Merge branch 'lukas/erts/spawn_driver_relative_cd/ERL-175/OTP-13733' into maint

* lukas/erts/spawn_driver_relative_cd/ERL-175/OTP-13733:
  erts: Add port_SUITE:cd invalid dir testcase
  erts: Fix spawn driver with relative cd option
  erts: Fix HARD_DEBUG printouts in erl_child_setup
  erts: Improve error printouts in erl_child_setup

Conflicts:
	erts/emulator/test/port_SUITE.erl

2 files changed, 91 insertions, 38 deletions

diff --git a/erts/emulator/sys/unix/erl_child_setup.c b/erts/emulator/sys/unix/erl_child_setup.c
index de61726e5b..6b9ddd8da4 100644
--- a/erts/emulator/sys/unix/erl_child_setup.c
+++ b/erts/emulator/sys/unix/erl_child_setup.c
@@ -75,7 +75,7 @@
 
 //#define HARD_DEBUG
 #ifdef HARD_DEBUG
-#define DEBUG_PRINT(fmt, ...) fprintf(stderr, fmt "\r\n", ##__VA_ARGS__)
+#define DEBUG_PRINT(fmt, ...) fprintf(stderr, "%d:" fmt "\r\n", getpid(), ##__VA_ARGS__)
 #else
 #define DEBUG_PRINT(fmt, ...)
 #endif
@@ -131,12 +131,13 @@ static int sigchld_pipe[2];
 static int
 start_new_child(int pipes[])
 {
+    int errln = -1;
     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;
 
-    Sint cnt, flags;
+    Sint32 cnt, flags;
 
     /* only child executes here */
 
@@ -145,6 +146,7 @@ start_new_child(int pipes[])
     } while(res < 0 && (errno == EINTR || errno == ERRNO_BLOCK));
 
     if (res <= 0) {
+        errln = __LINE__;
         goto child_error;
     }
 
@@ -156,10 +158,12 @@ start_new_child(int pipes[])
         if ((res = read(pipes[0], buff + pos, size - pos)) < 0) {
             if (errno == ERRNO_BLOCK || errno == EINTR)
                 continue;
+            errln = __LINE__;
             goto child_error;
         }
         if (res == 0) {
             errno = EPIPE;
+            errln = __LINE__;
             goto child_error;
         }
         pos += res;
@@ -168,12 +172,16 @@ start_new_child(int pipes[])
     o_buff = buff;
 
     flags = get_int32(buff);
-    buff += sizeof(Sint32);
+    buff += sizeof(flags);
 
     DEBUG_PRINT("flags = %d", flags);
 
     cmd = buff;
     buff += strlen(buff) + 1;
+
+    cwd = buff;
+    buff += strlen(buff) + 1;
+
     if (*buff == '\0') {
         wd = NULL;
     } else {
@@ -185,10 +193,10 @@ start_new_child(int pipes[])
     DEBUG_PRINT("wd = %s", wd);
 
     cnt = get_int32(buff);
-    buff += sizeof(Sint32);
+    buff += sizeof(cnt);
     new_environ = malloc(sizeof(char*)*(cnt + 1));
 
-    DEBUG_PRINT("env_len = %ld", cnt);
+    DEBUG_PRINT("env_len = %d", cnt);
     for (i = 0; i < cnt; i++, buff++) {
         new_environ[i] = buff;
         while(*buff != '\0') buff++;
@@ -198,7 +206,7 @@ start_new_child(int pipes[])
     if (o_buff + size != buff) {
         /* This is a spawn executable call */
         cnt = get_int32(buff);
-        buff += sizeof(Sint32);
+        buff += sizeof(cnt);
         args = malloc(sizeof(char*)*(cnt + 1));
         for (i = 0; i < cnt; i++, buff++) {
             args[i] = buff;
@@ -209,7 +217,12 @@ start_new_child(int pipes[])
 
     if (o_buff + size != buff) {
         errno = EINVAL;
-        goto child_error;
+        errln = __LINE__;
+        fprintf(stderr,"erl_child_setup: failed with protocol "
+                "error %d on line %d", errno, errln);
+        /* we abort here as it is most likely a symptom of an
+           emulator/erl_child_setup bug */
+        abort();
     }
 
