X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=fd.c;h=bdba2765a0fe3c6be12a9b32679bd79c267c6eb3;hp=22550286d57747ec90bcdc4aa050c8bea8259e65;hb=60ef885705932a682097ad2b9f2379282d814e79;hpb=6ce3524dbc2e688aca298836cef0d3f314f70d9b diff --git a/fd.c b/fd.c index 22550286..bdba2765 100644 --- a/fd.c +++ b/fd.c @@ -1,23 +1,231 @@ /* - * Copyright (C) 2006-2007 Andre Noll + * Copyright (C) 2006-2010 Andre Noll * * Licensed under the GPL v2. For licencing details see COPYING. */ -/** \file fd.c helper functions for file descriptor handling */ +/** \file fd.c Helper functions for file descriptor handling. */ +#include #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. + * + * \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. + */ +int write_all(int fd, const char *buf, size_t *len) +{ + size_t total = *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; +} + +/** + * Write a buffer to a non-blocking 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. + * + * 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 Negative on errors, number of bytes written else. + */ +int write_nonblock(int fd, const char *buf, size_t len, + size_t max_bytes_per_write) +{ + 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) + return written; + if (ret < 0) + return -ERRNO_TO_PARA_ERROR(errno); + written += ret; + } + return written; +} + +/** + * 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 occured. 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. + * + * 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); + + 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); + } + free(buf); + return ret; +} + /** - * check whether a file exists + * Check whether a file exists. * - * \param fn the file name + * \param fn The file name. * * \return Non-zero iff file exists. */ @@ -49,16 +257,33 @@ int file_exists(const char *fn) int para_select(int n, fd_set *readfds, fd_set *writefds, struct timeval *timeout_tv) { - int ret, err; - do { + int ret; + do ret = select(n, readfds, writefds, NULL, timeout_tv); - err = errno; - } while (ret < 0 && err == EINTR); + while (ret < 0 && errno == EINTR); if (ret < 0) return -ERRNO_TO_PARA_ERROR(errno); return ret; } +/** + * 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. * @@ -66,7 +291,7 @@ int para_select(int n, fd_set *readfds, fd_set *writefds, * * \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) @@ -78,24 +303,20 @@ int mark_fd_nonblock(int fd) } /** - * set a file descriptor in a fd_set + * 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 + * \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 + * \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); - } + assert(fd >= 0 && fd < FD_SETSIZE); #if 0 { int flags = fcntl(fd, F_GETFL); @@ -110,15 +331,16 @@ void para_fd_set(int fd, fd_set *fds, int *max_fileno) } /** -* 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. -*/ + * 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: @@ -139,25 +361,32 @@ 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 + * \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. + * \param map Result pointer. * - * \return This function either returns a valid pointer to the mapped area - * or calls exit() on errors. + * \return Standard. + * + * \sa mmap(2). */ -void *para_mmap(size_t length, int prot, int flags, int fd, off_t offset) +int para_mmap(size_t length, int prot, int flags, int fd, off_t offset, + void *map) { - 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); + void **m = map; + + errno = EINVAL; + if (!length) + goto err; + *m = mmap(NULL, length, prot, flags, fd, offset); + if (*m != MAP_FAILED) + return 1; +err: + *m = NULL; + return -ERRNO_TO_PARA_ERROR(errno); } /** @@ -167,8 +396,8 @@ void *para_mmap(size_t length, int prot, int flags, int fd, off_t offset) * \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. + * 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. * @@ -186,9 +415,9 @@ int para_open(const char *path, int flags, mode_t mode) /** * Wrapper for chdir(2). * - * \param path the specified directory. + * \param path The specified directory. * - * \return Positive on success, negative on errors. + * \return Standard. */ int para_chdir(const char *path) { @@ -240,10 +469,10 @@ int para_opendir(const char *dirname, DIR **dir, int *cwd) if (*dir) return 1; ret = -ERRNO_TO_PARA_ERROR(errno); -/* Ignore return value of fchdir() and close(). We're busted anyway. */ -change_to_orig_dir: - if (cwd) - fchdir(*cwd); + /* Ignore return value of fchdir() and close(). We're busted anyway. */ + if (cwd) { + int __a_unused ret2 = fchdir(*cwd); /* STFU, gcc */ + } close_cwd: if (cwd) close(*cwd); @@ -253,7 +482,7 @@ close_cwd: /** * A wrapper for fchdir(). * - * \param fd An open file descriptor + * \param fd An open file descriptor. * * \return Standard. */ @@ -278,3 +507,176 @@ int para_mkdir(const char *path, mode_t mode) return 1; return -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; + ret = para_mmap(*size, mmap_prot, mmap_flags, fd, 0, 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. + * + * \return Standard. + * + * \sa munmap(2), mmap_full_file(). + */ +int para_munmap(void *start, size_t length) +{ + int err; + if (munmap(start, length) >= 0) + return 1; + err = errno; + PARA_ERROR_LOG("munmap (%p/%zu) failed: %s\n", start, length, + strerror(err)); + return -ERRNO_TO_PARA_ERROR(err); +} + +/** + * 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. + */ + +int write_ok(int fd) +{ + struct timeval tv; + fd_set wfds; + + FD_ZERO(&wfds); + FD_SET(fd, &wfds); + tv.tv_sec = 0; + tv.tv_usec = 0; + return para_select(fd + 1, NULL, &wfds, &tv); +} + +/** + * 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. + * + * \sa okir's Black Hats Manual. + */ +void valid_fd_012(void) +{ + while (1) { + int fd = open("/dev/null", O_RDWR); + if (fd < 0) + exit(EXIT_FAILURE); + if (fd > 2) { + close(fd); + break; + } + } +} + +/** + * Traverse the given directory recursively. + * + * \param dirname The directory to traverse. + * \param func The function to call for each entry. + * \param private_data Pointer to an arbitrary data structure. + * + * For each regular file under \a dirname, the supplied function \a func is + * called. The full path of the regular file and the \a private_data pointer + * are passed to \a func. Directories for which the calling process has no + * permissions to change to are silently ignored. + * + * \return Standard. + */ +int for_each_file_in_dir(const char *dirname, + int (*func)(const char *, void *), void *private_data) +{ + DIR *dir; + struct dirent *entry; + int cwd_fd, ret2, ret = para_opendir(dirname, &dir, &cwd_fd); + + if (ret < 0) + return ret == -ERRNO_TO_PARA_ERROR(EACCES)? 1 : ret; + /* scan cwd recursively */ + while ((entry = readdir(dir))) { + mode_t m; + char *tmp; + struct stat s; + + if (!strcmp(entry->d_name, ".")) + continue; + if (!strcmp(entry->d_name, "..")) + continue; + if (lstat(entry->d_name, &s) == -1) + continue; + m = s.st_mode; + if (!S_ISREG(m) && !S_ISDIR(m)) + continue; + tmp = make_message("%s/%s", dirname, entry->d_name); + if (!S_ISDIR(m)) { + ret = func(tmp, private_data); + free(tmp); + if (ret < 0) + goto out; + continue; + } + /* directory */ + ret = for_each_file_in_dir(tmp, func, private_data); + free(tmp); + if (ret < 0) + goto out; + } + ret = 1; +out: + closedir(dir); + ret2 = para_fchdir(cwd_fd); + if (ret2 < 0 && ret >= 0) + ret = ret2; + close(cwd_fd); + return ret; +}