-/*
- * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
+/* Copyright (C) 2006 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
+
+/** \file fd.c Helper functions for file descriptor handling. */
+
+#include <regex.h>
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/mman.h>
+
+#include "para.h"
+#include "error.h"
+#include "string.h"
+#include "fd.h"
+
+/**
+ * Change the name or location of a file.
+ *
+ * \param oldpath File to be moved.
+ * \param newpath Destination.
*
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
+ * This is just a simple wrapper for the rename(2) system call which returns a
+ * paraslash error code and prints an error message on failure.
*
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
+ * \return Standard.
*
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
+ * \sa rename(2).
*/
+int xrename(const char *oldpath, const char *newpath)
+{
+ int ret = rename(oldpath, newpath);
-/** \file fd.c helper functions for file descriptor handling */
+ if (ret >= 0)
+ return 1;
+ ret = -ERRNO_TO_PARA_ERROR(errno);
+ PARA_ERROR_LOG("failed to rename %s -> %s\n", oldpath, newpath);
+ return ret;
+}
-#include "para.h"
+/**
+ * Write an array of buffers, handling non-fatal errors.
+ *
+ * \param fd The file descriptor to write to.
+ * \param iov Pointer to one or more buffers.
+ * \param iovcnt The number of buffers.
+ *
+ * EAGAIN, EWOULDBLOCK and EINTR are not considered error conditions. If a
+ * write operation fails with EAGAIN or EWOULDBLOCK, the number of bytes that
+ * have been written so far is returned. In the EINTR case the operation is
+ * retried. Short writes are handled by issuing a subsequent write operation
+ * for the remaining part.
+ *
+ * \return Negative on fatal errors, number of bytes written else.
+ *
+ * For blocking file descriptors, this function returns either the sum of all
+ * buffer sizes or a negative error code which indicates the fatal error that
+ * caused a write call to fail.
+ *
+ * For nonblocking file descriptors there is a third possibility: Any
+ * non-negative return value less than the sum of the buffer sizes indicates
+ * that a write operation returned EAGAIN/EWOULDBLOCK.
+ *
+ * \sa writev(2), \ref xwrite().
+ */
+int xwritev(int fd, struct iovec *iov, int iovcnt)
+{
+ size_t written = 0;
+ int i;
+ struct iovec saved_iov, *curiov;
-#include <fcntl.h>
-#include <sys/select.h>
+ i = 0;
+ curiov = iov;
+ saved_iov = *curiov;
+ while (i < iovcnt && curiov->iov_len > 0) {
+ ssize_t ret = writev(fd, curiov, iovcnt - i);
+ if (ret >= 0) {
+ written += ret;
+ while (ret > 0) {
+ if (ret < curiov->iov_len) {
+ curiov->iov_base += ret;
+ curiov->iov_len -= ret;
+ break;
+ }
+ ret -= curiov->iov_len;
+ *curiov = saved_iov;
+ i++;
+ if (i >= iovcnt)
+ return written;
+ curiov++;
+ saved_iov = *curiov;
+ }
+ continue;
+ }
+ if (errno == EINTR)
+ /*
+ * The write() call was interrupted by a signal before
+ * any data was written. Try again.
+ */
+ continue;
+ if (errno == EAGAIN || errno == EWOULDBLOCK)
+ /*
+ * We don't consider this an error. Note that POSIX
+ * allows either error to be returned, and does not
+ * require these constants to have the same value.
+ */
+ return written;
+ /* fatal error */
+ return -ERRNO_TO_PARA_ERROR(errno);
+ }
+ return written;
+}
-#include "error.h"
/**
- * check whether a file exists
+ * Write a buffer to a file descriptor, re-writing on short writes.
*
- * \param fn the file name
+ * \param fd The file descriptor.
+ * \param buf The buffer to write.
+ * \param len The number of bytes to write.
*
- * \return Non-zero iff file exists.
+ * This is a simple wrapper for \ref xwritev().
