h/fish-shell
1
Fork 0
mirror of https://github.com/fish-shell/fish-shell.git synced 2026-06-06 08:51:14 -03:00
Code Issues Packages Projects Releases Wiki Activity

Don't use posix_spawn for commands that need to be put into foreground to avoid a race

Browse Source 
Fix for race where a command's output may not be fully drained
This commit is contained in:
ridiculousfish
2012-11-04 15:45:52 -08:00
parent e46324ced9
commit 5e371e8fe7
4 changed files with 28 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
exec.cpp
View File

@@ -506,11 +506,22 @@ static void do_builtin_io( const char *out, const char *err )
/* Returns whether we can use posix spawn for a given process in a given job.
Per https://github.com/fish-shell/fish-shell/issues/364 , error handling for file redirections is too difficult with posix_spawn
So in that case we use fork/exec.
So in that case we use fork/exec
Furthermore, to avoid the race between the caller calling tcsetpgrp() and the client checking the foreground process group, we don't use posix_spawn if we're going to foreground the process. (If we use fork(), we can call tcsetpgrp after the fork, before the exec, and avoid the racse).
*/
static bool can_use_posix_spawn_for_job(const job_t *job, const process_t *process)
{
if ( job_get_flag( job, JOB_CONTROL ) )
{
/* We are going to use job control; therefore when we launch this job it will get its own process group ID. But will it be foregrounded? */
if ( job_get_flag( job, JOB_TERMINAL ) && job_get_flag( job, JOB_FOREGROUND ) )
{
/* It will be foregrounded, so we will call tcsetpgrp(), therefore do not use posix_spawn */
return false;
}
}
bool result = true;
for (size_t idx = 0; idx < job->io.size(); idx++)
{
@@ -1142,7 +1153,7 @@ void exec( parser_t &parser, job_t *j )
( ! get_stdout_buffer().empty() ) &&
( buffer_stdout ) )
{
std::string res = wcs2string( get_stdout_buffer() );
const std::string res = wcs2string( get_stdout_buffer() );
io->out_buffer_append( res.c_str(), res.size() );
skip_fork = 1;
}
@@ -1268,6 +1279,10 @@ void exec( parser_t &parser, job_t *j )
{
/* We successfully made the attributes and actions; actually call posix_spawn */
int spawn_ret = posix_spawn(&pid, actual_cmd, &actions, &attr, argv, envv);
/* This usleep can be used to test for various race conditions (https://github.com/fish-shell/fish-shell/issues/360) */
//usleep(10000);
if (spawn_ret != 0)
{
safe_report_exec_error(spawn_ret, actual_cmd, argv, envv);