server: Adding spec-decode counters to /metrics endpoint (#26389)

* * server: add spec-decode counters to /metrics endpoint

* server: fixed review comments and now aligned param names exactly with vLLM.

.github/workflows/build-apple.yml

@@ -60,7 +60,6 @@ jobs:
             -DCMAKE_BUILD_RPATH="@loader_path" \
             -DLLAMA_FATAL_WARNINGS=ON \
             -DLLAMA_BUILD_BORINGSSL=ON \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=OFF \
             -DGGML_METAL_SHADER_DEBUG=ON \
             -DGGML_RPC=ON \
@@ -127,7 +126,6 @@ jobs:
         run: |
           sysctl -a
           cmake -B build -G Xcode \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=ON \
             -DLLAMA_OPENSSL=OFF \
             -DLLAMA_BUILD_APP=OFF \
@@ -178,7 +176,6 @@ jobs:
         run: |
           sysctl -a
           cmake -B build -G Xcode \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=ON \
             -DLLAMA_BUILD_COMMON=OFF \
             -DLLAMA_BUILD_APP=OFF \
@@ -212,7 +209,6 @@ jobs:
         run: |
           sysctl -a
           cmake -B build -G Xcode \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=ON \
             -DLLAMA_BUILD_COMMON=OFF \
             -DLLAMA_BUILD_APP=OFF \
@@ -257,7 +253,6 @@ jobs:
         run: |
           sysctl -a
           cmake -B build -G Xcode \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=ON \
             -DLLAMA_OPENSSL=OFF \
             -DLLAMA_BUILD_APP=OFF \

.github/workflows/release.yml

@@ -93,13 +93,13 @@ jobs:
           - build: 'arm64'
             arch: 'arm64'
             os: macos-26
-            defines: "-DGGML_METAL_USE_BF16=ON -DGGML_METAL_EMBED_LIBRARY=ON -DCMAKE_OSX_DEPLOYMENT_TARGET=13.3"
+            defines: "-DGGML_METAL_EMBED_LIBRARY=ON -DCMAKE_OSX_DEPLOYMENT_TARGET=13.3"
           # TODO: this build is disabled to save Github Actions resources (https://github.com/ggml-org/llama.cpp/pull/23780)
           #       in order to enable it again, we have to provision dedicated runners  to run it
           #- build: 'arm64-kleidiai'
           #  arch: 'arm64'
           #  os: macos-14
-          #  defines: "-DGGML_METAL_USE_BF16=ON -DGGML_METAL_EMBED_LIBRARY=ON -DCMAKE_OSX_DEPLOYMENT_TARGET=13.3 -DGGML_CPU_KLEIDIAI=ON"
+          #  defines: "-DGGML_METAL_EMBED_LIBRARY=ON -DCMAKE_OSX_DEPLOYMENT_TARGET=13.3 -DGGML_CPU_KLEIDIAI=ON"
           - build: 'x64'
             arch: 'x64'
             os: macos-15-intel
@@ -1402,7 +1402,6 @@ jobs:
         run: |
           sysctl -a
           cmake -B build -G Xcode \
-            -DGGML_METAL_USE_BF16=ON \
             -DGGML_METAL_EMBED_LIBRARY=ON \
             -DLLAMA_OPENSSL=OFF \
             -DLLAMA_BUILD_APP=OFF \

build-xcframework.sh

@@ -17,7 +17,6 @@ LLAMA_BUILD_MTMD=ON
 GGML_METAL=ON
 GGML_METAL_EMBED_LIBRARY=ON
 GGML_BLAS_DEFAULT=ON
-GGML_METAL_USE_BF16=ON
 GGML_OPENMP=OFF
 
 COMMON_C_FLAGS="-Wno-macro-redefined -Wno-shorten-64-to-32 -Wno-unused-command-line-argument -g"
@@ -44,7 +43,6 @@ COMMON_CMAKE_ARGS=(
     -DGGML_METAL_EMBED_LIBRARY=${GGML_METAL_EMBED_LIBRARY}
     -DGGML_BLAS_DEFAULT=${GGML_BLAS_DEFAULT}
     -DGGML_METAL=${GGML_METAL}
-    -DGGML_METAL_USE_BF16=${GGML_METAL_USE_BF16}
     -DGGML_NATIVE=OFF
     -DGGML_OPENMP=${GGML_OPENMP}
 )

gguf-py/gguf/scripts/gguf_convert_endian.py

@@ -59,11 +59,29 @@ def byteswap_q6_k(tensor, block_offs):
     delta.byteswap(inplace=True)
 
