elf: Compile with -Wextra

-Wextra enables a bunch of rather useful checks which this fixes.

This changes the return value for the case when no ELF headers were found
to avoid (ugly-ish) cast of -1 to unsigned.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v2:
* cast the return value to (int)
* added missing (long)

include/libelf.h

@@ -96,9 +96,9 @@ void elf_relocate64(void *file_addr, signed long offset);
 
 int elf_forth_claim(void *addr, long size);
 
-long elf_get_file_size(const void *buffer, const long buffer_size);
-long elf_get_file_size32(const void *buffer, const long buffer_size);
-long elf_get_file_size64(const void *buffer, const long buffer_size);
+long elf_get_file_size(const void *buffer, const unsigned long buffer_size);
+long elf_get_file_size32(const void *buffer, const unsigned long buffer_size);
+long elf_get_file_size64(const void *buffer, const unsigned long buffer_size);
 
 #ifdef __BIG_ENDIAN__
 #define elf64_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2MSB ? (x) : bswap_64(x))

lib/libelf/elf.c

@@ -202,7 +202,7 @@ elf_get_base_addr(void *file_addr)
  * buffer larger than the size of the file
  * @return  The size of the ELF image or < 0 for error
  */
-long elf_get_file_size(const void *buffer, const long buffer_size)
+long elf_get_file_size(const void *buffer, const unsigned long buffer_size)
 {
 	const struct ehdr *ehdr = (const struct ehdr *)buffer;
 

lib/libelf/elf32.c

@@ -212,13 +212,13 @@ elf_byteswap_header32(void *file_addr)
  * file.
  * @return Return -1 on error, size of file otherwise.
  */
-long elf_get_file_size32(const void *buffer, const long buffer_size)
+long elf_get_file_size32(const void *buffer, const unsigned long buffer_size)
 {
 	const struct ehdr32 *ehdr = (const struct ehdr32 *) buffer;
 	const uint8_t *buffer_end = buffer + buffer_size;
 	const struct phdr32 *phdr;
 	const struct shdr32 *shdr;
-	long elf_size = -1;
+	unsigned long elf_size = 0;
 	uint16_t entsize;
 	unsigned i;
 
@@ -258,5 +258,5 @@ long elf_get_file_size32(const void *buffer, const long buffer_size)
 	if (elf_size > buffer_size)
 		return -1;
 
-	return elf_size;
+	return (long) elf_size;
 }

lib/libelf/elf64.c

@@ -389,7 +389,7 @@ elf_apply_all_rela64(void *file_addr, signed long offset, struct shdr64 *shdrs,
 	struct rela *relaentry;
 	struct sym64 *symtabentry;
 	uint32_t symbolidx;
-	int i;
+	unsigned i;
 
 	/* If the referenced section has not been allocated, then it has
 	 * not been loaded and thus does not need to be relocated. */
@@ -481,13 +481,13 @@ uint32_t elf_get_eflags_64(void *file_addr)
  * file.
  * @return Return -1 on error, size of file otherwise.
  */
-long elf_get_file_size64(const void *buffer, const long buffer_size)
+long elf_get_file_size64(const void *buffer, const unsigned long buffer_size)
 {
 	const struct ehdr64 *ehdr = (const struct ehdr64 *) buffer;
 	const uint8_t *buffer_end = buffer + buffer_size;
 	const struct phdr64 *phdr;
 	const struct shdr64 *shdr;
-	long elf_size = -1;
+	unsigned long elf_size = 0;
 	uint16_t entsize;
 	unsigned i;
 
@@ -527,5 +527,5 @@ long elf_get_file_size64(const void *buffer, const long buffer_size)
 	if (elf_size > buffer_size)
 		return -1;
 
-	return elf_size;
+	return (long) elf_size;
 }