Attachment 121477 Details for Bug 164473 – patch-io.c

patch-io.c

patch-io.c (text/x-csrc), 5.44 KB, created by Oleksii Samorukov on 2012-01-25 13:33:30 UTC

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Creator: Oleksii Samorukov

Created: 2012-01-25 13:33:30 UTC

Size: 5.44 KB

patch

obsolete

>--- libexfat/io.c	2012-01-25 13:07:21.467957180 +0000
>+++ libexfat/io.c	2012-01-25 13:26:10.599952890 +0000
>@@ -23,6 +23,7 @@
> #include <sys/types.h>
> #include <sys/uio.h>
> #include <sys/stat.h>
>+#include <string.h>
> #include <fcntl.h>
> #define __USE_UNIX98 /* for pread() in Linux */
> #include <unistd.h>
>@@ -49,26 +50,177 @@
> 		exfat_error("failed to fstat `%s'", spec);
> 		return -1;
> 	}
>-	if (!S_ISBLK(stbuf.st_mode) && !S_ISREG(stbuf.st_mode))
>+	if (!S_ISCHR(stbuf.st_mode) && !S_ISREG(stbuf.st_mode) && !S_ISBLK(stbuf.st_mode))
> 	{
> 		close(fd);
>-		exfat_error("`%s' is neither a block device, nor a regular file",
>+		exfat_error("`%s' is neither a special device, nor a regular file",
> 				spec);
> 		return -1;
> 	}
> 	return fd;
> }
> 
>+#define RAW_IO_MAX_SIZE (128 * 1024 * 1024)
>+#define DEVBSIZE 512 // better get from the device, but 512 should work as well
>+#define RAW_IO_ALIGNED(offset, count)			\
>+	(DEVBSIZE == 0 ||			\
>+	 ((offset) % DEVBSIZE == 0 &&	\
>+	  (count) % DEVBSIZE == 0))
>+#define RAW_IO_ALIGN(offset)				\
>+	((offset) / DEVBSIZE * DEVBSIZE)
>+#define RAW_IO_MAX_SIZE (128 * 1024 * 1024)
>+
>+
>+static int64_t aligned_pread(int fd, void *buf, int64_t count, int64_t offset)
>+{
>+	int64_t start, start_aligned;
>+	int64_t end, end_aligned;
>+	size_t count_aligned;
>+	char *buf_aligned;
>+	ssize_t nr;
>+
>+	/* short-circuit for regular files */
>+	start = offset;
>+	if (count > RAW_IO_MAX_SIZE)
>+		count = RAW_IO_MAX_SIZE;
>+	if (RAW_IO_ALIGNED(start, count))
>+		return pread(fd, buf, count, start); 
>+
>+	/*
>+	 * +- start_aligned                 +- end_aligned
>+	 * |                                |
>+	 * |     +- start           +- end  |
>+	 * v     v                  v       v
>+	 * |----------|----------|----------|
>+	 *       ^                  ^
>+	 *       +----- count ------+
>+	 * ^                                ^
>+	 * +-------- count_aligned ---------+
>+	 */
>+	start_aligned = RAW_IO_ALIGN(start);
>+	end = start + count;
>+	end_aligned = RAW_IO_ALIGN(end) +
>+	    (RAW_IO_ALIGNED(end, 0) ? 0 : DEVBSIZE);
>+	count_aligned = end_aligned - start_aligned;
>+/*	exfat_debug(
>+	    "%s: count = 0x%llx/0x%x, start = 0x%llx/0x%llx, end = 0x%llx/0x%llx\n",
>+	    dev->d_name, count, count_aligned,
>+	    start, start_aligned, end, end_aligned);
>+*/
>+	/* allocate buffer */
>+	buf_aligned = malloc(count_aligned);
>+	if (buf_aligned == NULL) {
>+		exfat_debug("malloc(%zu) failed\n", count_aligned);
>+		return -1;
>+	}
>+
>+	/* read aligned data */
>+	nr = pread(fd, buf_aligned, count_aligned, start_aligned);
>+	if (nr == 0)
>+		return 0;
>+	if (nr < 0 || nr < start - start_aligned) {
>+		free(buf_aligned);
>+		return -1;
>+	}
>+
>+	/* copy out */
>+	memcpy(buf, buf_aligned + (start - start_aligned), count);
