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------------------------------------------------------------------------------ -- -- -- GNAT COMPILER COMPONENTS -- -- -- -- S Y S T E M . O S _ L I B -- -- -- -- S p e c -- -- -- -- Copyright (C) 1995-2012, Free Software Foundation, Inc. -- -- -- -- GNAT is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 3, or (at your option) any later ver- -- -- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. -- -- -- -- As a special exception under Section 7 of GPL version 3, you are granted -- -- additional permissions described in the GCC Runtime Library Exception, -- -- version 3.1, as published by the Free Software Foundation. -- -- -- -- You should have received a copy of the GNU General Public License and -- -- a copy of the GCC Runtime Library Exception along with this program; -- -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- -- <http://www.gnu.org/licenses/>. -- -- -- -- GNAT was originally developed by the GNAT team at New York University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- Operating system interface facilities -- This package contains types and procedures for interfacing to the -- underlying OS. It is used by the GNAT compiler and by tools associated -- with the GNAT compiler, and therefore works for the various operating -- systems to which GNAT has been ported. This package will undoubtedly grow -- as new services are needed by various tools. -- This package tends to use fairly low-level Ada in order to not bring in -- large portions of the RTL. For example, functions return access to string -- as part of avoiding functions returning unconstrained types. -- Except where specifically noted, these routines are portable across all -- GNAT implementations on all supported operating systems. -- Note: this package is in the System hierarchy so that it can be directly -- be used by other predefined packages. User access to this package is via -- a renaming of this package in GNAT.OS_Lib (file g-os_lib.ads). pragma Compiler_Unit; with System; with System.Strings; package System.OS_Lib is pragma Elaborate_Body (OS_Lib); ----------------------- -- String Operations -- ----------------------- -- These are reexported from package Strings (which was introduced to -- avoid different packages declaring different types unnecessarily). -- See package System.Strings for details. subtype String_Access is Strings.String_Access; function "=" (Left, Right : String_Access) return Boolean renames Strings."="; procedure Free (X : in out String_Access) renames Strings.Free; subtype String_List is Strings.String_List; function "=" (Left, Right : String_List) return Boolean renames Strings."="; function "&" (Left : String_Access; Right : String_Access) return String_List renames Strings."&"; function "&" (Left : String_Access; Right : String_List) return String_List renames Strings."&"; function "&" (Left : String_List; Right : String_Access) return String_List renames Strings."&"; function "&" (Left : String_List; Right : String_List) return String_List renames Strings."&"; subtype String_List_Access is Strings.String_List_Access; function "=" (Left, Right : String_List_Access) return Boolean renames Strings."="; procedure Free (Arg : in out String_List_Access) renames Strings.Free; --------------------- -- Time/Date Stuff -- --------------------- type OS_Time is private; -- The OS's notion of time is represented by the private type OS_Time. -- This is the type returned by the File_Time_Stamp functions to obtain -- the time stamp of a specified file. Functions and a procedure (modeled -- after the similar subprograms in package Calendar) are provided for -- extracting information from a value of this type. Although these are -- called GM, the intention is not that they provide GMT times in all -- cases but rather the actual (time-zone independent) time stamp of the -- file (of course in Unix systems, this *is* in GMT form). Invalid_Time : constant OS_Time; -- A special unique value used to flag an invalid time stamp value subtype Year_Type is Integer range 1900 .. 2099; subtype Month_Type is Integer range 1 .. 12; subtype Day_Type is Integer range 1 .. 31; subtype Hour_Type is Integer range 0 .. 23; subtype Minute_Type is Integer range 0 .. 59; subtype Second_Type is Integer range 0 .. 59; -- Declarations similar to those in Calendar, breaking down the time function Current_Time return OS_Time; -- Return the system clock value as OS_Time function GM_Year (Date : OS_Time) return Year_Type; function GM_Month (Date : OS_Time) return Month_Type; function GM_Day (Date : OS_Time) return Day_Type; function GM_Hour (Date : OS_Time) return Hour_Type; function GM_Minute (Date : OS_Time) return Minute_Type; function GM_Second (Date : OS_Time) return Second_Type; -- Functions to extract information from OS_Time value function "<" (X, Y : OS_Time) return Boolean; function ">" (X, Y : OS_Time) return Boolean; function ">=" (X, Y : OS_Time) return Boolean; function "<=" (X, Y : OS_Time) return Boolean; -- Basic comparison operators on OS_Time with obvious meanings. Note that -- these have Intrinsic convention, so for example it is not permissible -- to create accesses to any of these functions. procedure GM_Split (Date : OS_Time; Year : out Year_Type; Month : out Month_Type; Day : out Day_Type; Hour : out Hour_Type; Minute : out Minute_Type; Second : out Second_Type); -- Analogous to the Split routine in Ada.Calendar, takes an OS_Time and -- provides a representation of it as a set of component parts, to be -- interpreted as a date point in UTC. ---------------- -- File Stuff -- ---------------- -- These routines give access to the open/creat/close/read/write level of -- I/O routines in the typical C library (these functions are not part of -- the ANSI C standard, but are typically available in all systems). See -- also package Interfaces.C_Streams for access to the stream level -- routines. -- Note on file names. If a file name is passed as type String in any of -- the following specifications, then the name is a normal Ada string and -- need not be NUL-terminated. However, a trailing NUL character is -- permitted, and will be ignored (more accurately, the NUL and any -- characters that follow it will be ignored). type File_Descriptor is new Integer; -- Corresponds to the int file handle values used in the C routines Standin : constant File_Descriptor := 0; Standout : constant File_Descriptor := 1; Standerr : constant File_Descriptor := 2; -- File descriptors for standard input output files Invalid_FD : constant File_Descriptor := -1; -- File descriptor returned when error in opening/creating file type Mode is (Binary, Text); for Mode'Size use Integer'Size; for Mode use (Binary => 0, Text => 1); -- Used in all the Open and Create calls to specify if the file is to be -- opened in binary mode or text mode. In systems like Unix, this has no -- effect, but in systems capable of text mode translation, the use of -- Text as the mode parameter causes the system to do CR/LF translation -- and also to recognize the DOS end of file character on input. The use -- of Text where appropriate allows programs to take a portable Unix view -- of DOS-format files and process them appropriately. function Open_Read (Name : String; Fmode : Mode) return File_Descriptor; -- Open file Name for reading, returning file descriptor File descriptor -- returned is Invalid_FD if file cannot be opened. function Open_Read_Write (Name : String; Fmode : Mode) return File_Descriptor; -- Open file Name for both reading and writing, returning file descriptor. -- File descriptor returned is Invalid_FD if file cannot be opened. function Create_File (Name : String; Fmode : Mode) return File_Descriptor; -- Creates new file with given name for writing, returning file descriptor -- for subsequent use in Write calls. If the file already exists, it is -- overwritten. File descriptor returned is Invalid_FD if file cannot be -- successfully created. function Create_Output_Text_File (Name : String) return File_Descriptor; -- Creates new text file with given name suitable to redirect standard -- output, returning file descriptor. File descriptor returned is -- Invalid_FD if file cannot be successfully created. function Create_New_File (Name : String; Fmode : Mode) return File_Descriptor; -- Create new file with given name for writing, returning file descriptor -- for subsequent use in Write calls. This differs from Create_File in -- that it fails if the file already exists. File descriptor returned is -- Invalid_FD if the file exists or cannot be created. Temp_File_Len : constant Integer := 12; -- Length of name returned by Create_Temp_File call (GNAT-XXXXXX & NUL) subtype Temp_File_Name is String (1 .. Temp_File_Len); -- String subtype set by Create_Temp_File procedure Create_Temp_File (FD : out File_Descriptor; Name : out Temp_File_Name); -- Create and open for writing a temporary file in the current working -- directory. The name of the file and the File Descriptor are returned. -- The File Descriptor returned is Invalid_FD in the case of failure. No -- mode parameter is provided. Since this is a temporary file, there is no -- point in doing text translation on it. -- -- On some operating systems, the maximum number of temp files that can be -- created with this procedure may be limited. When the maximum is reached, -- this procedure returns Invalid_FD. On some operating systems, there may -- be a race condition between processes trying to create temp files at the -- same time in the same directory using this procedure. procedure Create_Temp_File (FD : out File_Descriptor; Name : out String_Access); -- Create and open for writing a temporary file in the current working -- directory. The name of the file and the File Descriptor are returned. -- It is the responsibility of the caller to deallocate the access value -- returned in Name. -- -- The file is opened in binary mode (no text translation). -- -- This procedure will always succeed if the current working directory is -- writable. If the current working directory is not writable, then -- Invalid_FD is returned for the file descriptor and null for the Name. -- There is no race condition problem between processes trying to create -- temp files at the same time in the same directory. procedure Create_Temp_Output_File (FD : out File_Descriptor; Name : out String_Access); -- Create and open for writing a temporary file in the current working -- directory suitable to redirect standard output. The name of the file and -- the File Descriptor are