Refactor libpsl to use GetPwUid()

src/libpsl-native/src/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_library(psl-native SHARED
   getstat.cpp
+  getpwuid.cpp
   getfileowner.cpp
   getcurrentprocessorid.cpp
   getusername.cpp

src/libpsl-native/src/getfileowner.cpp

@@ -9,6 +9,7 @@
 #include <string.h>
 #include <unistd.h>
 #include "getstat.h"
+#include "getpwuid.h"
 #include "getfileowner.h"
 
 //! @brief GetFileOwner returns the owner of a file
@@ -22,17 +23,8 @@
 //! char* is marshaled as an LPStr, which on Linux is UTF-8.
 //! @endparblock
 //!
-//! @exception errno Passes these errors via errno to GetLastError:
+//! @exception errno Passes this error via errno to GetLastError:
 //! - ERROR_INVALID_PARAMETER: parameter is not valid
-//! - ERROR_FILE_NOT_FOUND: file does not exist
-//! - ERROR_ACCESS_DENIED: access is denied
-//! - ERROR_INVALID_ADDRESS: attempt to access invalid address
-//! - ERROR_STOPPED_ON_SYMLINK: too many symbolic links
-//! - ERROR_GEN_FAILURE: I/O error occurred
-//! - ERROR_INVALID_NAME: file provided is not a symbolic link
-//! - ERROR_INVALID_FUNCTION: incorrect function
-//! - ERROR_BAD_PATH_NAME: pathname is too long
-//! - ERROR_OUTOFMEMORY insufficient kernal memory
 //!
 //! @retval file owner, or NULL if unsuccessful
 //!
@@ -47,59 +39,12 @@ char* GetFileOwner(const char* fileName)
         return NULL;
     }
 
-    struct stat fileStat;
-    ret = GetStat(fileName, &fileStat);
+    struct stat buf;
+    ret = GetStat(fileName, &buf);
     if (ret != 0)
     {
         return NULL;
     }
 
-    struct passwd pwd;
-    struct passwd* result = NULL;
-    char* buf;
-
-    int buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
-    if (buflen < 1)
-    {
-        buflen = 2048;
-    }
-
-allocate:
-    buf = (char*)calloc(buflen, sizeof(char));
-
-    ret = getpwuid_r(fileStat.st_uid, &pwd, buf, buflen, &result);
-
-    if (ret != 0)
-    {
-        switch(errno)
-        {
-        case ERANGE:
-            free(buf);
-            buflen *= 2;
-            goto allocate;
-        case ENOENT:
-        case ESRCH:
-        case EBADF:
-        case EPERM:
-            errno = ERROR_NO_SUCH_USER;
-            break;
-        case ENOMEM:
-            errno = ERROR_OUTOFMEMORY;
-            break;
-       default:
-            errno = ERROR_GEN_FAILURE;
-        }
-        return NULL;
-    }
-
-    // no result
-    if (result == NULL)
-    {
-        return NULL;
-    }
-
-    size_t userlen = strnlen(pwd.pw_name, buflen);
-    char* username = strndup(pwd.pw_name, userlen);
-    free(buf);
-    return username;
+    return GetPwUid(buf.st_uid);
 }

