unix: make get(set)_process_title MT-safe

Used a shared uv_mutex_t in unix implementations of these functions
to prevent simultaneous execution.

Fixes: https://github.com/libuv/libuv/issues/271
PR-URL: https://github.com/libuv/libuv/pull/1640
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>

Makefile.am

@@ -222,6 +222,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-poll-closesocket.c \
                          test/test-poll-oob.c \
                          test/test-process-title.c \
+                         test/test-process-title-threadsafe.c \
                          test/test-queue-foreach-delete.c \
                          test/test-ref.c \
                          test/test-run-nowait.c \

checksparse.sh

@@ -128,6 +128,7 @@ test/test-platform-output.c
 test/test-poll-close.c
 test/test-poll.c
 test/test-process-title.c
+test/test-process-title-threadsafe.c
 test/test-ref.c
 test/test-run-nowait.c
 test/test-run-once.c

docs/src/misc.rst

@@ -197,8 +197,7 @@ API
     `UV_EINVAL` is returned. If `size` cannot accommodate the process title and
     terminating `NULL` character, the function returns `UV_ENOBUFS`.
 
-    .. warning::
-        `uv_get_process_title` is not thread safe on any platform except Windows.
+    .. versionchanged:: 1.18.1 now thread-safe on all supported platforms.
 
 .. c:function:: int uv_set_process_title(const char* title)
 
@@ -208,8 +207,7 @@ API
     larger than the available space. Other platforms will return `UV_ENOMEM` if
     they cannot allocate enough space to duplicate the contents of `title`.
 
-    .. warning::
-        `uv_set_process_title` is not thread safe on any platform except Windows.
+    .. versionchanged:: 1.18.1 now thread-safe on all supported platforms.
 
 .. c:function:: int uv_resident_set_memory(size_t* rss)
 

src/unix/aix.c

@@ -65,11 +65,18 @@
 #define RDWR_BUF_SIZE   4096
 #define EQ(a,b)         (strcmp(a,b) == 0)
 
+static uv_mutex_t process_title_mutex;
+static uv_once_t process_title_mutex_once = UV_ONCE_INIT;
 static void* args_mem = NULL;
 static char** process_argv = NULL;
 static int process_argc = 0;
 static char* process_title_ptr = NULL;
 
+static void init_process_title_mutex_once(void) {
+  uv_mutex_init(&process_title_mutex);
+}
+
+
 int uv__platform_loop_init(uv_loop_t* loop) {
   loop->fs_fd = -1;
 
@@ -856,6 +863,9 @@ int uv_set_process_title(const char* title) {
   if (new_title == NULL)
     return -ENOMEM;
 
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
   /* If this is the first time this is set,
    * don't free and set argv[1] to NULL.
    */
@@ -868,6 +878,8 @@ int uv_set_process_title(const char* title) {
   if (process_argc > 1)
      process_argv[1] = NULL;
 
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 
@@ -880,8 +892,13 @@ int uv_get_process_title(char* buffer, size_t size) {
   else if (size <= len)
     return -ENOBUFS;
 
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
   memcpy(buffer, process_argv[0], len + 1);
 
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 

src/unix/freebsd.c

@@ -47,9 +47,16 @@
 # define CP_INTR 4
 #endif
 
+static uv_mutex_t process_title_mutex;
+static uv_once_t process_title_mutex_once = UV_ONCE_INIT;
 static char *process_title;
 
 
+static void init_process_title_mutex_once(void) {
+  uv_mutex_init(&process_title_mutex);
+}
+
+
 int uv__platform_loop_init(uv_loop_t* loop) {
   return uv__kqueue_init(loop);
 }
@@ -163,8 +170,15 @@ int uv_set_process_title(const char* title) {
   char* new_title;
 
   new_title = uv__strdup(title);
-  if (process_title == NULL)
+
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
+  if (process_title == NULL) {
+    uv_mutex_unlock(&process_title_mutex);
     return -ENOMEM;
+  }
+
   uv__free(process_title);
   process_title = new_title;
 
@@ -180,6 +194,8 @@ int uv_set_process_title(const char* title) {
          process_title,
          strlen(process_title) + 1);
 
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 
@@ -190,17 +206,24 @@ int uv_get_process_title(char* buffer, size_t size) {
   if (buffer == NULL || size == 0)
     return -EINVAL;
 
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
   if (process_title) {
     len = strlen(process_title) + 1;
 
