libelf: Fix some 32bit offset/size issues that break updating 4G+ files.

Some years ago, in commit b1d0b0fc "libelf: Use int64_t for offsets in
libelf.h", we changed the public interface to use 64bit offsets/sizes.
This wasn't really a API change, before we relied on loff_t always
being 64bits on all platforms.

We didn't change the implementation to use the int64_t type though.
That was a little confusing, since the function definitions used a
different type, int64_t, from the function implementations, off_t.
Since we always build with _FILE_OFFSET_BITS=64 this should be fine.
But it was a bit sloppy and confusing.

Worse is that we got the translation of offset/sizes wrong in a
couple of places when translating to ELF types. In various places
we would use Elf32_Word or Elf64_Word. But both are 32bit (unsigned)
types! As is GElf_Word. Elf32_Off is 32bits and Elf64_Off is 64bits.
But we were not using those consistently.

This patch introduces comments for the usage of [G]Elf(32|64)Word in
libelf that are correct. And introduces Elf(32|64)_SizeWord in
elf32_updatenull.c where we want to make a difference between sizes
and offsets (the ELF variants are both unsigned, while int64_t/loff_t
is signed).

It also includes a new run-large-elf-file.sh test that creates a
large ELF files (one 64bit, little endian, rel and another big endian,
non-rel) and runs eu-strip, eu-elflint, eu-unstrip and eu-elfcmp.
Before this patch, that test case fails and creates corrupt ELF files.

The test is guarded by some checks that try to make sure there is
enough disk space and memory available on the machine. The test is
skipped otherwise.

Signed-off-by: Mark Wielaard <mark@klomp.org>

1 files changed, 9 insertions, 9 deletions

diff --git a/libelf/libelfP.h b/libelf/libelfP.h
index 51344142..b55d5c48 100644
--- a/libelf/libelfP.h
+++ b/libelf/libelfP.h
@@ -296,7 +296,7 @@ struct Elf
   int fildes;
 
   /* Offset in the archive this file starts or zero.  */
-  off_t start_offset;
+  int64_t start_offset;
 
   /* Size of the file in the archive or the entire file size, or ~0
      for an (yet) unknown size.  */
@@ -350,7 +350,7 @@ struct Elf
       int ehdr_flags;		/* Flags (dirty) for ELF header.  */
       int phdr_flags;		/* Flags (dirty|malloc) for program header.  */
       int shdr_malloced;	/* Nonzero if shdr array was allocated.  */
-      off_t sizestr_offset;	/* Offset of the size string in the parent
+      int64_t sizestr_offset;	/* Offset of the size string in the parent
 				   if this is an archive member.  */
       Elf32_Ehdr ehdr_mem;	/* Memory used for ELF header when not
 				   mmaped.  */
@@ -375,7 +375,7 @@ struct Elf
       int ehdr_flags;		/* Flags (dirty) for ELF header.  */
       int phdr_flags;		/* Flags (dirty|malloc) for program header.  */
       int shdr_malloced;	/* Nonzero if shdr array was allocated.  */
-      off_t sizestr_offset;	/* Offset of the size string in the parent
+      int64_t sizestr_offset;	/* Offset of the size string in the parent
 				   if this is an archive member.  */
       Elf64_Ehdr ehdr_mem;	/* Memory used for ELF header when not
 				   mmaped.  */
@@ -392,7 +392,7 @@ struct Elf
       char *long_names;		/* If no index is available but long names
 				   are used this elements points to the data.*/
       size_t long_names_len;	/* Length of the long name table.  */
-      off_t offset;		/* Offset in file we are currently at.
+      int64_t offset;		/* Offset in file we are currently at.
 				   elf_next() advances this to the next
 				   member of the archive.  */
       Elf_Arhdr elf_ar_hdr;	/* Structure returned by 'elf_getarhdr'.  */
@@ -445,7 +445,7 @@ extern Elf_Type __libelf_data_type (Elf *elf, int sh_type, GElf_Xword align)
 
 /* Create Elf descriptor from memory image.  */
 extern Elf *__libelf_read_mmaped_file (int fildes, void *map_address,
-				       off_t offset, size_t maxsize,
+				       int64_t offset, size_t maxsize,
 				       Elf_Cmd cmd, Elf *parent)
      internal_function;
 
@@ -467,10 +467,10 @@ extern int __libelf_set_rawdata_wrlock (Elf_Scn *scn) internal_function;
 
 
 /* Helper functions for elf_update.  */
-extern off_t __elf32_updatenull_wrlock (Elf *elf, int *change_bop,
-					size_t shnum) internal_function;
-extern off_t __elf64_updatenull_wrlock (Elf *elf, int *change_bop,
-					size_t shnum) internal_function;
+extern int64_t __elf32_updatenull_wrlock (Elf *elf, int *change_bop,
+					  size_t shnum) internal_function;
+extern int64_t __elf64_updatenull_wrlock (Elf *elf, int *change_bop,
+					  size_t shnum) internal_function;
 
 extern int __elf32_updatemmap (Elf *elf, int change_bo, size_t shnum)
      internal_function;