 
+def byteswap_q1_0(tensor, block_offs):
+    # Each block_q1_0 consists of an f16 delta followed by 16 int8 quantizations.
+
+    # Byte-Swap f16 sized delta field
+    delta = tensor.data[block_offs:block_offs + 2].view(dtype=np.uint16)
+    delta.byteswap(inplace=True)
+
+
+def byteswap_tq2_0(tensor, block_offs):
+    # Each block_tq2_0 consists of 64 int8 values followed by 1 f16 value.
+
+    # Byte-Swap f16 sized field
+    delta = tensor.data[block_offs + 64:block_offs + 66].view(dtype=np.uint16)
+    delta.byteswap(inplace=True)
+
+
 byteswap_tensors = {
+    gguf.GGMLQuantizationType.Q1_0:  byteswap_q1_0,
     gguf.GGMLQuantizationType.Q4_0:  byteswap_q4_0,
     gguf.GGMLQuantizationType.Q8_0:  byteswap_q8_0,
     gguf.GGMLQuantizationType.Q4_K:  byteswap_q4_k,
     gguf.GGMLQuantizationType.Q6_K:  byteswap_q6_k,
+    gguf.GGMLQuantizationType.TQ2_0: byteswap_tq2_0,
     gguf.GGMLQuantizationType.MXFP4: byteswap_noop,
     gguf.GGMLQuantizationType.NVFP4: byteswap_noop,
 }

scripts/sync_vendor.py

@@ -24,10 +24,31 @@ vendor = {
     "https://raw.githubusercontent.com/sheredom/subprocess.h/8671cee1fc09f11a70ce3782a0ee13177c3aa387/subprocess.h": "vendor/sheredom/subprocess.h",
 }
 
+# TODO @ngxson : this is temporary, to be removed in the future
+patches = [
+    # https://github.com/sheredom/subprocess.h/pull/102
+    "vendor/sheredom/patch-bsd.patch",
+    # https://github.com/sheredom/subprocess.h/pull/101
+    "vendor/sheredom/patch-windows-quote-backslash.patch",
+    # https://github.com/sheredom/subprocess.h/pull/104
+    # note: must be applied after patch-bsd.patch, they touch adjacent lines
+    "vendor/sheredom/patch-glibc-older-than-2.29.patch",
+]
+
 for url, filename in vendor.items():
     print(f"downloading {url} to {filename}") # noqa: NP100
     urllib.request.urlretrieve(url, filename)
 
+for patch in patches:
+    print(f"applying {patch}") # noqa: NP100
+    try:
+        subprocess.check_call([
+            "git", "apply", "--directory", os.path.dirname(patch), patch
+        ])
+    except Exception as e:
+        print(f"Error: {e}") # noqa: NP100
+        sys.exit(1)
+
 print("Splitting httplib.h...") # noqa: NP100
 try:
     subprocess.check_call([

tools/server/README.md

@@ -1076,6 +1076,10 @@ In *router mode* the query param `?model={model_id}` has to be set. This endpoin
 | `llamacpp:n_tokens_max` | Counter | High watermark of the context size observed. |
 | `llamacpp:n_decode_total` | Counter | Total Number of llama_decode() calls. |
 | `llamacpp:n_busy_slots_per_decode` | Gauge | Average number of busy slots per llama_decode() call. |
+| `llamacpp:spec_decode_num_draft_tokens_total` | Counter | Total draft tokens generated (0 when spec-decode is off). |
+| `llamacpp:spec_decode_num_accepted_tokens_total` | Counter | Total draft tokens accepted by the target model (0 when spec-decode is off). |
+| `llamacpp:spec_decode_num_drafts_total` | Counter | Total speculative decoding verification steps (0 when spec-decode is off). |
+| `llamacpp:spec_decode_num_accepted_tokens_per_pos_total` | Counter | Accepted tokens per draft position (labeled `position="N"`; absent when spec-decode is off or before the first completed speculative request). |
 
 ### POST `/slots/{id_slot}?action=save`: Save the prompt cache of the specified slot to a file.
 

tools/server/server-context.cpp

@@ -845,6 +845,11 @@ struct server_metrics {
     uint64_t n_decode_total     = 0;
     uint64_t n_busy_slots_total = 0;
 
