Merging upstream version 1.33.0.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

11 files changed, 734 insertions, 458 deletions

diff --git a/libnetdata/Makefile.am b/libnetdata/Makefile.am
index 598b72f5..e787801c 100644
--- a/libnetdata/Makefile.am
+++ b/libnetdata/Makefile.am
@@ -8,6 +8,7 @@ SUBDIRS = \
     avl \
     buffer \
     clocks \
+    completion \
     config \
     dictionary \
     ebpf \
diff --git a/libnetdata/completion/Makefile.am b/libnetdata/completion/Makefile.am
new file mode 100644
index 00000000..babdcf0d
--- /dev/null
+++ b/libnetdata/completion/Makefile.am
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
diff --git a/libnetdata/completion/completion.c b/libnetdata/completion/completion.c
new file mode 100644
index 00000000..77818f40
--- /dev/null
+++ b/libnetdata/completion/completion.c
@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "completion.h"
+
+void completion_init(struct completion *p)
+{
+    p->completed = 0;
+    fatal_assert(0 == uv_cond_init(&p->cond));
+    fatal_assert(0 == uv_mutex_init(&p->mutex));
+}
+
+void completion_destroy(struct completion *p)
+{
+    uv_cond_destroy(&p->cond);
+    uv_mutex_destroy(&p->mutex);
+}
+
+void completion_wait_for(struct completion *p)
+{
+    uv_mutex_lock(&p->mutex);
+    while (0 == p->completed) {
+        uv_cond_wait(&p->cond, &p->mutex);
+    }
+    fatal_assert(1 == p->completed);
+    uv_mutex_unlock(&p->mutex);
+}
+
+void completion_mark_complete(struct completion *p)
+{
+    uv_mutex_lock(&p->mutex);
+    p->completed = 1;
+    uv_mutex_unlock(&p->mutex);
+    uv_cond_broadcast(&p->cond);
+}
diff --git a/libnetdata/completion/completion.h b/libnetdata/completion/completion.h
new file mode 100644
index 00000000..667360a4
--- /dev/null
+++ b/libnetdata/completion/completion.h
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_COMPLETION_H
+#define NETDATA_COMPLETION_H
+
+#include "../libnetdata.h"
+
+struct completion {
+    uv_mutex_t mutex;
+    uv_cond_t cond;
+    volatile unsigned completed;
+};
+
+void completion_init(struct completion *p);
+
+void completion_destroy(struct completion *p);
+
+void completion_wait_for(struct completion *p);
+
+void completion_mark_complete(struct completion *p);
+
+#endif /* NETDATA_COMPLETION_H */
diff --git a/libnetdata/ebpf/ebpf.c b/libnetdata/ebpf/ebpf.c
index 1ccaa7b4..ca40492f 100644
--- a/libnetdata/ebpf/ebpf.c
+++ b/libnetdata/ebpf/ebpf.c
@@ -110,9 +110,23 @@ int ebpf_get_kernel_version()
         *move++ = *version++;
     *move = '\0';
 
-    return ((int)(str2l(major) * 65536) + (int)(str2l(minor) * 256) + (int)str2l(patch));
+    // This new rule is fixing kernel version according the formula:
+    //     KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
+    // that was extracted from /usr/include/linux/version.h
+    int ipatch = (int)str2l(patch);
+    if (ipatch > 255)
+        ipatch = 255;
+
+    return ((int)(str2l(major) * 65536) + (int)(str2l(minor) * 256) + ipatch);
 }
 
+/**
+ * Get RH release
+ *
+ * Read Red Hat release from /etc/redhat-release
+ *
+ * @return It returns RH release on success and -1 otherwise
+ */
 int get_redhat_release()
 {
     char buffer[VERSION_STRING_LEN + 1];
@@ -249,64 +263,189 @@ int has_condition_to_run(int version)
 
 //----------------------------------------------------------------------------------------------------------------------
 
-char *ebpf_kernel_suffix(int version, int isrh)
+/**
+ * Kernel Name
+ *
+ * Select kernel name used by eBPF programs
+ *
+ * Netdata delivers for users eBPF programs with specific suffixes that represent the kernels they were
+ * compiled, when we load the eBPF program, the suffix must be the nereast possible of the kernel running.
+ *
+ * @param selector select the kernel version.
+ *
+ * @return It returns the string to load kernel.
+ */
+static char *ebpf_select_kernel_name(uint32_t selector)
 {
-    if (isrh) {
-        if (version >= NETDATA_EBPF_KERNEL_4_11)
-            return "4.18";
-        else
-            return "3.10";
-    } else {
-        if (version >= NETDATA_EBPF_KERNEL_5_11)
-            return "5.11";
-        else if (version >= NETDATA_EBPF_KERNEL_5_10)
-            return "5.10";
-        else if (version >= NETDATA_EBPF_KERNEL_4_17)
-            return "5.4";
-        else if (version >= NETDATA_EBPF_KERNEL_4_15)
-            return "4.16";
-        else if (version >= NETDATA_EBPF_KERNEL_4_11)
-            return "4.14";
+    static char *kernel_names[] = { NETDATA_IDX_STR_V3_10, NETDATA_IDX_STR_V4_14, NETDATA_IDX_STR_V4_16,
+                                    NETDATA_IDX_STR_V4_18, NETDATA_IDX_STR_V5_4,  NETDATA_IDX_STR_V5_10,
+                                    NETDATA_IDX_STR_V5_11, NETDATA_IDX_STR_V5_15
+                                  };
+
+    return kernel_names[selector];
+}
+
+/**
+ * Select Max Index
+ *
+ * Select last index that will be tested on host.
+ *
+ * @param is_rhf is Red Hat fammily?
+ * @param kver   the kernel version
+ *
+ * @return it returns the index to access kernel string.
+ */
+static int ebpf_select_max_index(int is_rhf, uint32_t kver)
+{
+    if (is_rhf > 0) { // Is Red Hat family
+        if (kver >= NETDATA_EBPF_KERNEL_4_11)
+            return NETDATA_IDX_V4_18;
+    } else { // Kernels from kernel.org
+        if (kver >= NETDATA_EBPF_KERNEL_5_15)
+            return NETDATA_IDX_V5_15;
+        else if (kver >= NETDATA_EBPF_KERNEL_5_11)
+            return NETDATA_IDX_V5_11;
+        else if (kver >= NETDATA_EBPF_KERNEL_5_10)
+            return NETDATA_IDX_V5_10;
+        else if (kver >= NETDATA_EBPF_KERNEL_4_17)
+            return NETDATA_IDX_V5_4;
+        else if (kver >= NETDATA_EBPF_KERNEL_4_15)
+            return NETDATA_IDX_V4_16;
+        else if (kver >= NETDATA_EBPF_KERNEL_4_11)
+            return NETDATA_IDX_V4_14;
     }
 
