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closefrom(3c) [opensolaris man page]

closefrom(3C)						   Standard C Library Functions 					     closefrom(3C)

closefrom, fdwalk - close or iterate over open file descriptors SYNOPSIS
#include <stdlib.h> void closefrom(int lowfd); int fdwalk(int (*func)(void *, int), void *cd); DESCRIPTION
The closefrom() function calls close(2) on all open file descriptors greater than or equal to lowfd. The effect of closefrom(lowfd) is the same as the code #include <sys/resource.h> struct rlimit rl; int i; getrlimit(RLIMIT_NOFILE, &rl); for (i = lowfd; i < rl.rlim_max; i++) (void) close(i); except that close() is called only on file descriptors that are actually open, not on every possible file descriptor greater than or equal to lowfd, and close() is also called on any open file descriptors greater than or equal to rl.rlim_max (and lowfd), should any exist. The fdwalk() function first makes a list of all currently open file descriptors. Then for each file descriptor in the list, it calls the user-defined function, func(cd, fd), passing it the pointer to the callback data, cd, and the value of the file descriptor from the list, fd. The list is processed in file descriptor value order, lowest numeric value first. If func() returns a non-zero value, the iteration over the list is terminated and fdwalk() returns the non-zero value returned by func(). Otherwise, fdwalk() returns 0 after having called func() for every file descriptor in the list. The fdwalk() function can be used for fine-grained control over the closing of file descriptors. For example, the closefrom() function can be implemented as: static int close_func(void *lowfdp, int fd) { if (fd >= *(int *)lowfdp) (void) close(fd); return(0); } void closefrom(int lowfd) { (void) fdwalk(close_func, &lowfd); } The fdwalk() function can then be used to count the number of open files in the process. RETURN VALUES
No return value is defined for closefrom(). If close() fails for any of the open file descriptors, the error is ignored and the file descriptors whose close() operation failed might remain open on return from closefrom(). The fdwalk() function returns the return value of the last call to the callback function func(), or 0 if func() is never called (no open files). ERRORS
No errors are defined. The closefrom() and fdwalk() functions do not set errno but errno can be set by close() or by another function called by the callback function, func(). FILES
/proc/self/fd directory (list of open files) USAGE
The act of closing all open file descriptors should be performed only as the first action of a daemon process. Closing file descriptors that are in use elsewhere in the current process normally leads to disastrous results. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |MT-Level |Unsafe | +-----------------------------+-----------------------------+ SEE ALSO
close(2), getrlimit(2), proc(4), attributes(5) SunOS 5.11 27 Apr 2000 closefrom(3C)

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posix_spawn_file_actions_addclose(3C)			   Standard C Library Functions 		     posix_spawn_file_actions_addclose(3C)

posix_spawn_file_actions_addclose, posix_spawn_file_actions_addopen - add close or open action to spawn file actions object SYNOPSIS
#include <spawn.h> int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t *file_actions, int fildes, ); int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t *restrict file_actions, int fildes, const char *restrict path, int oflag, mode_t mode); DESCRIPTION
These functions add or delete a close or open action to a spawn file actions object. A spawn file actions object is of type posix_spawn_file_actions_t (defined in <spawn.h>) and is used to specify a series of actions to be performed by a posix_spawn(3C) or posix_spawn(3C) operation to arrive at the set of open file descriptors for the child process given the set of open file descriptors of the parent. A spawn file actions object, when passed to posix_spawn() or posix_spawnp(), specifies how the set of open file descriptors in the calling process is transformed into a set of potentially open file descriptors for the spawned process. This transformation occurs as though the specified sequence of actions was performed exactly once, in the context of the spawned process (prior to execution of the new process image), in the order in which the actions were added to the object. Additionally, when the new process image is executed, any file descriptor (from this new set) which has its FD_CLOEXEC flag set is closed (see posix_spawn(3C)). The posix_spawn_file_actions_addclose() function adds a close action to the object referenced by file_actions that causes the file descrip- tor fildes to be closed (as if close(fildes) had been called) when a new process is spawned using this file actions object. The posix_spawn_file_actions_addopen() function adds an open action to the object referenced by file_actions that causes the file named by path to be opened (as if open(path, oflag, mode) had been called, and the returned file descriptor, if not fildes, had been changed to fildes) when a new process is spawned using this file actions object. If fildes was already an open file descriptor, it is closed before the new file is opened. The string described by path is copied by the posix_spawn_file_actions_addopen() function. RETURN VALUES
Upon successful completion, these functions return 0. Otherwise, an error number is returned to indicate the error. ERRORS
These functions will fail if: EBADF The value specified by fildes is negative or greater than or equal to {OPEN_MAX}. These functions may fail if: EINVAL The value specified by file_actions is invalid. ENOMEM Insufficient memory exists to add to the spawn file actions object. It is not considered an error for the fildes argument passed to these functions to specify a file descriptor for which the specified opera- tion could not be performed at the time of the call. Any such error will be detected when the associated file actions object is later used during a posix_spawn() or posix_spawnp() operation. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
close(2), dup(2), open(2), posix_spawn(3C), posix_spawn_file_actions_adddup2(3C), posix_spawn_file_actions_destroy(3C), attributes(5), standards(5) SunOS 5.10 30 Jan 2004 posix_spawn_file_actions_addclose(3C)

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