[2/2] elf: Use nocancel pread64() instead of lseek()+read()
diff mbox series

Message ID MWHPR2101MB073287753F9E8D211AF49DD3E8DA0@MWHPR2101MB0732.namprd21.prod.outlook.com
State New
Headers show
Series
  • [1/2] Add nocancel version of pread64()
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Commit Message

Leandro Pereira Aug. 5, 2019, 9:56 p.m. UTC
Transforms this, when linking in a shared object:

  openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
  read(3, "\177ELF\2\1\1\3"..., 832) = 832
  lseek(3, 792, SEEK_SET)           = 792
  read(3, "\4\0\0\0\24\0\0\0"..., 68) = 68
  fstat(3, {st_mode=S_IFREG|0755, st_size=6699224, ...}) = 0
  lseek(3, 792, SEEK_SET)           = 792
  read(3, "\4\0\0\0\24\0\0\0"..., 68) = 68
  lseek(3, 864, SEEK_SET)           = 864
  read(3, "\4\0\0\0\20\0\0\0"..., 32) = 32

Into this:

  openat(AT_FDCWD, "/lib64/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
  read(3, "\177ELF\2\1\1\3"..., 832) = 832
  pread(3, "\4\0\0\0\24\0\0\0"..., 68, 792) = 68
  fstat(3, {st_mode=S_IFREG|0755, st_size=6699224, ...}) = 0
  pread(3, "\4\0\0\0\24\0\0\0"..., 68, 792) = 68
  pread(3, "\4\0\0\0\20\0\0\0"..., 32, 864) = 32

2019-08-05  Leandro Pereira  <leandro.pereira@microsoft.com>

	* elf/dl-load.c: Use __pread64_nocancel() instead of __lseek()+
	__read_nocancel().
	* sysdeps/x86/dl-prop.h: Likewise.

---
 elf/dl-load.c         | 9 +++------
 sysdeps/x86/dl-prop.h | 3 +--
 2 files changed, 4 insertions(+), 8 deletions(-)

Patch
diff mbox series

diff --git a/elf/dl-load.c b/elf/dl-load.c
index 5abeb867f1..462c425a13 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1005,8 +1005,7 @@  _dl_map_object_from_fd (const char *name, const char *origname, int fd,
   else
     {
       phdr = alloca (maplength);
-      __lseek (fd, header->e_phoff, SEEK_SET);
-      if ((size_t) __read_nocancel (fd, (void *) phdr, maplength) != maplength)
+      if ((size_t) __pread64_nocancel (fd, (void *) phdr, maplength, header->e_phoff) != maplength)
 	{
 	  errstring = N_("cannot read file data");
 	  goto call_lose_errno;
@@ -1659,8 +1658,7 @@  open_verify (const char *name, int fd,
       else
 	{
 	  phdr = alloca (maplength);
-	  __lseek (fd, ehdr->e_phoff, SEEK_SET);
-	  if ((size_t) __read_nocancel (fd, (void *) phdr, maplength)
+	  if ((size_t) __pread64_nocancel (fd, (void *) phdr, maplength, ehdr->e_phoff)
 	      != maplength)
 	    {
 	    read_error:
@@ -1710,8 +1708,7 @@  open_verify (const char *name, int fd,
 
 		    abi_note = abi_note_malloced;
 		  }
-		__lseek (fd, ph->p_offset, SEEK_SET);
-		if (__read_nocancel (fd, (void *) abi_note, size) != size)
+		if (__pread64_nocancel (fd, (void *) abi_note, size, ph->p_offset) != size)
 		  {
 		    free (abi_note_malloced);
 		    goto read_error;
diff --git a/sysdeps/x86/dl-prop.h b/sysdeps/x86/dl-prop.h
index 1b335ccbb3..080d66a971 100644
--- a/sysdeps/x86/dl-prop.h
+++ b/sysdeps/x86/dl-prop.h
@@ -167,8 +167,7 @@  _dl_process_pt_note (struct link_map *l, const ElfW(Phdr) *ph,
 	  note_malloced = malloc (size);
 	  note = note_malloced;
 	}
-      __lseek (fd, ph->p_offset, SEEK_SET);
-      if (__read_nocancel (fd, (void *) note, size) != size)
+      if (__pread64_nocancel (fd, (void *) note, size, ph->p_offset) != size)
 	{
 	  if (note_malloced)
 	    free (note_malloced);