     DEBUG_PRINT("read ack");
@@ -221,12 +234,32 @@ 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("Do that forking business: '%s'\n",cmd);
+    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) {
+        int err = errno;
+        fprintf(stderr,"spawn: Could not cd to %s\r\n", wd);
+        _exit(err);
+    }
+
+    DEBUG_PRINT("Do that forking business: '%s'",cmd);
 
     /* When the dup2'ing below is done, only
        fd's 0, 1, 2 and maybe 3, 4 should survive the
@@ -236,25 +269,34 @@ start_new_child(int pipes[])
     if (flags & FORKER_FLAG_USE_STDIO) {
         /* stdin for process */
         if (flags & FORKER_FLAG_DO_WRITE &&
-            dup2(pipes[0], 0) < 0)
+            dup2(pipes[0], 0) < 0) {
+            errln = __LINE__;
             goto child_error;
+        }
         /* stdout for process */
         if (flags & FORKER_FLAG_DO_READ &&
-            dup2(pipes[1], 1) < 0)
+            dup2(pipes[1], 1) < 0) {
+            errln = __LINE__;
             goto child_error;
+        }
     }
     else {	/* XXX will fail if pipes[0] == 4 (unlikely..) */
-        if (flags & FORKER_FLAG_DO_READ && dup2(pipes[1], 4) < 0)
+        if (flags & FORKER_FLAG_DO_READ && dup2(pipes[1], 4) < 0) {
+            errln = __LINE__;
             goto child_error;
-        if (flags & FORKER_FLAG_DO_WRITE && dup2(pipes[0], 3) < 0)
+        }
+        if (flags & FORKER_FLAG_DO_WRITE && dup2(pipes[0], 3) < 0) {
+            errln = __LINE__;
             goto child_error;
+        }
     }
 
-    if (dup2(pipes[2], 2) < 0)
-        goto child_error;
-
-    if (wd && chdir(wd) < 0)
+    /* we do the dup2 of stderr last so that errors
+       in child_error will be printed to stderr */
+    if (dup2(pipes[2], 2) < 0) {
+        errln = __LINE__;
         goto child_error;
+    }
 
 #if defined(USE_SETPGRP_NOARGS)		/* SysV */
     (void) setpgrp();
@@ -276,9 +318,14 @@ start_new_child(int pipes[])
     } else {
         execle(SHELL, "sh", "-c", cmd, (char *) NULL, new_environ);
     }
+
+    DEBUG_PRINT("exec error: %d",errno);
+    _exit(errno);
+
 child_error:
-    DEBUG_PRINT("exec error: %d\r\n",errno);
-    _exit(128 + errno);
+    fprintf(stderr,"erl_child_setup: failed with error %d on line %d\r\n",
+            errno, errln);
+    _exit(errno);
 }
 
 
@@ -469,7 +516,7 @@ main(int argc, char *argv[])
 
             proto.action = ErtsSysForkerProtoAction_SigChld;
             proto.u.sigchld.error_number = ibuff[1];
-            DEBUG_PRINT("send %s to %d", buff, uds_fd);
+            DEBUG_PRINT("send sigchld to %d (errno = %d)", uds_fd, ibuff[1]);
             if (write(uds_fd, &proto, sizeof(proto)) < 0) {
                 if (errno == EINTR)
                     continue;
diff --git a/erts/emulator/sys/unix/sys_drivers.c b/erts/emulator/sys/unix/sys_drivers.c
index 3d7be020e1..400f163652 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++;
@@ -704,10 +704,16 @@ 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;