-    return NULL;
+    return NETDATA_IDX_V3_10;
+}
+
+/**
+ * Select Index
+ *
+ * Select index to load data.
+ *
+ * @param kernels is the variable with kernel versions.
+ * @param is_rhf  is Red Hat fammily?
+ * param  kver    the kernel version
+ */
+static uint32_t ebpf_select_index(uint32_t kernels, int is_rhf, uint32_t kver)
+{
+    uint32_t start = ebpf_select_max_index(is_rhf, kver);
+    uint32_t idx;
+
+    for (idx = start; idx; idx--) {
+        if (kernels & 1 << idx)
+            break;
+    }
+
+    return idx;
+}
+
+/**
+ *  Mount Name
+ *
+ *  Mount name of eBPF program to be loaded.
+ *
+ *  Netdata eBPF programs has the following format:
+ *
+ *      Tnetdata_ebpf_N.V.o
+ *
+ *  where:
+ *     T - Is the eBPF type. When starts with 'p', this means we are only adding probes,
+ *         and when they start with 'r' we are using retprobes.
+ *     N - The eBPF program name.
+ *     V - The kernel version in string format.
+ *
+ *  @param out       the vector where the name will be stored
+ *  @param path
+ *  @param len       the size of the out vector.
+ *  @param kver      the kernel version
+ *  @param name      the eBPF program name.
+ *  @param is_return is return or entry ?
+ */
+static void ebpf_mount_name(char *out, size_t len, char *path, uint32_t kver, const char *name, int is_return)
+{
+    char *version = ebpf_select_kernel_name(kver);
+    snprintfz(out, len, "%s/ebpf.d/%cnetdata_ebpf_%s.%s.o",
+              path,
+              (is_return) ? 'r' : 'p',
+              name,
+              version);
 }
 
 //----------------------------------------------------------------------------------------------------------------------
 
 /**
- *  Update Kernel
+ * Statistics from targets
  *
- *  Update string used to load eBPF programs
+ * Count the information from targets.
  *
- * @param ks      vector to store the value
- * @param length  available length to store kernel
- * @param isrh    Is a Red Hat distribution?
- * @param version the kernel version
+ * @param report  the output structure
+ * @param targets  vector with information about the eBPF plugin.
  */
-void ebpf_update_kernel(char *ks, size_t length, int isrh, int version)
+static void ebpf_stats_targets(ebpf_plugin_stats_t *report, netdata_ebpf_targets_t *targets)
 {
-    char *kernel = ebpf_kernel_suffix(version, (isrh < 0) ? 0 : 1);
-    size_t len = strlen(kernel);
-    if (len > length)
-        len = length - 1;
-    strncpyz(ks, kernel, len);
-    ks[len] = '\0';
+    if (!targets) {
+        report->probes = report->tracepoints = report->trampolines = 0;
+        return;
+    }
+
+    int i = 0;
+    while (targets[i].name) {
+        switch (targets[i].mode) {
+            case EBPF_LOAD_PROBE: {
+                report->probes++;
+                break;
+            }
+            case EBPF_LOAD_RETPROBE: {
+                report->retprobes++;
+                break;
+            }
+            case EBPF_LOAD_TRACEPOINT: {
+                report->tracepoints++;
+                break;
+            }
+            case EBPF_LOAD_TRAMPOLINE: {
+                report->trampolines++;
+                break;
+            }
+        }
+
+        i++;
+    }
 }
 
-static int select_file(char *name, const char *program, size_t length, int mode, char *kernel_string)
+/**
+ * Update General stats
+ *
+ * Update eBPF plugin statistics that has relationship with the thread.
+ *
+ * This function must be called with mutex associated to charts is locked.
+ *
+ * @param report  the output structure
+ * @param em      the structure with information about how the module/thread is working.
+ */
+void ebpf_update_stats(ebpf_plugin_stats_t *report, ebpf_module_t *em)
 {
-    int ret = -1;
-    if (!mode)
-        ret = snprintf(name, length, "rnetdata_ebpf_%s.%s.o", program, kernel_string);
-    else if (mode == 1)
-        ret = snprintf(name, length, "dnetdata_ebpf_%s.%s.o", program, kernel_string);
-    else if (mode == 2)
-        ret = snprintf(name, length, "pnetdata_ebpf_%s.%s.o", program, kernel_string);
+    report->threads++;
 
-    return ret;
+    // It is not necessary to report more information.
+    if (!em->enabled)
+        return;
+
+    report->running++;
+
+    // In theory the `else if` is useless, because when this function is called, the module should not stay in
+    // EBPF_LOAD_PLAY_DICE. We have this additional condition to detect errors from developers.
+    if (em->load == EBPF_LOAD_LEGACY)
+        report->legacy++;
+    else if (em->load == EBPF_LOAD_CORE)
+        report->core++;
+
+    ebpf_stats_targets(report, em->targets);
 }
 
+//----------------------------------------------------------------------------------------------------------------------
+
 void ebpf_update_pid_table(ebpf_local_maps_t *pid, ebpf_module_t *em)
 {
     pid->user_input = em->pid_map_size;
@@ -375,18 +514,21 @@ static struct bpf_link **ebpf_attach_programs(struct bpf_object *obj, size_t len
     struct bpf_link **links = callocz(length , sizeof(struct bpf_link *));
     size_t i = 0;
     struct bpf_program *prog;
+    ebpf_specify_name_t *w;
     bpf_object__for_each_program(prog, obj)
     {
-        links[i] = bpf_program__attach(prog);
-        if (libbpf_get_error(links[i]) && names) {
+        if (names) {
             const char *name = bpf_program__name(prog);
-            ebpf_specify_name_t *w = ebpf_find_names(names, name);
-            if (w) {
-                enum bpf_prog_type type = bpf_program__get_type(prog);
-                if (type == BPF_PROG_TYPE_KPROBE)
-                    links[i] = bpf_program__attach_kprobe(prog, w->retprobe, w->optional);
-            }
-        }
+            w = ebpf_find_names(names, name);
+        } else
+            w = NULL;
+
+        if (w) {
+            enum bpf_prog_type type = bpf_program__get_type(prog);
+            if (type == BPF_PROG_TYPE_KPROBE)
+                links[i] = bpf_program__attach_kprobe(prog, w->retprobe, w->optional);
+        } else
+            links[i] = bpf_program__attach(prog);
 
         if (libbpf_get_error(links[i])) {
             links[i] = NULL;
@@ -449,17 +591,28 @@ static void ebpf_update_controller(ebpf_module_t *em, struct bpf_object *obj)
     }
 }
 
