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/*
* Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
/** \file fd.c helper functions for file descriptor handling */
#include "para.h"
#include <sys/mman.h>
#include <fcntl.h>
#include <sys/select.h>
#include "error.h"
/**
* check whether a file exists
*
* \param fn the file name
*
* \return Non-zero iff file exists.
*/
int file_exists(const char *fn)
{
struct stat statbuf;
return !stat(fn, &statbuf);
}
/**
* paraslash's wrapper for select(2)
*
* It calls select(2) (with no exceptfds) and starts over if select() was
* interrupted by a signal.
*
* \param n the highest-numbered descriptor in any of the two sets, plus 1
* \param readfds fds that should be checked for readability
* \param writefds fds that should be checked for writablility
* \param timeout_tv upper bound on the amount of time elapsed before select()
* returns
*
* \return The return value of the underlying select() call.
*
* All arguments are passed verbatim to select(2).
* \sa select(2) select_tut(2)
*/
int para_select(int n, fd_set *readfds, fd_set *writefds,
struct timeval *timeout_tv)
{
int ret, err;
do {
ret = select(n, readfds, writefds, NULL, timeout_tv);
err = errno;
} while (ret < 0 && err == EINTR);
if (ret < 0) {
PARA_CRIT_LOG("select error: %s, max_fileno: %d\n",
strerror(err), n);
ret = -E_SELECT;
}
return ret;
}
/**
* set a file descriptor to non-blocking mode
*
* \param fd The file descriptor
*
* \returns 1 on success, -E_F_GETFL, -E_F_SETFL, on errors.
*/
int mark_fd_nonblock(int fd)
{
int flags = fcntl(fd, F_GETFL);
if (flags < 0)
return -E_F_GETFL;
if (fcntl(fd, F_SETFL, ((long)flags) | O_NONBLOCK) < 0)
return -E_F_SETFL;
return 1;
}
/**
* set a file descriptor in a fd_set
*
* \param fd the file descriptor to be set
* \param fds the file descriptor set
* \param max_fileno highest-numbered file descriptor
*
* This wrapper for FD_SET() passes its first two arguments to \p FD_SET. Upon
* return, \a max_fileno contains the maximum of the old_value and \a fd.
*
* \sa para_select
*/
void para_fd_set(int fd, fd_set *fds, int *max_fileno)
{
if (fd < 0 || fd >= FD_SETSIZE) {
PARA_EMERG_LOG("fatal: tried to add invalid fd %d\n", fd);
exit(EXIT_FAILURE);
}
#if 0
{
int flags = fcntl(fd, F_GETFL);
if (!(flags & O_NONBLOCK)) {
PARA_EMERG_LOG("fd %d is a blocking file descriptor\n", fd);
exit(EXIT_FAILURE);
}
}
#endif
FD_SET(fd, fds);
*max_fileno = PARA_MAX(*max_fileno, fd);
}
/**
* paraslash's wrapper for fgets(3)
* \param line pointer to the buffer to store the line
* \param size the size of the buffer given by \a line
* \param f the stream to read from
*
* \return Unlike the standard fgets() function, an integer value
* is returned. On success, this function returns 1. On errors, -E_FGETS
* is returned. A zero return value indicates an end of file condition.
*/
__must_check int para_fgets(char *line, int size, FILE *f)
{
again:
if (fgets(line, size, f))
return 1;
if (feof(f))
return 0;
if (!ferror(f))
return -E_FGETS;
if (errno != EINTR) {
PARA_ERROR_LOG("%s\n", strerror(errno));
return -E_FGETS;
}
clearerr(f);
goto again;
}
/**
* *paraslash's wrapper for mmap
*
* \param length number of bytes to mmap
* \param prot either PROT_NONE or the bitwise OR of one or more of
* PROT_EXEC PROT_READ PROT_WRITE
* \param flags exactly one of MAP_SHARED and MAP_PRIVATE
* \param fd the file to mmap from
* \param offset mmap start
*
* \return This function either returns a valid pointer to the mapped area
* or calls exit() on errors.
*/
void *para_mmap(size_t length, int prot, int flags, int fd, off_t offset)
{
void *ret = mmap(NULL, length, prot, flags, fd, offset);
if (ret != MAP_FAILED)
return ret;
PARA_EMERG_LOG("mmap failed: %s\n", strerror(errno));
PARA_EMERG_LOG("length: %zu, flags: %d, fd: %d, offset: %zu\n",
length, flags, fd, (size_t)offset);
exit(EXIT_FAILURE);
}
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