X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=fd.c;h=1c67f22bb284ab11ffda80bb90c0693661b0328c;hp=5db30b63fd9ed62148b8d04390ec8456826337a3;hb=337d7784b0f8bc30b1fa9af56ace503acd97d40d;hpb=f2a7b00cf72104a38733b7bf3add9fb19dd71c93;ds=sidebyside

diff --git a/fd.c b/fd.c
index 5db30b63..1c67f22b 100644
--- a/fd.c
+++ b/fd.c
@@ -1,8 +1,88 @@
+/*
+ * Copyright (C) 2006-2009 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file fd.c Helper functions for file descriptor handling. */
+
+#include <sys/types.h>
+#include <dirent.h>
+#include <sys/mman.h>
+#include <fcntl.h>
+#include <sys/select.h>
+
 #include "para.h"
+#include "error.h"
+#include "string.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;
+}
+
 /**
- * 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.
  */
@@ -12,3 +92,453 @@ int file_exists(const char *fn)
 
 	return !stat(fn, &statbuf);
 }
+
+/**
+ * Paraslash's wrapper for select(2).
+ *
+ * It calls select(2) (with no exceptfds) and starts over if select() was
+ * interrupted by a signal.
+ *
+ * \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_tv upper bound on the amount of time elapsed before select()
+ * returns.
+ *
+ * \return The return value of the underlying select() call on success, the
+ * negative system error code on errors.
+ *
+ * All arguments are passed verbatim to select(2).
+ * \sa select(2) select_tut(2).
+ */
+int para_select(int n, fd_set *readfds, fd_set *writefds,
+		struct timeval *timeout_tv)
+{
+	int ret, err;
+	do {
+		ret = select(n, readfds, writefds, NULL, timeout_tv);
+		err = errno;
+	} while (ret < 0 && err == 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.
+ *
+ * \param fd The file descriptor.
+ *
+ * \return Standard.
+ */
+__must_check int mark_fd_nonblocking(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 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.
+ *
+ * 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.
+*/
+void para_fd_set(int fd, fd_set *fds, int *max_fileno)
+{
+	assert(fd >= 0 && fd < FD_SETSIZE);
+#if 0
+	{
+		int flags = fcntl(fd, F_GETFL);
+		if (!(flags & O_NONBLOCK)) {
+			PARA_EMERG_LOG("fd %d is a blocking file descriptor\n", fd);
+			exit(EXIT_FAILURE);
+		}
+	}
+#endif
+	FD_SET(fd, fds);
+	*max_fileno = PARA_MAX(*max_fileno, fd);
+}
+
+/**
+ * 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:
+	if (fgets(line, size, f))
+		return 1;
+	if (feof(f))
+		return 0;
+	if (!ferror(f))
+		return -E_FGETS;
+	if (errno != EINTR) {
+		PARA_ERROR_LOG("%s\n", strerror(errno));
+		return -E_FGETS;
+	}
+	clearerr(f);
+	goto 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 map Result pointer.
+ *
+ * \return Standard.
+ *
+ * \sa mmap(2).
+ */
+int para_mmap(size_t length, int prot, int flags, int fd, off_t offset,
+		void *map)
+{
+	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);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * Wrapper for chdir(2).
+ *
+ * \param path The specified directory.
+ *
+ * \return Standard.
+ */
+int para_chdir(const char *path)
+{
+	int ret = chdir(path);
+
+	if (ret >= 0)
+		return 1;
+	return -ERRNO_TO_PARA_ERROR(errno);
+}
+
+/**
+ * Save the cwd and open a given directory.
+ *
+ * \param dirname Path to the directory to open.
+ * \param dir Result pointer.
+ * \param cwd File descriptor of the current working directory.
+ *
+ * \return Standard.
+ *
+ * Opening the current directory (".") and calling fchdir() to return is
+ * usually faster and more reliable than saving cwd in some buffer and calling
+ * chdir() afterwards.
+ *
+ * If \a cwd is not \p NULL "." is opened and the resulting file descriptor is
+ * stored in \a cwd. If the function returns success, and \a cwd is not \p
+ * NULL, the caller must close this file descriptor (probably after calling
+ * fchdir(*cwd)).
+ *
+ * On errors, the function undos everything, so the caller needs neither close
+ * any files, nor change back to the original working directory.
+ *
+ * \sa getcwd(3).
+ *
+ */
+int para_opendir(const char *dirname, DIR **dir, int *cwd)
+{
+	int ret;
+
+	if (cwd) {
+		ret = para_open(".", O_RDONLY, 0);
+		if (ret < 0)
+			return ret;
+		*cwd = ret;
+	}
+	ret = para_chdir(dirname);
+	if (ret < 0)
+		goto close_cwd;
+	*dir = opendir(".");
+	if (*dir)
+		return 1;
+	ret = -ERRNO_TO_PARA_ERROR(errno);
+	/* 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);
+	return ret;
+}
+
+/**
+ * A wrapper for fchdir().
+ *
+ * \param fd An open file descriptor.
+ *
+ * \return Standard.
+ */
+int para_fchdir(int fd)
+{
+	if (fchdir(fd) < 0)
+		return -ERRNO_TO_PARA_ERROR(errno);
+	return 1;
+}
+
+/**
+ * A wrapper for mkdir(2).
+ *
+ * \param path Name of the directory to create.
+ * \param mode The permissions to use.
+ *
+ * \return Standard.
+ */
+int para_mkdir(const char *path, mode_t mode)
+{
+	if (!mkdir(path, 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 Positive on success, \p -E_MUNMAP on errors.
+ *
+ * \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 = {0, 0};
+	fd_set wfds;
+	int ret;
+again:
+	FD_ZERO(&wfds);
+	FD_SET(fd, &wfds);
+	tv.tv_sec = 0;
+	tv.tv_usec = 0;
+	ret = select(fd + 1, NULL, &wfds, NULL, &tv);
+	if (ret < 0 && errno == EINTR)
+		goto again;
+	return ret;
+}
+
+/**
+ * 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;
+}