LLDB - Simplify GetProgramFileSpec

[zturner]

I think the new version may actually be wrong. Shouldn't it be PATH_MAX+1? That said, what's the motivation for changing this?

[devnexen]

In D46518#1089917, @zturner wrote:

I think the new version may actually be wrong. Shouldn't it be PATH_MAX+1? That said, what's the motivation for changing this?

I actually think PATH_MAX/MAXPATHLEN is correct. Otherwise it s just simplifying it.

[zturner]

I don't personally know, but the one example I came across online is using +1.

https://common-lisp.net/~alendvai/darcs/sbcl/src/runtime/bsd-os.c

Search the page for the function os_get_runtime_executable_path. Let's see what @emaste has to say.

[emaste]

From sysctl_kern_proc_pathname:

error = vn_fullpath(req->td, vp, &retbuf, &freebuf);
vrele(vp);
if (error)
        return (error);
error = SYSCTL_OUT(req, retbuf, strlen(retbuf) + 1);

and in vn_fullpath:

buf = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);

So the pathname, including the '\0' fits in MAXPATHLEN/PATH_MAX.

[emaste]

This is fine with me as a little simplification and avoid an extra syscall.

lldb/trunk/source/Host/freebsd/HostInfoFreeBSD.cpp

bool HostInfoFreeBSD::GetOSKernelDescription(std::string &s) {
 
   return true;
 }
 
 FileSpec HostInfoFreeBSD::GetProgramFileSpec() {
   static FileSpec g_program_filespec;
   if (!g_program_filespec) {
     int exe_path_mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, getpid()};
-    size_t exe_path_size;
-    if (sysctl(exe_path_mib, 4, NULL, &exe_path_size, NULL, 0) == 0) {
-      char *exe_path = new char[exe_path_size];
-      if (sysctl(exe_path_mib, 4, exe_path, &exe_path_size, NULL, 0) == 0)
-        g_program_filespec.SetFile(exe_path, FileSpec::Style::native);
-      delete[] exe_path;
-    }
+    char exe_path[PATH_MAX];
+    size_t exe_path_size = sizeof(exe_path);
+      g_program_filespec.SetFile(exe_path, false);
   }
   return g_program_filespec;
 }