returned. It is the responsibility of the caller -- to deallocate the access value returned in Name. -- -- The file is opened in text mode -- -- This procedure will always succeed if the current working directory is -- writable. If the current working directory is not writable, then -- Invalid_FD is returned for the file descriptor and null for the Name. -- There is no race condition problem between processes trying to create -- temp files at the same time in the same directory. procedure Close (FD : File_Descriptor; Status : out Boolean); -- Close file referenced by FD. Status is False if the underlying service -- failed. Reasons for failure include: disk full, disk quotas exceeded -- and invalid file descriptor (the file may have been closed twice). procedure Close (FD : File_Descriptor); -- Close file referenced by FD. This form is used when the caller wants to -- ignore any possible error (see above for error cases). procedure Set_Close_On_Exec (FD : File_Descriptor; Close_On_Exec : Boolean; Status : out Boolean); -- When Close_On_Exec is True, mark FD to be closed automatically when new -- program is executed by the calling process (i.e. prevent FD from being -- inherited by child processes). When Close_On_Exec is False, mark FD to -- not be closed on exec (i.e. allow it to be inherited). Status is False -- if the operation could not be performed. procedure Delete_File (Name : String; Success : out Boolean); -- Deletes file. Success is set True or False indicating if the delete is -- successful. procedure Rename_File (Old_Name : String; New_Name : String; Success : out Boolean); -- Rename a file. Success is set True or False indicating if the rename is -- successful or not. -- The following defines the mode for the Copy_File procedure below. Note -- that "time stamps and other file attributes" in the descriptions below -- refers to the creation and last modification times, and also the file -- access (read/write/execute) status flags. type Copy_Mode is (Copy, -- Copy the file. It is an error if the target file already exists. The -- time stamps and other file attributes are preserved in the copy. Overwrite, -- If the target file exists, the file is replaced otherwise the file -- is just copied. The time stamps and other file attributes are -- preserved in the copy. Append); -- If the target file exists, the contents of the source file is -- appended at the end. Otherwise the source file is just copied. The -- time stamps and other file attributes are preserved if the -- destination file does not exist. type Attribute is (Time_Stamps, -- Copy time stamps from source file to target file. All other -- attributes are set to normal default values for file creation. Full, -- All attributes are copied from the source file to the target file. -- This includes the timestamps, and for example also includes -- read/write/execute attributes in Unix systems. None); -- No attributes are copied. All attributes including the time stamp -- values are set to normal default values for file creation. -- Note: The default is Time_Stamps, which corresponds to the normal -- default on Windows style systems. Full corresponds to the typical -- effect of "cp -p" on Unix systems, and None corresponds to the typical -- effect of "cp" on Unix systems. -- Note: Time_Stamps and Full are not supported on VMS and VxWorks 5 procedure Copy_File (Name : String; Pathname : String; Success : out Boolean; Mode : Copy_Mode := Copy; Preserve : Attribute := Time_Stamps); -- Copy a file. Name must designate a single file (no wild cards allowed). -- Pathname can be a filename or directory name. In the latter case Name -- is copied into the directory preserving the same file name. Mode -- defines the kind of copy, see above with the default being a normal -- copy in which the target file must not already exist. Success is set to -- True or False indicating if the copy is successful (depending on the -- specified Mode). -- -- Note: this procedure is only supported to a very limited extent on VMS. -- The only supported mode is Overwrite, and the only supported value for -- Preserve is None, resulting in the default action which for Overwrite -- is to leave attributes unchanged. Furthermore, the copy only works for -- simple text files. procedure Copy_Time_Stamps (Source, Dest : String; Success : out Boolean); -- Copy Source file time stamps (last modification and last access time -- stamps) to Dest file. Source and Dest must be valid filenames, -- furthermore Dest must be writable. Success will be set to True if the -- operation was successful and False otherwise. -- -- Note: this procedure is not supported on VMS and VxWorks 5. On these -- platforms, Success is always set to False. function Read (FD : File_Descriptor; A : System.Address; N : Integer) return Integer; -- Read N bytes to address A from file referenced by FD. Returned value is -- count of bytes actually read, which can be less than N at EOF. function Write (FD : File_Descriptor; A : System.Address; N : Integer) return Integer; -- Write N bytes from address A to file referenced by FD. The returned -- value is the number of bytes written, which can be less than N if a -- disk full condition was detected. Seek_Cur : constant := 1; Seek_End : constant := 2; Seek_Set : constant := 0; -- Used to indicate origin for Lseek call procedure Lseek (FD : File_Descriptor; offset : Long_Integer; origin : Integer); pragma Import (C, Lseek, "__gnat_lseek"); -- Sets the current file pointer to the indicated offset value, relative -- to the current position (origin = SEEK_CUR), end of file (origin = -- SEEK_END), or start of file (origin = SEEK_SET). function File_Length (FD : File_Descriptor) return Long_Integer; pragma Import (C, File_Length, "__gnat_file_length"); -- Get length of file from file descriptor FD function File_Time_Stamp (Name : String) return OS_Time; -- Given the name of a file or directory, Name, obtains and returns the -- time stamp. This function can be used for an unopened file. Returns -- Invalid_Time is Name doesn't correspond to an existing file. function File_Time_Stamp (FD : File_Descriptor) return OS_Time; -- Get time stamp of file from file descriptor FD Returns Invalid_Time is -- FD doesn't correspond to an existing file. function Normalize_Pathname (Name : String; Directory : String := ""; Resolve_Links : Boolean := True; Case_Sensitive : Boolean := True) return String; -- Returns a file name as an absolute path name, resolving all relative -- directories, and symbolic links. The parameter Directory is a fully -- resolved path name for a directory, or the empty string (the default). -- Name is the name of a file, which is either relative to the given -- directory name, if Directory is non-null, or to the current working -- directory if Directory is null. The result returned is the normalized -- name of the file. For most cases, if two file names designate the same -- file through different paths, Normalize_Pathname will return the same -- canonical name in both cases. However, there are cases when this is not -- true; for example, this is not true in Unix for two hard links -- designating the same file. -- -- On Windows, the returned path will start with a drive letter except -- when Directory is not empty and does not include a drive letter. If -- Directory is empty (the default) and Name is a relative path or an -- absolute path without drive letter, the letter of the current drive -- will start the returned path. If Case_Sensitive is True (the default), -- then this drive letter will be forced to upper case ("C:\..."). -- -- If Resolve_Links is set to True, then the symbolic links, on systems -- that support them, will be fully converted to the name of the file or -- directory pointed to. This is slightly less efficient, since it -- requires system calls. -- -- If Name cannot be resolved or is null on entry (for example if there is -- symbolic link circularity, e.g. A is a symbolic link for B, and B is a -- symbolic link for A), then Normalize_Pathname returns an empty string. -- -- In VMS, if Name follows the VMS syntax file specification, it is first -- converted into Unix syntax. If the conversion fails, Normalize_Pathname -- returns an empty string. -- -- For case-sensitive file systems, the value of Case_Sensitive parameter -- is ignored. For file systems that are not case-sensitive, such as -- Windows and OpenVMS, if this parameter is set to False, then the file -- and directory names are folded to lower case. This allows checking -- whether two files are the same by applying this function to their names -- and comparing the results. If Case_Sensitive is set to True, this -- function does not change the casing of file and directory names. function Is_Absolute_Path (Name : String) return Boolean; -- Returns True if Name is an absolute path name, i.e. it designates a -- file or directory absolutely rather than relative to another directory. function Is_Regular_File (Name : String) return Boolean; -- Determines if the given string, Name, is the name of an existing -- regular file. Returns True if so, False otherwise. Name may be an -- absolute path name or a relative path name, including a simple file -- name. If it is a relative path name, it is relative to the current -- working directory. function Is_Directory (Name : String) return Boolean; -- Determines if the given string, Name, is the name of a directory. -- Returns True if so, False otherwise. Name may be an absolute path -- name or a relative path name, including a simple file name. If it is -- a relative path name, it is relative to the current working directory. function Is_Readable_File (Name : String) return Boolean; -- Determines if the given string, Name, is the name of an existing file -- that is readable. Returns True if so, False otherwise. Note that this -- function simply interrogates the file attributes (e.g. using the C -- function stat), so it does not indicate a situation in which a file may -- not actually be readable due to some other process having exclusive -- access. function Is_Executable_File (Name : String) return Boolean; -- Determines if the given string, Name, is the name of an existing file -- that is executable. Returns True if so, False otherwise. Note that this -- function simply interrogates the file attributes (e.g. using the C -- function stat), so it does not indicate a situation in which a file may -- not actually be readable due to some other process having exclusive -- access. function Is_Writable_File (Name : String) return Boolean; -- Determines if the