dynload_win.c 6.89 KB
Newer Older
1 2 3 4 5

/* Support for dynamic loading of extension modules */

#include <windows.h>
#include <direct.h>
6
#include <ctype.h>
7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

#include "Python.h"
#include "importdl.h"

const struct filedescr _PyImport_DynLoadFiletab[] = {
#ifdef _DEBUG
	{"_d.pyd", "rb", C_EXTENSION},
	{"_d.dll", "rb", C_EXTENSION},
#else
	{".pyd", "rb", C_EXTENSION},
	{".dll", "rb", C_EXTENSION},
#endif
	{0, 0}
};


23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152
/* Case insensitive string compare, to avoid any dependencies on particular
   C RTL implementations */

static int strcasecmp (char *string1, char *string2)
{ 
	int first, second;

	do {
		first  = tolower(*string1);
		second = tolower(*string2);
		string1++;
		string2++;
	} while (first && first == second);

	return (first - second);
} 


/* Function to return the name of the "python" DLL that the supplied module
   directly imports.  Looks through the list of imported modules and
   returns the first entry that starts with "python" (case sensitive) and
   is followed by nothing but numbers until the separator (period).

   Returns a pointer to the import name, or NULL if no matching name was
   located.

   This function parses through the PE header for the module as loaded in
   memory by the system loader.  The PE header is accessed as documented by
   Microsoft in the MSDN PE and COFF specification (2/99), and handles
   both PE32 and PE32+.  It only worries about the direct import table and
   not the delay load import table since it's unlikely an extension is
   going to be delay loading Python (after all, it's already loaded).

   If any magic values are not found (e.g., the PE header or optional
   header magic), then this function simply returns NULL. */

#define DWORD_AT(mem) (*(DWORD *)(mem))
#define WORD_AT(mem)  (*(WORD *)(mem))

static char *GetPythonImport (HINSTANCE hModule)
{
	unsigned char *dllbase, *import_data, *import_name;
	DWORD pe_offset, opt_offset;
	WORD opt_magic;
	int num_dict_off, import_off;

	/* Safety check input */
	if (hModule == NULL) {
		return NULL;
	}

	/* Module instance is also the base load address.  First portion of
	   memory is the MS-DOS loader, which holds the offset to the PE
	   header (from the load base) at 0x3C */
	dllbase = (unsigned char *)hModule;
	pe_offset = DWORD_AT(dllbase + 0x3C);

	/* The PE signature must be "PE\0\0" */
	if (memcmp(dllbase+pe_offset,"PE\0\0",4)) {
		return NULL;
	}

	/* Following the PE signature is the standard COFF header (20
	   bytes) and then the optional header.  The optional header starts
	   with a magic value of 0x10B for PE32 or 0x20B for PE32+ (PE32+
	   uses 64-bits for some fields).  It might also be 0x107 for a ROM
	   image, but we don't process that here.

	   The optional header ends with a data dictionary that directly
	   points to certain types of data, among them the import entries
	   (in the second table entry). Based on the header type, we
	   determine offsets for the data dictionary count and the entry
	   within the dictionary pointing to the imports. */

	opt_offset = pe_offset + 4 + 20;
	opt_magic = WORD_AT(dllbase+opt_offset);
	if (opt_magic == 0x10B) {
		/* PE32 */
		num_dict_off = 92;
		import_off   = 104;
	} else if (opt_magic == 0x20B) {
		/* PE32+ */
		num_dict_off = 108;
		import_off   = 120;
	} else {
		/* Unsupported */
		return NULL;
	}

	/* Now if an import table exists, offset to it and walk the list of
	   imports.  The import table is an array (ending when an entry has
	   empty values) of structures (20 bytes each), which contains (at
	   offset 12) a relative address (to the module base) at which a
	   string constant holding the import name is located. */

	if (DWORD_AT(dllbase + opt_offset + num_dict_off) >= 2) {
		import_data = dllbase + DWORD_AT(dllbase +
						 opt_offset +
						 import_off);
		while (DWORD_AT(import_data)) {
			import_name = dllbase + DWORD_AT(import_data+12);
			if (strlen(import_name) >= 6 &&
			    !strncmp(import_name,"python",6)) {
				char *pch;

