From f9953afbfc53862e81c5c4e3527afd76df7648cd Mon Sep 17 00:00:00 2001
From: Florian Forster <octo@collectd.org>
Date: Wed, 27 Sep 2017 08:07:10 +0200
Subject: [PATCH] email, exec and unixsock plugins: Use _SC_GETPW_R_SIZE_MAX.

Fixes: #2208
---
 src/email.c    |  8 +++++++-
 src/exec.c     | 17 +++++++++++++++--
 src/unixsock.c |  8 +++++++-
 3 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/src/email.c b/src/email.c
index b7a5bcad..b4a5e811 100644
--- a/src/email.c
+++ b/src/email.c
@@ -403,9 +403,15 @@ static void *open_connection(void __attribute__((unused)) * arg) {
   {
     struct group sg;
     struct group *grp;
-    char grbuf[4096];
     int status;
 
+    long int grbuf_size = sysconf(_SC_GETGR_R_SIZE_MAX);
+    if (grbuf_size <= 0)
+      grbuf_size = sysconf(_SC_PAGESIZE);
+    if (grbuf_size <= 0)
+      grbuf_size = 4096;
+    char grbuf[grbuf_size];
+
     grp = NULL;
     status = getgrnam_r(group, &sg, grbuf, sizeof(grbuf), &grp);
     if (status != 0) {
diff --git a/src/exec.c b/src/exec.c
index 3e480283..e499f112 100644
--- a/src/exec.c
+++ b/src/exec.c
@@ -369,11 +369,17 @@ static int fork_child(program_list_t *pl, int *fd_in, int *fd_out,
 
   struct passwd *sp_ptr;
   struct passwd sp;
-  char nambuf[4096];
 
   if (pl->pid != 0)
     return (-1);
 
+  long int nambuf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
+  if (nambuf_size <= 0)
+    nambuf_size = sysconf(_SC_PAGESIZE);
+  if (nambuf_size <= 0)
+    nambuf_size = 4096;
+  char nambuf[nambuf_size];
+
   if ((create_pipe(fd_pipe_in) == -1) || (create_pipe(fd_pipe_out) == -1) ||
       (create_pipe(fd_pipe_err) == -1))
     goto failed;
@@ -406,7 +412,14 @@ static int fork_child(program_list_t *pl, int *fd_in, int *fd_out,
       struct group *gr_ptr = NULL;
       struct group gr;
 
-      status = getgrnam_r(pl->group, &gr, nambuf, sizeof(nambuf), &gr_ptr);
+      long int grbuf_size = sysconf(_SC_GETGR_R_SIZE_MAX);
+      if (grbuf_size <= 0)
+        grbuf_size = sysconf(_SC_PAGESIZE);
+      if (grbuf_size <= 0)
+        grbuf_size = 4096;
+      char grbuf[grbuf_size];
+
+      status = getgrnam_r(pl->group, &gr, grbuf, sizeof(grbuf), &gr_ptr);
       if (0 != status) {
         ERROR("exec plugin: Failed to get group information "
               "for group ``%s'': %s",
diff --git a/src/unixsock.c b/src/unixsock.c
index 020a577a..3a9d25b2 100644
--- a/src/unixsock.c
+++ b/src/unixsock.c
@@ -134,7 +134,13 @@ static int us_open_socket(void) {
     const char *grpname;
     struct group *g;
     struct group sg;
-    char grbuf[4096];
+
+    long int grbuf_size = sysconf(_SC_GETGR_R_SIZE_MAX);
+    if (grbuf_size <= 0)
+      grbuf_size = sysconf(_SC_PAGESIZE);
+    if (grbuf_size <= 0)
+      grbuf_size = 4096;
+    char grbuf[grbuf_size];
 
     grpname = (sock_group != NULL) ? sock_group : COLLECTD_GRP_NAME;
     g = NULL;
-- 
2.30.2