Windows, Unix and ANSI C API Comparison

Article
03/20/2009

　　The "Windows System Programming"(3E)
has a great appendix about Windows, Unix, C Library API comparison.
It's obvious that this appendix lacks of many APIs in Memory, DLL and
Security related areas, but it is still very helpful for referencing
when doing system programming on windows platform.

　　Original content can be found here: https://my.safaribooksonline.com/0321256190/app02

1. I/O

1. 1 File & Directory

Subject	Windows	UNIX	C Library	Comments
Console I/O	`AllocConsole`	terminal I/O	N/A
Console I/O	`FreeConsole`	terminal I/O	N/A
Console I/O	`ReadConsole`	`read`	`getc, scanf, gets`
Console I/O	`SetConsoleMode`	`ioctl`	N/A
Console I/O	`WriteConsole`	`write`	`putc, printf, puts`
Directory Mgt	`CreateDirectory`	`mkdir*`	N/A	Make a new directory
Directory Mgt	`FindClose`	`closedir*`	N/A	Close a directory search handle
Directory Mgt	`FindFirstFile`	`opendir,` `readdir`	N/A	Find first file matching a pattern
Directory Mgt	`FindNextFile`	`readdir*`	N/A	Find subsequent files
Directory Mgt	`GetCurrentDirectory`	`getcwd*`	N/A
Directory Mgt	`GetFullPathName`	N/A	N/A
Directory Mgt	`GetSystemDirectory`	Well-known pathnames	N/A
Directory Mgt	`RemoveDirectory`	`rmdir, unlink*`	`remove`
Directory Mgt	`SearchPath`	Use `opendir, readdir`	N/A	Search for a file on a specified path
Directory Mgt	`SetCurrentDirectory`	`chdir*, fchdir`	N/A	Change the working directory
Error Handling	`FormatMessage`	`strerror`	`perror`
Error Handling	`GetLastError`	`errno`	`errno`	Global variable
Error Handling	`SetLastError`	`errno`	`errno`	Global variable
File Locking	`LockFile`	`fcntl (cmd=F_GETLK,` ..)	N/A
File Locking	`LockFileEx`	`fcntl (cmd=F_GETLK,` ..)	N/A
File Locking	`UnlockFile`	`fcntl (cmd=F_GETLK,` ..)	N/A
File Locking	`UnlockFileEx`	`fcntl (cmd=F_GETLK,` ..)	N/A
File System	`CloseHandle` (file handle)	`close*`	`fclose`	`CloseHandle` is not limited to files
File System	`CopyFile`	`open; read; write; close`	`fopen; fread; fwrite; fclose`	Duplicate a file
File System	`CreateFile`	`open,` `creat`	`fopen`	Open/create a file
File System	`DeleteFile`	`unlink*`	`remove`	Delete a file
File System	`FlushFileBuffers`	`fsynch`	`fflush`	Write file buffers
File System	`GetFileAttributes`	`stat,` `fstat, lstat`	N/A
File System	`GetFileInformationByHandle`	`stat,` `fstat, lstat`	N/A	Fill structure with file info
File System	`GetFileSize`	`stat,` `fstat, lstat`	`ftell, fseek`	Get length of file in bytes
File System	`GetFileTime`	`stat,` `fstat, lstat`	N/A
File System	`GetFileType`	`stat,` `fstat, lstat`	N/A	Check for character stream device or file
File System	`GetStdHandle`	Use file desc 0, 1, or 2	Use `stdin`, `stdout`, `stderr`
File System	`GetTempFileName`	Use C library	`tmpnam`	Create a unique file name
File System	`GetTempFileName, CreateFile`	Use C library	`tmpfile`	Create a temporary file
File System	`GetTempPath`	`/temp path`	N/A	Directory for temp files
File System	`MoveFile, MoveFileEx`	Use C library	`rename`	Rename a file or directory
File System	`CreateHardLink`	`link,` `unlink*`	N/A	Windows does not support links
File System	N/A	`symlink`	N/A	Create a symbolic link
File System	N/A	`readlink`	N/A	Read name in a symbolic link
File System	N/A, `ReadFile` returns 0 bytes	N/A, `read` returns 0 bytes	`feof`	Rest for end of file
File System	N/A, use multiple `ReadFile`s	`readv`	N/A, use multiple `freads`	Scatter read
File System	N/A, use multiple `WriteFile`s	`writev`	N/A, use multiple `fwrites`	Gather write
File System	`ReadFile`	`read`	`fread`	Read data from a file
File System	`SetEndOfFile`	`chsize*`	N/A
File System	`SetFileAttributes`	`fcntl`	N/A
File System	`SetFilePointer`	`lseek`	`fseek`	Set file pointer
FileSystem	`SetFilePointer` (to 0)	`lseek (0)`	`rewind`
File System	`SetFileTime`	`utime*`	N/A
File System	`SetStdHandle`	`close,` `dup,` `dup2,` or `fcntl`	`freopen`	`dup2` or `fcntl`
File System	`WriteFile`	`write`	`fwrite`	Write data to a file

