darwin: implement uv_set_process_title, part 2

Make changes to the process title visible to tools like `ps`.

The argv clobber technique is reasonably portable across Unices;
the common code has been moved into src/unix/proctitle.c and is used
on Linux and OS X. Other platforms will probably follow in the future.

Author: bnoordhuis

config-unix.mk

@@ -78,6 +78,7 @@ SOEXT = dylib
 OBJS += src/unix/darwin.o
 OBJS += src/unix/kqueue.o
 OBJS += src/unix/fsevents.o
+OBJS += src/unix/proctitle.o
 OBJS += src/unix/darwin-proctitle.o
 endif
 
@@ -87,7 +88,8 @@ LDFLAGS+=-ldl -lrt
 RUNNER_CFLAGS += -D_GNU_SOURCE
 OBJS += src/unix/linux-core.o \
         src/unix/linux-inotify.o \
-        src/unix/linux-syscalls.o
+        src/unix/linux-syscalls.o \
+        src/unix/proctitle.o
 endif
 
 ifeq (freebsd,$(OS))

src/unix/darwin.c

@@ -37,8 +37,6 @@
 #include <sys/sysctl.h>
 #include <unistd.h>  /* sysconf */
 
-static char *process_title;
-
 /* Forward declarations */
 void uv__cf_loop_runner(void* arg);
 void uv__cf_loop_cb(void* arg);
@@ -254,43 +252,6 @@ void uv_loadavg(double avg[3]) {
 }
 
 
-char** uv_setup_args(int argc, char** argv) {
-  process_title = argc ? strdup(argv[0]) : NULL;
-  return argv;
-}
-
-
-uv_err_t uv_set_process_title(const char* title) {
-  int uv__set_process_title(const char*);
-
-  if (process_title != NULL)
-    free(process_title);
-
-  process_title = strdup(title);
-
-  if (process_title == NULL)
-    return uv__new_artificial_error(UV_ENOMEM);
-
-  if (uv__set_process_title(title))
-    return uv__new_artificial_error(UV_ENOSYS);
-
-  return uv_ok_;
-}
-
-
-uv_err_t uv_get_process_title(char* buffer, size_t size) {
-  if (process_title) {
-    strncpy(buffer, process_title, size);
-  } else {
-    if (size > 0) {
-      buffer[0] = '\0';
-    }
-  }
-
-  return uv_ok_;
-}
-
-
 uv_err_t uv_resident_set_memory(size_t* rss) {
   struct task_basic_info t_info;
   mach_msg_type_number_t t_info_count = TASK_BASIC_INFO_COUNT;

src/unix/linux-core.c

@@ -57,25 +57,12 @@
 # define CLOCK_BOOTTIME 7
 #endif
 
-static void* args_mem;
-
-static struct {
-  char *str;
-  size_t len;
-} process_title;
-
 static void read_models(unsigned int numcpus, uv_cpu_info_t* ci);
 static void read_speeds(unsigned int numcpus, uv_cpu_info_t* ci);
 static void read_times(unsigned int numcpus, uv_cpu_info_t* ci);
 static unsigned long read_cpufreq(unsigned int cpunum);
 
 
-__attribute__((destructor))
-static void free_args_mem(void) {
-  free(args_mem); /* keep valgrind happy */
-}
-
-
 int uv__platform_loop_init(uv_loop_t* loop, int default_loop) {
   int fd;
 
