/*
- * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
+ * Copyright (C) 2006-2012 Andre Noll <maan@systemlinux.org>
*
* Licensed under the GPL v2. For licencing details see COPYING.
*/
#include <dirent.h>
#include <sys/mman.h>
#include <fcntl.h>
-#include <sys/select.h>
+#include <sys/uio.h>
#include "para.h"
#include "error.h"
#include "string.h"
+#include "fd.h"
/**
- * Write a buffer to a file descriptor, re-write on short writes.
+ * Write an array of buffers to a file descriptor.
+ *
+ * \param fd The file descriptor.
+ * \param iov Pointer to one or more buffers.
+ * \param iovcnt The number of buffers.
+ *
+ * EAGAIN/EWOULDBLOCK is not considered a fatal error condition. For example
+ * DCCP CCID3 has a sending wait queue which fills up and is emptied
+ * asynchronously. The EAGAIN case means that there is currently no space in
+ * the wait queue, but this can change at any moment.
+ *
+ * \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 the error code of the fatal error that caused the last
+ * write call to fail.
+ *
+ * For nonblocking file descriptors there is a third possibility: Any positive
+ * return value less than the sum of the buffer sizes indicates that some bytes
+ * have been written but the next write would block.
+ *
+ * \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;
+
+ 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;
+}
+
+/**
+ * Write a buffer to a file descriptor, re-writing on short writes.
+ *
+ * \param fd The file descriptor.
+ * \param buf The buffer to write.
+ * \param len The number of bytes to write.
+ *
+ * This is a simple wrapper for \ref xwritev().
+ *
+ * \return The return value of the underlying call to \ref xwritev().
+ */
+int xwrite(int fd, const char *buf, size_t len)
+{
+ struct iovec iov = {.iov_base = (void *)buf, .iov_len = len};
+ return xwritev(fd, &iov, 1);
+}
+
+/**
+ * Write all data to a file descriptor.
*
* \param fd The file descriptor.
* \param buf The buffer to be sent.
* \param len The length of \a buf.
*
- * \return Standard. In any case, the number of bytes that have been written is
- * stored in \a len.
+ * This is like \ref xwrite() but returns \p -E_SHORT_WRITE 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 write_all(int fd, const char *buf, size_t len)
{
- size_t total = *len;
+ int ret = xwrite(fd, buf, len);
- assert(total);
- *len = 0;
- while (*len < total) {
- int ret = write(fd, buf + *len, total - *len);
- if (ret == -1)
- return -ERRNO_TO_PARA_ERROR(errno);
- *len += ret;
- }
- return 1;
+ if (ret < 0)
+ return ret;
+ if (ret != len)
+ return -E_SHORT_WRITE;
+ return ret;
}
/**
- * Write a buffer to a non-blocking file descriptor.
+ * Write a buffer given by a format string.
*
* \param fd The file descriptor.
- * \param buf the buffer to write.
- * \param len the number of bytes of \a buf.
- * \param max_bytes_per_write Do not write more than that many bytes at once.
+ * \param fmt A format string.
+ *
+ * \return The return value of the underlying call to \ref write_all().
+ */
+__printf_2_3 int write_va_buffer(int fd, const char *fmt, ...)
+{
+ char *msg;
+ int ret;
+ va_list ap;
+
+ va_start(ap, fmt);
+ ret = xvasprintf(&msg, fmt, 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 rfds An optional fd set pointer.
+ * \param num_bytes Result pointer. Contains the number of bytes read from \a fd.
+ *
+ * If \a rfds is not \p NULL and the (non-blocking) file descriptor \a fd is
+ * not set in \a rfds, this function returns early without doing anything.
+ * Otherwise The function tries to read up to \a sz bytes from \a fd. As for
+ * xwrite(), EAGAIN is not considered an error condition. 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 \p EAGAIN, a negative return value 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, fd_set *rfds,
+ size_t *num_bytes)
+{
+ int ret, i, j;
+
+ *num_bytes = 0;
+ /*
+ * Avoid a shortcoming of select(): Reads from a non-blocking fd might
+ * return EAGAIN even if FD_ISSET() returns true. However, FD_ISSET()
+ * returning false definitely means that no data can currently be read.
