sandbox: Return error code from read/write/seek

The existing API for these functions is different from the rest of
U-Boot, in that any error code must be obtained from the errno variable
on failure. This variable is part of the C library, so accessing it
outside of the special 'sandbox' shim-functions is not ideal.

Adjust the API to return an error code, to avoid this. Update existing
uses to check for any negative value, rather than just -1.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/cpu/os.c

@@ -47,12 +47,24 @@ struct os_mem_hdr {
 
 ssize_t os_read(int fd, void *buf, size_t count)
 {
-	return read(fd, buf, count);
+	ssize_t ret;
+
+	ret = read(fd, buf, count);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 ssize_t os_write(int fd, const void *buf, size_t count)
 {
-	return write(fd, buf, count);
+	ssize_t ret;
+
+	ret = write(fd, buf, count);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 int os_printf(const char *fmt, ...)
@@ -69,6 +81,8 @@ int os_printf(const char *fmt, ...)
 
 off_t os_lseek(int fd, off_t offset, int whence)
 {
+	off_t ret;
+
 	if (whence == OS_SEEK_SET)
 		whence = SEEK_SET;
 	else if (whence == OS_SEEK_CUR)
@@ -77,7 +91,11 @@ off_t os_lseek(int fd, off_t offset, int whence)
 		whence = SEEK_END;
 	else
 		os_exit(1);
-	return lseek(fd, offset, whence);
+	ret = lseek(fd, offset, whence);
+	if (ret == -1)
+		return -errno;
+
+	return ret;
 }
 
 int os_open(const char *pathname, int os_flags)

arch/sandbox/cpu/spl.c

@@ -195,16 +195,14 @@ static ulong read_fit_image(struct spl_load_info *load, ulong offset,
 
 	ret = os_lseek(load_ctx->fd, offset, OS_SEEK_SET);
 	if (ret < 0) {
-		printf("Failed to seek to %zx, got %zx (errno=%d)\n", offset,
-		       ret, errno);
-		return log_msg_ret("lse", -errno);
+		printf("Failed to seek to %zx, got %zx\n", offset, ret);
+		return log_msg_ret("lse", ret);
 	}
 
 	res = os_read(load_ctx->fd, buf, size);
 	if (res < 0) {
-		printf("Failed to read %lx bytes, got %ld (errno=%d)\n",
-		       size, res, errno);
-		return log_msg_ret("osr", -errno);
+		printf("Failed to read %lx bytes, got %ld\n", size, res);
+		return log_msg_ret("osr", res);
 	}
 
 	return size;
@@ -238,9 +236,9 @@ int sandbox_spl_load_fit(char *fname, int maxlen, struct spl_image_info *image)
 	}
 	ret = os_read(fd, header, sizeof(*header));
 	if (ret != sizeof(*header)) {
-		printf("Failed to read %lx bytes, got %ld (errno=%d)\n",
-		       sizeof(*header), ret, -errno);
-		return log_msg_ret("rea", -errno);
+		printf("Failed to read %lx bytes, got %d\n", sizeof(*header),
+		       ret);
+		return log_msg_ret("rea", ret);
 	}
 	load_ctx.fd = fd;
 

drivers/block/sandbox.c

@@ -25,7 +25,7 @@ static unsigned long host_block_read(struct udevice *dev,
 	struct udevice *host_dev = dev_get_parent(dev);
 	struct host_sb_plat *plat = dev_get_plat(host_dev);
 
-	if (os_lseek(plat->fd, start * desc->blksz, OS_SEEK_SET) == -1) {
+	if (os_lseek(plat->fd, start * desc->blksz, OS_SEEK_SET) < 0) {
 		printf("ERROR: Invalid block %lx\n", start);
 		return -1;
 	}
@@ -44,7 +44,7 @@ static unsigned long host_block_write(struct udevice *dev,
 	struct udevice *host_dev = dev_get_parent(dev);
 	struct host_sb_plat *plat = dev_get_plat(host_dev);
 
-	if (os_lseek(plat->fd, start * desc->blksz, OS_SEEK_SET) == -1) {
+	if (os_lseek(plat->fd, start * desc->blksz, OS_SEEK_SET) < 0) {
 		printf("ERROR: Invalid block %lx\n", start);
 		return -1;
 	}

drivers/usb/emul/sandbox_flash.c

@@ -196,7 +196,7 @@ static int handle_ufi_command(struct sandbox_flash_priv *priv, const void *buff,
 		   priv->fd != -1) {
 		offset = os_lseek(priv->fd, info->seek_block * info->block_size,
 				  OS_SEEK_SET);
-		if (offset == (off_t)-1)
+		if (offset < 0)
 			setup_fail_response(priv);
 		else
 			setup_response(priv);

fs/sandbox/sandboxfs.c

@@ -28,7 +28,7 @@ int sandbox_fs_read_at(const char *filename, loff_t pos, void *buffer,
 	if (fd < 0)
 		return fd;
 	ret = os_lseek(fd, pos, OS_SEEK_SET);
-	if (ret == -1) {
+	if (ret < 0) {
 		os_close(fd);
 		return ret;
 	}
@@ -65,14 +65,14 @@ int sandbox_fs_write_at(const char *filename, loff_t pos, void *buffer,
 	if (fd < 0)
 		return fd;
 	ret = os_lseek(fd, pos, OS_SEEK_SET);
-	if (ret == -1) {
+	if (ret < 0) {
 		os_close(fd);
 		return ret;
 	}
 	size = os_write(fd, buffer, towrite);
 	os_close(fd);
 
-	if (size == -1) {
+	if (size < 0) {
 		ret = -1;
 	} else {
 		ret = 0;

include/os.h

@@ -29,7 +29,7 @@ int os_printf(const char *format, ...);
  * @fd:		File descriptor as returned by os_open()
  * @buf:	Buffer to place data
  * @count:	Number of bytes to read
- * Return:	number of bytes read, or -1 on error
+ * Return:	number of bytes read, or -errno on error
  */
 ssize_t os_read(int fd, void *buf, size_t count);
 
@@ -39,7 +39,7 @@ ssize_t os_read(int fd, void *buf, size_t count);
  * @fd:		File descriptor as returned by os_open()
  * @buf:	Buffer containing data to write
  * @count:	Number of bytes to write
- * Return:	number of bytes written, or -1 on error
+ * Return:	number of bytes written, or -errno on error
  */
 ssize_t os_write(int fd, const void *buf, size_t count);
 
@@ -49,7 +49,7 @@ ssize_t os_write(int fd, const void *buf, size_t count);
  * @fd:		File descriptor as returned by os_open()
  * @offset:	File offset (based on whence)
  * @whence:	Position offset is relative to (see below)
- * Return:	new file offset
+ * Return:	new file offset, or -errno on error
  */
 off_t os_lseek(int fd, off_t offset, int whence);