@@ -296,78 +283,6 @@ uint64_t uv_get_total_memory(void) {
 }
 
 
-char** uv_setup_args(int argc, char** argv) {
-  char **new_argv;
-  char **new_env;
-  size_t size;
-  int envc;
-  char *s;
-  int i;
-
-  for (envc = 0; environ[envc]; envc++);
-
-  s = envc ? environ[envc - 1] : argv[argc - 1];
-
-  process_title.str = argv[0];
-  process_title.len = s + strlen(s) + 1 - argv[0];
-
-  size = process_title.len;
-  size += (argc + 1) * sizeof(char **);
-  size += (envc + 1) * sizeof(char **);
-
-  if (NULL == (s = malloc(size))) {
-    process_title.str = NULL;
-    process_title.len = 0;
-    return argv;
-  }
-  args_mem = s;
-
-  new_argv = (char **) s;
-  new_env = new_argv + argc + 1;
-  s = (char *) (new_env + envc + 1);
-  memcpy(s, process_title.str, process_title.len);
-
-  for (i = 0; i < argc; i++)
-    new_argv[i] = s + (argv[i] - argv[0]);
-  new_argv[argc] = NULL;
-
-  s += environ[0] - argv[0];
-
-  for (i = 0; i < envc; i++)
-    new_env[i] = s + (environ[i] - environ[0]);
-  new_env[envc] = NULL;
-
-  environ = new_env;
-  return new_argv;
-}
-
-
-uv_err_t uv_set_process_title(const char* title) {
-  /* No need to terminate, last char is always '\0'. */
-  if (process_title.len)
-    strncpy(process_title.str, title, process_title.len - 1);
-
-#if defined(PR_SET_NAME)
-  prctl(PR_SET_NAME, title);
-#endif
-
-  return uv_ok_;
-}
-
-
-uv_err_t uv_get_process_title(char* buffer, size_t size) {
-  if (process_title.str) {
-    strncpy(buffer, process_title.str, size);
-  } else {
-    if (size > 0) {
-      buffer[0] = '\0';
-    }
-  }
-
-  return uv_ok_;
-}
-
-
 uv_err_t uv_resident_set_memory(size_t* rss) {
   FILE* f;
   int itmp;
@@ -787,3 +702,10 @@ void uv_free_interface_addresses(uv_interface_address_t* addresses,
 
   free(addresses);
 }
+
+
+void uv__set_process_title(const char* title) {
+#if defined(PR_SET_NAME)
+  prctl(PR_SET_NAME, title);  /* Only copies first 16 characters. */
+#endif
+}

src/unix/proctitle.c

@@ -0,0 +1,126 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "internal.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+extern void uv__set_process_title(const char* title);
+
+static void* args_mem;
+
+static struct {
+  char* str;
+  int len;
+} process_title;
+
+
+char** uv_setup_args(int argc, char** argv) {
+  char** new_argv;
+  char** new_env;
+  size_t size;
+  int envc;
+  char* s;
+  int i;
+
+#if defined(__APPLE__)
+  char*** _NSGetArgv(void);
+  char*** _NSGetEnviron(void);
+  char** environ = *_NSGetEnviron();
+#else
+  extern char** environ;
+#endif
+
+  for (envc = 0; environ[envc]; envc++);
+
+  if (envc == 0)
+    s = argv[argc - 1];
+  else
+    s = environ[envc - 1];
+
+  process_title.str = argv[0];
+  process_title.len = s + strlen(s) + 1 - argv[0];
+
+  size = process_title.len;
+  size += (argc + 1) * sizeof(char**);
+  size += (envc + 1) * sizeof(char**);
+  s = args_mem = malloc(size);
+
+  if (s == NULL) {
+    process_title.str = NULL;
+    process_title.len = 0;
+    return argv;
+  }
+
+  new_argv = (char**) s;
+  new_env = new_argv + argc + 1;
+  s = (char*) (new_env + envc + 1);
+  memcpy(s, process_title.str, process_title.len);
+
+  for (i = 0; i < argc; i++)
+    new_argv[i] = s + (argv[i] - argv[0]);
+  new_argv[argc] = NULL;
+
+  s += environ[0] - argv[0];
+
+  for (i = 0; i < envc; i++)
+    new_env[i] = s + (environ[i] - environ[0]);
+  new_env[envc] = NULL;
+
+#if defined(__APPLE__)
+  *_NSGetArgv() = new_argv;
+  *_NSGetEnviron() = new_env;
+#else
+  environ = new_env;
+#endif
+
+  return new_argv;
+}
+
+
+uv_err_t uv_set_process_title(const char* title) {
+  if (process_title.len == 0)
+    return uv_ok_;
+
+  /* No need to terminate, last char is always '\0'. */
+  strncpy(process_title.str, title, process_title.len - 1);
+  uv__set_process_title(title);
+
+  return uv_ok_;
+}
+
+
+uv_err_t uv_get_process_title(char* buffer, size_t size) {
+  if (process_title.len > 0)
+    strncpy(buffer, process_title.str, size);
+  else if (size > 0)
+    buffer[0] = '\0';
+
+  return uv_ok_;
+}
+
+
+__attribute__((destructor))
+static void free_args_mem(void) {
+  free(args_mem);  /* Keep valgrind happy. */
+  args_mem = NULL;
+}

uv.gyp

@@ -157,6 +157,9 @@
             }],
           ],
         }],
+        [ 'OS=="linux" or OS=="mac"', {
+          'sources': [ 'src/unix/proctitle.c' ],
+        }],
         [ 'OS=="mac"', {
           'sources': [
             'src/unix/darwin.c',