>+	free(buf_aligned);
>+
>+	nr -= start - start_aligned;
>+	if (nr > count)
>+		nr = count;
>+	return nr;
>+}
>+
>+/**
>+ * aligned_pwrite - Perform an aligned positioned write from the device
>+ */
>+static int64_t aligned_pwrite(int fd, void const *buf, size_t count, off_t offset)
>+{
>+	int64_t start, start_aligned;
>+	int64_t end, end_aligned;
>+	size_t count_aligned;
>+	char *buf_aligned;
>+	ssize_t nw;
>+
>+	/* short-circuit for regular files */
>+	start = offset;
>+	if (count > RAW_IO_MAX_SIZE)
>+		count = RAW_IO_MAX_SIZE;
>+	if (RAW_IO_ALIGNED(start, count))
>+		return pwrite(fd, buf, count, start);
>+
>+	/*
>+	 * +- start_aligned                 +- end_aligned
>+	 * |                                |
>+	 * |     +- start           +- end  |
>+	 * v     v                  v       v
>+	 * |----------|----------|----------|
>+	 *       ^                  ^
>+	 *       +----- count ------+
>+	 * ^                                ^
>+	 * +-------- count_aligned ---------+
>+	 */
>+	start_aligned = RAW_IO_ALIGN(start);
>+	end = start + count;
>+	end_aligned = RAW_IO_ALIGN(end) +
>+	    (RAW_IO_ALIGNED(end, 0) ? 0 : DEVBSIZE);
>+	count_aligned = end_aligned - start_aligned;
>+	exfat_debug(
>+	    "device:%d: count = 0x%llx/0x%x, start = 0x%llx/0x%llx, end = 0x%llx/0x%llx\n",
>+	    fd, count, count_aligned,
>+	    start, start_aligned, end, end_aligned);
>+
>+	/* allocate buffer */
>+	buf_aligned = malloc(count_aligned);
>+	if (buf_aligned == NULL) {
>+		exfat_error("malloc(%d) failed\n", count_aligned);
>+		return -1;
>+	}
>+
>+	/* read aligned lead-in */
>+	if (pread(fd, buf_aligned, DEVBSIZE, start_aligned) != DEVBSIZE) {
>+		exfat_debug("read lead-in failed\n");
>+		free(buf_aligned);
>+		return -1;
>+	}
>+
>+	/* read aligned lead-out */
>+	if (end != end_aligned && count_aligned > DEVBSIZE) {
>+		if (pread(fd, buf_aligned + count_aligned - DEVBSIZE, DEVBSIZE, end_aligned - DEVBSIZE) != DEVBSIZE) {
>+			exfat_error("read lead-out failed\n");
>+			free(buf_aligned);
>+			return -1;
>+		}
>+	}
>+
>+	/* copy data to write */
>+	memcpy(buf_aligned + (start - start_aligned), buf, count);
>+
>+	/* write aligned data */
>+	nw = pwrite(fd, buf_aligned, count_aligned, start_aligned);
>+	free(buf_aligned);
>+	if (nw < 0 || nw < start - start_aligned)
>+		return -1;
>+
>+	nw -= start - start_aligned;
>+	if (nw > count)
>+		nw = count;
>+	return nw;
>+}
>+
>+
> void exfat_read_raw(void* buffer, size_t size, off_t offset, int fd)
> {
>-	if (pread(fd, buffer, size, offset) != size)
>+	if (aligned_pread(fd, buffer, size, offset) != size)
> 		exfat_bug("failed to read %zu bytes from file at %"PRIu64, size,
> 				(uint64_t) offset);
> }
> 
> void exfat_write_raw(const void* buffer, size_t size, off_t offset, int fd)
> {
>-	if (pwrite(fd, buffer, size, offset) != size)
>+	if (aligned_pwrite(fd, buffer, size, offset) != size)
> 		exfat_bug("failed to write %zu bytes to file at %"PRIu64, size,
> 				(uint64_t) offset);
> }

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Attachments on bug 164473: 121476 | 121477