mirror of https://github.com/tstack/lnav.git
170 lines
3.5 KiB
C++
170 lines
3.5 KiB
C++
/**
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* @file auto_fd.hh
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*/
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#ifndef __auto_fd_hh
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#define __auto_fd_hh
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#include <assert.h>
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#include <unistd.h>
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#include <sys/select.h>
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#include <new>
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#include <exception>
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/**
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* Resource management class for file descriptors.
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*
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* @see auto_ptr
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*/
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class auto_fd {
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public:
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/**
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* Wrapper for the posix pipe(2) function that stores the file descriptor
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* results in an auto_fd array.
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*
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* @param af An array of atleast two auto_fd elements, where the first
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* contains the reader end of the pipe and the second contains the writer.
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* @return The result of the pipe(2) function.
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*/
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static int pipe(auto_fd *af)
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{
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int retval, fd[2];
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assert(fd != NULL);
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if ((retval = ::pipe(fd)) == 0) {
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af[0] = fd[0];
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af[1] = fd[1];
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}
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return(retval);
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};
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/**
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* Construct an auto_fd to manage the given file descriptor.
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*
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* @param fd The file descriptor to be managed.
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*/
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auto_fd(int fd = -1)
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: af_fd(fd)
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{
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assert(fd >= -1);
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assert(fd < FD_SETSIZE);
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};
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/**
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* Non-const copy constructor. Management of the file descriptor will be
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* transferred from the source to this object and the source will be
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* cleared.
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*
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* @param af The source of the file descriptor.
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*/
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auto_fd(auto_fd &af)
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: af_fd(af.release()) { };
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/**
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* Const copy constructor. The file descriptor from the source will be
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* dup(2)'d and the new descriptor stored in this object.
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*
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* @param af The source of the file descriptor.
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*/
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auto_fd(const auto_fd &af)
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: af_fd(-1)
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{
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if (af.af_fd != -1 && (this->af_fd = dup(af.af_fd)) == -1) {
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throw std::bad_alloc();
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}
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};
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/**
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* Destructor that will close the file descriptor managed by this object.
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*/
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~auto_fd() { this->reset(); };
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/** @return The file descriptor as a pain integer. */
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operator int(void) const { return(this->af_fd); };
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/**
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* Replace the current descriptor with the given one. The current
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* descriptor will be closed.
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*
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* @param fd The file descriptor to store in this object.
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* @return *this
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*/
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auto_fd &operator=(int fd)
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{
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assert(fd >= -1);
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assert(fd < FD_SETSIZE);
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this->reset(fd);
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return(*this);
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};
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/**
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* Transfer management of the given file descriptor to this object.
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*
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* @param af The old manager of the file descriptor.
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* @return *this
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*/
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auto_fd &operator=(auto_fd &af)
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{
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this->reset(af.release());
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return(*this);
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};
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/**
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* Return a pointer that can be passed to functions that require an out
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* parameter for file descriptors (e.g. openpty).
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*
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* @return A pointer to the internal integer.
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*/
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int *out(void)
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{
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this->reset();
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return(&this->af_fd);
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};
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/**
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* Stop managing the file descriptor in this object and return its value.
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*
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* @return The file descriptor.
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*/
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int release(void)
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{
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int retval = this->af_fd;
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this->af_fd = -1;
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return(retval);
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};
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/**
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* @return The file descriptor.
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*/
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int get(void) const { return(this->af_fd); };
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/**
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* Closes the current file descriptor and replaces its value with the given
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* one.
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*
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* @param fd The new file descriptor to be managed.
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*/
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void reset(int fd = -1)
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{
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assert(fd >= -1);
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assert(fd < FD_SETSIZE);
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if (this->af_fd != fd) {
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if (this->af_fd != -1) {
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close(this->af_fd);
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}
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this->af_fd = fd;
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}
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};
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private:
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int af_fd; /*< The managed file descriptor. */
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};
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#endif
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