-struct bpf_link **ebpf_load_program(char *plugins_dir, ebpf_module_t *em, char *kernel_string,
+/**
+ * Load Program
+ *
+ * Load eBPF program into kernel
+ *
+ * @param plugins_dir    directory where binary are stored
+ * @param em             structure with information about eBPF program we will load.
+ * @param kver           the kernel version according /usr/include/linux/version.h
+ * @param is_rhf         is a kernel from Red Hat Family?
+ * @param obj            structure where we will store object loaded.
+ *
+ * @return it returns a link for each target we associated an eBPF program.
+ */
+struct bpf_link **ebpf_load_program(char *plugins_dir, ebpf_module_t *em, int kver, int is_rhf,
                                     struct bpf_object **obj)
 {
     char lpath[4096];
-    char lname[128];
 
-    int test = select_file(lname, em->thread_name, (size_t)127, em->mode, kernel_string);
-    if (test < 0 || test > 127)
-        return NULL;
+    uint32_t idx = ebpf_select_index(em->kernels, is_rhf, kver);
+
+    ebpf_mount_name(lpath, 4095, plugins_dir, idx, em->thread_name, em->mode);
 
-    snprintf(lpath, 4096, "%s/ebpf.d/%s", plugins_dir, lname);
     *obj = bpf_object__open_file(lpath, NULL);
     if (libbpf_get_error(obj)) {
         error("Cannot open BPF object %s", lpath);
@@ -480,10 +633,14 @@ struct bpf_link **ebpf_load_program(char *plugins_dir, ebpf_module_t *em, char *
 
     size_t count_programs =  ebpf_count_programs(*obj);
 
+#ifdef NETDATA_INTERNAL_CHECKS
+    info("eBPF program %s loaded with success!", lpath);
+#endif
+
     return ebpf_attach_programs(*obj, count_programs, em->names);
 }
 
-static char *ebpf_update_name(char *search)
+char *ebpf_find_symbol(char *search)
 {
     char filename[FILENAME_MAX + 1];
     char *ret = NULL;
@@ -521,7 +678,7 @@ void ebpf_update_names(ebpf_specify_name_t *opt, ebpf_module_t *em)
     size_t i = 0;
     while (opt[i].program_name) {
         opt[i].retprobe = (mode == MODE_RETURN);
-        opt[i].optional = ebpf_update_name(opt[i].function_to_attach);
+        opt[i].optional = ebpf_find_symbol(opt[i].function_to_attach);
 
         i++;
     }
diff --git a/libnetdata/ebpf/ebpf.h b/libnetdata/ebpf/ebpf.h
index 73128f52..12529967 100644
--- a/libnetdata/ebpf/ebpf.h
+++ b/libnetdata/ebpf/ebpf.h
@@ -23,14 +23,6 @@
 #define EBPF_CFG_CGROUP "cgroups"
 
 /**
- * The next magic number is got doing the following math:
- *  294960 = 4*65536 + 11*256 + 0
- *
- *  For more details, please, read /usr/include/linux/version.h
- */
-#define NETDATA_MINIMUM_EBPF_KERNEL 264960
-
-/**
  * The RedHat magic number was got doing:
  *
  * 1797 = 7*256 + 5
@@ -46,46 +38,63 @@
 #define NETDATA_RH_8 2048
 
 /**
- *  Kernel 5.11
+ *  Kernel Version
  *
- *  330240 = 5*65536 + 11*256
- */
-#define NETDATA_EBPF_KERNEL_5_11 330496
-
-/**
- *  Kernel 5.10
+ *  Kernel versions are calculated using the following formula:
  *
- *  330240 = 5*65536 + 10*256
- */
-#define NETDATA_EBPF_KERNEL_5_10 330240
-
-/**
- *  Kernel 5.0
+ *  VERSION = LINUX_VERSION_MAJOR*65536 + LINUX_VERSION_PATCHLEVEL*256 + LINUX_VERSION_SUBLEVEL
  *
- *  327680 = 5*65536 +256*0
- */
-#define NETDATA_EBPF_KERNEL_5_0 327680
-
-/**
- *  Kernel 4.17
+ *  Where LINUX_VERSION_MAJOR, LINUX_VERSION_PATCHLEVEL, and LINUX_VERSION_SUBLEVEL are extracted
+ *  from /usr/include/linux/version.h.
  *
- *  266496 = 4*65536 + 17*256
- */
-#define NETDATA_EBPF_KERNEL_4_17 266496
-
-/**
- *  Kernel 4.15
+ *  LINUX_VERSION_SUBLEVEL has the maximum value 255, but linux can have more SUBLEVELS.
  *
- *  265984 = 4*65536 + 15*256
  */
-#define NETDATA_EBPF_KERNEL_4_15 265984
+enum netdata_ebpf_kernel_versions {
+    NETDATA_EBPF_KERNEL_4_11 = 264960,  //  264960 = 4 * 65536 + 15 * 256
+    NETDATA_EBPF_KERNEL_4_15 = 265984,  //  265984 = 4 * 65536 + 15 * 256
+    NETDATA_EBPF_KERNEL_4_17 = 266496,  //  266496 = 4 * 65536 + 17 * 256
+    NETDATA_EBPF_KERNEL_5_0  = 327680,  //  327680 = 5 * 65536 +  0 * 256
+    NETDATA_EBPF_KERNEL_5_10 = 330240,  //  330240 = 5 * 65536 + 10 * 256
+    NETDATA_EBPF_KERNEL_5_11 = 330496,  //  330240 = 5 * 65536 + 11 * 256
+    NETDATA_EBPF_KERNEL_5_15 = 331520   //  331520 = 5 * 65536 + 15 * 256
+};
+
+enum netdata_kernel_flag {
+    NETDATA_V3_10 = 1 << 0,
+    NETDATA_V4_14 = 1 << 1,
+    NETDATA_V4_16 = 1 << 2,
+    NETDATA_V4_18 = 1 << 3,
+    NETDATA_V5_4  = 1 << 4,
+    NETDATA_V5_10 = 1 << 5,
+    NETDATA_V5_11 = 1 << 6,
+    NETDATA_V5_15 = 1 << 7
+};
+
+enum netdata_kernel_idx {
+    NETDATA_IDX_V3_10,
+    NETDATA_IDX_V4_14,
+    NETDATA_IDX_V4_16,
+    NETDATA_IDX_V4_18,
+    NETDATA_IDX_V5_4 ,
+    NETDATA_IDX_V5_10,
+    NETDATA_IDX_V5_11,
+    NETDATA_IDX_V5_15
+};
+
+#define NETDATA_IDX_STR_V3_10 "3.10"
+#define NETDATA_IDX_STR_V4_14 "4.14"
+#define NETDATA_IDX_STR_V4_16 "4.16"
+#define NETDATA_IDX_STR_V4_18 "4.18"
+#define NETDATA_IDX_STR_V5_4  "5.4"
+#define NETDATA_IDX_STR_V5_10 "5.10"
+#define NETDATA_IDX_STR_V5_11 "5.11"
+#define NETDATA_IDX_STR_V5_15 "5.15"
 