+ *
+ * \return The return value of the underlying call to \ref xwritev().
*/
-int file_exists(const char *fn)
+int xwrite(int fd, const char *buf, size_t len)
{
- struct stat statbuf;
+ struct iovec iov = {.iov_base = (void *)buf, .iov_len = len};
+ return xwritev(fd, &iov, 1);
+}
- return !stat(fn, &statbuf);
+/**
+ * Write to a file descriptor, fail on short writes.
+ *
+ * \param fd The file descriptor.
+ * \param buf The buffer to be written.
+ * \param len The length of the buffer.
+ *
+ * For blocking file descriptors this function behaves identical to \ref
+ * xwrite(). For non-blocking file descriptors it returns -E_SHORT_WRITE
+ * (rather than a value less than len) if not all data could be written.
+ *
+ * \return Number of bytes written on success, negative error code else.
+ */
+int write_all(int fd, const char *buf, size_t len)
+{
+ int ret = xwrite(fd, buf, len);
+
+ if (ret < 0)
+ return ret;
+ if (ret != len)
+ return -E_SHORT_WRITE;
+ return ret;
}
/**
- * paraslash's wrapper for select(2)
+ * A fprintf-like function for raw file descriptors.
+ *
+ * This function creates a string buffer according to the given format and
+ * writes this buffer to a file descriptor.
*
- * It calls select(2) (with no exceptfds) and starts over if select() was
- * interrupted by a signal.
+ * \param fd The file descriptor.
+ * \param fmt A format string.
*
- * \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 upper bound on the amount of time elapsed before select()
- * returns
+ * The difference to fprintf(3) is that the first argument is a file
+ * descriptor, not a FILE pointer. This function does not rely on stdio.
*
- * \return The return value of the underlying select() call.
+ * \return The return value of the underlying call to \ref write_all().
*
- * All arguments are passed verbatim to select(2).
- * \sa select(2) select_tut(2)
+ * \sa fprintf(3), \ref xvasprintf().
*/
-int para_select(int n, fd_set *readfds, fd_set *writefds,
- struct timeval *timeout)
+__printf_2_3 int write_va_buffer(int fd, const char *fmt, ...)
{
- int ret, err;
- do {
- ret = select(n, readfds, writefds, NULL, timeout);
- err = errno;
- } while (ret < 0 && err == EINTR);
+ char *msg;
+ int ret;
+ va_list ap;
+
+ va_start(ap, fmt);
+ ret = xvasprintf(&msg, fmt, ap);
+ va_end(ap);
+ ret = write_all(fd, msg, ret);
+ free(msg);
+ return ret;
+}
+
+/**
+ * Read from a non-blocking file descriptor into multiple buffers.
+ *
+ * \param fd The file descriptor to read from.
+ * \param iov Scatter/gather array used in readv().
+ * \param iovcnt Number of elements in \a iov.
+ * \param num_bytes Result pointer. Contains the number of bytes read from \a fd.
+ *
+ * This function tries to read up to sz bytes from fd, where sz is the sum of
+ * the lengths of all vectors in iov. Like \ref xwrite(), EAGAIN and EINTR are
+ * not considered error conditions. However, EOF is.
+ *
+ * \return Zero or a negative error code. If the underlying call to readv(2)
+ * returned zero (indicating an end of file condition) or failed for some
+ * reason other than EAGAIN or EINTR, a negative error code is returned.
+ *
+ * In any case, \a num_bytes contains the number of bytes that have been
+ * successfully read from \a fd (zero if the first readv() call failed with
+ * EAGAIN). Note that even if the function returns negative, some data might
+ * have been read before the error occurred. In this case \a num_bytes is
+ * positive.
+ *
+ * \sa \ref xwrite(), read(2), readv(2).
