Add DLL-loading head <android/utils/dll.h>

This patch adds several functions to make loading shared libraries
dynamically easier. This will be used to load the GLES emulation
libraries.

Change-Id: Ib401af339530bc647bfa86fb23a2840fe0a201dd

4 files changed, 299 insertions, 0 deletions

diff --git a/android/utils/dll.c b/android/utils/dll.c
new file mode 100644
index 0000000..a46a462
--- /dev/null
+++ b/android/utils/dll.c
@@ -0,0 +1,194 @@
+/* Copyright (C) 2011 The Android Open Source Project
+**
+** This software is licensed under the terms of the GNU General Public
+** License version 2, as published by the Free Software Foundation, and
+** may be copied, distributed, and modified under those terms.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+*/
+#include <android/utils/dll.h>
+#include <android/utils/system.h>
+#include <android/utils/path.h>
+
+#include <stdlib.h>
+
+/* Utility function, append one string to another, caller must free result */
+static char*
+append_string( const char* str1, const char* str2 )
+{
+    int   len1   = strlen(str1);
+    int   len2   = strlen(str2);
+    char* result = malloc(len1+len2+1);
+
+    if (result != NULL) {
+        memcpy(result, str1, len1);
+        memcpy(result + len1, str2, len2);
+        result[len1+len2] = '\0';
+    }
+    return result;
+}
+
+#ifdef _WIN32
+
+#include <windows.h>
+
+/* This function is used to revert all forward slashes (/) in a path
+ * string into unquoted backwards one (\). This is necessary because
+ * LoadLibrary() and AddDllDirectory() do not support forward slashes.
+ *
+ * Caller must free the result string
+ */
+static char*
+reverse_slashes( const char* path )
+{
+    int   len    = strlen(path);
+    char* result = malloc(len+1);
+    int   nn;
+
+    for (nn = 0; nn < len; nn++) {
+        int ch = path[nn];
+        if (ch == '/') {
+            ch = '\\';
+        }
+        result[nn] = (char)ch;
+    }
+    result[nn] = '\0';
+
+    return result;
+}
+
+ADynamicLibrary*
+adynamicLibrary_open( const char*  libraryName,
+                      char**       pError)
+{
+    char*  libName = (char*) libraryName;
+    void*  result;
+
+    /* Append a .dll to the library name if it doesn't have an extension */
+    if (strchr(libraryName,'.') == NULL) {
+        libName = append_string(libraryName, ".dll");
+    }
+
+    /* Now do our magic */
+    *pError = NULL;
+    result = (ADynamicLibrary*) LoadLibrary( libName );
+    if (result == NULL) {
+        *pError = ASTRDUP("Could not load DLL!");
+    }
+
+    /* Free the library name if we modified it */
+    if (libName != libraryName) {
+        free(libName);
+    }
+
+    return (ADynamicLibrary*) result;
+}
+
+void*
+adynamicLibrary_findSymbol( ADynamicLibrary*  lib,
+                            const char*       symbolName,
+                            char**            pError)
+{
+    void* result;
+
+    *pError = NULL;
+
+    if (lib == NULL) {
+        *pError = strdup("NULL library pointer");
+        return NULL;
+    }
+    if (symbolName == NULL || symbolName[0] == '\0') {
+        *pError = strdup("NULL or empty symbolName");
+        return NULL;
+    }
+    result = GetProcAddress( (HMODULE)lib, symbolName );
+    if (result == NULL) {
+        *pError = ASTRDUP("Could not find symbol");
+    }
+    return result;
+}
+
+/* Close/unload a given dynamic library */
+void
+adynamicLibrary_close( ADynamicLibrary*  lib )
+{
+    if (lib != NULL) {
+        FreeLibrary( (HMODULE)lib );
+    }
+}
+
+#else /* !_WIN32 */
+
+#include <dlfcn.h>
+#include <stdlib.h>
+
+ADynamicLibrary*
+adynamicLibrary_open( const char*  libraryName,
+                      char**       pError)
+{
+    char*  libName = (char*) libraryName;
+    void*  result;
+
+#ifdef __APPLE__
+#  define SO_EXTENSION ".dylib"
+#else
+#  define SO_EXTENSION ".so"
+#endif
+
+    /* Append a .so to the library name if it doesn't have an extension */
+    if (strchr(libraryName,'.') == NULL) {
+        libName = append_string(libraryName, SO_EXTENSION);
+    }
+
+    /* Now do our magic */
+    *pError = NULL;
+    result  = dlopen( libName, RTLD_LAZY );
+    if (result == NULL) {
+        *pError = strdup(dlerror());
+    }
+
+    /* Free the library name if we modified it */
+    if (libName != (char*)libraryName) {
+        free(libName);
+    }
+
+    return (ADynamicLibrary*) result;
+}
+
+void*
+adynamicLibrary_findSymbol( ADynamicLibrary*  lib,
+                            const char*       symbolName,
+                            char**            pError)
+{
+    void* result;
+
+    *pError = NULL;
+
+    if (lib == NULL) {
+        *pError = strdup("NULL library pointer");
+        return NULL;
+    }
+    if (symbolName == NULL || symbolName[0] == '\0') {
+        *pError = strdup("NULL or empty symbolName");
+        return NULL;
+    }
+    result = dlsym(lib, symbolName);
+    if (result == NULL) {
+        *pError = strdup(dlerror());
+    }
+    return result;
+}
+
+/* Close/unload a given dynamic library */
+void
+adynamicLibrary_close( ADynamicLibrary*  lib )
+{
+    if (lib != NULL) {
+        dlclose(lib);
+    }
+}
+
+#endif /* !_WIN32 */
diff --git a/android/utils/dll.h b/android/utils/dll.h
new file mode 100644
index 0000000..66f3a6d
--- /dev/null
+++ b/android/utils/dll.h
@@ -0,0 +1,44 @@
+/* Copyright (C) 2011 The Android Open Source Project
+**
+** This software is licensed under the terms of the GNU General Public
+** License version 2, as published by the Free Software Foundation, and
+** may be copied, distributed, and modified under those terms.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+*/
+#ifndef ANDROID_UTILS_DLL_H
+#define ANDROID_UTILS_DLL_H
+
+/* Opaque type to model a dynamic library handle */
+typedef struct ADynamicLibrary   ADynamicLibrary;
+
+/* Try to load/open a dynamic library named 'libraryName', looking for
+ * it in the optional paths listed by 'libraryPaths'.
+ *
+ * Once opened, you can use adynamicLibrary_findSymbol() and
+ * adynamicLibrary_close() on it.
+ *
+ * libraryName :: library name, if no extension is provided, then '.so'
+ *                will be appended on Unix systems, or '.dll' on Windows.
+ *
+ * pError :: On success, '*pError' will be set to NULL. On error, it will
+ *           point to a string describing the error, which must be freed by
+ *           the caller.
+ *
+ * returns an ADynamicLibrary pointer.
+ */
+ADynamicLibrary*   adynamicLibrary_open( const char*  libraryName,
+                                         char**       pError);
+
+/* Find a symbol inside a dynamic library. */
+void* adynamicLibrary_findSymbol( ADynamicLibrary*  lib,
+                                  const char*       symbolName,
+                                  char**            pError);
+
+/* Close/unload a given dynamic library */
+void  adynamicLibrary_close( ADynamicLibrary*  lib );
+
+#endif /* ANDROID_UTILS_DLL_H */
diff --git a/android/utils/path.c b/android/utils/path.c
index f64e517..1bcdc4e 100644
--- a/android/utils/path.c
+++ b/android/utils/path.c
@@ -427,6 +427,61 @@ path_is_absolute( const char*  path )
 #endif
 }
 