 /**
- *  Kernel 4.11
- *
- *  264960 = 4*65536 + 15*256
+ * Minimum value has relationship with libbpf support.
  */
-#define NETDATA_EBPF_KERNEL_4_11 264960
+#define NETDATA_MINIMUM_EBPF_KERNEL NETDATA_EBPF_KERNEL_4_11
 
 #define VERSION_STRING_LEN 256
 #define EBPF_KERNEL_REJECT_LIST_FILE "ebpf_kernel_reject_list.txt"
@@ -148,6 +157,39 @@ typedef struct ebpf_specify_name {
     bool retprobe;
 } ebpf_specify_name_t;
 
+typedef enum netdata_ebpf_load_mode {
+    EBPF_LOAD_LEGACY,        // Select legacy mode, this means we will load binaries
+    EBPF_LOAD_CORE,          // When CO-RE is used, it is necessary to use the souce code
+
+    EBPF_LOAD_PLAY_DICE      // Take a look on environment and choose the best option
+} netdata_ebpf_load_mode_t;
+
+typedef enum netdata_ebpf_program_loaded {
+    EBPF_LOAD_PROBE,         // Attach probes on targets
+    EBPF_LOAD_RETPROBE,      // Attach retprobes on targets
+    EBPF_LOAD_TRACEPOINT,    // This stores log given description about the errors raised
+    EBPF_LOAD_TRAMPOLINE,    // This attaches kprobe when the function is called
+} netdata_ebpf_program_loaded_t;
+
+typedef struct netdata_ebpf_targets {
+    char *name;
+    netdata_ebpf_program_loaded_t mode;
+} netdata_ebpf_targets_t;
+
+typedef struct ebpf_plugin_stats {
+    // Load options
+    uint32_t legacy;      // Legacy codes
+    uint32_t core;        // CO-RE codes, this means we are using source code compiled.
+
+    uint32_t threads;     // Total number of threads
+    uint32_t running;     // total number of threads running
+
+    uint32_t probes;      // Number of kprobes loaded
+    uint32_t retprobes;   // Number of kretprobes loaded
+    uint32_t tracepoints; // Number of tracepoints used
+    uint32_t trampolines; // Number of trampolines used
+} ebpf_plugin_stats_t;
+
 typedef struct ebpf_module {
     const char *thread_name;
     const char *config_name;
@@ -166,25 +208,27 @@ typedef struct ebpf_module {
     uint32_t pid_map_size;
     struct config *cfg;
     const char *config_file;
+    uint64_t kernels;
+    netdata_ebpf_load_mode_t load;
+    netdata_ebpf_targets_t *targets;
 } ebpf_module_t;
 
 extern int ebpf_get_kernel_version();
 extern int get_redhat_release();
 extern int has_condition_to_run(int version);
 extern char *ebpf_kernel_suffix(int version, int isrh);
-extern void ebpf_update_kernel(char *ks, size_t length, int isrh, int version);
-extern struct bpf_link **ebpf_load_program(char *plugins_dir,
-                             ebpf_module_t *em,
-                             char *kernel_string,
-                             struct bpf_object **obj);
+extern struct bpf_link **ebpf_load_program(char *plugins_dir, ebpf_module_t *em, int kver, int is_rhf,
+                                           struct bpf_object **obj);
 
 extern void ebpf_mount_config_name(char *filename, size_t length, char *path, const char *config);
 extern int ebpf_load_config(struct config *config, char *filename);
 extern void ebpf_update_module(ebpf_module_t *em);
 extern void ebpf_update_names(ebpf_specify_name_t *opt, ebpf_module_t *em);
+extern char *ebpf_find_symbol(char *search);
 extern void ebpf_load_addresses(ebpf_addresses_t *fa, int fd);
 extern void ebpf_fill_algorithms(int *algorithms, size_t length, int algorithm);
 extern char **ebpf_fill_histogram_dimension(size_t maximum);
+extern void ebpf_update_stats(ebpf_plugin_stats_t *report, ebpf_module_t *em);
 
 // Histogram
 #define NETDATA_EBPF_HIST_MAX_BINS 24UL
diff --git a/libnetdata/libnetdata.c b/libnetdata/libnetdata.c
index eb6fce74..18d02240 100644
--- a/libnetdata/libnetdata.c
+++ b/libnetdata/libnetdata.c
@@ -14,7 +14,6 @@ struct rlimit rlimit_nofile = { .rlim_cur = 1024, .rlim_max = 1024 };
 int enable_ksm = 1;
 
 volatile sig_atomic_t netdata_exit = 0;
-const char *os_type = NETDATA_OS_TYPE;
 const char *program_version = VERSION;
 
 // ----------------------------------------------------------------------------
diff --git a/libnetdata/libnetdata.h b/libnetdata/libnetdata.h
index b49ab21a..809cefa0 100644
--- a/libnetdata/libnetdata.h
+++ b/libnetdata/libnetdata.h
@@ -274,7 +274,6 @@ extern int verify_netdata_host_prefix();
 extern int recursively_delete_dir(const char *path, const char *reason);
 
 extern volatile sig_atomic_t netdata_exit;
-extern const char *os_type;
 
 extern const char *program_version;
 
@@ -303,9 +302,14 @@ extern char *find_and_replace(const char *src, const char *find, const char *rep
 #define KILOBITS_IN_A_MEGABIT 1000
 