-    if (size < len)
+    if (size < len) {
+      uv_mutex_unlock(&process_title_mutex);
       return -ENOBUFS;
+    }
 
     memcpy(buffer, process_title, len);
   } else {
     len = 0;
   }
 
+  uv_mutex_unlock(&process_title_mutex);
+
   buffer[len] = '\0';
 
   return 0;

src/unix/netbsd.c

@@ -40,9 +40,16 @@
 #include <unistd.h>
 #include <time.h>
 
+static uv_mutex_t process_title_mutex;
+static uv_once_t process_title_mutex_once = UV_ONCE_INIT;
 static char *process_title;
 
 
+static void init_process_title_mutex_once(void) {
+  uv_mutex_init(&process_title_mutex);
+}
+
+
 int uv__platform_loop_init(uv_loop_t* loop) {
   return uv__kqueue_init(loop);
 }
@@ -137,12 +144,21 @@ int uv_set_process_title(const char* title) {
   char* new_title;
 
   new_title = uv__strdup(title);
-  if (process_title == NULL)
+
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
+  if (process_title == NULL) {
+    uv_mutex_unlock(&process_title_mutex);
     return -ENOMEM;
+  }
+
   uv__free(process_title);
   process_title = new_title;
   setproctitle("%s", title);
 
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 
@@ -153,17 +169,24 @@ int uv_get_process_title(char* buffer, size_t size) {
   if (buffer == NULL || size == 0)
     return -EINVAL;
 
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
   if (process_title) {
     len = strlen(process_title) + 1;
 
-    if (size < len)
+    if (size < len) {
+      uv_mutex_unlock(&process_title_mutex);
       return -ENOBUFS;
+    }
 
     memcpy(buffer, process_title, len);
   } else {
     len = 0;
   }
 
+  uv_mutex_unlock(&process_title_mutex);
+
   buffer[len] = '\0';
 
   return 0;

src/unix/openbsd.c

@@ -36,9 +36,16 @@
 #include <unistd.h>
 
 
+static uv_mutex_t process_title_mutex;
+static uv_once_t process_title_mutex_once = UV_ONCE_INIT;
 static char *process_title;
 
 
+static void init_process_title_mutex_once(void) {
+  uv_mutex_init(&process_title_mutex);
+}
+
+
 int uv__platform_loop_init(uv_loop_t* loop) {
   return uv__kqueue_init(loop);
 }
@@ -149,11 +156,21 @@ int uv_set_process_title(const char* title) {
   char* new_title;
 
   new_title = uv__strdup(title);
-  if (process_title == NULL)
+
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
+  if (process_title == NULL) {
+    uv_mutex_unlock(&process_title_mutex);
     return -ENOMEM;
+  }
+
   uv__free(process_title);
   process_title = new_title;
   setproctitle("%s", title);
+
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 
@@ -164,17 +181,24 @@ int uv_get_process_title(char* buffer, size_t size) {
   if (buffer == NULL || size == 0)
     return -EINVAL;
 
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
   if (process_title) {
     len = strlen(process_title) + 1;
 
-    if (size < len)
+    if (size < len) {
+      uv_mutex_unlock(&process_title_mutex);
       return -ENOBUFS;
+    }
 
     memcpy(buffer, process_title, len);
   } else {
     len = 0;
   }
 
+  uv_mutex_unlock(&process_title_mutex);
+
   buffer[len] = '\0';
 
   return 0;

src/unix/proctitle.c

@@ -26,6 +26,8 @@
 
 extern void uv__set_process_title(const char* title);
 
+static uv_mutex_t process_title_mutex;
+static uv_once_t process_title_mutex_once = UV_ONCE_INIT;
 static void* args_mem;
 
 static struct {
@@ -34,6 +36,11 @@ static struct {
 } process_title;
 
 
+static void init_process_title_mutex_once(void) {
+  uv_mutex_init(&process_title_mutex);
+}
+
+
 char** uv_setup_args(int argc, char** argv) {
   char** new_argv;
   size_t size;
@@ -81,12 +88,16 @@ char** uv_setup_args(int argc, char** argv) {
 
 
 int uv_set_process_title(const char* title) {
-  if (process_title.len == 0)
-    return 0;
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
 
+  if (process_title.len != 0) {
     /* No need to terminate, byte after is always '\0'. */
     strncpy(process_title.str, title, process_title.len);
     uv__set_process_title(title);
+  }
+
+  uv_mutex_unlock(&process_title_mutex);
 
   return 0;
 }
@@ -95,14 +106,22 @@ int uv_set_process_title(const char* title) {
 int uv_get_process_title(char* buffer, size_t size) {
   if (buffer == NULL || size == 0)
     return -EINVAL;
-  else if (size <= process_title.len)
+
+  uv_once(&process_title_mutex_once, init_process_title_mutex_once);
+  uv_mutex_lock(&process_title_mutex);
+
+  if (size <= process_title.len) {
+    uv_mutex_unlock(&process_title_mutex);
     return -ENOBUFS;
+  }
 
   if (process_title.len != 0)
     memcpy(buffer, process_title.str, process_title.len + 1);
 
   buffer[process_title.len] = '\0';
 
