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In EXT:RUN-PROGRAM, synchronize the child so that it waits until the parent has set up the process structure.

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This commit is contained in:
Juanjo Garcia-Ripoll 2012-04-26 16:16:05 +02:00
parent 54cce8b643
commit 47bc44daa0
2 changed files with 30 additions and 5 deletions
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4
src/CHANGELOG
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@ -31,6 +31,10 @@ ECL 12.2.2:
- ENSURE-DIRECTORIES-EXIST accepts the keyword argument :MODE which is
passed to MKDIR.
- In EXT:RUN-PROGRAM the child process is delayed until the parent has created
the process structure and stored the process id in it. Formerly we had race
conditions due to the child exiting before the parent was able to call sigwait().
* Metaobject protocol:
- Implemented CLOS:COMPUTE-APPLICABLE-METHODS-USING-CLASSES.

31
src/c/unixsys.d
View file

@ -623,6 +623,7 @@ make_windows_handle(HANDLE h)
#else /* mingw */
{
int child_stdin, child_stdout, child_stderr;
int pipe_fd[2];
argv = CONS(command, ecl_nconc(argv, ecl_list1(Cnil)));
argv = cl_funcall(3, @'coerce', argv, @'vector');
AGAIN_INPUT:
@ -701,14 +702,22 @@ make_windows_handle(HANDLE h)
error);
}
add_external_process(the_env, process);
/* We have to protect this, to avoid the signal being delivered or handled
* before we set the process pid */
ecl_bds_bind(the_env, @'ext::*interrupts-enabled*', Cnil);
pipe(pipe_fd);
child_pid = fork();
if (child_pid == 0) {
/* Child */
int j;
void **argv_ptr = (void **)argv->vector.self.t;
{
/* Wait for the parent to set up its process structure */
char sync[1];
close(pipe_fd[1]);
while (read(pipe_fd[0], sync, 1) < 1) {
printf("\nError reading child pipe %d", errno);
fflush(stdout);
}
close(pipe_fd[0]);
}
dup2(child_stdin, STDIN_FILENO);
if (parent_write) close(parent_write);
dup2(child_stdout, STDOUT_FILENO);
@ -740,8 +749,20 @@ make_windows_handle(HANDLE h)
pid = MAKE_FIXNUM(child_pid);
}
set_external_process_pid(process, pid);
ecl_bds_unwind1(the_env);
ecl_check_pending_interrupts(the_env);
{
/* This guarantees that the child process does not exit
* before we have created the process structure. If we do not
* do this, the SIGPIPE signal may arrive before
* set_external_process_pid() and our call to external-process-wait
* down there may block indefinitely. */
char sync[1];
close(pipe_fd[0]);
while (write(pipe_fd[1], sync, 1) < 1) {
printf("\nError writing child pipe %d", errno);
fflush(stdout);
}
close(pipe_fd[1]);
}
close(child_stdin);
close(child_stdout);
close(child_stderr);