+    uint64_t n_draft_tokens_total      = 0;
+    uint64_t n_draft_accepted_total    = 0;
+    uint64_t n_draft_verif_steps_total = 0;
+    std::vector<uint64_t> n_accepted_per_pos_total;
+
     void init() {
         t_start = ggml_time_us();
     }
@@ -863,6 +868,17 @@ struct server_metrics {
         n_tokens_predicted         += slot.n_decoded;
         t_tokens_generation        += slot.t_token_generation;
         t_tokens_generation_total  += slot.t_token_generation;
+
+        n_draft_tokens_total      += slot.n_draft_total;
+        n_draft_accepted_total    += slot.n_draft_accepted;
+        n_draft_verif_steps_total += slot.n_draft_verif_steps;
+
+        if (n_accepted_per_pos_total.size() < slot.n_accepted_per_pos.size()) {
+            n_accepted_per_pos_total.resize(slot.n_accepted_per_pos.size(), 0);
+        }
+        for (size_t i = 0; i < slot.n_accepted_per_pos.size(); i++) {
+            n_accepted_per_pos_total[i] += slot.n_accepted_per_pos[i];
+        }
     }
 
     void on_decoded(const std::vector<server_slot> & slots) {
@@ -2552,6 +2568,11 @@ private:
                     res->n_decode_total          = metrics.n_decode_total;
                     res->n_busy_slots_total      = metrics.n_busy_slots_total;
 
+                    res->n_draft_tokens_total      = metrics.n_draft_tokens_total;
+                    res->n_draft_accepted_total    = metrics.n_draft_accepted_total;
+                    res->n_draft_verif_steps_total = metrics.n_draft_verif_steps_total;
+                    res->n_accepted_per_pos_total  = metrics.n_accepted_per_pos_total;
+
                     if (task.metrics_reset_bucket) {
                         metrics.reset_bucket();
                     }
@@ -4440,6 +4461,18 @@ void server_routes::init_routes() {
                     {"name",  "n_tokens_max"},
                     {"help",  "Largest observed n_tokens."},
                     {"value",  res_task->n_tokens_max}
+            }, {
+                    {"name",  "spec_decode_num_draft_tokens_total"},
+                    {"help",  "Total draft tokens generated"},
+                    {"value",  res_task->n_draft_tokens_total}
+            }, {
+                    {"name",  "spec_decode_num_accepted_tokens_total"},
+                    {"help",  "Total draft tokens accepted by the target model"},
+                    {"value",  res_task->n_draft_accepted_total}
+            }, {
+                    {"name",  "spec_decode_num_drafts_total"},
+                    {"help",  "Total speculative decoding verification steps"},
+                    {"value",  res_task->n_draft_verif_steps_total}
             }}},
             {"gauge", {{
                     {"name",  "prompt_tokens_seconds"},
@@ -4481,6 +4514,17 @@ void server_routes::init_routes() {
             }
         }
 
+        // labeled counter: one time series per draft position
+        if (!res_task->n_accepted_per_pos_total.empty()) {
+            prometheus << "# HELP llamacpp:spec_decode_num_accepted_tokens_per_pos_total"
+                          " Accepted tokens per draft position\n"
+                       << "# TYPE llamacpp:spec_decode_num_accepted_tokens_per_pos_total counter\n";
+            for (size_t i = 0; i < res_task->n_accepted_per_pos_total.size(); i++) {
+                prometheus << "llamacpp:spec_decode_num_accepted_tokens_per_pos_total{position=\""
+                           << i << "\"} " << res_task->n_accepted_per_pos_total[i] << "\n";
+            }
+        }
+
         res->headers["Process-Start-Time-Unix"] = std::to_string(res_task->t_start);
         res->content_type = "text/plain; version=0.0.4";
         res->status = 200;

tools/server/server-task.cpp

@@ -1560,6 +1560,11 @@ json server_task_result_metrics::to_json() {
         { "n_decode_total",                  n_decode_total },
         { "n_busy_slots_total",              n_busy_slots_total },
 