+ */
+int readv_nonblock(int fd, struct iovec *iov, int iovcnt, size_t *num_bytes)
+{
+ int ret, i, j;
+
+ *num_bytes = 0;
+ for (i = 0, j = 0; i < iovcnt;) {
+ /* fix up the first iov */
+ assert(j < iov[i].iov_len);
+ iov[i].iov_base += j;
+ iov[i].iov_len -= j;
+ ret = readv(fd, iov + i, iovcnt - i);
+ iov[i].iov_base -= j;
+ iov[i].iov_len += j;
+
+ if (ret == 0)
+ return -E_EOF;
+ if (ret < 0) {
+ if (errno == EAGAIN || errno == EINTR)
+ return 0;
+ return -ERRNO_TO_PARA_ERROR(errno);
+ }
+ *num_bytes += ret;
+ while (ret > 0) {
+ if (ret < iov[i].iov_len - j) {
+ j += ret;
+ break;
+ }
+ ret -= iov[i].iov_len - j;
+ j = 0;
+ if (++i >= iovcnt)
+ break;
+ }
+ }
+ return 0;
+}
+
+/**
+ * Read from a non-blocking file descriptor into a single buffer.
+ *
+ * \param fd The file descriptor to read from.
+ * \param buf The buffer to read data to.
+ * \param sz The size of \a buf.
+ * \param num_bytes \see \ref readv_nonblock().
+ *
+ * This is a simple wrapper for readv_nonblock() which uses an iovec with a single
+ * buffer.
+ *
+ * \return The return value of the underlying call to readv_nonblock().
+ */
+int read_nonblock(int fd, void *buf, size_t sz, size_t *num_bytes)
+{
+ struct iovec iov = {.iov_base = buf, .iov_len = sz};
+ return readv_nonblock(fd, &iov, 1, num_bytes);
+}
+
+/**
+ * Read a buffer and compare its contents to a string, ignoring case.
+ *
+ * \param fd The file descriptor to read from.
+ * \param expectation The expected string to compare to.
+ *
+ * The given file descriptor is expected to be in non-blocking mode. The string
+ * comparison is performed using strncasecmp(3).
+ *
+ * \return Zero if no data was available, positive if a buffer was read whose
+ * contents compare as equal to the expected string, negative otherwise.
+ * Possible errors: (a) not enough data was read, (b) the buffer contents
+ * compared as non-equal, (c) a read error occurred. In the first two cases,
+ * -E_READ_PATTERN is returned. In the read error case the (negative) return
+ * value of the underlying call to \ref read_nonblock() is returned.
+ */
+int read_and_compare(int fd, const char *expectation)
+{
+ size_t n, len = strlen(expectation);
+ char *buf = alloc(len + 1);
+ int ret = read_nonblock(fd, buf, len, &n);
+
if (ret < 0)
- PARA_CRIT_LOG("select error (%s)\n", strerror(err));
+ goto out;
+ buf[n] = '\0';
+ ret = 0;
+ if (n == 0)
+ goto out;
+ ret = -E_READ_PATTERN;
+ if (n < len)
+ goto out;
+ if (strncasecmp(buf, expectation, len) != 0)
+ goto out;
+ ret = 1;
+out:
+ free(buf);
return ret;
}
/**
- * set a file descriptor to non-blocking mode
+ * Set a file descriptor to blocking mode.
+ *
+ * \param fd The file descriptor.
+ *
+ * \return Standard.
+ */
+__must_check int mark_fd_blocking(int fd)
+{
+ int flags = fcntl(fd, F_GETFL);
+ if (flags < 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ flags = fcntl(fd, F_SETFL, ((long)flags) & ~O_NONBLOCK);
+ if (flags < 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ return 1;
+}
+
+/**
+ * Set a file descriptor to non-blocking mode.
*
- * \param fd The file descriptor
+ * \param fd The file descriptor.
*
- * \returns 1 on success, -E_F_GETFL, -E_F_SETFL, on errors.
+ * \return Standard.
*/
-int mark_fd_nonblock(int fd)
+__must_check int mark_fd_nonblocking(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 -ERRNO_TO_PARA_ERROR(errno);
+ flags = fcntl(fd, F_SETFL, ((long)flags) | O_NONBLOCK);
+ if (flags < 0)
+ return -ERRNO_TO_PARA_ERROR(errno);
return 1;
}
/**
- * set a file descriptor in a fd_set
+ * 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 map Result pointer.
