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Fix Process changing GAP's directory on Cygwin #6776

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Merged
fingolfin merged 1 commit into from
Oct 23, 2026
Merged

Fix Process changing GAP's directory on Cygwin #6776

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29 changes: 20 additions & 9 deletions src/iostream.c
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Original file line number Diff line number Diff line change
Expand Up @@ -628,12 +628,6 @@ SyExecuteProcess(Char * dir, Char * prg, Int in, Int out, Char * args[])
int res;
SyProcessResult result = { 0, 0, 0 };

// change the working directory
if (chdir(dir) == -1) {
result.execError = errno;
return result;
}

// if <in> is -1 open "/dev/null"
if (in == -1)
tin = open("/dev/null", O_RDONLY);
Expand Down Expand Up @@ -671,6 +665,7 @@ SyExecuteProcess(Char * dir, Char * prg, Int in, Int out, Char * args[])
fcntl(0, F_SETFD, 0);
}

savestdout = -1;
if (tout != 1) {
savestdout = dup(1);
if (savestdout == -1 || dup2(tout, 1) == -1) {
Expand All @@ -690,9 +685,25 @@ SyExecuteProcess(Char * dir, Char * prg, Int in, Int out, Char * args[])
}

FreezeStdin = 1;
// now try to execute the program
res = spawnve(_P_WAIT, prg, (const char * const *)args,
(const char * const *)environ);

// spawnve cannot set the child's working directory, so change GAP's own
// just for the call
int oldwd = open(".", O_RDONLY | O_DIRECTORY | O_CLOEXEC);
if (oldwd == -1 || chdir(dir) == -1)
res = -1;
else
res = spawnve(_P_WAIT, prg, (const char * const *)args,
(const char * const *)environ);

// restore it, keeping errno from chdir or spawnve
if (oldwd != -1) {
int savedErrno = errno;
if (fchdir(oldwd) == -1)
PErr("SyExecuteProcess: cannot restore working directory");
close(oldwd);
errno = savedErrno;
}

// remember why, before the repairs below overwrite errno
int spawnErrno = errno;

Expand Down
6 changes: 5 additions & 1 deletion tst/testinstall/process.tst
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Original file line number Diff line number Diff line change
Expand Up @@ -41,11 +41,15 @@ rec( status := 0 )
gap> out;
"hi\n"

# the working directory can be chosen
# the working directory can be chosen, without changing GAP's own (ask the
# kernel, as DirectoryCurrent() is cached)
gap> cwd := GAP_getcwd();;
gap> dir := DirectoryTemporary();;
gap> PrintTo(Filename(dir, "marker"), "");
gap> RunProcess("ls", rec(directory := dir)).output;
"marker\n"
gap> GAP_getcwd() = cwd;
true

# error cases
gap> RunProcess();
Expand Down
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