given string, Name, is the name of an existing file -- that is writable. Returns True if so, False otherwise. Note that this -- function simply interrogates the file attributes (e.g. using the C -- function stat), so it does not indicate a situation in which a file may -- not actually be writeable due to some other process having exclusive -- access. function Is_Symbolic_Link (Name : String) return Boolean; -- Determines if the given string, Name, is the path of a symbolic link on -- systems that support it. Returns True if so, False if the path is not a -- symbolic link or if the system does not support symbolic links. -- -- A symbolic link is an indirect pointer to a file; its directory entry -- contains the name of the file to which it is linked. Symbolic links may -- span file systems and may refer to directories. procedure Set_Writable (Name : String); -- Change permissions on the named file to make it writable for its owner procedure Set_Non_Writable (Name : String); -- Change permissions on the named file to make it non-writable for its -- owner. The readable and executable permissions are not modified. procedure Set_Read_Only (Name : String) renames Set_Non_Writable; -- This renaming is provided for backwards compatibility with previous -- versions. The use of Set_Non_Writable is preferred (clearer name). procedure Set_Executable (Name : String); -- Change permissions on the named file to make it executable for its owner procedure Set_Readable (Name : String); -- Change permissions on the named file to make it readable for its -- owner. procedure Set_Non_Readable (Name : String); -- Change permissions on the named file to make it non-readable for -- its owner. The writable and executable permissions are not -- modified. function Locate_Exec_On_Path (Exec_Name : String) return String_Access; -- Try to locate an executable whose name is given by Exec_Name in the -- directories listed in the environment Path. If the Exec_Name does not -- have the executable suffix, it will be appended before the search. -- Otherwise works like Locate_Regular_File below. If the executable is -- not found, null is returned. -- -- Note that this function allocates memory for the returned value. This -- memory needs to be deallocated after use. function Locate_Regular_File (File_Name : String; Path : String) return String_Access; -- Try to locate a regular file whose name is given by File_Name in the -- directories listed in Path. If a file is found, its full pathname is -- returned; otherwise, a null pointer is returned. If the File_Name given -- is an absolute pathname, then Locate_Regular_File just checks that the -- file exists and is a regular file. Otherwise, if the File_Name given -- includes directory information, Locate_Regular_File first checks if the -- file exists relative to the current directory. If it does not, or if -- the File_Name given is a simple file name, the Path argument is parsed -- according to OS conventions, and for each directory in the Path a check -- is made if File_Name is a relative pathname of a regular file from that -- directory. -- -- Note that this function allocates some memory for the returned value. -- This memory needs to be deallocated after use. function Get_Debuggable_Suffix return String_Access; -- Return the debuggable suffix convention. Usually this is the same as -- the convention for Get_Executable_Suffix. The result is allocated on -- the heap and should be freed after use to avoid storage leaks. function Get_Target_Debuggable_Suffix return String_Access; -- Return the target debuggable suffix convention. Usually this is the same -- as the convention for Get_Executable_Suffix. The result is allocated on -- the heap and should be freed after use to avoid storage leaks. function Get_Executable_Suffix return String_Access; -- Return the executable suffix convention. The result is allocated on the -- heap and should be freed after use to avoid storage leaks. function Get_Object_Suffix return String_Access; -- Return the object suffix convention. The result is allocated on the heap -- and should be freed after use to avoid storage leaks. function Get_Target_Executable_Suffix return String_Access; -- Return the target executable suffix convention. The result is allocated -- on the heap and should be freed after use to avoid storage leaks. function Get_Target_Object_Suffix return String_Access; -- Return the target object suffix convention. The result is allocated on -- the heap and should be freed after use to avoid storage leaks. -- The following section contains low-level routines using addresses to -- pass file name and executable name. In each routine the name must be -- Nul-Terminated. For complete documentation refer to the equivalent -- routine (using String in place of C_File_Name) defined above. subtype C_File_Name is System.Address; -- This subtype is used to document that a parameter is the address of a -- null-terminated string containing the name of a file. -- All the following functions need comments ??? function Open_Read (Name : C_File_Name; Fmode : Mode) return File_Descriptor; function Open_Read_Write (Name : C_File_Name; Fmode : Mode) return File_Descriptor; function Create_File (Name : C_File_Name; Fmode : Mode) return File_Descriptor; function