1.2 Async I/O

Subject	Windows	UNIX	C Library	Comments
Asynch I/O	`GetOverlappedResult`	N/A	N/A
Asynch I/O	`ReadFileEx`	N/A	N/A	Extended I/O with completion routine
Asynch I/O	`SleepEx`	N/A	N/A	Alertable wait
Asynch I/O	`WaitForMultipleObjects` (file handles)	`poll, select`	N/A
Asynch I/O	`WaitForMultipleObjectsEx`	N/A	N/A	Alertable wait
Asynch I/O	`WriteFileEx`	N/A	N/A	Extended I/O with completion routine
Asynch I/O	`WaitForSingleObjectEx`	`waitpid`	N/A	Alertable wait

2. Memory & DLL

Subject	Windows	UNIX	C Library
Mapped Files	`CreateFileMapping`	`shmget`	N/A
Mapped Files	`MapViewOfFile`	`mmap, shmat`	N/A
Mapped Files	`MapViewOfFileEx`	`mmap, shmat`	N/A
Mapped Files	`OpenFileMapping`	`shmget`	N/A
Mapped Files	`UnmapViewOfFile`	`munmap, shmdt, shmctl`	N/A
Memory Mgt	`GetProcessHeap`	N/A	N/A
Memory Mgt	`GetSystemInfo`	N/A	N/A
Memory Mgt	`HeapAlloc`	`sbrk`, `brk`, or C library	`malloc, calloc`
Memory Mgt	`HeapCreate`	N/A	N/A
Memory Mgt	`HeapDestroy`	N/A	N/A
Memory Mgt	`HeapFree`	Use C library	`free`
Memory Mgt	`HeapReAlloc`	Use C library	`realloc`
Memory Mgt	`HeapSize`	N/A	N/A
Shared Memory	`CloseHandle` (map handle)	`shmctl`	N/A
Shared Memory	`CreateFileMapping, OpenFileMapping`	`shmget`	N/A
Shared Memory	`MapViewOfFile`	`shmat`	N/A
Shared Memory	`UnmapViewOfFile`	`shmdt`	N/A
DLLs	`LoadLibrary`	`dlopen`	N/A
DLLs	`FreeLibrary`	`dlclose`	N/A
DLLs	`GetProcAddress`	`dlsyn`	N/A
DLLs	`DllMain`	`pthread_once`	N/A

3. Process & Thread

3.1 Process

Subject	Windows	UNIX	C Library	Comments
Process Mgt	`CreateProcess`	`fork ();` `execl ()*, system()`	N/A	There are 6 `execxx` functions
Process Mgt	`ExitProcess`	`_exit`	`exit`
Process Mgt	`GetCommandLine`	`argv []`	`argv []`
Process Mgt	`GetCurrentProcess`	`getpid*`	N/A
Process Mgt	`GetCurrentProcessId`	`getpid*`	N/A
Process Mgt	`GetEnvironmentStrings`	N/A	`getenv`
Process Mgt	`GetEnvironmentVariable`	N/A	`getenv`
Process Mgt	`GetExitCodeProcess`	`wait, waitpid`	N/A
Process Mgt	`GetProcessTimes`	`times, wait3, wait4`	N/A
Process Mgt	`GetProcessWorkingSetSize`	`wait3, wait4`	N/A
Process Mgt	N/A	`execl, execv, execle, execve, execlp, execvp`	N/A	Windows does not have a direct equivalent
Process Mgt	N/A	`fork, vfork`	N/A	Windows does not have a direct equivalent
Process Mgt	N/A	`getppid`	N/A	No parent/child relationships in Windows
Process Mgt	N/A	`getgid, getegid`	N/A	No process groups in Windows
Process Mgt	N/A	`getpgrp`	N/A
Process Mgt	N/A	`setpgid`	N/A
Process Mgt	N/A	`setsid`	N/A
Process Mgt	N/A	`tcgetpgrp`	N/A
Process Mgt	N/A	`tcsetpgrp`	N/A
Process Mgt	`OpenProcess`	N/A	N/A
Process Mgt	`SetEnvironmentVariable`	`putenv`	N/A	`putenv` is not part of the Standard C library
Process Mgt	`TerminateProcess`	`kill`	N/A
Synch: Process	`WaitForMultipleObjects` (process handles)	`waitpid`	N/A
Synch: Process	`WaitForSingleObject` (process handle)	`wait, waitpid`	N/A
Timers	`KillTimer`	`alarm (0)`	N/A
Timers	`SetTimer`	`alarm`	N/A
Timers	`Sleep`	`sleep`	N/A
Timers	`Sleep`	`poll` or `select`, no file descriptor	N/A

3.2 Thread

Subject	Windows	UNIX/Pthreads	Comments
Thread Mgt		N/A
TLS
TLS
TLS
TLS
Thread Mgt
Thread Mgt
Thread Mgt
Thread Mgt		N/A
Thread Mgt
Thread Mgt		N/A
Thread Mgt		N/A
Thread Mgt			is safer
Thread Mgt	(thread handle)
Thread Priority
Thread Priority
Thread Priority
Thread Priority
Note: Pthreads, while a part of all modern UNIX offerings, are available on non-UNIX systems as well.