 /* misc. */
+
 #define UNUSED(x) (void)(x)
 #define error_report(x, args...) do { errno = 0; error(x, ##args); } while(0)
 
+// Taken from linux kernel
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
+
+
 extern void netdata_cleanup_and_exit(int ret) NORETURN;
 extern void send_statistics(const char *action, const char *action_result, const char *action_data);
 extern char *netdata_configured_host_prefix;
@@ -318,6 +322,7 @@ extern char *netdata_configured_host_prefix;
 #include "avl/avl.h"
 #include "inlined.h"
 #include "clocks/clocks.h"
+#include "completion/completion.h"
 #include "popen/popen.h"
 #include "simple_pattern/simple_pattern.h"
 #ifdef ENABLE_HTTPS
diff --git a/libnetdata/log/log.c b/libnetdata/log/log.c
index 95d3d98d..90581269 100644
--- a/libnetdata/log/log.c
+++ b/libnetdata/log/log.c
@@ -24,10 +24,10 @@ const char *facility_log = NULL;
 // Log facility(https://tools.ietf.org/html/rfc5424)
 //
 // The facilities accepted in the Netdata are in according with the following
-// header files for their respective operate system:
-// 	sys/syslog.h (Linux )
-// 	sys/sys/syslog.h (FreeBSD)
-// 	bsd/sys/syslog.h (darwin-xnu)
+// header files for their respective operating system:
+// sys/syslog.h (Linux )
+// sys/sys/syslog.h (FreeBSD)
+// bsd/sys/syslog.h (darwin-xnu)
 
 #define LOG_AUTH_KEY "auth"
 #define LOG_AUTHPRIV_KEY "authpriv"
@@ -71,229 +71,229 @@ const char *facility_log = NULL;
 