+char*
+path_get_absolute( const char* path )
+{
+    if (path_is_absolute(path)) {
+        return ASTRDUP(path);
+    }
+
+#ifdef _WIN32
+    {
+        char* result;
+        int   pathLen    = strlen(path);
+        int   currentLen = GetCurrentDirectory(0, NULL);
+
+        if (currentLen <= 0) {
+            /* Could not get size of working directory. something is
+             * really fishy here, return a simple copy */
+            return ASTRDUP(path);
+        }
+        result = malloc(currentLen + pathLen + 2);
+
+        GetCurrentDirectory(currentLen+1, result);
+        if (currentLen == 0 || result[currentLen-1] != '\\') {
+            result[currentLen++] = '\\';
+        }
+        memcpy(result + currentLen, path, pathLen+1);
+
+        return result;
+    }
+#else
+    {
+        int   pathLen    = strlen(path);
+        char  currentDir[PATH_MAX];
+        int   currentLen;
+        char* result;
+
+        if (getcwd(currentDir, sizeof(currentDir)) == NULL) {
+            /* Could not get the current working directory. something is really
+            * fishy here, so don't do anything and return a copy */
+            return ASTRDUP(path);
+        }
+
+        /* Make a new path with <current-path>/<path> */
+        currentLen = strlen(currentDir);
+        result     = malloc(currentLen + pathLen + 2);
+
+        memcpy(result, currentDir, currentLen);
+        if (currentLen == 0 || result[currentLen-1] != '/') {
+            result[currentLen++] = '/';
+        }
+        memcpy(result + currentLen, path, pathLen+1);
+
+        return result;
+    }
+#endif
+}
 
 /** OTHER FILE UTILITIES
  **
diff --git a/android/utils/path.h b/android/utils/path.h
index 419e6bf..2926e5e 100644
--- a/android/utils/path.h
+++ b/android/utils/path.h
@@ -118,6 +118,12 @@ extern char*  path_basename( const char*  path );
  */
 extern char*  path_search_exec( const char* filename );
 
+/* Return the absolute version of a path. If 'path' is already absolute,
+ * this will be a simple copy. Otherwise, this function will prepend the
+ * current working directory to the result.
+ */
+extern char*  path_get_absolute( const char* path );
+
 /** OTHER FILE UTILITIES
  **
  **  path_empty_file() creates an empty file at a given path location.