fs: Create functions to load and allocate a file

This functionality current sits in bootstd, but it is more generally
useful. Add a function to load a file into memory, allocating it as
needed. Adjust bootstd to use this version.

Note: Tests are added in the subsequent patch which converts the 'cat'
command to use this function.

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

boot/bootmeth-uclass.c

@@ -301,32 +301,6 @@ int bootmeth_try_file(struct bootflow *bflow, struct blk_desc *desc,
 	return 0;
 }
 
-static int alloc_file(const char *fname, uint size, void **bufp)
-{
-	loff_t bytes_read;
-	ulong addr;
-	char *buf;
-	int ret;
-
-	buf = malloc(size + 1);
-	if (!buf)
-		return log_msg_ret("buf", -ENOMEM);
-	addr = map_to_sysmem(buf);
-
-	ret = fs_read(fname, addr, 0, size, &bytes_read);
-	if (ret) {
-		free(buf);
-		return log_msg_ret("read", ret);
-	}
-	if (size != bytes_read)
-		return log_msg_ret("bread", -EIO);
-	buf[size] = '\0';
-
-	*bufp = buf;
-
-	return 0;
-}
-
 int bootmeth_alloc_file(struct bootflow *bflow, uint size_limit, uint align)
 {
 	void *buf;
@@ -338,7 +312,7 @@ int bootmeth_alloc_file(struct bootflow *bflow, uint size_limit, uint align)
 	if (size > size_limit)
 		return log_msg_ret("chk", -E2BIG);
 
-	ret = alloc_file(bflow->fname, bflow->size, &buf);
+	ret = fs_read_alloc(bflow->fname, bflow->size, align, &buf);
 	if (ret)
 		return log_msg_ret("all", ret);
 
@@ -374,7 +348,7 @@ int bootmeth_alloc_other(struct bootflow *bflow, const char *fname,
 	if (ret)
 		return log_msg_ret("fs", ret);
 
-	ret = alloc_file(path, size, &buf);
+	ret = fs_read_alloc(path, size, 0, &buf);
 	if (ret)
 		return log_msg_ret("all", ret);
 

fs/fs.c

@@ -13,6 +13,7 @@
 #include <env.h>
 #include <lmb.h>
 #include <log.h>
+#include <malloc.h>
 #include <mapmem.h>
 #include <part.h>
 #include <ext4fs.h>
@@ -26,6 +27,7 @@
 #include <asm/io.h>
 #include <div64.h>
 #include <linux/math64.h>
+#include <linux/sizes.h>
 #include <efi_loader.h>
 #include <squashfs.h>
 #include <erofs.h>
@@ -1008,3 +1010,59 @@ int do_fs_types(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
 	puts("\n");
 	return CMD_RET_SUCCESS;
 }
+
+int fs_read_alloc(const char *fname, ulong size, uint align, void **bufp)
+{
+	loff_t bytes_read;
+	ulong addr;
+	char *buf;
+	int ret;
+
+	buf = memalign(align, size + 1);
+	if (!buf)
+		return log_msg_ret("buf", -ENOMEM);
+	addr = map_to_sysmem(buf);
+
+	ret = fs_read(fname, addr, 0, size, &bytes_read);
+	if (ret) {
+		free(buf);
+		return log_msg_ret("read", ret);
+	}
+	if (size != bytes_read)
+		return log_msg_ret("bread", -EIO);
+	buf[size] = '\0';
+
+	*bufp = buf;
+
+	return 0;
+}
+
+int fs_load_alloc(const char *ifname, const char *dev_part_str,
+		  const char *fname, ulong max_size, ulong align, void **bufp,
+		  ulong *sizep)
+{
+	loff_t size;
+	void *buf;
+	int ret;
+
+	if (fs_set_blk_dev(ifname, dev_part_str, FS_TYPE_ANY))
+		return log_msg_ret("set", -ENOMEDIUM);
+
+	ret = fs_size(fname, &size);
+	if (ret)
+		return log_msg_ret("sz", -ENOENT);
+
+	if (size >= (max_size ?: SZ_1G))
+		return log_msg_ret("sz", -E2BIG);
+
+	if (fs_set_blk_dev(ifname, dev_part_str, FS_TYPE_ANY))
+		return log_msg_ret("set", -ENOMEDIUM);
+
+	ret = fs_read_alloc(fname, size, align, &buf);
+	if (ret)
+		return log_msg_ret("al", ret);
+	*sizep = size;
+	*bufp = buf;
+
+	return 0;
+}

include/fs.h

@@ -300,4 +300,42 @@ int do_fs_type(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]);
  */
 int do_fs_types(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[]);
 
+/**
+ * fs_read_alloc() - Allocate space for a file and read it
+ *
+ * You must call fs_set_blk_dev() or a similar function before calling this,
+ * since that sets up the block device to use.
+ *
+ * The file is terminated with a nul character
+ *
+ * @fname: Filename to read
+ * @size: Size of file to read (must be correct!)
+ * @align: Alignment to use for memory allocation (0 for default)
+ * @bufp: On success, returns the allocated buffer with the nul-terminated file
+ *	in it
+ * Return: 0 if OK, -ENOMEM if out of memory, -EIO if read failed
+ */
+int fs_read_alloc(const char *fname, ulong size, uint align, void **bufp);
+
+/**
+ * fs_load_alloc() - Load a file into allocated space
+ *
+ * The file is terminated with a nul character
+ *
+ * @ifname: Interface name to read from (e.g. "mmc")
+ * @dev_part_str: Device and partition string (e.g. "1:2")
+ * @fname: Filename to read
+ * @max_size: Maximum allowed size for the file (use 0 for 1GB)
+ * @align: Alignment to use for memory allocation (0 for default)
+ * @bufp: On success, returns the allocated buffer with the nul-terminated file
+ *	in it
+ * @sizep: On success, returns the size of the file
+ * Return: 0 if OK, -ENOMEM if out of memory, -ENOENT if the file does not
+ * exist, -ENOMEDIUM if the device does not exist, -E2BIG if the file is too
+ * large (greater than @max_size), -EIO if read failed
+ */
+int fs_load_alloc(const char *ifname, const char *dev_part_str,
+		  const char *fname, ulong max_size, ulong align, void **bufp,
+		  ulong *sizep);
+
 #endif /* _FS_H */