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authorLukas Larsson <[email protected]>2016-06-21 14:49:03 +0200
committerLukas Larsson <[email protected]>2016-07-01 11:19:23 +0200
commit46e16383d62990b4b07eac32560ca8abec82b710 (patch)
tree6617bacec7a18655ea46575034d85a5ea4d861e0
parent3f64be5c822e1ee4d1dc2a4289e4906d789c64ac (diff)
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erts: Improve error printouts in erl_child_setup
Add prints to stderr with a small description of the error so that errors will be easier to debug. Also if a protocol error is detected, erl_child_setup will abort instead of exit.
-rw-r--r--erts/emulator/sys/unix/erl_child_setup.c51
1 files changed, 40 insertions, 11 deletions
diff --git a/erts/emulator/sys/unix/erl_child_setup.c b/erts/emulator/sys/unix/erl_child_setup.c
index 6beb316350..b2263371dd 100644
--- a/erts/emulator/sys/unix/erl_child_setup.c
+++ b/erts/emulator/sys/unix/erl_child_setup.c
@@ -123,6 +123,7 @@ 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;
@@ -137,6 +138,7 @@ start_new_child(int pipes[])
} while(res < 0 && (errno == EINTR || errno == ERRNO_BLOCK));
if (res <= 0) {
+ errln = __LINE__;
goto child_error;
}
@@ -148,10 +150,12 @@ 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;
@@ -201,7 +205,12 @@ 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");
@@ -215,11 +224,17 @@ start_new_child(int pipes[])
} 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);
+ if (wd && chdir(wd) < 0) {
+ errln = __LINE__;
+ goto child_error;
+ }
+
/* When the dup2'ing below is done, only
fd's 0, 1, 2 and maybe 3, 4 should survive the
exec. All other fds (i.e. the unix domain sockets
@@ -228,25 +243,34 @@ 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();
@@ -268,9 +292,14 @@ 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",
+ errno, errln);
+ _exit(errno);
}