Initial implementation of process.execPath

Darwin, Linux, Solaris. FreeBSD still needs testing.

TODO: Amend the tests where we use spawn with argv[0].

src/node.cc

@@ -1732,6 +1732,16 @@ static void Load(int argc, char *argv[]) {
 
   process->Set(String::NewSymbol("pid"), Integer::New(getpid()));
 
+  size_t size = 2*PATH_MAX;
+  char execPath[size];
+  if (OS::GetExecutablePath(execPath, &size) != 0) {
+    // as a last ditch effort, fallback on argv[0] ?
+    process->Set(String::NewSymbol("execPath"), String::New(argv[0]));
+  } else {
+    process->Set(String::NewSymbol("execPath"), String::New(execPath));
+  }
+
+
   // define various internal methods
   NODE_SET_METHOD(process, "loop", Loop);
   NODE_SET_METHOD(process, "unloop", Unloop);

src/platform.h

@@ -6,6 +6,7 @@ namespace node {
 class OS {
  public:
   static int GetMemory(size_t *rss, size_t *vsize);
+  static int GetExecutablePath(char* buffer, size_t* size);
 };
 
 

src/platform_darwin.cc

@@ -3,6 +3,7 @@
 
 #include <mach/task.h>
 #include <mach/mach_init.h>
+#include <mach-o/dyld.h> /* _NSGetExecutablePath */
 
 namespace node {
 
@@ -26,4 +27,16 @@ int OS::GetMemory(size_t *rss, size_t *vsize) {
 }
 
 
+int OS::GetExecutablePath(char* buffer, size_t* size) {
+  uint32_t usize = *size;
+  int result = _NSGetExecutablePath(buffer, &usize);
+  if (result) return result;
+  char *path = realpath(buffer, NULL);
+  if (path == NULL) return -1;
+  strncpy(buffer, path, *size);
+  free(path);
+  *size = strlen(buffer);
+  return 0;
+}
+
 }  // namespace node

src/platform_freebsd.cc

@@ -41,5 +41,17 @@ error:
 }
 
 
+int OS::GetExecutablePath(char* buffer, size_t* size) {
+  int mib[4];
+  mib[0] = CTL_KERN;
+  mib[1] = KERN_PROC;
+  mib[2] = KERN_PROC_PATHNAME;
+  mib[3] = -1;
+
+  if (sysctl(mib, 4, buffer, size, NULL, 0) == -1) {
+    return -1;
+  }
+  return 0;
+}
 
 }  // namespace node

src/platform_linux.cc

@@ -89,4 +89,11 @@ error:
 }
 
 
+int OS::GetExecutablePath(char* buffer, size_t* size) {
+  *size = readlink("/proc/self/exe", buffer, *size - 1);
+  if (*size <= 0) return -1;
+  buffer[*size] = '\0';
+  return 0;
+}
+
 }  // namespace node

src/platform_none.cc

@@ -12,5 +12,9 @@ int OS::GetMemory(size_t *rss, size_t *vsize) {
   return 0;
 }
 
+int OS::GetExecutablePath(char *buffer, size_t* size) {
+  *size = 0;
+  return 0;
+}
 
 }  // namespace node

src/platform_sunos.cc

@@ -3,6 +3,9 @@
 
 
 #include <unistd.h> /* getpagesize() */
+#include <stdlib.h> /* getexecname() */
+#include <strings.h> /* strncpy() */
+
 
 #if (!defined(_LP64)) && (_FILE_OFFSET_BITS - 0 == 64)
 #define PROCFS_FILE_OFFSET_BITS_HACK 1
@@ -48,5 +51,24 @@ int OS::GetMemory(size_t *rss, size_t *vsize) {
 }
 
 
+int OS::GetExecutablePath(char* buffer, size_t* size) {
+  const char *execname = getexecname();
+  if (!execname) return -1;
+  if (execname[0] == '/') {
+    char *result = strncpy(buffer, execname, *size);
+    *size = strlen(result);
+  } else {
+    char *result = getcwd(buffer, *size);
+    if (!result) return -1;
+    result = strncat(buffer, "/", *size);
+    if (!result) return -1;
+    result = strncat(buffer, execname, *size);
+    if (!result) return -1;
+    *size = strlen(result);
+  }
+  return 0;
+}
+
+
 }  // namespace node
 

test/simple/test-executable-path.js

@@ -0,0 +1,19 @@
+require("../common");
+
+path = require("path");
+
+isDebug = (process.version.indexOf('debug') >= 0);
+
+nodePath = path.join(__dirname,
+                     "..",
+                     "..",
+                     "build",
+                     isDebug ? 'debug' : 'default',
+                     isDebug ? 'node_g' : 'node');
+nodePath = path.normalize(nodePath);
+
+puts('nodePath: ' + nodePath);
+puts('process.execPath: ' + process.execPath);
+
+
+assert.equal(nodePath, process.execPath);