				/* Ensure python prefix is followed only
				   by numbers to the end of the basename */
				pch = import_name + 6;
				while (*pch && *pch != '.') {
					if (*pch >= '0' && *pch <= '9') {
						pch++;
					} else {
						pch = NULL;
						break;
					}
				}
	    
				if (pch) {
					/* Found it - return the name */
					return import_name;
				}
			}
			import_data += 20;
		}
	}

	return NULL;
}


153
dl_funcptr _PyImport_GetDynLoadFunc(const char *fqname, const char *shortname,
154 155 156
				    const char *pathname, FILE *fp)
{
	dl_funcptr p;
157
	char funcname[258], *import_python;
158

159
	PyOS_snprintf(funcname, sizeof(funcname), "init%.200s", shortname);
160 161

	{
162
		HINSTANCE hDLL = NULL;
163
		char pathbuf[260];
164 165 166 167 168 169 170 171 172 173 174 175 176
		LPTSTR dummy;
		/* We use LoadLibraryEx so Windows looks for dependent DLLs 
		    in directory of pathname first.  However, Windows95
		    can sometimes not work correctly unless the absolute
		    path is used.  If GetFullPathName() fails, the LoadLibrary
		    will certainly fail too, so use its error code */
		if (GetFullPathName(pathname,
				    sizeof(pathbuf),
				    pathbuf,
				    &dummy))
			/* XXX This call doesn't exist in Windows CE */
			hDLL = LoadLibraryEx(pathname, NULL,
					     LOAD_WITH_ALTERED_SEARCH_PATH);
177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199
		if (hDLL==NULL){
			char errBuf[256];
			unsigned int errorCode;

			/* Get an error string from Win32 error code */
			char theInfo[256]; /* Pointer to error text
					      from system */
			int theLength; /* Length of error text */

			errorCode = GetLastError();

			theLength = FormatMessage(
				FORMAT_MESSAGE_FROM_SYSTEM, /* flags */
				NULL, /* message source */
				errorCode, /* the message (error) ID */
				0, /* default language environment */
				(LPTSTR) theInfo, /* the buffer */
				sizeof(theInfo), /* the buffer size */
				NULL); /* no additional format args. */

			/* Problem: could not get the error message.
			   This should not happen if called correctly. */
			if (theLength == 0) {
200 201 202
				PyOS_snprintf(errBuf, sizeof(errBuf),
				      "DLL load failed with error code %d",
					      errorCode);
203
			} else {
204
				size_t len;
205 206 207 208 209 210 211 212 213 214 215 216 217 218 219
				/* For some reason a \r\n
				   is appended to the text */
				if (theLength >= 2 &&
				    theInfo[theLength-2] == '\r' &&
				    theInfo[theLength-1] == '\n') {
					theLength -= 2;
					theInfo[theLength] = '\0';
				}
				strcpy(errBuf, "DLL load failed: ");
				len = strlen(errBuf);
				strncpy(errBuf+len, theInfo,
					sizeof(errBuf)-len);
				errBuf[sizeof(errBuf)-1] = '\0';
			}
			PyErr_SetString(PyExc_ImportError, errBuf);
220
			return NULL;
221 222 223
		} else {
			char buffer[256];

224
			PyOS_snprintf(buffer, sizeof(buffer), "python%d%d.dll",
225
				      PY_MAJOR_VERSION,PY_MINOR_VERSION);
226 227 228 229
			import_python = GetPythonImport(hDLL);

			if (import_python &&
			    strcasecmp(buffer,import_python)) {
230 231 232 233
				PyOS_snprintf(buffer, sizeof(buffer),
					      "Module use of %.150s conflicts "
					      "with this version of Python.",
					      import_python);
234 235 236 237
				PyErr_SetString(PyExc_ImportError,buffer);
				FreeLibrary(hDLL);
				return NULL;
			}
238 239 240 241 242 243
		}
		p = GetProcAddress(hDLL, funcname);
	}

	return p;
}