+        { "n_draft_tokens_total",            n_draft_tokens_total },
+        { "n_draft_accepted_total",          n_draft_accepted_total },
+        { "n_draft_verif_steps_total",       n_draft_verif_steps_total },
+        { "n_accepted_per_pos_total",        n_accepted_per_pos_total },
+
         { "slots",                           slots_data },
     };
 }

tools/server/server-task.h

@@ -532,6 +532,11 @@ struct server_task_result_metrics : server_task_result {
     uint64_t n_decode_total     = 0;
     uint64_t n_busy_slots_total = 0;
 
+    uint64_t n_draft_tokens_total      = 0;
+    uint64_t n_draft_accepted_total    = 0;
+    uint64_t n_draft_verif_steps_total = 0;
+    std::vector<uint64_t> n_accepted_per_pos_total;
+
     // while we can also use std::vector<server_slot> this requires copying the slot object which can be quite messy
     // therefore, we use json to temporarily store the slot.to_json() result
     json slots_data = json::array();

tools/ui/src/lib/constants/settings-registry.ts

@@ -198,7 +198,7 @@ const SETTINGS_REGISTRY: Record<string, SettingsSectionEntry> = {
 				key: SETTINGS_KEYS.SHOW_MESSAGE_STATS,
 				label: 'Show message generation statistics',
 				help: 'Display generation statistics (tokens/second, token count, duration) below each assistant message.',
-				defaultValue: false,
+				defaultValue: true,
 				type: SettingsFieldType.CHECKBOX,
 				section: SETTINGS_SECTION_SLUGS.DISPLAY
 			},

vendor/sheredom/patch-bsd.patch

@@ -0,0 +1,19 @@
+Fix build on NetBSD, which provides posix_spawn_file_actions_addchdir()
+but not the _np() variant.
+
+Upstream PR: https://github.com/sheredom/subprocess.h/pull/102
+Applied locally by scripts/sync_vendor.py until it is merged upstream.
+
+diff --git a/subprocess.h b/subprocess.h
+index 5e809023a4..74a4e006c7 100644
+--- a/subprocess.h
++++ b/subprocess.h
+@@ -1205,7 +1205,7 @@ cleanup:
+ 
+   // Set working directory
+   if (process_cwd) {
+-#if defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= 260000
++#if defined(__NetBSD__) || (defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= 260000)
+     posix_error = posix_spawn_file_actions_addchdir(&actions, process_cwd);
+ #else
+ #if defined(__APPLE__) && defined(__clang__)

vendor/sheredom/patch-glibc-older-than-2.29.patch

@@ -0,0 +1,47 @@
+Fix building against glibc older than 2.29, which has no
+posix_spawn_file_actions_addchdir_np (the symbol is genuinely absent from
+libc.so, so no feature-test macro helps). Affects manylinux2014 (glibc 2.17)
+and manylinux_2_28, and was reported on RHEL 8.1. A requested process_cwd now
+fails with ENOSYS there instead of failing the build.
+
+Upstream PR: https://github.com/sheredom/subprocess.h/pull/104
+Applied locally by scripts/sync_vendor.py until it is merged upstream.
+
+(the README.md and test/ changes from the PR are omitted, we only vendor
+subprocess.h; rebased on top of patch-bsd.patch, so apply it after that one)
+
+diff --git a/subprocess.h b/subprocess.h
+index 1ef424a..c363393 100644
+--- a/subprocess.h
++++ b/subprocess.h
+@@ -274,6 +274,21 @@ subprocess_weak int subprocess_alive(struct subprocess_s *const process);
+ #include <unistd.h>
+ #endif
+ 
++/* Whether subprocess_create_ex can honour process_cwd. glibc only gained
++   posix_spawn_file_actions_addchdir_np in 2.29. Define this yourself to
++   override the detection, for instance on musl older than 1.1.24. */
++#if !defined(SUBPROCESS_HAVE_CWD)
++#if defined(__GLIBC__)
++#if __GLIBC_PREREQ(2, 29)
++#define SUBPROCESS_HAVE_CWD 1
++#else
++#define SUBPROCESS_HAVE_CWD 0
++#endif
++#else
++#define SUBPROCESS_HAVE_CWD 1
++#endif
++#endif
++
+ #if defined(_WIN32)
+ 
+ #include <wchar.h>
+@@ -1219,6 +1234,8 @@ cleanup:
+   if (process_cwd) {
+ #if defined(__NetBSD__) || (defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= 260000)
+     posix_error = posix_spawn_file_actions_addchdir(&actions, process_cwd);
++#elif !SUBPROCESS_HAVE_CWD
++    posix_error = ENOSYS;
+ #else
+ #if defined(__APPLE__) && defined(__clang__)
+ #pragma clang diagnostic push