+ * This is the common case, so it is worth to avoid the overhead of the
+ * read() system call in this case.
+ */
+ if (rfds && !FD_ISSET(fd, rfds))
+ return 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)
+ 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.
*
- * If \a max_bytes_per_write is non-zero, do not send more than that many bytes
- * per write().
+ * \param fd The file descriptor to read from.
+ * \param buf The buffer to read data to.
+ * \param sz The size of \a buf.
+ * \param rfds \see \ref readv_nonblock().
+ * \param num_bytes \see \ref readv_nonblock().
*
- * EAGAIN is not considered an error condition. For example CCID3 has a
- * sending wait queue which fills up and is emptied asynchronously. The EAGAIN
- * case means that there is currently no space in the wait queue, but this can
- * change at any moment.
+ * This is a simple wrapper for readv_nonblock() which uses an iovec with a single
+ * buffer.
*
- * \return Negative on errors, number of bytes written else.
+ * \return The return value of the underlying call to readv_nonblock().
*/
-int write_nonblock(int fd, const char *buf, size_t len,
- size_t max_bytes_per_write)
+int read_nonblock(int fd, void *buf, size_t sz, fd_set *rfds, size_t *num_bytes)
{
- size_t written = 0;
- int ret = 0;
+ struct iovec iov = {.iov_base = buf, .iov_len = sz};
+ return readv_nonblock(fd, &iov, 1, rfds, num_bytes);
+}
- while (written < len) {
- size_t num = len - written;
+/**
+ * Read a buffer and check its content for a pattern.
+ *
+ * \param fd The file descriptor to receive from.
+ * \param pattern The expected pattern.
+ * \param bufsize The size of the internal buffer.
+ * \param rfds Passed to read_nonblock().
+ *
+ * This function tries to read at most \a bufsize bytes from the non-blocking
+ * file descriptor \a fd. If at least \p strlen(\a pattern) bytes have been
+ * received, the beginning of the received buffer is compared with \a pattern,
+ * ignoring case.
+ *
+ * \return Positive if \a pattern was received, negative on errors, zero if no data
+ * was available to read.
+ *
+ * \sa \ref read_nonblock(), \sa strncasecmp(3).
+ */
+int read_pattern(int fd, const char *pattern, size_t bufsize, fd_set *rfds)
+{
+ size_t n, len;
+ char *buf = para_malloc(bufsize + 1);
+ int ret = read_nonblock(fd, buf, bufsize, rfds, &n);
- if (max_bytes_per_write && max_bytes_per_write < num)
- num = max_bytes_per_write;
- ret = write(fd, buf + written, num);
- if (ret < 0 && errno == EAGAIN)
- return written;
- if (ret < 0)
- return -ERRNO_TO_PARA_ERROR(errno);
- written += ret;
+ buf[n] = '\0';
+ if (ret < 0)
+ goto out;
+ ret = 0;
+ if (n == 0)
+ goto out;
+ ret = -E_READ_PATTERN;
+ len = strlen(pattern);
+ if (n < len)
+ goto out;
+ if (strncasecmp(buf, pattern, len) != 0)
+ goto out;
+ ret = 1;
+out:
+ if (ret < 0) {
+ PARA_NOTICE_LOG("%s\n", para_strerror(-ret));
+ PARA_NOTICE_LOG("recvd %zu bytes: %s\n", n, buf);
}
- return written;
+ free(buf);
+ return ret;
}
/**
* \sa getcwd(3).
*
*/
-int para_opendir(const char *dirname, DIR **dir, int *cwd)
+static int para_opendir(const char *dirname, DIR **dir, int *cwd)
{
int ret;
*
* \return Standard.
*/
-int para_fchdir(int fd)
+static int para_fchdir(int fd)
{
if (fchdir(fd) < 0)
return -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, 0, map);
out:
if (ret < 0 || !fd_ptr)
int para_munmap(void *start, size_t length)
{
int err;
+
+ if (!start)
+ return 0;
if (munmap(start, length) >= 0)
return 1;
err = errno;
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