X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=fd.c;h=6a26ce5e3d4d5f2993affc76a544e96db1a5738c;hp=46be22891e93f2f094f3118daef5780c067b4cea;hb=8eaa28075189eea5db470422e8b4110df723cce3;hpb=e8089cd5efad59a5eec689117acf563a38b8c6c7 diff --git a/fd.c b/fd.c index 46be2289..6a26ce5e 100644 --- a/fd.c +++ b/fd.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2006-2010 Andre Noll + * Copyright (C) 2006 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ @@ -10,96 +10,308 @@ #include #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. + * Change the name or location of a file. * - * \param fd The file descriptor. - * \param buf The buffer to be sent. - * \param len The length of \a buf. + * \param oldpath File to be moved. + * \param newpath Destination. + * + * 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. + * + * \return Standard. * - * \return Standard. In any case, the number of bytes that have been written is - * stored in \a len. + * \sa rename(2). */ -int write_all(int fd, const char *buf, size_t *len) +int xrename(const char *oldpath, const char *newpath) { - size_t total = *len; + int ret = rename(oldpath, newpath); - 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 1; + ret = -ERRNO_TO_PARA_ERROR(errno); + PARA_ERROR_LOG("failed to rename %s -> %s\n", oldpath, newpath); + return ret; } /** - * Write a buffer to a non-blocking file descriptor. + * Write an array of buffers to a file descriptor. * * \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 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. * - * If \a max_bytes_per_write is non-zero, do not send more than that many bytes - * per write(). + * 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. * - * 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. + * 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. * - * \return Negative on errors, number of bytes written else. + * \sa writev(2), \ref xwrite(). */ -int write_nonblock(int fd, const char *buf, size_t len, - size_t max_bytes_per_write) +int xwritev(int fd, struct iovec *iov, int iovcnt) { 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) + 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; - 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(). + * 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. + * + * 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 ret = xwrite(fd, buf, len); + + if (ret < 0) + return ret; + if (ret != len) + return -E_SHORT_WRITE; + return ret; +} + +/** + * Write a buffer given by a format string. + * + * \param fd The file descriptor. + * \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); + 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 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, where \a + * sz is the sum of the lengths of all vectors in \a iov. As for xwrite(), + * \p EAGAIN is not considered an error condition. However, \p 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 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, 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; } @@ -333,10 +545,11 @@ 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; + *dir = NULL; if (cwd) { ret = para_open(".", O_RDONLY, 0); if (ret < 0) @@ -367,7 +580,7 @@ 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); @@ -428,6 +641,22 @@ int mmap_full_file(const char *path, int open_mode, void **map, 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) @@ -450,6 +679,9 @@ out: int para_munmap(void *start, size_t length) { int err; + + if (!start) + return 0; if (munmap(start, length) >= 0) return 1; err = errno;