From 412d7dfcfb667bb2b329b8e35c929c2b5abcc2b1 Mon Sep 17 00:00:00 2001
From: Lukas Larsson <lukas@erlang-solutions.com>
Date: Mon, 27 Jun 2016 18:40:36 +0200
Subject: erts: Fix spawn driver with relative cd option

---
 erts/emulator/sys/unix/erl_child_setup.c | 22 ++++++++++++++---
 erts/emulator/sys/unix/sys_drivers.c     | 42 ++++++++++++++++++--------------
 2 files changed, 43 insertions(+), 21 deletions(-)

(limited to 'erts/emulator/sys')

diff --git a/erts/emulator/sys/unix/erl_child_setup.c b/erts/emulator/sys/unix/erl_child_setup.c
index 219ca98c71..fa4750a6e9 100644
--- a/erts/emulator/sys/unix/erl_child_setup.c
+++ b/erts/emulator/sys/unix/erl_child_setup.c
@@ -127,7 +127,7 @@ start_new_child(int pipes[])
     int size, res, i, pos = 0;
     char *buff, *o_buff;
 
-    char *cmd, *wd, **new_environ, **args = NULL;
+    char *cmd, *cwd, *wd, **new_environ, **args = NULL;
 
     Sint32 cnt, flags;
 
@@ -170,6 +170,10 @@ start_new_child(int pipes[])
 
     cmd = buff;
     buff += strlen(buff) + 1;
+
+    cwd = buff;
+    buff += strlen(buff) + 1;
+
     if (*buff == '\0') {
         wd = NULL;
     } else {
@@ -222,17 +226,29 @@ start_new_child(int pipes[])
             ASSERT(res == sizeof(proto));
         }
     } while(res < 0 && (errno == EINTR || errno == ERRNO_BLOCK));
+
     if (res < 1) {
         errno = EPIPE;
         errln = __LINE__;
         goto child_error;
     }
 
+    DEBUG_PRINT("Set cwd to: '%s'",cwd);
+
+    if (chdir(cwd) < 0) {
+        /* This is not good, it probably means that the cwd of
+           beam is invalid. We ignore it and try anyways as
+           the child might now need a cwd or the chdir below
+           could take us to a valid directory.
+        */
+    }
+
     DEBUG_PRINT("Set wd to: '%s'",wd);
 
     if (wd && chdir(wd) < 0) {
-        errln = __LINE__;
-        goto child_error;
+        int err = errno;
+        fprintf(stderr,"spawn: Could not cd to %s\r\n", wd);
+        _exit(err);
     }
 
     DEBUG_PRINT("Do that forking business: '%s'",cmd);
diff --git a/erts/emulator/sys/unix/sys_drivers.c b/erts/emulator/sys/unix/sys_drivers.c
index 812112fb91..78e7086bd8 100644
--- a/erts/emulator/sys/unix/sys_drivers.c
+++ b/erts/emulator/sys/unix/sys_drivers.c
@@ -554,7 +554,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name,
     ErtsSysDriverData *dd;
     char *cmd_line;
     char wd_buff[MAXPATHLEN+1];
-    char *wd;
+    char *wd, *cwd;
     int ifd[2], ofd[2], stderrfd;
 
     if (pipe(ifd) < 0) return ERL_DRV_ERROR_ERRNO;
@@ -631,24 +631,22 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name,
 	return ERL_DRV_ERROR_ERRNO;
     }
 
-    if (opts->wd == NULL) {
-        if ((wd = getcwd(wd_buff, MAXPATHLEN+1)) == NULL) {
-            /* on some OSs this call opens a fd in the
-               background which means that this can
-               return EMFILE */
-            int err = errno;
-            close_pipes(ifd, ofd);
-            erts_free(ERTS_ALC_T_TMP, (void *) cmd_line);
-            if (new_environ != environ)
-                erts_free(ERTS_ALC_T_ENVIRONMENT, (void *) new_environ);
-            erts_smp_rwmtx_runlock(&environ_rwmtx);
-            errno = err;
-            return ERL_DRV_ERROR_ERRNO;
-        }
-    } else {
-        wd = opts->wd;
+    if ((cwd = getcwd(wd_buff, MAXPATHLEN+1)) == NULL) {
+        /* on some OSs this call opens a fd in the
+           background which means that this can
+           return EMFILE */
+        int err = errno;
+        close_pipes(ifd, ofd);
+        erts_free(ERTS_ALC_T_TMP, (void *) cmd_line);
+        if (new_environ != environ)
+            erts_free(ERTS_ALC_T_ENVIRONMENT, (void *) new_environ);
+        erts_smp_rwmtx_runlock(&environ_rwmtx);
+        errno = err;
+        return ERL_DRV_ERROR_ERRNO;
     }
 
+    wd = opts->wd;
+
     {
         struct iovec *io_vector;
         int iov_len = 5;
@@ -660,6 +658,8 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name,
             | (opts->read_write & DO_READ ? FORKER_FLAG_DO_READ : 0)
             | (opts->read_write & DO_WRITE ? FORKER_FLAG_DO_WRITE : 0);
 
+        if (wd) iov_len++;
+
         /* count number of elements in environment */
         while(new_environ[env_len] != NULL)
             env_len++;
@@ -700,10 +700,16 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name,
         io_vector[i++].iov_len = len;
         buffsz += len;
 
-        io_vector[i].iov_base = wd;
+        io_vector[i].iov_base = cwd;
         io_vector[i].iov_len = strlen(io_vector[i].iov_base) + 1;
         buffsz += io_vector[i++].iov_len;
 
+        if (wd) {
+            io_vector[i].iov_base = wd;
+            io_vector[i].iov_len = strlen(io_vector[i].iov_base) + 1;
+            buffsz += io_vector[i++].iov_len;
+        }
+
         io_vector[i].iov_base = nullbuff;
         io_vector[i++].iov_len = 1;
         buffsz += io_vector[i-1].iov_len;
-- 
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