+ *
+ * \return Standard.
+ *
+ * \sa mmap(2).
+ */
+int para_mmap(size_t length, int prot, int flags, int fd, void *map)
+{
+ void **m = map;
+
+ errno = EINVAL;
+ if (!length)
+ goto err;
+ *m = mmap(NULL, length, prot, flags, fd, (off_t)0);
+ if (*m != MAP_FAILED)
+ return 1;
+err:
+ *m = NULL;
+ return -ERRNO_TO_PARA_ERROR(errno);
+}
+
+/**
+ * Wrapper for the open(2) system call.
+ *
+ * \param path The filename.
+ * \param flags The usual open(2) flags.
+ * \param mode Specifies the permissions to use.
+ *
+ * The mode parameter must be specified when O_CREAT is in the flags, and is
+ * ignored otherwise.
+ *
+ * \return The file descriptor on success, negative on errors.
+ *
+ * \sa open(2).
+ */
+int para_open(const char *path, int flags, mode_t mode)
+{
+ int ret = open(path, flags, mode);
+
+ if (ret >= 0)
+ return ret;
+ return -ERRNO_TO_PARA_ERROR(errno);
+}
+
+/**
+ * Create a directory, don't fail if it already exists.
*
- * \param fd the file descriptor to be set
- * \param fds the file descriptor set
- * \param max_fileno highest-numbered file descriptor
+ * \param path Name of the directory to create.
*
- * 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.
-*/
-void para_fd_set(int fd, fd_set *fds, int *max_fileno)
+ * This function passes the fixed mode value 0777 to mkdir(3) (which consults
+ * the file creation mask and restricts this value).
+ *
+ * \return Zero if the path already existed as a directory or as a symbolic
+ * link which leads to a directory, one if the path did not exist and the
+ * directory has been created successfully, negative error code else.
+ */
+int para_mkdir(const char *path)
+{
+ /*
+ * We call opendir(3) rather than relying on stat(2) because this way
+ * we don't need extra code to get the symlink case right.
+ */
+ DIR *dir = opendir(path);
+
+ if (dir) {
+ closedir(dir);
+ return 0;
+ }
+ if (errno != ENOENT)
+ return -ERRNO_TO_PARA_ERROR(errno);
+ return mkdir(path, 0777) == 0? 1 : -ERRNO_TO_PARA_ERROR(errno);
+}
+
+/**
+ * Open a file and map it into memory.
+ *
+ * \param path Name of the regular file to map.
+ * \param open_mode Either \p O_RDONLY or \p O_RDWR.
+ * \param map On success, the mapping is returned here.
+ * \param size size of the mapping.
+ * \param fd_ptr The file descriptor of the mapping.
+ *
+ * If \a fd_ptr is \p NULL, the file descriptor resulting from the underlying
+ * open call is closed after mmap(). Otherwise the file is kept open and the
+ * file descriptor is returned in \a fd_ptr.
+ *
+ * \return Standard.
+ *
+ * \sa para_open(), mmap(2).
+ */
+int mmap_full_file(const char *path, int open_mode, void **map,
+ size_t *size, int *fd_ptr)
+{
+ int fd, ret, mmap_prot, mmap_flags;
+ struct stat file_status;
+
+ if (open_mode == O_RDONLY) {
+ mmap_prot = PROT_READ;
+ mmap_flags = MAP_PRIVATE;
+ } else {
+ mmap_prot = PROT_READ | PROT_WRITE;
+ mmap_flags = MAP_SHARED;
+ }
+ ret = para_open(path, open_mode, 0);
+ if (ret < 0)
+ return ret;
+ fd = ret;
+ if (fstat(fd, &file_status) < 0) {
+ ret = -ERRNO_TO_PARA_ERROR(errno);
+ goto out;
+ }
+ *size = file_status.st_size;
+ /*
+ * If the file is empty, *size is zero and mmap() would return EINVAL
+ * (Invalid argument). This error is common enough to spend an extra
+ * error code which explicitly states the problem.