3.3 Synchronization

Subject	Windows	UNIX/Pthreads	Comments
Synch: CritSec		Use mutexes to emulate critical sections. Some systems provide proprietary equivalents.	C library is not applicable
Synch: CritSec			C library is not applicable
Synch: CritSec
Synch: CritSec
Synch: Event	(event handle)
Synch: Event
Synch: Event			Manual-reset event
Synch: Event		N/A
Synch: Event			Auto-reset event
Synch: Event	(event handle)
Synch: Event	(event handle)
Synch: Mutex	(mutex handle)
Synch: Mutex
Synch: Mutex
Synch: Mutex	(mutex handle)
Synch: Sem
Synch: Sem	N/A		Windows does not directly support all these options
Synch: Sem
Synch: Sem
Synch: Sem	(semaphore handle)		Windows can wait for only one count

3.4 IPC

Subject	Windows	UNIX	C Library	Comments
IPC	`CallNamedPipe`	N/A	N/A	`CreateFile, WriteFile, ReadFile, CloseHandle`
IPC	`CloseHandle` (pipe handle)	`close, msgctl`	`pclose`	Not part of the Standard C library—see Stevens
IPC	`ConnectNamedPipe`	N/A	N/A
IPC	`CreateMailslot`	N/A	N/A
IPC	`CreateNamedPipe`	`mkfifo, msgget`	N/A
IPC	`CreatePipe`	`pipe`	`popen`	Not part of the Standard C library—see Stevens
IPC	`DuplicateHandle`	`dup, dup2,` or `fcntl`	N/A	Or use file names `CONIN$`, `CONOUT$`
IPC	`GetNamedPipeHandleState`	`stat, fstat, lstat64`	N/A
IPC	`GetNamedPipeInfo`	`stat, fstat, lstat`	N/A
IPC	`ImpersonateNamedPipeClient`	N/A	N/A
IPC	`PeekNamedPipe`	N/A	N/A
IPC	`ReadFile` (named pipe handle)	`read` (fifo)`, msgsnd`	N/A
IPC	`RevertToSelf`	N/A	N/A
IPC	`SetNamedPipeHandleState`	N/A	N/A
IPC	`TransactNamedPipe`	N/A	N/A	`WriteFile; ReadFile`
IPC	`WriteFile` (named pipe handle)	`write` (fifo)`, msgrcv`	N/A
Misc.	`GetComputerName`	`uname`	N/A
Misc.	`SetComputerName`	N/A	N/A
Security	`SetNamedPipeIdentity`	Use directory sticky bit	N/A

4. Misc

4.1 Security

Subject	Windows	UNIX	Comments
Security			C library does not support security
Security
Security		N/A
Security		N/A
Security
Security		N/A
Security
Security
Security
Security		N/A
Security
Security
Security		N/A
Security
Security
Security
Security	N/A
Security	N/A
Security	N/A
Security	N/A
Security
Security
Security		N/A
Security
Security
Security
Security		N/A

4.2 Exception Handling

Subject	Windows	UNIX	C Library
SEH		Use C library signals	Use C library signals
SEH		Use C library signals	Use C library signals
SEH		Use C library signals	Use C library signals
SEH		Use C library signals	Use C library signals
SEH		Use C library signals
Signals	Use block	Use C library
Signals	Use C library or terminate process
Signals	Use C library	Use C library
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH		N/A
Signals	Use SEH, VEH, or C library	Use C library
Note: Many UNIX vendors provide proprietary exception handling capabilities.

4.3 System Information & Time

Subject	Windows	UNIX	C Library	Comments
System Info	`GetDiskFreeSpace`	N/A	N/A
System Info	`GetSystemInfo`	`getrusage`	N/A
System Info	`GetVersion`	`uname`	N/A
System Info	`GetVolumeInformation`	N/A	N/A
System Info	`GlobalMemoryStatus`	`getrlimit`	N/A
System Info	Various defined constants	`sysconf, pathconf, fpathconf`	N/A
Time	`GetSystemTime`	Use C library	`time, gmtime`
Time	See `ls` program,	Use C library	`asctime`
Time	`CompareFileTime`	Use C library	`difftime`	Compare "calendar" times
Time	`FileTimeToLocalFileTime, FileTimeToSystemTime`	Use C library	`localtime`
Time	`FileTimeToSystemTime`	Use C library	`gmtime`
Time	`GetLocalTime`	Use C library	`time, localtime`
Time	See `touch` program,	Use C library	`strftime`
Time	`SetLocalTime`	N/A	N/A
Time	`SetSystemTime`	N/A	N/A
Time	Subtract file times	Use C library	`difftime`
Time	`SystemTimeToFileTime`	Use C library	`mktime`

Windows, Unix and ANSI C API Comparison

Additional resources