Bug 8719 – spawnvp() (POSIX) throws exception in fork()ed child process

On POSIX systems, std.process.spawnvp() exposes its implementation to the caller in an unexpected way: if the call to std.c.process.execvp() fails, it throws an exception *in the forked child process*. Sample program: import std.stdio; import std.process; int main() { string[] command = ["nosuchcommand"]; int status; writefln("[pid %d]: spawning %s", getpid(), command); try { status = spawnvp(P_WAIT, command[0], command); } catch (Exception err) { stderr.writefln("[pid %d] %s failed: %s", getpid(), command[0], err.msg); return -1; } writefln("[pid %d] %s exited with status %d", getpid(), command[0], status); return status; } Running it produces this output: [pid 8923] spawning ["nosuchcommand"] [pid 8924] nosuchcommand failed: Cannot spawn nosuchcommand; No such file or directory [errno 2] [pid 8923] nosuchcommand exited with status 255 The unexpected surprise is that *both* of my post-spawnvp() writefln() calls happen. I expected the writefln() in the catch block to be called, but not the one outside the catch block. The explanation is obvious once you add the PID. The workaround is fairly easy: catch Exception and turn it into "return -1" (or whatever you please). However, this is probably *not* the right thing to do on Windows, where there is no fork() call. Basically the problem is that the POSIX implementation of spawnvp() leaks an implementation detail: the use of fork().

spawnvp is deprecated, use spawnProcess.