 static int log_facility_id(const char *facility_name)
 {
-	static int 
-		hash_auth = 0,
-		hash_authpriv = 0,
+    static int
+        hash_auth = 0,
+        hash_authpriv = 0,
 #ifdef __FreeBSD__
-		hash_console = 0,
+        hash_console = 0,
 #endif
-		hash_cron = 0,
-		hash_daemon = 0,
-		hash_ftp = 0,
+        hash_cron = 0,
+        hash_daemon = 0,
+        hash_ftp = 0,
 #ifdef __APPLE__
-		hash_install = 0,
+        hash_install = 0,
 #endif
-		hash_kern = 0,
-		hash_lpr = 0,
-		hash_mail = 0,
-//		hash_mark = 0,
+        hash_kern = 0,
+        hash_lpr = 0,
+        hash_mail = 0,
+//      hash_mark = 0,
 #ifdef __APPLE__
-		hash_netinfo = 0,
-		hash_ras = 0,
-		hash_remoteauth = 0,
+        hash_netinfo = 0,
+        hash_ras = 0,
+        hash_remoteauth = 0,
 #endif
-		hash_news = 0,
+        hash_news = 0,
 #ifdef __FreeBSD__
-		hash_ntp = 0,
+        hash_ntp = 0,
 #endif
-		hash_security = 0,
-		hash_syslog = 0,
-		hash_user = 0,
-		hash_uucp = 0,
+        hash_security = 0,
+        hash_syslog = 0,
+        hash_user = 0,
+        hash_uucp = 0,
 #ifdef __APPLE__
-		hash_launchd = 0,
+        hash_launchd = 0,
 #endif
-		hash_local0 = 0,
-		hash_local1 = 0,
-		hash_local2 = 0,
-		hash_local3 = 0,
-		hash_local4 = 0,
-		hash_local5 = 0,
-		hash_local6 = 0,
-		hash_local7 = 0;
-
-	if(unlikely(!hash_auth))
-	{
-		hash_auth = simple_hash(LOG_AUTH_KEY);
-		hash_authpriv = simple_hash(LOG_AUTHPRIV_KEY);
+        hash_local0 = 0,
+        hash_local1 = 0,
+        hash_local2 = 0,
+        hash_local3 = 0,
+        hash_local4 = 0,
+        hash_local5 = 0,
+        hash_local6 = 0,
+        hash_local7 = 0;
+
+    if(unlikely(!hash_auth))
+    {
+        hash_auth = simple_hash(LOG_AUTH_KEY);
+        hash_authpriv = simple_hash(LOG_AUTHPRIV_KEY);
 #ifdef __FreeBSD__
-		hash_console = simple_hash(LOG_CONSOLE_KEY);
+        hash_console = simple_hash(LOG_CONSOLE_KEY);
 #endif
-		hash_cron = simple_hash(LOG_CRON_KEY);
-		hash_daemon = simple_hash(LOG_DAEMON_KEY);
-		hash_ftp = simple_hash(LOG_FTP_KEY);
+        hash_cron = simple_hash(LOG_CRON_KEY);
+        hash_daemon = simple_hash(LOG_DAEMON_KEY);
+        hash_ftp = simple_hash(LOG_FTP_KEY);
 #ifdef __APPLE__
-		hash_install = simple_hash(LOG_INSTALL_KEY);
+        hash_install = simple_hash(LOG_INSTALL_KEY);
 #endif
-		hash_kern = simple_hash(LOG_KERN_KEY);
-		hash_lpr = simple_hash(LOG_LPR_KEY);
-		hash_mail = simple_hash(LOG_MAIL_KEY);
-//		hash_mark = simple_uhash();
+        hash_kern = simple_hash(LOG_KERN_KEY);
+        hash_lpr = simple_hash(LOG_LPR_KEY);
+        hash_mail = simple_hash(LOG_MAIL_KEY);
+//        hash_mark = simple_uhash();
 #ifdef __APPLE__
-		hash_netinfo = simple_hash(LOG_NETINFO_KEY);
-		hash_ras = simple_hash(LOG_RAS_KEY);
-		hash_remoteauth = simple_hash(LOG_REMOTEAUTH_KEY);
+        hash_netinfo = simple_hash(LOG_NETINFO_KEY);
+        hash_ras = simple_hash(LOG_RAS_KEY);
+        hash_remoteauth = simple_hash(LOG_REMOTEAUTH_KEY);
 #endif
-		hash_news = simple_hash(LOG_NEWS_KEY);
+        hash_news = simple_hash(LOG_NEWS_KEY);
 #ifdef __FreeBSD__
-		hash_ntp = simple_hash(LOG_NTP_KEY);
+        hash_ntp = simple_hash(LOG_NTP_KEY);
 #endif
-		hash_security = simple_hash(LOG_SECURITY_KEY);
-		hash_syslog = simple_hash(LOG_SYSLOG_KEY);
-		hash_user = simple_hash(LOG_USER_KEY);
-		hash_uucp = simple_hash(LOG_UUCP_KEY);
+        hash_security = simple_hash(LOG_SECURITY_KEY);
+        hash_syslog = simple_hash(LOG_SYSLOG_KEY);
+        hash_user = simple_hash(LOG_USER_KEY);
+        hash_uucp = simple_hash(LOG_UUCP_KEY);
 #ifdef __APPLE__
-		hash_launchd = simple_hash(LOG_LAUNCHD_KEY);
+        hash_launchd = simple_hash(LOG_LAUNCHD_KEY);
 #endif
-		hash_local0 = simple_hash(LOG_LOCAL0_KEY);
-		hash_local1 = simple_hash(LOG_LOCAL1_KEY);
-		hash_local2 = simple_hash(LOG_LOCAL2_KEY);
-		hash_local3 = simple_hash(LOG_LOCAL3_KEY);
-		hash_local4 = simple_hash(LOG_LOCAL4_KEY);
-		hash_local5 = simple_hash(LOG_LOCAL5_KEY);
-		hash_local6 = simple_hash(LOG_LOCAL6_KEY);
-		hash_local7 = simple_hash(LOG_LOCAL7_KEY);
-	}
-
-	int hash = simple_hash(facility_name);
-	if ( hash == hash_auth )
-	{
-		return LOG_AUTH;
-	}
-	else if  ( hash == hash_authpriv )
-	{
-		return LOG_AUTHPRIV;
-	}
+        hash_local0 = simple_hash(LOG_LOCAL0_KEY);
+        hash_local1 = simple_hash(LOG_LOCAL1_KEY);
+        hash_local2 = simple_hash(LOG_LOCAL2_KEY);
+        hash_local3 = simple_hash(LOG_LOCAL3_KEY);
+        hash_local4 = simple_hash(LOG_LOCAL4_KEY);
+        hash_local5 = simple_hash(LOG_LOCAL5_KEY);
+        hash_local6 = simple_hash(LOG_LOCAL6_KEY);
+        hash_local7 = simple_hash(LOG_LOCAL7_KEY);
+    }
+
+    int hash = simple_hash(facility_name);
+    if ( hash == hash_auth )
+    {
+        return LOG_AUTH;
+    }
+    else if  ( hash == hash_authpriv )
+    {
+        return LOG_AUTHPRIV;
+    }
 #ifdef __FreeBSD__
-	else if ( hash == hash_console )
-	{
-		return LOG_CONSOLE;
-	}
+    else if ( hash == hash_console )
+    {
+        return LOG_CONSOLE;
+    }
 #endif
-	else if ( hash == hash_cron )
-	{
-		return LOG_CRON;
-	}
-	else if ( hash == hash_daemon )
-	{
-		return LOG_DAEMON;
-	}
-	else if ( hash == hash_ftp )
-	{
-		return LOG_FTP;
-	}
+    else if ( hash == hash_cron )
+    {
+        return LOG_CRON;
+    }
+    else if ( hash == hash_daemon )
+    {
+        return LOG_DAEMON;
+    }
+    else if ( hash == hash_ftp )
+    {
+        return LOG_FTP;
+    }
 #ifdef __APPLE__
-	else if ( hash == hash_install )
-	{
-		return LOG_INSTALL;
-	}
+    else if ( hash == hash_install )
+    {
+        return LOG_INSTALL;
+    }
 #endif
-	else if ( hash == hash_kern )
-	{
-		return LOG_KERN;
-	}
-	else if ( hash == hash_lpr )
-	{
-		return LOG_LPR;
-	}
-	else if ( hash == hash_mail )
-	{
-		return LOG_MAIL;
-	}
-	/*
-	else if ( hash == hash_mark )
-	{
-		//this is internal for all OS
-		return INTERNAL_MARK;
-	}
-	*/
+    else if ( hash == hash_kern )
+    {
+        return LOG_KERN;
+    }
+    else if ( hash == hash_lpr )
+    {
+        return LOG_LPR;
+    }
+    else if ( hash == hash_mail )
+    {
+        return LOG_MAIL;
+    }
+    /*
+    else if ( hash == hash_mark )
+    {
+        //this is internal for all OS
+        return INTERNAL_MARK;
+    }
+    */
 #ifdef __APPLE__
-	else if ( hash == hash_netinfo )
-	{
-		return LOG_NETINFO;
-	}
-	else if ( hash == hash_ras )
-	{
-		return LOG_RAS;
-	}
-	else if ( hash == hash_remoteauth )
-	{
-		return LOG_REMOTEAUTH;
-	}
+    else if ( hash == hash_netinfo )
+    {
+        return LOG_NETINFO;
+    }
+    else if ( hash == hash_ras )
+    {
+        return LOG_RAS;
+    }
+    else if ( hash == hash_remoteauth )
+    {
+        return LOG_REMOTEAUTH;
+    }
 #endif
-	else if ( hash == hash_news )
-	{
-		return LOG_NEWS;
-	}
+    else if ( hash == hash_news )
+    {
+        return LOG_NEWS;
+    }
 #ifdef __FreeBSD__
-	else if ( hash == hash_ntp )
-	{
-		return LOG_NTP;
-	}
+    else if ( hash == hash_ntp )
+    {
+        return LOG_NTP;
+    }
 #endif
-	else if ( hash == hash_security )
-	{
-		//FreeBSD is the unique that does not consider
-		//this facility deprecated. We are keeping
-		//it for other OS while they are kept in their headers.
+    else if ( hash == hash_security )
+    {
+        //FreeBSD is the unique that does not consider
+        //this facility deprecated. We are keeping
+        //it for other OS while they are kept in their headers.
 #ifdef __FreeBSD__
-		return LOG_SECURITY;
+        return LOG_SECURITY;
 #else
-		return LOG_AUTH;
+        return LOG_AUTH;
 #endif
-	}
-	else if ( hash == hash_syslog )
-	{
-		return LOG_SYSLOG;
-	}
-	else if ( hash == hash_user )
-	{
-		return LOG_USER;
-	}
-	else if ( hash == hash_uucp )
-	{
-		return LOG_UUCP;
-	}
-	else if ( hash == hash_local0 )
-	{
-		return LOG_LOCAL0;
-	}
-	else if ( hash == hash_local1 )
-	{
-		return LOG_LOCAL1;
-	}
-	else if ( hash == hash_local2 )
-	{
-		return LOG_LOCAL2;
-	}
-	else if ( hash == hash_local3 )
-	{
-		return LOG_LOCAL3;
-	}
-	else if ( hash == hash_local4 )
-	{
-		return LOG_LOCAL4;
-	}
-	else if ( hash == hash_local5 )
-	{
-		return LOG_LOCAL5;
-	}
-	else if ( hash == hash_local6 )
-	{
-		return LOG_LOCAL6;
-	}
-	else if ( hash == hash_local7 )
-	{
-		return LOG_LOCAL7;
-	}
+    }
+    else if ( hash == hash_syslog )
+    {
+        return LOG_SYSLOG;
+    }
+    else if ( hash == hash_user )
+    {
+        return LOG_USER;
+    }
+    else if ( hash == hash_uucp )
+    {
+        return LOG_UUCP;
+    }
+    else if ( hash == hash_local0 )
+    {
+        return LOG_LOCAL0;
+    }
+    else if ( hash == hash_local1 )
+    {
+        return LOG_LOCAL1;
+    }
+    else if ( hash == hash_local2 )
+    {
+        return LOG_LOCAL2;
+    }
+    else if ( hash == hash_local3 )
+    {
+        return LOG_LOCAL3;
+    }
+    else if ( hash == hash_local4 )
+    {
+        return LOG_LOCAL4;
+    }
+    else if ( hash == hash_local5 )
+    {
+        return LOG_LOCAL5;
+    }
+    else if ( hash == hash_local6 )
+    {
+        return LOG_LOCAL6;
+    }
+    else if ( hash == hash_local7 )
+    {
+        return LOG_LOCAL7;
+    }
 #ifdef __APPLE__
-	else if ( hash == hash_launchd )
-	{
-		return LOG_LAUNCHD;
-	}
+    else if ( hash == hash_launchd )
+    {
+        return LOG_LAUNCHD;
+    }
 #endif
 
