The entry for each function in this reference typically includes the following sections:
This section gives the header files that should be included within a source file that references the function or macro. It also shows an appropriate declaration for the function or for a function that could be substituted for a macro. This declaration isn't included in your program; only the header file(s) should be included.
When a pointer argument is passed to a function that doesn't modify the item indicated by that pointer, the argument is shown with const before the argument. For example, the following indicates that the array pointed at by string isn't changed:
const char *string
The synopsis might include synonyms for the standard types for exact-width integers (e.g., _Uint16t or _uint16t instead of uint16_t), but the synonyms correspond in a fairly obvious way to the standard types.
This section gives a brief description of the arguments to the function.
This section indicates the library that you need to bind with your application in order to use the function.
To link against a library, use the -l option to qcc, omitting the lib prefix and any extension from the library's name. For example, to link against libsocket, specify -l socket. For more information, see the Compiling and Debugging chapter of the QNX Neutrino Programmer's Guide.
This section describes the function or macro.
This section gives the return value (if any) for the function or macro.
If this section says that a function returns a certain value if an error occurred, but doesn't say what it returns on success (or the other way around), don't make any assumptions about the value returned for the undocumented case. For example, if a function is only documented as returning -1 on error, don't assume that it returns 0 on success. Instead of writing this:
if ( some_function() == EOK) {
/* Everything's OK */
}
write this:
if ( some_function() == -1) {
/* An error occurred; handle it appropriately */
} else {
/* Everything's OK */
}
This section describes the special values that the function might assign to the global variable errno or return.
This optional section gives one or more examples of the use of the function. The examples are often just code snippets, not complete programs.
This section tells where the function or macro is commonly found, which may be helpful when porting code from one environment to another. Here are the classes:
In header files and code, don't refer directly to _FILE_OFFSET_BITS or _LARGEFILE64_SOURCE; use __OFF_BITS__ and __EXT_LF64SRC instead.
This standard incorporates the POSIX 1003.2-1992 and 1003.1-1996 standards, the approved drafts (POSIX 1003.1a, POSIX 1003.1d, POSIX 1003.1g and POSIX 1003.1j) and the Standard Unix specification. A joint technical working group—the Austin Common Standards Revision Group (CSRG)—was formed to merge these standards.
A classification of “POSIX 1003.1” can be followed by one or more codes that indicate which option or options the functions belong to. The codes include the following:
| Code | Meaning |
|---|---|
| ADV | Advisory Information |
| CPT | Process CPU-Time Clocks |
| CX | Extension to the ISO C standard |
| FSC | File Synchronization |
| MC1 | Non-Robust Mutex Priority Protection or Non-Robust Mutex Priority Inheritance or Robust Mutex Priority Protection or Robust Mutex Priority Inheritance |
| ML | Process Memory Locking |
| MLR | Range Memory Locking |
| MSG | Message Passing |
| OB | Obsolescent |
| PS | Process Scheduling |
| RPP | Robust Mutex Priority Protection |
| SHM | Shared Memory Objects |
| SIO | Synchronous Input/Output |
| SPN | Spawn |
| TCT | Thread CPU-Time Clocks |
| TPI | Non-Robust Mutex Priority Inheritance |
| TPP | Non-Robust Mutex Priority Protection |
| TPS | Thread Execution Scheduling |
| TSA | Thread Stack Address Attribute |
| TSH | Thread Process-Shared Synchronization |
| TSS | Thread Stack Size Attribute |
| TYM | Typed Memory Objects |
| XSI | X/Open Systems Interfaces Extension |
| XSR | XSI Streams |
If two codes are separated by a space, you need to use both options; if the codes are separated by a vertical bar (|), the functionality is supported if you use either option.
For more information, see the Standard for Information Technology — Portable Operating System Interface: Base Definitions.
We've created the following Unix categories to differentiate:
This section summarizes whether or not it's safe to use the C library functions in certain situations:
If you use TraceEvent() to add a dynamic rules filter, the only library functions that you can call in your event handler are those that are safe to call from an interrupt handler.
Some of the signal-safe functions modify errno on failure. If you use any of these in a signal handler, asynchronous signals may have the side effect of modifying errno in an unpredictable way. If any of the code that can be interrupted checks the value of errno (this also applies to library calls, so you should assume that most library calls may internally check errno), make sure that your signal handler saves errno on entry and restores it on exit.
All of the above also applies to signal-unsafe functions, with one exception: if a signal handler calls a signal-unsafe function, make sure that signal doesn't interrupt a signal-unsafe function.
For a summary, see the Full Safety Information appendix.
This optional section provides a list of related functions or macros, as well as pertinent docs to read for more information.