Create_New_File (Name : C_File_Name; Fmode : Mode) return File_Descriptor; procedure Delete_File (Name : C_File_Name; Success : out Boolean); procedure Rename_File (Old_Name : C_File_Name; New_Name : C_File_Name; Success : out Boolean); procedure Copy_File (Name : C_File_Name; Pathname : C_File_Name; Success : out Boolean; Mode : Copy_Mode := Copy; Preserve : Attribute := Time_Stamps); procedure Copy_Time_Stamps (Source, Dest : C_File_Name; Success : out Boolean); function File_Time_Stamp (Name : C_File_Name) return OS_Time; -- Returns Invalid_Time is Name doesn't correspond to an existing file function Is_Regular_File (Name : C_File_Name) return Boolean; function Is_Directory (Name : C_File_Name) return Boolean; function Is_Readable_File (Name : C_File_Name) return Boolean; function Is_Executable_File (Name : C_File_Name) return Boolean; function Is_Writable_File (Name : C_File_Name) return Boolean; function Is_Symbolic_Link (Name : C_File_Name) return Boolean; function Locate_Regular_File (File_Name : C_File_Name; Path : C_File_Name) return String_Access; ------------------ -- Subprocesses -- ------------------ subtype Argument_List is String_List; -- Type used for argument list in call to Spawn. The lower bound of the -- array should be 1, and the length of the array indicates the number of -- arguments. subtype Argument_List_Access is String_List_Access; -- Type used to return Argument_List without dragging in secondary stack. -- Note that there is a Free procedure declared for this subtype which -- frees the array and all referenced strings. procedure Normalize_Arguments (Args : in out Argument_List); -- Normalize all arguments in the list. This ensure that the argument list -- is compatible with the running OS and will works fine with Spawn and -- Non_Blocking_Spawn for example. If Normalize_Arguments is called twice -- on the same list it will do nothing the second time. Note that Spawn -- and Non_Blocking_Spawn call Normalize_Arguments automatically, but -- since there is a guarantee that a second call does nothing, this -- internal call will have no effect if Normalize_Arguments is called -- before calling Spawn. The call to Normalize_Arguments assumes that the -- individual referenced arguments in Argument_List are on the heap, and -- may free them and reallocate if they are modified. procedure Spawn (Program_Name : String; Args : Argument_List; Success : out Boolean); -- This procedure spawns a program with a given list of arguments. The -- first parameter of is the name of the executable. The second parameter -- contains the arguments to be passed to this program. Success is False -- if the named program could not be spawned or its execution completed -- unsuccessfully. Note that the caller will be blocked until the -- execution of the spawned program is complete. For maximum portability, -- use a full path name for the Program_Name argument. On some systems -- (notably Unix systems) a simple file name may also work (if the -- executable can be located in the path). -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. -- -- Note: Arguments in Args that contain spaces and/or quotes such as -- "--GCC=gcc -v" or "--GCC=""gcc -v""" are not portable across all -- operating systems, and would not have the desired effect if they were -- passed directly to the operating system. To avoid this problem, Spawn -- makes an internal call to Normalize_Arguments, which ensures that such -- arguments are modified in a manner that ensures that the desired effect -- is obtained on all operating systems. The caller may call -- Normalize_Arguments explicitly before the call (e.g. to print out the -- exact form of arguments passed to the operating system). In this case -- the guarantee a second call to Normalize_Arguments has no effect -- ensures that the internal call will not affect the result. Note that -- the implicit call to Normalize_Arguments may free and reallocate some -- of the individual arguments. -- -- This function will always set Success to False under VxWorks and other -- similar operating systems which have no notion of the concept of -- dynamically executable file. Otherwise Success is set True if the exit -- status of the spawned process is zero. function Spawn (Program_Name : String; Args : Argument_List) return Integer; -- Similar to the above procedure, but returns the actual status returned -- by the operating system, or -1 under VxWorks and any other similar -- operating systems which have no notion of separately spawnable programs. -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. procedure Spawn (Program_Name : String; Args : Argument_List; Output_File_Descriptor : File_Descriptor; Return_Code : out Integer; Err_To_Out : Boolean := True); -- Similar to the procedure above, but redirects the output to the file -- designated by Output_File_Descriptor. If Err_To_Out is True, then the -- Standard Error output is also redirected. -- Return_Code is set to the status code returned by the operating system -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. procedure Spawn (Program_Name : String; Args : Argument_List; Output_File : String; Success : out Boolean; Return_Code : out Integer; Err_To_Out : Boolean := True); -- Similar to the procedure above, but saves the output of the