Fixed bug #75525 Access Violation in vcruntime140.dll

It was a mistake to make d_name a pointer. d_name has to be allocated
in the body of struct dirent as per POSIX.1-2008. The binary
compatibility is kept through the extra padding, which will be removed
in 7.3.

Author: weltling

win32/readdir.c

@@ -37,7 +37,7 @@ DIR *opendir(const char *dir)
 		return NULL;
 	}
 
-	dp = (DIR *) calloc(1, sizeof(DIR));
+	dp = (DIR *) calloc(1, sizeof(DIR) + MAXPATHLEN*sizeof(char));
 	if (dp == NULL) {
 		return NULL;
 	}
@@ -104,9 +104,8 @@ struct dirent *readdir(DIR *dp)
 		/* wide to utf8 failed, should never happen. */
 		return NULL;
 	}
-	if (dp->dent.d_name)
-		free(dp->dent.d_name);
-	dp->dent.d_name = _tmp;
+	memmove(dp->dent.d_name, _tmp, reclen + 1);
+	free(_tmp);
 	dp->dent.d_reclen = (unsigned short)reclen;
 
 	dp->offset++;
@@ -141,9 +140,8 @@ int readdir_r(DIR *dp, struct dirent *entry, struct dirent **result)
 		result = NULL;
 		return 0;
 	}
-	if (dp->dent.d_name)
-		free(dp->dent.d_name);
-	dp->dent.d_name = _tmp;
+	memmove(dp->dent.d_name, _tmp, reclen + 1);
+	free(_tmp);
 	dp->dent.d_reclen = (unsigned short)reclen;
 
 	dp->offset++;
@@ -169,8 +167,6 @@ int closedir(DIR *dp)
 	}
 	if (dp->dirw)
 		free(dp->dirw);
-	if (dp->dent.d_name)
-		free(dp->dent.d_name);
 	if (dp)
 		free(dp);
 

win32/readdir.h

@@ -22,7 +22,11 @@ struct dirent {
 	long d_ino;					/* inode (always 1 in WIN32) */
 	off_t d_off;					/* offset to this dirent */
 	unsigned short d_reclen;			/* length of d_name */
-	char *d_name;	/* null terminated filename in the current encoding, glyph number <= 255 wchar_t's + \0 byte */
+	unsigned short pad0;
+#if defined(_WIN64)
+	uint32_t pad1;
+#endif
+	char d_name[1];	/* null terminated filename in the current encoding, glyph number <= 255 wchar_t's + \0 byte */
 };
 
 /* typedef DIR - not the same as Unix */