vendor/sheredom/patch-windows-quote-backslash.patch

@@ -0,0 +1,107 @@
+Fix Windows command line quoting of backslash runs: a trailing backslash, or
+backslashes preceding a double quote, were not doubled, so CommandLineToArgvW
+in the child parsed them as escapes and mangled the argument list.
+
+Upstream PR: https://github.com/sheredom/subprocess.h/pull/101
+Applied locally by scripts/sync_vendor.py until it is merged upstream.
+
+(the test/ changes from the PR are omitted, we only vendor subprocess.h)
+
+diff --git a/subprocess.h b/subprocess.h
+index 5e80902..b06ad4d 100644
+--- a/subprocess.h
++++ b/subprocess.h
+@@ -653,6 +653,7 @@ int subprocess_create_ex(const char *const commandLine[], int options,
+   int wide_len;
+   int i, j;
+   int need_quoting;
++  subprocess_size_t bs_run;
+   unsigned long flags = 0;
+   unsigned long last_error = 0;
+   int result = subprocess_error_unknown;
+@@ -906,25 +907,29 @@ int subprocess_create_ex(const char *const commandLine[], int options,
+     len++;
+ 
+     // Quote the argument if it has a space in it
+-    if (strpbrk(commandLine[i], "\t\v ") != SUBPROCESS_NULL ||
+-        commandLine[i][0] == SUBPROCESS_NULL)
++    need_quoting = strpbrk(commandLine[i], "\t\v ") != SUBPROCESS_NULL ||
++                   commandLine[i][0] == SUBPROCESS_NULL;
++    if (need_quoting)
+       len += 2;
+ 
++    bs_run = 0;
+     for (j = 0; '\0' != commandLine[i][j]; j++) {
+-      switch (commandLine[i][j]) {
+-      default:
+-        break;
+-      case '\\':
+-        if (commandLine[i][j + 1] == '"') {
+-          len++;
+-        }
++      len++;
+ 
+-        break;
+-      case '"':
+-        len++;
+-        break;
++      if ('\\' == commandLine[i][j]) {
++        bs_run++;
++      } else {
++        if ('"' == commandLine[i][j]) {
++          // Duplicate the preceding run and escape the quote.
++          len += bs_run + 1;
++        }
++        bs_run = 0;
+       }
+-      len++;
++    }
++
++    if (need_quoting) {
++      // Duplicate trailing slashes before the generated closing quote.
++      len += bs_run;
+     }
+   }
+ 
+@@ -949,22 +954,29 @@ int subprocess_create_ex(const char *const commandLine[], int options,
+       commandLineCombined[len++] = '"';
+     }
+ 
+-    for (j = 0; '\0' != commandLine[i][j]; j++) {
+-      switch (commandLine[i][j]) {
+-      default:
+-        break;
+-      case '\\':
+-        if (commandLine[i][j + 1] == '"') {
+-          commandLineCombined[len++] = '\\';
+-        }
++    for (j = 0; '\0' != commandLine[i][j];) {
++      bs_run = 0;
++      while ('\\' == commandLine[i][j]) {
++        bs_run++;
++        j++;
++      }
++
++      if ('"' == commandLine[i][j]) {
++        // 2n + 1 slashes preserve n slashes and escape the quote.
++        bs_run = (bs_run * 2) + 1;
++      } else if ('\0' == commandLine[i][j] && need_quoting) {
++        // 2n slashes preserve n slashes before the closing quote.
++        bs_run *= 2;
++      }
+ 
+-        break;
+-      case '"':
++      while (bs_run > 0) {
+         commandLineCombined[len++] = '\\';
+-        break;
++        bs_run--;
+       }
+ 
+-      commandLineCombined[len++] = commandLine[i][j];
++      if ('\0' != commandLine[i][j]) {
++        commandLineCombined[len++] = commandLine[i][j++];
++      }
+     }
+     if (need_quoting) {
+       commandLineCombined[len++] = '"';

vendor/sheredom/subprocess.h

@@ -274,6 +274,21 @@ subprocess_weak int subprocess_alive(struct subprocess_s *const process);
 #include <unistd.h>
 #endif
 
