X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=fd.c;h=830b15dad62f755ee75e1999b656d78a15890d10;hp=32d11079267abb8c53db0f2dea5756f77f24d6f5;hb=65b6448b8eb6f7442ba64affff58c388306a9159;hpb=eecc102ad0abeb0335fe994bb72031a15b9090d7 diff --git a/fd.c b/fd.c index 32d11079..830b15da 100644 --- a/fd.c +++ b/fd.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2009 Andre Noll + * Copyright (C) 2006-2012 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ @@ -11,11 +11,12 @@ #include #include #include -#include +#include #include "para.h" #include "error.h" #include "string.h" +#include "fd.h" /** * Write a buffer to a file descriptor, re-write on short writes. @@ -24,81 +25,228 @@ * \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. + * \return Standard. */ -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; + size_t total = len; assert(total); - *len = 0; - while (*len < total) { - int ret = write(fd, buf + *len, total - *len); + len = 0; + while (len < total) { + int ret = write(fd, buf + len, total - len); if (ret == -1) return -ERRNO_TO_PARA_ERROR(errno); - *len += ret; + len += ret; } - return 1; + return len; } /** - * Write a buffer to a non-blocking file descriptor. + * Send 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. * - * If \a max_bytes_per_write is non-zero, do not send more than that many bytes - * per write(). - * - * 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. + * \return Standard. + */ +__printf_2_3 int write_va_buffer(int fd, const char *fmt, ...) +{ + char *msg; + int ret; + + PARA_VSPRINTF(fmt, msg); + ret = write_buffer(fd, msg); + free(msg); + return ret; +} + +/** + * Write a buffer to a file descriptor, re-writing on short writes. * - * \return Negative on errors, number of bytes written else. + * \param fd The file descriptor. + * \param buf The buffer to write. + * \param len The number of bytes to write. + * + * 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 \a len 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: A positive return value < \a + * len indicates that some bytes have been written but the next write would + * block. */ -int write_nonblock(int fd, const char *buf, size_t len, - size_t max_bytes_per_write) +int write_nonblock(int fd, const char *buf, size_t len) { size_t written = 0; - int ret = 0; while (written < len) { - size_t num = len - written; - - 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) + ssize_t ret = write(fd, buf + written, len - written); + if (ret >= 0) { + written += ret; + 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; - if (ret < 0) - return -ERRNO_TO_PARA_ERROR(errno); - written += ret; + /* fatal error */ + return -ERRNO_TO_PARA_ERROR(errno); } return written; } /** - * Simple wrapper for readv(). + * 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 + * write_nonblock(), 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 write_nonblock(), 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. + * + * \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(). + * + * 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, fd_set *rfds, size_t *num_bytes) +{ + struct iovec iov = {.iov_base = buf, .iov_len = sz}; + return readv_nonblock(fd, &iov, 1, rfds, num_bytes); +} + +/** + * 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(). * - * \return A negative error code on errors, the return value of the underlying - * call to readv() otherwise. + * 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. * - * \sa readv(2). + * \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 para_readv(int fd, struct iovec *iov, int iovcnt) +int read_pattern(int fd, const char *pattern, size_t bufsize, fd_set *rfds) { - int ret = readv(fd, iov, iovcnt); + size_t n, len; + char *buf = para_malloc(bufsize + 1); + int ret = read_nonblock(fd, buf, bufsize, rfds, &n); + buf[n] = '\0'; if (ret < 0) - return -ERRNO_TO_PARA_ERROR(errno); + 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); + } + free(buf); return ret; } @@ -332,7 +480,7 @@ int para_chdir(const char *path) * \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; @@ -366,7 +514,7 @@ close_cwd: * * \return Standard. */ -int para_fchdir(int fd) +static int para_fchdir(int fd) { if (fchdir(fd) < 0) return -ERRNO_TO_PARA_ERROR(errno); @@ -449,6 +597,9 @@ out: int para_munmap(void *start, size_t length) { int err; + + if (!start) + return 0; if (munmap(start, length) >= 0) return 1; err = errno;