X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Ffile_io.c;h=752c1121e8ee5f388452cc8bb9cfc8c927ef9c65;hb=0436be80bd6eea1e80d921d362ae546f17879e40;hp=7a3673235226e20b9974283ac78097121cd33de5;hpb=e8c3ca2d1d0cac3d64985b45a9f654d2029a7518;p=wimlib

diff --git a/src/file_io.c b/src/file_io.c
index 7a367323..752c1121 100644
--- a/src/file_io.c
+++ b/src/file_io.c
@@ -25,21 +25,27 @@
 #  include "config.h"
 #endif
 
+#include "wimlib/error.h"
 #include "wimlib/file_io.h"
+#include "wimlib/util.h"
 #ifdef __WIN32__
 #  include "wimlib/win32.h" /* For pread(), pwrite() replacements */
-#else
-#  include <sys/uio.h> /* for writev() and `struct iovec' */
 #endif
 
 #include <errno.h>
 #include <unistd.h>
 
 
-/* Like read(), but keep trying until everything has been written or we know for
- * sure that there was an error (or end-of-file). */
-size_t
-full_read(int fd, void *buf, size_t count)
+/* Wrapper around read() that checks for errors keeps retrying until all
+ * requested bytes have been read or until end-of file has occurred.
+ *
+ * Return values:
+ *	WIMLIB_ERR_SUCCESS			(0)
+ *	WIMLIB_ERR_READ				(errno set)
+ *	WIMLIB_ERR_UNEXPECTED_END_OF_FILE	(errno set to 0)
+ */
+int
+full_read(struct filedes *fd, void *buf, size_t count)
 {
 	ssize_t bytes_read;
 	size_t bytes_remaining;
@@ -48,69 +54,137 @@ full_read(int fd, void *buf, size_t count)
 	     bytes_remaining != 0;
 	     bytes_remaining -= bytes_read, buf += bytes_read)
 	{
-		bytes_read = read(fd, buf, bytes_remaining);
-		if (bytes_read <= 0) {
-			if (bytes_read == 0)
-				errno = EIO;
-			else if (errno == EINTR)
+		bytes_read = read(fd->fd, buf, bytes_remaining);
+		if (unlikely(bytes_read <= 0)) {
+			if (bytes_read == 0) {
+				errno = 0;
+				return WIMLIB_ERR_UNEXPECTED_END_OF_FILE;
+			} else if (errno == EINTR) {
 				continue;
-			break;
+			} else {
+				return WIMLIB_ERR_READ;
+			}
 		}
 	}
-	return count - bytes_remaining;
+	count -= bytes_remaining;
+	fd->offset += count;
+	return 0;
 }
 
-/* Like write(), but keep trying until everything has been written or we know
- * for sure that there was an error. */
-size_t
-full_write(int fd, const void *buf, size_t count)
+static int
+pipe_read(struct filedes *fd, void *buf, size_t count, off_t offset)
 {
-	ssize_t bytes_written;
+	int ret;
+
+	/* Verify the offset.  */
+	if (offset < fd->offset) {
+		ERROR("Can't seek backwards in pipe "
+		      "(offset %"PRIu64" => %"PRIu64").\n"
+		      "        Make sure the WIM was captured as "
+		      "pipable.", fd->offset, offset);
+		errno = ESPIPE;
+		return WIMLIB_ERR_RESOURCE_ORDER;
+	}
+
+	/* Manually seek to the requested position.  */
+	while (fd->offset != offset) {
+		size_t bytes_to_read = min(offset - fd->offset, BUFFER_SIZE);
+		u8 dummy[bytes_to_read];
+
+		ret = full_read(fd, dummy, bytes_to_read);
+		if (ret)
+			return ret;
+	}
+
+	/* Do the actual read.  */
+	return full_read(fd, buf, count);
+}
+
+/* Wrapper around pread() that checks for errors and keeps retrying until all
+ * requested bytes have been read or until end-of file has occurred.  This also
+ * transparently handle reading from pipe files, but the caller needs to be sure
+ * the requested offset is greater than or equal to the current offset, or else
+ * WIMLIB_ERR_RESOURCE_ORDER will be returned.
+ *
+ * Return values:
+ *	WIMLIB_ERR_SUCCESS			(0)
+ *	WIMLIB_ERR_READ				(errno set)
+ *	WIMLIB_ERR_UNEXPECTED_END_OF_FILE	(errno set to 0)
+ *	WIMLIB_ERR_RESOURCE_ORDER		(errno set to ESPIPE)
+ */
+int
+full_pread(struct filedes *fd, void *buf, size_t count, off_t offset)
+{
+	ssize_t bytes_read;
 	size_t bytes_remaining;
 
+	if (fd->is_pipe)
+		goto is_pipe;
+
 	for (bytes_remaining = count;
 	     bytes_remaining != 0;
-	     bytes_remaining -= bytes_written, buf += bytes_written)
+	     bytes_remaining -= bytes_read, buf += bytes_read,
+		offset += bytes_read)
 	{
-		bytes_written = write(fd, buf, bytes_remaining);
-		if (bytes_written < 0) {
-			if (errno == EINTR)
+		bytes_read = pread(fd->fd, buf, bytes_remaining, offset);
+		if (unlikely(bytes_read <= 0)) {
+			if (bytes_read == 0) {
+				errno = 0;
+				return WIMLIB_ERR_UNEXPECTED_END_OF_FILE;
+			} else if (errno == EINTR) {
 				continue;
-			break;
+			} else if (errno == ESPIPE) {
+				fd->is_pipe = 1;
+				goto is_pipe;
+			} else {
+				return WIMLIB_ERR_READ;
+			}
 		}
 	}
-	return count - bytes_remaining;
+	return 0;
+
+is_pipe:
+	return pipe_read(fd, buf, count, offset);
 }
 