+/* Whether subprocess_create_ex can honour process_cwd. glibc only gained
+   posix_spawn_file_actions_addchdir_np in 2.29. Define this yourself to
+   override the detection, for instance on musl older than 1.1.24. */
+#if !defined(SUBPROCESS_HAVE_CWD)
+#if defined(__GLIBC__)
+#if __GLIBC_PREREQ(2, 29)
+#define SUBPROCESS_HAVE_CWD 1
+#else
+#define SUBPROCESS_HAVE_CWD 0
+#endif
+#else
+#define SUBPROCESS_HAVE_CWD 1
+#endif
+#endif
+
 #if defined(_WIN32)
 
 #include <wchar.h>
@@ -653,6 +668,7 @@ int subprocess_create_ex(const char *const commandLine[], int options,
   int wide_len;
   int i, j;
   int need_quoting;
+  subprocess_size_t bs_run;
   unsigned long flags = 0;
   unsigned long last_error = 0;
   int result = subprocess_error_unknown;
@@ -906,25 +922,29 @@ int subprocess_create_ex(const char *const commandLine[], int options,
     len++;
 
     // Quote the argument if it has a space in it
-    if (strpbrk(commandLine[i], "\t\v ") != SUBPROCESS_NULL ||
-        commandLine[i][0] == SUBPROCESS_NULL)
+    need_quoting = strpbrk(commandLine[i], "\t\v ") != SUBPROCESS_NULL ||
+                   commandLine[i][0] == SUBPROCESS_NULL;
+    if (need_quoting)
       len += 2;
 
+    bs_run = 0;
     for (j = 0; '\0' != commandLine[i][j]; j++) {
-      switch (commandLine[i][j]) {
-      default:
-        break;
-      case '\\':
-        if (commandLine[i][j + 1] == '"') {
-          len++;
-        }
-
-        break;
-      case '"':
-        len++;
-        break;
-      }
       len++;
+
+      if ('\\' == commandLine[i][j]) {
+        bs_run++;
+      } else {
+        if ('"' == commandLine[i][j]) {
+          // Duplicate the preceding run and escape the quote.
+          len += bs_run + 1;
+        }
+        bs_run = 0;
+      }
+    }
+
+    if (need_quoting) {
+      // Duplicate trailing slashes before the generated closing quote.
+      len += bs_run;
     }
   }
 
@@ -949,22 +969,29 @@ int subprocess_create_ex(const char *const commandLine[], int options,
       commandLineCombined[len++] = '"';
     }
 
-    for (j = 0; '\0' != commandLine[i][j]; j++) {
-      switch (commandLine[i][j]) {
-      default:
-        break;
-      case '\\':
-        if (commandLine[i][j + 1] == '"') {
-          commandLineCombined[len++] = '\\';
-        }
-
-        break;
-      case '"':
-        commandLineCombined[len++] = '\\';
-        break;
+    for (j = 0; '\0' != commandLine[i][j];) {
+      bs_run = 0;
+      while ('\\' == commandLine[i][j]) {
+        bs_run++;
+        j++;
       }
 
-      commandLineCombined[len++] = commandLine[i][j];
+      if ('"' == commandLine[i][j]) {
+        // 2n + 1 slashes preserve n slashes and escape the quote.
+        bs_run = (bs_run * 2) + 1;
+      } else if ('\0' == commandLine[i][j] && need_quoting) {
+        // 2n slashes preserve n slashes before the closing quote.
+        bs_run *= 2;
+      }
+
+      while (bs_run > 0) {
+        commandLineCombined[len++] = '\\';
+        bs_run--;
+      }
+
+      if ('\0' != commandLine[i][j]) {
+        commandLineCombined[len++] = commandLine[i][j++];
+      }
     }
     if (need_quoting) {
       commandLineCombined[len++] = '"';
@@ -1205,8 +1232,10 @@ cleanup:
 
   // Set working directory
   if (process_cwd) {
-#if defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= 260000
+#if defined(__NetBSD__) || (defined(__APPLE__) && MAC_OS_X_VERSION_MIN_REQUIRED >= 260000)
     posix_error = posix_spawn_file_actions_addchdir(&actions, process_cwd);
+#elif !SUBPROCESS_HAVE_CWD
+    posix_error = ENOSYS;
 #else
 #if defined(__APPLE__) && defined(__clang__)
 #pragma clang diagnostic push