+  uv_mutex_unlock(&process_title_mutex);
+
   return 0;
 }
 

test/test-list.h

@@ -214,6 +214,7 @@ TEST_DECLARE   (async_null_cb)
 TEST_DECLARE   (eintr_handling)
 TEST_DECLARE   (get_currentexe)
 TEST_DECLARE   (process_title)
+TEST_DECLARE   (process_title_threadsafe)
 TEST_DECLARE   (cwd_and_chdir)
 TEST_DECLARE   (get_memory)
 TEST_DECLARE   (get_passwd)
@@ -672,6 +673,7 @@ TASK_LIST_START
   TEST_ENTRY  (get_currentexe)
 
   TEST_ENTRY  (process_title)
+  TEST_ENTRY  (process_title_threadsafe)
 
   TEST_ENTRY  (cwd_and_chdir)
 

test/test-process-title-threadsafe.c

@@ -0,0 +1,90 @@
+/* Copyright libuv project 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 "task.h"
+
+#include <string.h>
+
+#ifdef __APPLE__
+# define NUM_ITERATIONS 20
+#else
+# define NUM_ITERATIONS 50
+#endif
+
+static const char* titles[] = {
+  "8L2NY0Kdj0XyNFZnmUZigIOfcWjyNr0SkMmUhKw99VLUsZFrvCQQC3XIRfNR8pjyMjXObllled",
+  "jUAcscJN49oLSN8GdmXj2Wo34XX2T2vp2j5khfajNQarlOulp57cE130yiY53ipJFnPyTn5i82",
+  "9niCI5icXGFS72XudhXqo5alftmZ1tpE7B3cwUmrq0CCDjC84FzBNB8XAHqvpNQfI2QAQG6ztT",
+  "n8qXVXuG6IEHDpabJgTEiwtpY6LHMZ8MgznnMpdHARu5EywufA6hcBaQfetb0YhEsK0ykDd7JU"
+};
+
+static void getter_thread_body(void* arg) {
+  char buffer[512];
+
+  for (;;) {
+    ASSERT(0 == uv_get_process_title(buffer, sizeof(buffer)));
+    ASSERT(
+      0 == strcmp(buffer, titles[0]) ||
+      0 == strcmp(buffer, titles[1]) ||
+      0 == strcmp(buffer, titles[2]) ||
+      0 == strcmp(buffer, titles[3]));
+
+    uv_sleep(0);
+  }
+}
+
+
+static void setter_thread_body(void* arg) {
+  int i;
+
+  for (i = 0; i < NUM_ITERATIONS; i++) {
+    ASSERT(0 == uv_set_process_title(titles[0]));
+    ASSERT(0 == uv_set_process_title(titles[1]));
+    ASSERT(0 == uv_set_process_title(titles[2]));
+    ASSERT(0 == uv_set_process_title(titles[3]));
+  }
+}
+
+
+TEST_IMPL(process_title_threadsafe) {
+  uv_thread_t setter_threads[4];
+  uv_thread_t getter_thread;
+  int i;
+
+#if defined(__sun) || defined(__CYGWIN__) || defined(__MSYS__) || \
+    defined(__MVS__)
+  RETURN_SKIP("uv_(get|set)_process_title is not implemented.");
+#else
+
+  ASSERT(0 == uv_set_process_title(titles[0]));
+  ASSERT(0 == uv_thread_create(&getter_thread, getter_thread_body, NULL));
+
+  for (i = 0; i < (int) ARRAY_SIZE(setter_threads); i++)
+    ASSERT(0 == uv_thread_create(&setter_threads[i], setter_thread_body, NULL));
+
+  for (i = 0; i < (int) ARRAY_SIZE(setter_threads); i++)
+    ASSERT(0 == uv_thread_join(&setter_threads[i]));
+
+  return 0;
+#endif
+}

uv.gyp

@@ -427,6 +427,7 @@
         'test/test-poll-closesocket.c',
         'test/test-poll-oob.c',
         'test/test-process-title.c',
+        'test/test-process-title-threadsafe.c',
         'test/test-queue-foreach-delete.c',
         'test/test-ref.c',
         'test/test-run-nowait.c',