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authorNico Weber <nicolasweber@gmx.de>2016-03-21 01:41:15 (GMT)
committerNico Weber <nicolasweber@gmx.de>2016-03-21 01:42:17 (GMT)
commit89587196705f54afb904c8f4572e65de7274dd81 (patch)
treec5029715235334ab282237f941f86da3eaf68707 /src
parentb231274de33a6ebaa5ed284eb233fa360d84ad8f (diff)
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Use posix_spawn() instead of fork()/exec().
posix_spawn() is a syscall on OS X and Solaris and a bit faster. It's also easier emulate for cygwin, and the code is a bit simpler.
Diffstat (limited to 'src')
-rw-r--r--src/subprocess-posix.cc107
-rw-r--r--src/subprocess_test.cc3
2 files changed, 56 insertions, 54 deletions
diff --git a/src/subprocess-posix.cc b/src/subprocess-posix.cc
index ae7ae6f..5ffe85b 100644
--- a/src/subprocess-posix.cc
+++ b/src/subprocess-posix.cc
@@ -22,6 +22,9 @@
#include <stdio.h>
#include <string.h>
#include <sys/wait.h>
+#include <spawn.h>
+
+extern char** environ;
#include "util.h"
@@ -50,62 +53,60 @@ bool Subprocess::Start(SubprocessSet* set, const string& command) {
#endif // !USE_PPOLL
SetCloseOnExec(fd_);
- pid_ = fork();
- if (pid_ < 0)
- Fatal("fork: %s", strerror(errno));
-
- if (pid_ == 0) {
- close(output_pipe[0]);
-
- // Track which fd we use to report errors on.
- int error_pipe = output_pipe[1];
- do {
- if (sigaction(SIGINT, &set->old_int_act_, 0) < 0)
- break;
- if (sigaction(SIGTERM, &set->old_term_act_, 0) < 0)
- break;
- if (sigaction(SIGHUP, &set->old_hup_act_, 0) < 0)
- break;
- if (sigprocmask(SIG_SETMASK, &set->old_mask_, 0) < 0)
- break;
-
- if (!use_console_) {
- // Put the child in its own process group, so ctrl-c won't reach it.
- if (setpgid(0, 0) < 0)
- break;
-
- // Open /dev/null over stdin.
- int devnull = open("/dev/null", O_RDONLY);
- if (devnull < 0)
- break;
- if (dup2(devnull, 0) < 0)
- break;
- close(devnull);
-
- if (dup2(output_pipe[1], 1) < 0 ||
- dup2(output_pipe[1], 2) < 0)
- break;
-
- // Now can use stderr for errors.
- error_pipe = 2;
- close(output_pipe[1]);
- }
- // In the console case, output_pipe is still inherited by the child and
- // closed when the subprocess finishes, which then notifies ninja.
-
- execl("/bin/sh", "/bin/sh", "-c", command.c_str(), (char *) NULL);
- } while (false);
-
- // If we get here, something went wrong; the execl should have
- // replaced us.
- char* err = strerror(errno);
- if (write(error_pipe, err, strlen(err)) < 0) {
- // If the write fails, there's nothing we can do.
- // But this block seems necessary to silence the warning.
+ posix_spawn_file_actions_t action;
+ if (posix_spawn_file_actions_init(&action) != 0)
+ Fatal("posix_spawn_file_actions_init: %s", strerror(errno));
+
+ if (posix_spawn_file_actions_addclose(&action, output_pipe[0]) != 0)
+ Fatal("posix_spawn_file_actions_addclose: %s", strerror(errno));
+
+ posix_spawnattr_t attr;
+ if (posix_spawnattr_init(&attr) != 0)
+ Fatal("posix_spawnattr_init: %s", strerror(errno));
+
+ short flags = 0;
+
+ flags |= POSIX_SPAWN_SETSIGMASK;
+ if (posix_spawnattr_setsigmask(&attr, &set->old_mask_) != 0)
+ Fatal("posix_spawnattr_setsigmask: %s", strerror(errno));
+ // Signals which are set to be caught in the calling process image are set to
+ // default action in the new process image, so no explicit
+ // POSIX_SPAWN_SETSIGDEF parameter is needed.
+
+ // TODO: Consider using POSIX_SPAWN_USEVFORK on Linux with glibc?
+
+ if (!use_console_) {
+ // Put the child in its own process group, so ctrl-c won't reach it.
+ flags |= POSIX_SPAWN_SETPGROUP;
+ // No need to posix_spawnattr_setpgroup(&attr, 0), it's the default.
+
+ // Open /dev/null over stdin.
+ if (posix_spawn_file_actions_addopen(&action, 0, "/dev/null", O_RDONLY,
+ 0) != 0) {
+ Fatal("posix_spawn_file_actions_addopen: %s", strerror(errno));
}
- _exit(1);
+
+ if (posix_spawn_file_actions_adddup2(&action, output_pipe[1], 1) != 0)
+ Fatal("posix_spawn_file_actions_adddup2: %s", strerror(errno));
+ if (posix_spawn_file_actions_adddup2(&action, output_pipe[1], 2) != 0)
+ Fatal("posix_spawn_file_actions_adddup2: %s", strerror(errno));
+ // In the console case, output_pipe is still inherited by the child and
+ // closed when the subprocess finishes, which then notifies ninja.
}
+ if (posix_spawnattr_setflags(&attr, flags) != 0)
+ Fatal("posix_spawnattr_setflags: %s", strerror(errno));
+
+ const char* spawned_args[] = { "/bin/sh", "-c", command.c_str(), NULL };
+ if (posix_spawn(&pid_, "/bin/sh", &action, &attr,
+ const_cast<char**>(spawned_args), environ) != 0)
+ Fatal("posix_spawn: %s", strerror(errno));
+
+ if (posix_spawnattr_destroy(&attr) != 0)
+ Fatal("posix_spawnattr_destroy: %s", strerror(errno));
+ if (posix_spawn_file_actions_destroy(&action) != 0)
+ Fatal("posix_spawn_file_actions_destroy: %s", strerror(errno));
+
close(output_pipe[1]);
return true;
}
diff --git a/src/subprocess_test.cc b/src/subprocess_test.cc
index c8f2fb8..ee16190 100644
--- a/src/subprocess_test.cc
+++ b/src/subprocess_test.cc
@@ -226,7 +226,8 @@ TEST_F(SubprocessTest, SetWithLots) {
rlimit rlim;
ASSERT_EQ(0, getrlimit(RLIMIT_NOFILE, &rlim));
if (rlim.rlim_cur < kNumProcs) {
- printf("Raise [ulimit -n] well above %u (currently %lu) to make this test go\n", kNumProcs, rlim.rlim_cur);
+ printf("Raise [ulimit -n] above %u (currently %lu) to make this test go\n",
+ kNumProcs, rlim.rlim_cur);
return;
}