Add kak binary location to PATH env var automatically

That way the kak binary can be guaranteed to be available even
if not in user PATH.

src/file.cc

@@ -17,6 +17,10 @@
 #include <unistd.h>
 #include <dirent.h>
 
+#if defined(__APPLE__)
+#include <mach-o/dyld.h>
+#endif
+
 namespace Kakoune
 {
 
@@ -408,4 +412,24 @@ time_t get_fs_timestamp(StringView filename)
     return st.st_mtime;
 }
 
+String get_kak_binary_path()
+{
+    char buffer[2048];
+#if defined(__linux__) or defined(__CYGWIN__)
+    ssize_t res = readlink("/proc/self/exe", buffer, 2048);
+    kak_assert(res != -1);
+    buffer[res] = '\0';
+    return buffer;
+#elif defined(__APPLE__)
+    uint32_t bufsize = 2048;
+    _NSGetExecutablePath(buffer, &bufsize);
+    char* canonical_path = realpath(buffer, nullptr);
+    String path = canonical_path;
+    free(canonical_path);
+    return path;
+#else
+# error "finding executable path is not implemented on this platform"
+#endif
+}
+
 }

src/file.hh

@@ -29,6 +29,8 @@ String parse_filename(StringView filename);
 String real_path(StringView filename);
 String compact_path(StringView filename);
 
+String get_kak_binary_path();
+
 String read_fd(int fd);
 String read_file(StringView filename);
 

src/main.cc

@@ -24,10 +24,6 @@
 #include "interned_string.hh"
 #include "window.hh"
 
-#if defined(__APPLE__)
-#include <mach-o/dyld.h>
-#endif
-
 #include <unordered_map>
 #include <locale>
 #include <signal.h>
@@ -43,24 +39,11 @@ void run_unit_tests();
 
 String runtime_directory()
 {
-    char buffer[2048];
-#if defined(__linux__) or defined(__CYGWIN__)
-    ssize_t res = readlink("/proc/self/exe", buffer, 2048);
-    kak_assert(res != -1);
-    buffer[res] = '\0';
-#elif defined(__APPLE__)
-    uint32_t bufsize = 2048;
-    _NSGetExecutablePath(buffer, &bufsize);
-    char* canonical_path = realpath(buffer, nullptr);
-    strncpy(buffer, canonical_path, 2048);
-    free(canonical_path);
-#else
-# error "finding executable path is not implemented on this platform"
-#endif
-    char* ptr = strrchr(buffer, '/');
-    if (not ptr)
+    String bin_path = get_kak_binary_path();
+    size_t last_slash = bin_path.find_last_of('/');
+    if (last_slash == String::npos)
         throw runtime_error("unable to determine runtime directory");
-    return String(buffer, ptr) + "/../share/kak";
+    return bin_path.substr(0_byte, (int)last_slash) + "/../share/kak";
 }
 
 void register_env_vars()

src/shell_manager.cc

@@ -2,6 +2,7 @@
 
 #include "context.hh"
 #include "debug.hh"
+#include "file.hh"
 
 #include <cstring>
 #include <sys/types.h>
@@ -15,6 +16,15 @@ static const Regex env_var_regex(R"(\bkak_(\w+)\b)");
 
 ShellManager::ShellManager()
 {
+    const char* path = getenv("PATH");
+    String new_path;
+    if (path)
+        new_path = path + ":"_str;
+
+    String kak_path = get_kak_binary_path();
+    StringView kak_dir = kak_path.substr(0_byte, (int)kak_path.find_last_of('/'));
+    new_path += kak_dir;
+    setenv("PATH", new_path.c_str(), 1);
 }
 
 String ShellManager::eval(StringView cmdline, const Context& context,