The readlink() function now uses DOS packet I/O instead of trusting Lock() to do the right thing

library/unistd_readlink.c

@@ -58,9 +58,19 @@ readlink(const char * path_name, char * buffer, int buffer_size)
 	struct name_translation_info path_name_nti;
 	struct name_translation_info buffer_nti;
 	#endif /* UNIX_PATH_SEMANTICS */
+
+	D_S(struct bcpl_name, bname);
+	const size_t name_size = sizeof(bname->name);
+
 	BPTR lock = ZERO;
 	int result = ERROR;
-	int target_length = -1;
+    struct DevProc *dvp = NULL;
+	char * new_name = NULL;
+	char * path_part;
+	size_t name_len;
+	size_t new_name_size;
+	LONG readlink_result;
+	LONG error;
 
 	ENTER();
 
@@ -70,12 +80,12 @@ readlink(const char * path_name, char * buffer, int buffer_size)
 
 	assert( path_name != NULL && buffer != NULL );
 
-	if(__check_abort_enabled)
+	if (__check_abort_enabled)
 		__check_abort();
 
 	#if defined(CHECK_FOR_NULL_POINTERS)
 	{
-		if(path_name == NULL || buffer == NULL)
+		if (path_name == NULL || buffer == NULL)
 		{
 			SHOWSTRING("invalid parameters");
 
@@ -87,9 +97,9 @@ readlink(const char * path_name, char * buffer, int buffer_size)
 
 	#if defined(UNIX_PATH_SEMANTICS)
 	{
-		if(__unix_path_semantics)
+		if (__unix_path_semantics)
 		{
-			if(path_name[0] == '\0')
+			if (path_name[0] == '\0')
 			{
 				SHOWMSG("no name given");
 
@@ -97,53 +107,144 @@ readlink(const char * path_name, char * buffer, int buffer_size)
 				goto out;
 			}
 
-			if(__translate_unix_to_amiga_path_name(&path_name,&path_name_nti) != 0)
+			if (__translate_unix_to_amiga_path_name(&path_name, &path_name_nti) != 0)
 				goto out;
 		}
 	}
 	#endif /* UNIX_PATH_SEMANTICS */
 
-	D(("trying to get a lock on '%s'",path_name));
+	name_len = strlen(path_name);
+	if (name_len >= name_size)
+	{
+		SHOWMSG("name too long");
+
+		SetIoErr(ERROR_LINE_TOO_LONG);
+		goto out;
+	}
+
+	/* Convert the name into a BCPL string. */
+	bname->name[0] = name_len;
+	memcpy(&bname->name[1], path_name, name_len);
+
+    /* Get a handle on the device, volume or assignment name in the path. */
+	dvp = GetDeviceProc((STRPTR)path_name, dvp);
+	if (dvp == NULL)
+	{
+		SHOWMSG("dvp == NULL");
+		goto out;
+	}
+
+	/* Try to obtain a lock on the object. It should be a link and not
+	 * a file or directory.
+	 */
+	lock = DoPkt(dvp->dvp_Port, ACTION_LOCATE_OBJECT, dvp->dvp_Lock, MKBADDR(bname), SHARED_LOCK, 0, 0);
+	if (lock != ZERO)
+	{
+		SHOWMSG("lock != ZERO");
+
+		SetIoErr(ERROR_OBJECT_WRONG_TYPE);
+		goto out;
+	}
+
+	error = IoErr();
+
+	if (error != ERROR_IS_SOFT_LINK)
+	{
+		SHOWMSG("not a soft link");
+		goto out;
+	}
+
+	/* We only need the leading path name. */
+	name_len = ((BYTE *)PathPart(path_name)) - (BYTE *)path_name;
+
+	path_part = malloc(name_len+1);
+	if (path_part == NULL)
+	{
+		SHOWMSG("path_part too long");
+
+		SetIoErr(ERROR_NO_FREE_STORE);
+		goto out;
+	}
+
+	memcpy(path_part, path_name, name_len);
+	path_part[name_len] = '\0';
 
 	PROFILE_OFF();
-	lock = __lock((STRPTR)path_name,SHARED_LOCK,&target_length,buffer,(size_t)buffer_size);
+	lock = Lock((STRPTR)path_part, SHARED_LOCK);
 	PROFILE_ON();
 
-	if(lock != ZERO)
+	new_name_size = name_size+1;
+
+	/* Provide as much buffer space as possible. */
+	if (buffer_size > 0 && (size_t)buffer_size > new_name_size)
+		new_name_size = buffer_size;
+
+	/* For soft link resolution we need a temporary buffer to
+	   let the file system store the resolved path name in. */
+	new_name = malloc(new_name_size);
+	if (new_name == NULL)
 	{
-		__set_errno(EINVAL);
-		goto out;
-	}
-	else if (target_length <= 0) /* No a soft-link. */
-	{
-		__set_errno(__translate_io_error_to_errno(IoErr()));
+		SHOWMSG("new_name too long");
+
+		SetIoErr(ERROR_NO_FREE_STORE);
 		goto out;
 	}
 
-	#if defined(UNIX_PATH_SEMANTICS)
+	/* Now ask the file system to resolve the entire path. */
+	readlink_result = ReadLink(dvp->dvp_Port, lock, (STRPTR)FilePart(path_name), (STRPTR)new_name, (LONG)new_name_size);
+	if (readlink_result < 0)
 	{
-		if(__unix_path_semantics)
+		SHOWMSG("ReadLink");
+
+		/* This will return either -1 (resolution error) or -2
+		   (buffer too small). We regard both as trouble. */
+		SetIoErr(ERROR_INVALID_COMPONENT_NAME);
+		goto out;
+	}
+
+	assert( result > 0 );
+
+	/* If the caller supplied a buffer, copy as much of the name
+	   as possible into it. */
+	if (buffer != NULL && buffer_size > 0)
+	{
+		strlcpy(buffer, new_name, buffer_size);
+
+		#if defined(UNIX_PATH_SEMANTICS)
 		{
-			if(__translate_amiga_to_unix_path_name((char const **)&buffer,&buffer_nti) != 0)
-				goto out;
+			if (__unix_path_semantics)
+			{
+				if (__translate_amiga_to_unix_path_name((char const **)&buffer, &buffer_nti) != 0)
+					goto out;
 
-			__restore_path_name((char const **)&buffer,&buffer_nti);
+				__restore_path_name((char const **)&buffer,&buffer_nti);
 
-			strcpy(buffer,buffer_nti.substitute);
+				strcpy(buffer, buffer_nti.substitute);
+			}
 		}
+		#endif /* UNIX_PATH_SEMANTICS */
+
+		result = strlen(buffer);
+
+		SHOWSTRING(buffer);
+	}
+	else
+	{
+		result = 0;
 	}
-	#endif /* UNIX_PATH_SEMANTICS */
-
-	result = strlen(buffer);
-
-	SHOWSTRING(buffer);
 
  out:
 
 	PROFILE_OFF();
+
+	if (dvp != NULL)
+		FreeDeviceProc(dvp);
+
 	UnLock(lock);
+
 	PROFILE_ON();
 
 	RETURN(result);
-	return(result);
+
+	return result;
 }