*nix mono 找不到 MySql.Data Could not be loaded
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2010-05-30 更新：
最初遇到这个问题的时候，想到了由于unix系统的原因文件名大小写敏感导致了这个问题，这段时间看mono的源代码，找到的源码所在，更直观一些。
mono的底层库用的最开始用的是eglibc，访问文件正式用的这个库。当然，unix标准的库，大小写肯定不能放过。
加载程序集：
static MonoAssembly *
real_load (gchar **search_path, const gchar *culture, const gchar *name, gboolean refonly)
{
MonoAssembly *result = NULL;
gchar **path;
gchar *filename;
const gchar *local_culture;
gint len;
gboolean is_private = FALSE;
if (!culture || *culture == '\0') {
local_culture = "";
} else {
local_culture = culture;
}
filename = g_strconcat (name, ".dll", NULL);
len = strlen (filename);
for (path = search_path; *path; path++) {
if (**path == '\0') {
is_private = TRUE;
continue; /* Ignore empty ApplicationBase */
}
/* See test cases in bug #58992 and bug #57710 */
/* 1st try: [culture]/[name].dll (culture may be empty) */
strcpy (filename + len - 4, ".dll");
if (try_load_from (&result, *path, local_culture, "", filename, refonly, is_private))
break;
/* 2nd try: [culture]/[name].exe (culture may be empty) */
strcpy (filename + len - 4, ".exe");
if (try_load_from (&result, *path, local_culture, "", filename, refonly, is_private))
break;
/* 3rd try: [culture]/[name]/[name].dll (culture may be empty) */
strcpy (filename + len - 4, ".dll");
if (try_load_from (&result, *path, local_culture, name, filename, refonly, is_private))
break;
/* 4th try: [culture]/[name]/[name].exe (culture may be empty) */
strcpy (filename + len - 4, ".exe");
if (try_load_from (&result, *path, local_culture, name, filename, refonly, is_private))
break;
}
g_free (filename);
return result;
}
文件判断：
gboolean
g_file_test (const gchar *filename, GFileTest test)
{
struct stat st;
gboolean have_stat;
if (filename == NULL || test == 0)
return FALSE;
have_stat = FALSE;
if ((test & G_FILE_TEST_EXISTS) != 0) {
if (access (filename, F_OK) == 0)
return TRUE;
}
if ((test & G_FILE_TEST_IS_EXECUTABLE) != 0) {
if (access (filename, X_OK) == 0)
return TRUE;
}
if ((test & G_FILE_TEST_IS_SYMLINK) != 0) {
have_stat = (lstat (filename, &st) == 0);
if (have_stat && S_ISLNK (st.st_mode))
return TRUE;
}
if ((test & G_FILE_TEST_IS_REGULAR) != 0) {
if (!have_stat)
have_stat = (stat (filename, &st) == 0);
if (have_stat && S_ISREG (st.st_mode))
return TRUE;
}
if ((test & G_FILE_TEST_IS_DIR) != 0) {
if (!have_stat)
have_stat = (stat (filename, &st) == 0);
if (have_stat && S_ISDIR (st.st_mode))
return TRUE;
}
return FALSE;
}
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今天尝试着在linux下面用mono访问MySql。
官方提供了ADO.NET Driver for MYSQL (http://www.mysql.com/downloads/connector/net/).其中东西很简单，几个dll文件，以及一个MSDN样式的CHM文档文件。
运行程序的时候总是有问题，提示信息：
The following assembly Referenced from Test.exe could not be loaded:
Assembly: MySql.Data (assemblyref_index=1)
Version: 6.2.3.0
Public Key: c5687fc88969c44d
The assembly was not found in the Global Assembly Cache, a path listed in the MONO_PATH environment variable, or in the location of the executing assembly
但是我明明已经添加好了引用，而且目录中有官方提供的mysql.data.dll.试了几次都不行，于是猜测是不是文件明的问题，因为*nix下文件名大小写敏感。改成MySql.Data.dll了之后，居然就好了。
不知道这个问题算什么问题，哪天看看mono的代码，怎么觉得应该是他的问题。