no_fork = !ntflag && !(type&(FAMP|FPOU)) && !shp->subshell &&
!(shp->st.trapcom[SIGINT] && *shp->st.trapcom[SIGINT]) &&
@ -1572,7 +1588,7 @@ int sh_exec(register const Shnode_t *t, int flags)
if(parent<0)
{
if(shp->comsub==1 && usepipe && unpipe)
iounpipe(shp);
sh_iounpipe(shp);
break;
}
#else
@ -1590,6 +1606,8 @@ int sh_exec(register const Shnode_t *t, int flags)
nlock--;
job_unlock();
}
if(shp->subshell)
shp->spid = parent;
if(type&FPCL)
sh_close(shp->inpipe[0]);
if(type&(FCOOP|FAMP))
@ -1605,11 +1623,15 @@ int sh_exec(register const Shnode_t *t, int flags)
if(shp->pipepid)
shp->pipepid = parent;
else
{
job_wait(parent);
if(parent==shp->spid)
shp->spid = 0;
}
if(shp->topfd > topfd)
sh_iorestore(shp,topfd,0);
if(usepipe && tsetio && subdup && unpipe)
iounpipe(shp);
sh_iounpipe(shp);
if(!sh_isoption(SH_MONITOR))
{
shp->trapnote &= ~SH_SIGIGNORE;
@ -1809,7 +1831,7 @@ int sh_exec(register const Shnode_t *t, int flags)
shp->exitval = type;
}
if(shp->comsub==1 && usepipe)
iounpipe(shp);
sh_iounpipe(shp);
shp->pipepid = 0;
shp->st.ioset = 0;
if(simple && was_errexit)
@ -2857,7 +2879,7 @@ pid_t _sh_fork(Shell_t *shp,register pid_t parent,int flags,int *jobid)
{
if(shp->topfd > restorefd)
sh_iorestore(shp,restorefd,0);
iounpipe(shp);
sh_iounpipe(shp);
}
}
return(parent);
@ -3169,8 +3191,7 @@ static void sh_funct(Shell_t *shp,Namval_t *np,int argn, char *argv[],struct arg
struct funenv fun;
char *fname = nv_getval(SH_FUNNAMENOD);
struct Level *lp =(struct Level*)(SH_LEVELNOD->nvfun);
int level, pipepid=shp->pipepid, comsub=shp->comsub;
shp->comsub = 0;
int level, pipepid=shp->pipepid;
shp->pipepid = 0;
sh_stats(STAT_FUNCT);
if(!lp->hdr.disc)
@ -3213,7 +3234,6 @@ static void sh_funct(Shell_t *shp,Namval_t *np,int argn, char *argv[],struct arg
lp->maxlevel = level;
SH_LEVELNOD->nvalue.s = lp->maxlevel;
shp->last_root = nv_dict(DOTSHNOD);
shp->comsub = comsub;
nv_putval(SH_FUNNAMENOD,fname,NV_NOFREE);
nv_putval(SH_PATHNAMENOD,shp->st.filename,NV_NOFREE);
shp->pipepid = pipepid;