-/* Like pread(), but keep trying until everything has been read or we know for
- * sure that there was an error (or end-of-file) */
-size_t
-full_pread(int fd, void *buf, size_t count, off_t offset)
+/* Wrapper around write() that checks for errors and keeps retrying until all
+ * requested bytes have been written.
+ *
+ * Return values:
+ *	WIMLIB_ERR_SUCCESS			(0)
+ *	WIMLIB_ERR_WRITE			(errno set)
+ */
+int
+full_write(struct filedes *fd, const void *buf, size_t count)
 {
-	ssize_t bytes_read;
+	ssize_t bytes_written;
 	size_t bytes_remaining;
 
 	for (bytes_remaining = count;
 	     bytes_remaining != 0;
-	     bytes_remaining -= bytes_read, buf += bytes_read,
-	     	offset += bytes_read)
+	     bytes_remaining -= bytes_written, buf += bytes_written)
 	{
-		bytes_read = pread(fd, buf, bytes_remaining, offset);
-		if (bytes_read <= 0) {
-			if (bytes_read == 0)
-				errno = EIO;
-			else if (errno == EINTR)
+		bytes_written = write(fd->fd, buf, bytes_remaining);
+		if (unlikely(bytes_written < 0)) {
+			if (errno == EINTR)
 				continue;
-			break;
+			return WIMLIB_ERR_WRITE;
 		}
 	}
-	return count - bytes_remaining;
+	fd->offset += count;
+	return 0;
 }
 
-/* Like pwrite(), but keep trying until everything has been written or we know
- * for sure that there was an error. */
-size_t
-full_pwrite(int fd, const void *buf, size_t count, off_t offset)
+
+/* Wrapper around pwrite() that checks for errors and keeps retrying until all
+ * requested bytes have been written.
+ *
+ * Return values:
+ *	WIMLIB_ERR_SUCCESS	(0)
+ *	WIMLIB_ERR_WRITE	(errno set)
+ * */
+int
+full_pwrite(struct filedes *fd, const void *buf, size_t count, off_t offset)
 {
 	ssize_t bytes_written;
 	size_t bytes_remaining;
@@ -118,51 +192,45 @@ full_pwrite(int fd, const void *buf, size_t count, off_t offset)
 	for (bytes_remaining = count;
 	     bytes_remaining != 0;
 	     bytes_remaining -= bytes_written, buf += bytes_written,
-	     	offset += bytes_written)
+		offset += bytes_written)
 	{
-		bytes_written = pwrite(fd, buf, bytes_remaining, offset);
-		if (bytes_written < 0) {
+		bytes_written = pwrite(fd->fd, buf, bytes_remaining, offset);
+		if (unlikely(bytes_written < 0)) {
 			if (errno == EINTR)
 				continue;
-			break;
+			return WIMLIB_ERR_WRITE;
 		}
 	}
-	return count - bytes_remaining;
+	return 0;
+}
+
+ssize_t
+raw_pread(struct filedes *fd, void *buf, size_t count, off_t offset)
+{
+	return pread(fd->fd, buf, count, offset);
 }
 
-/* Like writev(), but keep trying until everything has been written or we know
- * for sure that there was an error. */
-size_t
-full_writev(int fd, struct iovec *iov, int iovcnt)
+ssize_t
+raw_pwrite(struct filedes *fd, const void *buf, size_t count, off_t offset)
 {
-	size_t total_bytes_written = 0;
-	while (iovcnt > 0) {
-		ssize_t bytes_written;
+	return pwrite(fd->fd, buf, count, offset);
+}
 
-		bytes_written = writev(fd, iov, iovcnt);
-		if (bytes_written < 0) {
-			if (errno == EINTR)
-				continue;
-			break;
-		}
-		total_bytes_written += bytes_written;
-		while (bytes_written) {
-			if (bytes_written >= iov[0].iov_len) {
-				bytes_written -= iov[0].iov_len;
-				iov++;
-				iovcnt--;
-			} else {
-				iov[0].iov_base += bytes_written;
-				iov[0].iov_len -= bytes_written;
-				bytes_written = 0;
-			}
-		}
+off_t filedes_seek(struct filedes *fd, off_t offset)
+{
+	if (fd->is_pipe) {
+		errno = ESPIPE;
+		return -1;
+	}
+	if (fd->offset != offset) {
+		if (lseek(fd->fd, offset, SEEK_SET) == -1)
+			return -1;
+		fd->offset = offset;
 	}
-	return total_bytes_written;
+	return offset;
 }
 
-off_t
-filedes_offset(int fd)
+bool filedes_is_seekable(struct filedes *fd)
 {
-	return lseek(fd, 0, SEEK_CUR);
+	return !fd->is_pipe && lseek(fd->fd, 0, SEEK_CUR) != -1;
 }