command to -- a file with the name Output_File. -- -- Success is set to True if the command is executed and its output -- successfully written to the file. If Success is True, then Return_Code -- will be set to the status code returned by the operating system. -- Otherwise, Return_Code is undefined. -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. type Process_Id is private; -- A private type used to identify a process activated by the following -- non-blocking calls. The only meaningful operation on this type is a -- comparison for equality. Invalid_Pid : constant Process_Id; -- A special value used to indicate errors, as described below function Pid_To_Integer (Pid : Process_Id) return Integer; -- Convert a process id to an Integer. Useful for writing hash functions -- for type Process_Id or to compare two Process_Id (e.g. for sorting). function Non_Blocking_Spawn (Program_Name : String; Args : Argument_List) return Process_Id; -- This is a non blocking call. The Process_Id of the spawned process is -- returned. Parameters are to be used as in Spawn. If Invalid_Pid is -- returned the program could not be spawned. -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. -- -- This function will always return Invalid_Pid under VxWorks, since there -- is no notion of executables under this OS. function Non_Blocking_Spawn (Program_Name : String; Args : Argument_List; Output_File_Descriptor : File_Descriptor; Err_To_Out : Boolean := True) return Process_Id; -- Similar to the procedure above, but redirects the output to the file -- designated by Output_File_Descriptor. If Err_To_Out is True, then the -- Standard Error output is also redirected. Invalid_Pid is returned -- if the program could not be spawned successfully. -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. -- -- This function will always return Invalid_Pid under VxWorks, since there -- is no notion of executables under this OS. function Non_Blocking_Spawn (Program_Name : String; Args : Argument_List; Output_File : String; Err_To_Out : Boolean := True) return Process_Id; -- Similar to the procedure above, but saves the output of the command to -- a file with the name Output_File. -- -- Success is set to True if the command is executed and its output -- successfully written to the file. Invalid_Pid is returned if the output -- file could not be created or if the program could not be spawned -- successfully. -- -- Spawning processes from tasking programs is not recommended. See -- "NOTE: Spawn in tasking programs" below. -- -- This function will always return Invalid_Pid under VxWorks, since there -- is no notion of executables under this OS. procedure Wait_Process (Pid : out Process_Id; Success : out Boolean); -- Wait for the completion of any of the processes created by previous -- calls to Non_Blocking_Spawn. The caller will be suspended until one of -- these processes terminates (normally or abnormally). If any of these -- subprocesses terminates prior to the call to Wait_Process (and has not -- been returned by a previous call to Wait_Process), then the call to -- Wait_Process is immediate. Pid identifies the process that has -- terminated (matching the value returned from Non_Blocking_Spawn). -- Success is set to True if this sub-process terminated successfully. If -- Pid = Invalid_Pid, there were no subprocesses left to wait on. -- -- This function will always set success to False under VxWorks, since -- there is no notion of executables under this OS. function Argument_String_To_List (Arg_String : String) return Argument_List_Access; -- Take a string that is a program and its arguments and parse it into an -- Argument_List. Note that the result is allocated on the heap, and must -- be freed by the programmer (when it is no longer needed) to avoid -- memory leaks. ------------------------------------- -- NOTE: Spawn in Tasking Programs -- ------------------------------------- -- Spawning processes in tasking programs using the above Spawn and -- Non_Blocking_Spawn subprograms is not recommended, because there are -- subtle interactions between creating a process and signals/locks that -- can cause trouble. These issues are not specific to Ada; they depend -- primarily on the operating system. -- If you need to spawn processes in a tasking program, you will need to -- understand the semantics of your operating system, and you are likely to -- write non-portable code, because operating systems differ in this area. -- The Spawn and Non_Blocking_Spawn subprograms call the following -- operating system functions: -- On Windows: spawnvp (blocking) or CreateProcess (non-blocking) -- On Solaris: fork1, followed in the child process by execv -- On other Unix-like systems, and on VMS: fork, followed in the child -- process by execv. -- On vxworks, nucleus, and RTX, spawning of processes is not supported -- For details, look at the functions __gnat_portable_spawn and -- __gnat_portable_no_block_spawn in adaint.c. -- You should read the operating-system-specific documentation for the -- above functions, paying special attention to subtle interactions with -- threading, signals, locks, and file descriptors. Most of the issues are -- related to the fact that on Unix, there is a window of time between fork -- and execv; Windows does not have