tlibthread: add threadspawnd - plan9port - [fork] Plan 9 from user space

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---

commit 9e4b56e7645e08311590355824863ecf9f334f0c

parent 81c2c5e775d83896f25981cf4c4e486c5cc91180

Author: Russ Cox 

Date:   Mon, 22 Oct 2012 12:32:09 -0400

libthread: add threadspawnd

R=rsc
http://codereview.appspot.com/6742064

Diffstat:
  M include/thread.h                    |       1 +
  M man/man3/thread.3                   |      11 +++++++++++
  M src/libthread/exec.c                |      17 +++++++++++++----
  M src/libthread/threadimpl.h          |       5 +++--

4 files changed, 28 insertions(+), 6 deletions(-)
---

diff --git a/include/thread.h b/include/thread.h

t@@ -175,6 +175,7 @@ long                iowrite(Ioproc *io, int fd, void *a, long n);
 void                threadexec(Channel*, int[3], char*, char *[]);
 void                threadexecl(Channel*, int[3], char*, ...);
 int                threadspawn(int[3], char*, char*[]);
+int                threadspawnd(int[3], char*, char*[], char*);
 int                threadspawnl(int[3], char*, ...);
 Channel*        threadwaitchan(void);
 

diff --git a/man/man3/thread.3 b/man/man3/thread.3

t@@ -42,6 +42,7 @@ threadsetgrp,
 threadsetname,
 threadsetstate,
 threadspawn,
+threadspawnd,
 threadspawnl,
 threadwaitchan,
 yield \- thread and proc management
t@@ -124,6 +125,7 @@ int        chanprint(Channel *c, char *fmt, ...)
 .XX
 int        threadspawnl(int fd[3], char *file, ...)
 int        threadspawn(int fd[3], char *file, char *args[])
+int        threadspawnd(int fd[3], char *file, char *args[], char *dir)
 int        threadexecl(Channel *cpid, int fd[3], char *file, ...)
 int        threadexec(Channel *cpid, int fd[3], char *file, char *args[])
 Channel*        threadwaitchan(void)
t@@ -240,6 +242,8 @@ Calls that do this are
 .IR threadexecl ,
 .IR threadexits ,
 .IR threadspawn ,
+.IR threadspawnd ,
+.IR threadspawnl ,
 .IR alt ,
 .IR send ,
 and
t@@ -419,6 +423,13 @@ and
 but do not replace the current thread.
 They return the pid of the invoked program on success, or
 \-1 on error.
+.I Threadspawnd
+is like
+.I threadspawn
+but takes as its final argument the directory in which to run the invoked program.
+The child will attempt to change into that directory before running the program,
+but it is only best effort: failure to change into the directory does not
+stop the running of the program.
 .PP
 .I Threadwaitchan
 returns a channel of pointers to

diff --git a/src/libthread/exec.c b/src/libthread/exec.c

t@@ -12,7 +12,7 @@ execproc(void *v)
         Waitmsg *w;
 
         e = v;
-        pid = _threadspawn(e->fd, e->cmd, e->argv);
+        pid = _threadspawn(e->fd, e->cmd, e->argv, e->dir);
         sendul(e->c, pid);
         if(pid > 0){
                 w = waitfor(pid);
t@@ -25,7 +25,7 @@ execproc(void *v)
 }
 
 int
-_runthreadspawn(int *fd, char *cmd, char **argv)
+_runthreadspawn(int *fd, char *cmd, char **argv, char *dir)
 {
         int pid;
         Execjob e;
t@@ -33,6 +33,7 @@ _runthreadspawn(int *fd, char *cmd, char **argv)
         e.fd = fd;
         e.cmd = cmd;
         e.argv = argv;
+        e.dir = dir;
         e.c = chancreate(sizeof(void*), 0);
         proccreate(execproc, &e, 65536);
         pid = recvul(e.c);
t@@ -57,7 +58,7 @@ threadwaitchan(void)
 }
 
 int
-_threadspawn(int fd[3], char *cmd, char *argv[])
+_threadspawn(int fd[3], char *cmd, char *argv[], char *dir)
 {
         int i, n, p[2], pid;
         char exitstr[100];
t@@ -77,6 +78,8 @@ _threadspawn(int fd[3], char *cmd, char *argv[])
                 return -1;
         case 0:
                 /* can't RFNOTEG - will lose tty */
+                if(dir != nil )
+                        chdir(dir); /* best effort */
                 dup2(fd[0], 0);
                 dup2(fd[1], 1);
                 dup2(fd[2], 2);
t@@ -112,7 +115,13 @@ _threadspawn(int fd[3], char *cmd, char *argv[])
 int
 threadspawn(int fd[3], char *cmd, char *argv[])
 {
-        return _runthreadspawn(fd, cmd, argv);
+        return _runthreadspawn(fd, cmd, argv, nil);
+}
+
+int
+threadspawnd(int fd[3], char *cmd, char *argv[], char *dir)
+{
+        return _runthreadspawn(fd, cmd, argv, dir);
 }
 
 int

diff --git a/src/libthread/threadimpl.h b/src/libthread/threadimpl.h

t@@ -121,6 +121,7 @@ struct Execjob
         int *fd;
         char *cmd;
         char **argv;
+        char *dir;
         Channel *c;
 };
 
t@@ -203,8 +204,8 @@ extern void _threadsetproc(Proc*);
 extern int _threadlock(Lock*, int, ulong);
 extern void _threadunlock(Lock*, ulong);
 extern void _pthreadinit(void);
-extern int _threadspawn(int*, char*, char**);
-extern int _runthreadspawn(int*, char*, char**);
+extern int _threadspawn(int*, char*, char**, char*);
+extern int _runthreadspawn(int*, char*, char**, char*);
 extern void _threadsetupdaemonize(void);
 extern void _threaddodaemonize(char*);
 extern void _threadpexit(void);