lib: move freader into buildid.h

Move struct freader and prototypes of the functions operating on it into
the buildid.h.

This allows reusing freader outside buildid, e.g. for file dynptr
support added later.

Signed-off-by: Mykyta Yatsenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Alexei Starovoitov <[e-mail]>

MAINTAINERS

···
 F:	arch/*/net/*
 F:	include/linux/bpf*
 F:	include/linux/btf*
+F:	include/linux/buildid.h
 F:	include/linux/filter.h
 F:	include/trace/events/xdp.h
 F:	include/uapi/linux/bpf*

include/linux/buildid.h

···
 static inline void init_vmlinux_build_id(void) { }
 #endif
 
+struct freader {
+	void *buf;
+	u32 buf_sz;
+	int err;
+	union {
+		struct {
+			struct file *file;
+			struct folio *folio;
+			void *addr;
+			loff_t folio_off;
+			bool may_fault;
+		};
+		struct {
+			const char *data;
+			u64 data_sz;
+		};
+	};
+};
+
+void freader_init_from_file(struct freader *r, void *buf, u32 buf_sz,
+			    struct file *file, bool may_fault);
+void freader_init_from_mem(struct freader *r, const char *data, u64 data_sz);
+const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz);
+void freader_cleanup(struct freader *r);
+
 #endif

lib/buildid.c

···
 
 #define MAX_PHDR_CNT 256
 
-struct freader {
-	void *buf;
-	u32 buf_sz;
-	int err;
-	union {
-		struct {
-			struct file *file;
-			struct folio *folio;
-			void *addr;
-			loff_t folio_off;
-			bool may_fault;
-		};
-		struct {
-			const char *data;
-			u64 data_sz;
-		};
-	};
-};
-
-static void freader_init_from_file(struct freader *r, void *buf, u32 buf_sz,
-				   struct file *file, bool may_fault)
+void freader_init_from_file(struct freader *r, void *buf, u32 buf_sz,
+			    struct file *file, bool may_fault)
 {
 	memset(r, 0, sizeof(*r));
 	r->buf = buf;
···
 	r->may_fault = may_fault;
 }
 
-static void freader_init_from_mem(struct freader *r, const char *data, u64 data_sz)
+void freader_init_from_mem(struct freader *r, const char *data, u64 data_sz)
 {
 	memset(r, 0, sizeof(*r));
 	r->data = data;
···
 	return 0;
 }
 
-static const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz)
+const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz)
 {
 	size_t folio_sz;
 
···
 	return r->addr + (file_off - r->folio_off);
 }
 
-static void freader_cleanup(struct freader *r)
+void freader_cleanup(struct freader *r)
 {
 	if (!r->buf)
 		return; /* non-file-backed mode */