-	return LOG_DAEMON;
+    return LOG_DAEMON;
 }
 
 //we do not need to use this now, but I already created this function to be
@@ -301,135 +301,135 @@ static int log_facility_id(const char *facility_name)
 /*
 char *log_facility_name(int code)
 {
-	char *defvalue = { "daemon" };
-	switch(code)
-	{
-		case LOG_AUTH:
-			{
-				return "auth";
-			}
-		case LOG_AUTHPRIV:
-			{
-				return "authpriv";
-			}
+    char *defvalue = { "daemon" };
+    switch(code)
+    {
+        case LOG_AUTH:
+            {
+                return "auth";
+            }
+        case LOG_AUTHPRIV:
+            {
+                return "authpriv";
+            }
 #ifdef __FreeBSD__
-		case LOG_CONSOLE:
-			{
-				return "console";
-			}
+        case LOG_CONSOLE:
+            {
+                return "console";
+            }
 #endif
-		case LOG_CRON:
-			{
-				return "cron";
-			}
-		case LOG_DAEMON:
-			{
-				return defvalue;
-			}
-		case LOG_FTP:
-			{
-				return "ftp";
-			}
+        case LOG_CRON:
+            {
+                return "cron";
+            }
+        case LOG_DAEMON:
+            {
+                return defvalue;
+            }
+        case LOG_FTP:
+            {
+                return "ftp";
+            }
 #ifdef __APPLE__
-		case LOG_INSTALL:
-			{
-				return "install";
-			}
+        case LOG_INSTALL:
+            {
+                return "install";
+            }
 #endif
-		case LOG_KERN:
-			{
-				return "kern";
-			}
-		case LOG_LPR:
-			{
-				return "lpr";
-			}
-		case LOG_MAIL:
-			{
-				return "mail";
-			}
+        case LOG_KERN:
+            {
+                return "kern";
+            }
+        case LOG_LPR:
+            {
+                return "lpr";
+            }
+        case LOG_MAIL:
+            {
+                return "mail";
+            }
 #ifdef __APPLE__
-		case LOG_NETINFO:
-			{
-				return "netinfo" ;
-			}
-		case LOG_RAS:
-			{
-				return "ras";
-			}
-		case LOG_REMOTEAUTH:
-			{
-				return "remoteauth";
-			}
+        case LOG_NETINFO:
+            {
+                return "netinfo" ;
+            }
+        case LOG_RAS:
+            {
+                return "ras";
+            }
+        case LOG_REMOTEAUTH:
+            {
+                return "remoteauth";
+            }
 #endif
-		case LOG_NEWS:
-			{
-				return "news";
-			}
+        case LOG_NEWS:
+            {
+                return "news";
+            }
 #ifdef __FreeBSD__
-		case LOG_NTP:
-			{
-				return "ntp" ;
-			}
-		case LOG_SECURITY:
-			{
-				return "security";
-			}
+        case LOG_NTP:
+            {
+                return "ntp" ;
+            }
+        case LOG_SECURITY:
+            {
+                return "security";
+            }
 #endif
-		case LOG_SYSLOG:
-			{
-				return "syslog";
-			}
-		case LOG_USER:
-			{
-				return "user";
-			}
-		case LOG_UUCP:
-			{
-				return "uucp";
-			}
-		case LOG_LOCAL0:
-			{
-				return "local0";
-			}
-		case LOG_LOCAL1:
-			{
-				return "local1";
-			}
-		case LOG_LOCAL2:
-			{
-				return "local2";
-			}
-		case LOG_LOCAL3:
-			{
-				return "local3";
-			}
-		case LOG_LOCAL4:
-			{
-				return "local4" ;
-			}
-		case LOG_LOCAL5:
-			{
-				return "local5";
-			}
-		case LOG_LOCAL6:
-			{
-				return "local6";
-			}
-		case LOG_LOCAL7:
-			{
-				return "local7" ;
-			}
+        case LOG_SYSLOG:
+            {
+                return "syslog";
+            }
+        case LOG_USER:
+            {
+                return "user";
+            }
+        case LOG_UUCP:
+            {
+                return "uucp";
+            }
+        case LOG_LOCAL0:
+            {
+                return "local0";
+            }
+        case LOG_LOCAL1:
+            {
+                return "local1";
+            }
+        case LOG_LOCAL2:
+            {
+                return "local2";
+            }
+        case LOG_LOCAL3:
+            {
+                return "local3";
+            }
+        case LOG_LOCAL4:
+            {
+                return "local4" ;
+            }
+        case LOG_LOCAL5:
+            {
+                return "local5";
+            }
+        case LOG_LOCAL6:
+            {
+                return "local6";
+            }
+        case LOG_LOCAL7:
+            {
+                return "local7" ;
+            }
 #ifdef __APPLE__
-		case LOG_LAUNCHD:
-			{
-				return "launchd";
-			}
+        case LOG_LAUNCHD:
+            {
+                return "launchd";
+            }
 #endif
-	}
+    }
 