src/libpsl-native/src/getpwuid.cpp

@@ -0,0 +1,81 @@
+//! @file getpwuid.cpp
+//! @author Andrew Schwartzmeyer <andschwa@microsoft.com>
+//! @brief returns the username for a uid
+
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <pwd.h>
+#include <string.h>
+#include <unistd.h>
+#include "getpwuid.h"
+
+//! @brief GetPwUid returns the username for a uid
+//!
+//! GetPwUid
+//!
+//! @param[in] uid
+//! @parblock
+//! The user identifier to lookup.
+//! @endparblock
+//!
+//! @exception errno Passes these errors via errno to GetLastError:
+//! - ERROR_NO_SUCH_USER: user lookup unsuccessful
+//! - ERROR_OUTOFMEMORY insufficient kernel memory
+//! - ERROR_GEN_FAILURE: anything else
+//!
+//! @retval username as UTF-8 string, or NULL if unsuccessful
+//!
+char* GetPwUid(uid_t uid)
+{
+    int32_t ret = 0;
+    struct passwd pwd;
+    struct passwd* result = NULL;
+    char* buf;
+
+    int buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
+    if (buflen < 1)
+    {
+        buflen = 2048;
+    }
+
+allocate:
+    buf = (char*)calloc(buflen, sizeof(char));
+
+    ret = getpwuid_r(uid, &pwd, buf, buflen, &result);
+
+    if (ret != 0)
+    {
+        switch(errno)
+        {
+        case ERANGE:
+            free(buf);
+            buflen *= 2;
+            goto allocate;
+        case ENOENT:
+        case ESRCH:
+        case EBADF:
+        case EPERM:
+            errno = ERROR_NO_SUCH_USER;
+            break;
+        case ENOMEM:
+            errno = ERROR_OUTOFMEMORY;
+            break;
+        default:
+            errno = ERROR_GEN_FAILURE;
+        }
+        return NULL;
+    }
+
+    // no result
+    if (result == NULL)
+    {
+        return NULL;
+    }
+
+    // allocate copy on heap so CLR can free it
+    size_t userlen = strnlen(pwd.pw_name, buflen);
+    char* username = strndup(pwd.pw_name, userlen);
+    free(buf);
+    return username;
+}

src/libpsl-native/src/getpwuid.h

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <sys/types.h>
+#include "pal.h"
+
+PAL_BEGIN_EXTERNC
+
+char* GetPwUid(uid_t uid);
+
+PAL_END_EXTERNC

src/libpsl-native/src/getusername.cpp

@@ -2,64 +2,16 @@
 //! @author Andrew Schwartzmeyer <andschwa@microsoft.com>
 //! @brief Implements GetUserName for Linux
 
-#include <errno.h>
-#include <locale.h>
 #include <unistd.h>
-#include <string>
-#include <pwd.h>
+#include "getpwuid.h"
 #include "getusername.h"
 
 //! @brief GetUserName retrieves the name of the user associated with
 //! the current thread.
 //!
-//! @exception errno Passes these errors via errno to GetLastError:
-//! - ERROR_INVALID_PARAMETER: parameter is not valid
-//! - ERROR_NO_SUCH_USER: there was no corresponding user
-//! - ERROR_GEN_FAILURE: sysconf() or getpwuid() failed for unknown reasons
-//!
 //! @retval username as UTF-8 string, or null if unsuccessful
 char* GetUserName()
 {
-    errno = 0;
-
-    struct passwd pwd;
-    struct passwd* result;
-    // gets the initial suggested size for buf
-    int buflen = sysconf(_SC_GETPW_R_SIZE_MAX);
-    if (buflen == -1)
-    {
-        errno = ERROR_GEN_FAILURE;
-        return NULL;
-    }
-    std::string buf(buflen, 0);
-
     // geteuid() gets the effective user ID of the calling process, and is always successful
-    int ret = getpwuid_r(geteuid(), &pwd, &buf[0], buflen, &result);
-
-    // Map errno to Win32 Error Codes
-    if (ret)
-    {
-        switch (errno)
-        {
-        case ENOENT:
-        case ESRCH:
-        case EBADF:
-        case EPERM:
-            errno = ERROR_NO_SUCH_USER;
-            break;
-        default:
-            errno = ERROR_GEN_FAILURE;
-        }
-        return NULL;
-    }
-
-    // Check if no user matched
-    if (result == NULL)
-    {
-        errno = ERROR_NO_SUCH_USER;
-        return NULL;
-    }
-
-    // allocate copy on heap so CLR can free it
-    return strdup(result->pw_name);
+    return GetPwUid(geteuid());
 }