this problem, because spawning is done -- in a single operation. -- On Posix-compliant systems, such as Linux, fork duplicates just the -- calling thread. (On Solaris, fork1 is the Posix-compliant version of -- fork.) -- You should avoid using signals while spawning. This includes signals -- used internally by the Ada run-time system, such as timer signals used -- to implement delay statements. -- It is best to spawn any subprocesses very early, before the parent -- process creates tasks, locks, or installs signal handlers. Certainly -- avoid doing simultaneous spawns from multiple threads of the same -- process. -- There is no problem spawning a subprocess that uses tasking: the -- problems are caused only by tasking in the parent. -- If the parent is using tasking, and needs to spawn subprocesses at -- arbitrary times, one technique is for the parent to spawn (very early) -- a particular spawn-manager subprocess whose job is to spawn other -- processes. The spawn-manager must avoid tasking. The parent sends -- messages to the spawn-manager requesting it to spawn processes, using -- whatever inter-process communication mechanism you like, such as -- sockets. -- In short, mixing spawning of subprocesses with tasking is a tricky -- business, and should be avoided if possible, but if it is necessary, -- the above guidelines should be followed, and you should beware of -- portability problems. ------------------- -- Miscellaneous -- ------------------- function Getenv (Name : String) return String_Access; -- Get the value of the environment variable. Returns an access to the -- empty string if the environment variable does not exist or has an -- explicit null value (in some operating systems these are distinct -- cases, in others they are not; this interface abstracts away that -- difference. The argument is allocated on the heap (even in the null -- case), and needs to be freed explicitly when no longer needed to avoid -- memory leaks. procedure Setenv (Name : String; Value : String); -- Set the value of the environment variable Name to Value. This call -- modifies the current environment, but does not modify the parent -- process environment. After a call to Setenv, Getenv (Name) will always -- return a String_Access referencing the same String as Value. This is -- true also for the null string case (the actual effect may be to either -- set an explicit null as the value, or to remove the entry, this is -- operating system dependent). Note that any following calls to Spawn -- will pass an environment to the spawned process that includes the -- changes made by Setenv calls. This procedure is not available on VMS. procedure OS_Exit (Status : Integer); pragma No_Return (OS_Exit); -- Exit to OS with given status code (program is terminated). Note that -- this is abrupt termination. All tasks are immediately terminated. There -- are no finalization or other Ada-specific cleanup actions performed. On -- systems with atexit handlers (such as Unix and Windows), atexit handlers -- are called. type OS_Exit_Subprogram is access procedure (Status : Integer); procedure OS_Exit_Default (Status : Integer); pragma No_Return (OS_Exit_Default); -- Default implementation of procedure OS_Exit OS_Exit_Ptr : OS_Exit_Subprogram := OS_Exit_Default'Access; -- OS_Exit is implemented through this access value. It it then possible to -- change the implementation of OS_Exit by redirecting OS_Exit_Ptr to an -- other implementation. procedure OS_Abort; pragma Import (C, OS_Abort, "abort"); pragma No_Return (OS_Abort); -- Exit to OS signalling an abort (traceback or other appropriate -- diagnostic information should be given if possible, or entry made to -- the debugger if that is possible). function Errno return Integer; pragma Import (C, Errno, "__get_errno"); -- Return the task-safe last error number procedure Set_Errno (Errno : Integer); pragma Import (C, Set_Errno, "__set_errno"); -- Set the task-safe error number Directory_Separator : constant Character; -- The character that is used to separate parts of a pathname Path_Separator : constant Character; -- The character to separate paths in an environment variable value private pragma Import (C, Path_Separator, "__gnat_path_separator"); pragma Import (C, Directory_Separator, "__gnat_dir_separator"); pragma Import (C, Current_Time, "__gnat_current_time"); type OS_Time is range -(2 ** (Standard'Address_Size - Integer'(1))) .. +(2 ** (Standard'Address_Size - Integer'(1)) - 1); -- Type used for timestamps in the compiler. This type is used to hold -- time stamps, but may have a different representation than C's time_t. -- This type needs to match the declaration of OS_Time in adaint.h. -- Add pragma Inline statements for comparison operations on OS_Time. It -- would actually be nice to use pragma Import (Intrinsic) here, but this -- was not properly supported till GNAT 3.15a, so that would cause -- bootstrap path problems. To be changed later ??? Invalid_Time : constant OS_Time := -1; -- This value should match the return value from __gnat_file_time_* pragma Inline ("<"); pragma Inline (">"); pragma Inline ("<="); pragma Inline (">="); type Process_Id is new Integer; Invalid_Pid : constant Process_Id := -1; end System.OS_Lib;
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