Add in utilities needed for log location

CMakeLists.txt

@@ -40,6 +40,7 @@ set(rcutils_sources
   src/get_env.c
   src/hash_map.c
   src/logging.c
+  src/process.c
   src/repl_str.c
   src/snprintf.c
   src/split.c

include/rcutils/get_env.h

@@ -61,6 +61,30 @@ RCUTILS_WARN_UNUSED
 const char *
 rcutils_get_env(const char * env_name, const char ** env_value);
 
+/// Retrieve the full path to the home directory.
+/**
+ * The c-string which is returned is only valid until the next time this
+ * function is called, because it is a direct pointer to the static storage.
+ * Also note that the string returned here should *not* be freed.
+ *
+ * The function first tries to get the HOME environment variable.
+ * If that variable exists and is non-empty, that will be returned.
+ * Otherwise, the function tries to get the USERPROFILE environment variable.
+ * If that variable exists and is non-empty, that will be returned.
+ * If neither exists, NULL will be returned.
+ * The above algorithm is portable across both Unix and Windows.
+ *
+ * The home directory will be truncated at 2048 characters on Windows.
+ *
+ * This function is not thread-safe.
+ *
+ * \return The home directory on success, NULL on failure.
+ */
+RCUTILS_PUBLIC
+RCUTILS_WARN_UNUSED
+const char *
+rcutils_get_home_dir(void);
+
 #ifdef __cplusplus
 }
 #endif

include/rcutils/process.h

@@ -0,0 +1,58 @@
+// Copyright 2019 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCUTILS__PROCESS_H_
+#define RCUTILS__PROCESS_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include "rcutils/allocator.h"
+#include "rcutils/macros.h"
+#include "rcutils/visibility_control.h"
+
+/// Retrieve the current process ID.
+/**
+ * This function returns the current process ID, and is always successful.
+ *
+ * This function is thread-safe.
+ *
+ * \return The current process ID.
+ */
+RCUTILS_PUBLIC
+RCUTILS_WARN_UNUSED
+int rcutils_get_pid(void);
+
+/// Retrieve the current executable name.
+/**
+ * This function portably retrieves the current program name and returns
+ * a copy of it.
+ * It is up to the caller to free the memory.
+ *
+ * This function is thread-safe.
+ *
+ * \param[in] allocator the allocator to use
+ * \return The program name on success, NULL on failure.
+ */
+RCUTILS_PUBLIC
+RCUTILS_WARN_UNUSED
+char * rcutils_get_executable_name(rcutils_allocator_t allocator);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // RCUTILS__PROCESS_H_

src/get_env.c

@@ -55,6 +55,28 @@ rcutils_get_env(const char * env_name, const char ** env_value)
   return NULL;
 }
 
+const char *
+rcutils_get_home_dir(void)
+{
+  const char * homedir;
+
+  if (rcutils_get_env("HOME", &homedir) == NULL && *homedir != '\0') {
+    // The HOME environment variable was set and is non-empty, return it.
+    return homedir;
+  }
+
+#ifdef _WIN32
+  // We didn't find a HOME variable, try USERPROFILE on Windows.
+  if (rcutils_get_env("USERPROFILE", &homedir) == NULL && *homedir != '\0') {
+    // The USERPROFILE environment variable was set and is non-empty, return it.
+    return homedir;
+  }
+#endif
+
+  // Couldn't get the home directory, return NULL.
+  return NULL;
+}
+
 #ifdef __cplusplus
 }
 #endif

src/process.c

@@ -0,0 +1,104 @@
+// Copyright 2019 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if defined _WIN32 || defined __CYGWIN__
+#include <Windows.h>
+#else
+#include <libgen.h>
+#include <unistd.h>
+#endif
+
+#include "rcutils/allocator.h"
+#include "rcutils/error_handling.h"
+#include "rcutils/process.h"
+
+int rcutils_get_pid(void)
+{
+#if defined _WIN32 || defined __CYGWIN__
+  return (int)GetCurrentProcessId();
+#else
+  return (int)getpid();
+#endif
+}
+
+char * rcutils_get_executable_name(rcutils_allocator_t allocator)
+{
+  RCUTILS_CHECK_ALLOCATOR_WITH_MSG(
+    &allocator, "invalid allocator", return NULL);
+
+#if defined __APPLE__
+  const char * appname = getprogname();
+#elif defined __GNUC__
+  const char * appname = program_invocation_name;
+#elif defined _WIN32 || defined __CYGWIN
+  char appname[MAX_PATH];
+  int32_t size = GetModuleFileNameA(NULL, appname, MAX_PATH);
+  if (size == 0) {
+    return NULL;
+  }
+#else
+#error "Unsupported OS"
+#endif
+
+  size_t applen = strlen(appname);
+
+  // Since the above memory may be static, and the caller may want to modify
+  // the argument, make and return a copy here.
+  char * basec = allocator.allocate(applen + 1, allocator.state);
+  if (NULL == basec) {
+    return NULL;
+  }
+
+  // Get just the executable name (Unix may return the absolute path)
+#if defined __APPLE__ || defined __GNUC__
+  // We need an intermediate copy because basename may modify its arguments
+  char * intermediate = allocator.allocate(applen + 1, allocator.state);
+  if (NULL == intermediate) {
+    allocator.deallocate(basec, allocator.state);
+    return NULL;
+  }
+  memcpy(intermediate, appname, applen);
+  intermediate[applen] = '\0';
+
+  char * bname = basename(intermediate);
+  size_t baselen = strlen(bname);
+  memcpy(basec, bname, baselen);
+  basec[baselen] = '\0';
+  allocator.deallocate(intermediate, allocator.state);
+#elif defined _WIN32 || defined __CYGWIN
+  errno_t err = _splitpath_s(appname, NULL, 0, NULL, 0, basec, applen, NULL, 0);
+  if (err != 0) {
+    allocator.deallocate(basec, allocator.state);
+    return NULL;
+  }
+#else
+#error "Unsupported OS"
+#endif
+
+  return basec;
+}
+
+#ifdef __cplusplus
+}
+#endif