-	return defvalue;
-}	
+    return defvalue;
+}
 */
 
 // ----------------------------------------------------------------------------
@@ -486,7 +486,7 @@ static FILE *open_log_file(int fd, FILE *fp, const char *filename, int *enabled_
         filename = "/dev/null";
         devnull = 1;
 
-	syslog_init();
+    syslog_init();
         if(enabled_syslog) *enabled_syslog = 1;
     }
     else if(enabled_syslog) *enabled_syslog = 0;
@@ -607,13 +607,15 @@ int error_log_limit(int reset) {
         if(prevented) {
             char date[LOG_DATE_LENGTH];
             log_date(date, LOG_DATE_LENGTH);
-            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION reset for process '%s' (prevented %lu logs in the last %ld seconds).\n"
-                    , date
-                    , program_name
-                    , program_name
-                    , prevented
-                    , now - start
-            );
+            fprintf(
+                stderr,
+                "%s: %s LOG FLOOD PROTECTION reset for process '%s' "
+                "(prevented %lu logs in the last %"PRId64" seconds).\n",
+                date,
+                program_name,
+                program_name,
+                prevented,
+                (int64_t)(now - start));
         }
 
         start = now;
@@ -628,13 +630,15 @@ int error_log_limit(int reset) {
         if(prevented) {
             char date[LOG_DATE_LENGTH];
             log_date(date, LOG_DATE_LENGTH);
-            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION resuming logging from process '%s' (prevented %lu logs in the last %ld seconds).\n"
-                    , date
-                    , program_name
-                    , program_name
-                    , prevented
-                    , error_log_throttle_period
-            );
+            fprintf(
+                stderr,
+                "%s: %s LOG FLOOD PROTECTION resuming logging from process '%s' "
+                "(prevented %lu logs in the last %"PRId64" seconds).\n",
+                date,
+                program_name,
+                program_name,
+                prevented,
+                (int64_t)error_log_throttle_period);
         }
 
         // restart the period accounting
@@ -650,15 +654,18 @@ int error_log_limit(int reset) {
         if(!prevented) {
             char date[LOG_DATE_LENGTH];
             log_date(date, LOG_DATE_LENGTH);
-            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION too many logs (%lu logs in %ld seconds, threshold is set to %lu logs in %ld seconds). Preventing more logs from process '%s' for %ld seconds.\n"
-                    , date
-                    , program_name
-                    , counter
-                    , now - start
-                    , error_log_errors_per_period
-                    , error_log_throttle_period
-                    , program_name
-                    , start + error_log_throttle_period - now);
+            fprintf(
+                stderr,
+                "%s: %s LOG FLOOD PROTECTION too many logs (%lu logs in %"PRId64" seconds, threshold is set to %lu logs "
+                "in %"PRId64" seconds). Preventing more logs from process '%s' for %"PRId64" seconds.\n",
+                date,
+                program_name,
+                counter,
+                (int64_t)(now - start),
+                error_log_errors_per_period,
+                (int64_t)error_log_throttle_period,
+                program_name,
+                (int64_t)(start + error_log_throttle_period - now));
         }
 
         prevented++;
diff --git a/libnetdata/os.c b/libnetdata/os.c
index 4271a917..196288a6 100644
--- a/libnetdata/os.c
+++ b/libnetdata/os.c
@@ -123,7 +123,9 @@ void get_system_HZ(void) {
 // =====================================================================================================================
 // FreeBSD
 
-#if (TARGET_OS == OS_FREEBSD)
+#if __FreeBSD__
+
+const char *os_type = "freebsd";
 
 int getsysctl_by_name(const char *name, void *ptr, size_t len) {
     size_t nlen = len;
@@ -198,7 +200,9 @@ int getsysctl_mib(const char *name, int *mib, size_t len) {
 // =====================================================================================================================
 // MacOS
 
-#if (TARGET_OS == OS_MACOS)
+#if __APPLE__
+
+const char *os_type = "macos";
 
 int getsysctl_by_name(const char *name, void *ptr, size_t len) {
     size_t nlen = len;
@@ -214,4 +218,13 @@ int getsysctl_by_name(const char *name, void *ptr, size_t len) {
     return 0;
 }
 
-#endif // (TARGET_OS == OS_MACOS)
+#endif
+
+// =====================================================================================================================
+// Linux
+
+#if __linux__
+
+const char *os_type = "linux";
+
+#endif
diff --git a/libnetdata/os.h b/libnetdata/os.h
index 2494174b..7872f82b 100644
--- a/libnetdata/os.h
+++ b/libnetdata/os.h
@@ -6,15 +6,9 @@
 #include "libnetdata.h"
 
 // =====================================================================================================================
-// Linux
-
-#if (TARGET_OS == OS_LINUX)
-
-
-// =====================================================================================================================
 // FreeBSD
 
-#elif (TARGET_OS == OS_FREEBSD)
+#if __FreeBSD__
 
 #include <sys/sysctl.h>
 
@@ -35,28 +29,24 @@ extern int getsysctl_simple(const char *name, int *mib, size_t miblen, void *ptr
 
 extern int getsysctl(const char *name, int *mib, size_t miblen, void *ptr, size_t *len);
 
+#endif
 
 // =====================================================================================================================
 // MacOS
 
-#elif (TARGET_OS == OS_MACOS)
+#if __APPLE__
 
 #include <sys/sysctl.h>
 
 #define GETSYSCTL_BY_NAME(name, var) getsysctl_by_name(name, &(var), sizeof(var))
 extern int getsysctl_by_name(const char *name, void *ptr, size_t len);
 
-
-// =====================================================================================================================
-// unknown O/S
-
-#else
-#error unsupported operating system
 #endif
 
-
 // =====================================================================================================================
-// common for all O/S
+// common defs for Apple/FreeBSD/Linux
+
+extern const char *os_type;
 
 extern int processors;
 extern long get_system_cpus(void);