+ */
+ ret = -E_EMPTY;
+ if (*size == 0)
+ goto out;
+ /*
+ * If fd refers to a directory, mmap() returns ENODEV (No such device),
+ * at least on Linux. "Is a directory" seems to be more to the point.
+ */
+ ret = -ERRNO_TO_PARA_ERROR(EISDIR);
+ if (S_ISDIR(file_status.st_mode))
+ goto out;
+
+ ret = para_mmap(*size, mmap_prot, mmap_flags, fd, map);
+out:
+ if (ret < 0 || !fd_ptr)
+ close(fd);
+ else
+ *fd_ptr = fd;
+ return ret;
+}
+
+/**
+ * A wrapper for munmap(2).
+ *
+ * \param start The start address of the memory mapping.
+ * \param length The size of the mapping.
+ *
+ * If NULL is passed as the start address, the length value is ignored and the
+ * function does nothing.
+ *
+ * \return Zero if NULL was passed, one if the memory area was successfully
+ * unmapped, a negative error code otherwise.
+ *
+ * \sa munmap(2), \ref mmap_full_file().
+ */
+int para_munmap(void *start, size_t length)
+{
+ if (!start)
+ return 0;
+ if (munmap(start, length) >= 0)
+ return 1;
+ return -ERRNO_TO_PARA_ERROR(errno);
+}
+
+/**
+ * Simple wrapper for poll(2).
+ *
+ * It calls poll(2) and starts over if the call was interrupted by a signal.
+ *
+ * \param fds See poll(2).
+ * \param nfds See poll(2).
+ * \param timeout See poll(2).
+ *
+ * \return The return value of the underlying poll() call on success, the
+ * negative paraslash error code on errors.
+ *
+ * All arguments are passed verbatim to poll(2).
+ */
+int xpoll(struct pollfd *fds, nfds_t nfds, int timeout)
+{
+ int ret;
+
+ do
+ ret = poll(fds, nfds, timeout);
+ while (ret < 0 && errno == EINTR);
+ return ret < 0? -ERRNO_TO_PARA_ERROR(errno) : ret;
+}
+
+/**
+ * Check a file descriptor for readability.
+ *
+ * \param fd The file descriptor.
+ *
+ * \return positive if fd is ready for reading, zero if it isn't, negative if
+ * an error occurred.
+ *
+ * \sa \ref write_ok().
+ */
+int read_ok(int fd)
+{
+ struct pollfd pfd = {.fd = fd, .events = POLLIN};
+ int ret = xpoll(&pfd, 1, 0);
+ return ret < 0? ret : pfd.revents & POLLIN;
+}
+
+/**
+ * Check a file descriptor for writability.
+ *
+ * \param fd The file descriptor.
+ *
+ * \return positive if fd is ready for writing, zero if it isn't, negative if
+ * an error occurred.
+ *
+ * \sa \ref read_ok().
+ */
+int write_ok(int fd)
+{
+ struct pollfd pfd = {.fd = fd, .events = POLLOUT};
+ int ret = xpoll(&pfd, 1, 0);
+ return ret < 0? ret : pfd.revents & POLLOUT;
+}
+
+/**
+ * Ensure that file descriptors 0, 1, and 2 are valid.
+ *
+ * Common approach that opens /dev/null until it gets a file descriptor greater
+ * than two.
+ */
+void valid_fd_012(void)
{
- FD_SET(fd, fds);
- *max_fileno = MAX(*max_fileno, fd);
+ while (1) {
+ int fd = open("/dev/null", O_RDWR);
+ if (fd < 0)
+ exit(EXIT_FAILURE);
+ if (fd > 2) {
+ close(fd);
+ break;
+ }
+ }
}
projects / paraslash.git / blobdiff