ext4: Allow reading files with non-zero offset, clamp read len

Support was already implemented, but not hooked up. This fixes several
fails in the test cases.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Acked-by: Stephen Warren <swarren@wwwdotorg.org>

common/spl/spl_ext.c

@@ -42,7 +42,7 @@ int spl_load_image_ext(struct spl_image_info *spl_image,
 		puts("spl: ext4fs_open failed\n");
 		goto end;
 	}
-	err = ext4fs_read((char *)header, sizeof(struct image_header), &actlen);
+	err = ext4fs_read((char *)header, 0, sizeof(struct image_header), &actlen);
 	if (err < 0) {
 		puts("spl: ext4fs_read failed\n");
 		goto end;
@@ -54,7 +54,7 @@ int spl_load_image_ext(struct spl_image_info *spl_image,
 		goto end;
 	}
 
-	err = ext4fs_read((char *)spl_image->load_addr, filelen, &actlen);
+	err = ext4fs_read((char *)spl_image->load_addr, 0, filelen, &actlen);
 
 end:
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
@@ -97,7 +97,7 @@ int spl_load_image_ext_os(struct spl_image_info *spl_image,
 			puts("spl: ext4fs_open failed\n");
 			goto defaults;
 		}
-		err = ext4fs_read((void *)CONFIG_SYS_SPL_ARGS_ADDR, filelen, &actlen);
+		err = ext4fs_read((void *)CONFIG_SYS_SPL_ARGS_ADDR, 0, filelen, &actlen);
 		if (err < 0) {
 			printf("spl: error reading image %s, err - %d, falling back to default\n",
 			       file, err);
@@ -127,7 +127,7 @@ defaults:
 	if (err < 0)
 		puts("spl: ext4fs_open failed\n");
 
-	err = ext4fs_read((void *)CONFIG_SYS_SPL_ARGS_ADDR, filelen, &actlen);
+	err = ext4fs_read((void *)CONFIG_SYS_SPL_ARGS_ADDR, 0, filelen, &actlen);
 	if (err < 0) {
 #ifdef CONFIG_SPL_LIBCOMMON_SUPPORT
 		printf("%s: error reading image %s, err - %d\n",

fs/ext4/ext4fs.c

@@ -65,8 +65,8 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
 	short status;
 
 	/* Adjust len so it we can't read past the end of the file. */
-	if (len > filesize)
-		len = filesize;
+	if (len + pos > filesize)
+		len = (filesize - pos);
 
 	blockcnt = lldiv(((len + pos) + blocksize - 1), blocksize);
 
@@ -190,12 +190,12 @@ int ext4fs_size(const char *filename, loff_t *size)
 	return ext4fs_open(filename, size);
 }
 
-int ext4fs_read(char *buf, loff_t len, loff_t *actread)
+int ext4fs_read(char *buf, loff_t offset, loff_t len, loff_t *actread)
 {
 	if (ext4fs_root == NULL || ext4fs_file == NULL)
-		return 0;
+		return -1;
 
-	return ext4fs_read_file(ext4fs_file, 0, len, buf, actread);
+	return ext4fs_read_file(ext4fs_file, offset, len, buf, actread);
 }
 
 int ext4fs_probe(struct blk_desc *fs_dev_desc,
@@ -217,11 +217,6 @@ int ext4_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
 	loff_t file_len;
 	int ret;
 
-	if (offset != 0) {
-		printf("** Cannot support non-zero offset **\n");
-		return -1;
-	}
-
 	ret = ext4fs_open(filename, &file_len);
 	if (ret < 0) {
 		printf("** File not found %s **\n", filename);
@@ -231,7 +226,7 @@ int ext4_read_file(const char *filename, void *buf, loff_t offset, loff_t len,
 	if (len == 0)
 		len = file_len;
 
-	return ext4fs_read(buf, len, len_read);
+	return ext4fs_read(buf, offset, len, len_read);
 }
 
 int ext4fs_uuid(char *uuid_str)

include/ext4fs.h

@@ -135,7 +135,7 @@ int ext4_write_file(const char *filename, void *buf, loff_t offset, loff_t len,
 
 struct ext_filesystem *get_fs(void);
 int ext4fs_open(const char *filename, loff_t *len);
-int ext4fs_read(char *buf, loff_t len, loff_t *actread);
+int ext4fs_read(char *buf, loff_t offset, loff_t len, loff_t *actread);
 int ext4fs_mount(unsigned part_length);
 void ext4fs_close(void);
 void ext4fs_reinit_global(void);