1 files changed, 192 insertions, 148 deletions

diff --git a/libelf/elf32_getshdr.c b/libelf/elf32_getshdr.c
index 8d658752..b36e5437 100644
--- a/libelf/elf32_getshdr.c
+++ b/libelf/elf32_getshdr.c
@@ -54,6 +54,7 @@
 
 #include <assert.h>
 #include <errno.h>
+#include <stdbool.h>
 #include <unistd.h>
 
 #include <system.h>
@@ -65,187 +66,230 @@
 #endif
 
 
-ElfW2(LIBELFBITS,Shdr) *
-__elfw2(LIBELFBITS,getshdr_internal) (scn, locked)
-     Elf_Scn *scn;
-     lockstat_t locked;
+static ElfW2(LIBELFBITS,Shdr) *
+load_shdr_rwlock (Elf_Scn *scn)
 {
-  /* XXX: no read locking here, figure out why is it not necessary. */
   ElfW2(LIBELFBITS,Shdr) *result;
 
-  if (scn == NULL)
-    return NULL;
+  /* Read the section header table.  */
+  Elf *elf = scn->elf;
+  ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr;
 
-  if (unlikely (scn->elf->state.elf.ehdr == NULL))
+  /* Try again, maybe the data is there now.  */
+  result = scn->shdr.ELFW(e,LIBELFBITS);
+  if (result != NULL)
+    goto out;
+
+  size_t shnum;
+  if (__elf_getshnum_rdlock (elf, &shnum) != 0)
+    goto out;
+  size_t size = shnum * sizeof (ElfW2(LIBELFBITS,Shdr));
+
+  /* Allocate memory for the section headers.  We know the number
+     of entries from the ELF header.  */
+  ElfW2(LIBELFBITS,Shdr) *shdr = elf->state.ELFW(elf,LIBELFBITS).shdr =
+    (ElfW2(LIBELFBITS,Shdr) *) malloc (size);
+  if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL)
     {
-      __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
-      return NULL;
+      __libelf_seterrno (ELF_E_NOMEM);
+      goto out;
     }
+  elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 1;
 
-  if (unlikely (scn->elf->class != ELFW(ELFCLASS,LIBELFBITS)))
+  if (elf->map_address != NULL)
     {
-      __libelf_seterrno (ELF_E_INVALID_CLASS);
-      return NULL;
-    }
+      ElfW2(LIBELFBITS,Shdr) *notcvt;
 
-  result = scn->shdr.ELFW(e,LIBELFBITS);
-  if (result == NULL)
-    {
-      /* Read the section header table.  */
-      Elf *elf = scn->elf;
-      ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr;
+      /* All the data is already mapped.  If we could use it
+	 directly this would already have happened.  */
+      void *file_shdr = ((char *) elf->map_address
+			 + elf->start_offset + ehdr->e_shoff);
 
-      rwlock_to_wrlock (locked, &elf->lock);
+      assert (ehdr->e_ident[EI_DATA] != MY_ELFDATA
+	      || (! ALLOW_UNALIGNED
+		  && ((uintptr_t) file_shdr
+		      & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0));
 
-      /* Try again, maybe the data is there now.  */
-      result = scn->shdr.ELFW(e,LIBELFBITS);
-      if (result != NULL)
-	goto out;
-
-      size_t shnum;
-      if (__elf_getshnum_internal (elf, &shnum, LS_WRLOCKED) != 0)
-	goto out;
-      size_t size = shnum * sizeof (ElfW2(LIBELFBITS,Shdr));
-
-      /* Allocate memory for the section headers.  We know the number
-	 of entries from the ELF header.  */
-      ElfW2(LIBELFBITS,Shdr) *shdr = elf->state.ELFW(elf,LIBELFBITS).shdr =
-	(ElfW2(LIBELFBITS,Shdr) *) malloc (size);
-      if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL)
+      /* Now copy the data and at the same time convert the byte order.  */
+      if (ehdr->e_ident[EI_DATA] == MY_ELFDATA)
 	{
-	  __libelf_seterrno (ELF_E_NOMEM);
-	  goto out;
+	  assert (! ALLOW_UNALIGNED);
+	  memcpy (shdr, file_shdr, size);
 	}
-      elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 1;
-
-      if (elf->map_address != NULL)
+      else
 	{
-	  ElfW2(LIBELFBITS,Shdr) *notcvt;
-
-	  /* All the data is already mapped.  If we could use it
-	     directly this would already have happened.  */
-	  void *file_shdr = ((char *) elf->map_address
-			     + elf->start_offset + ehdr->e_shoff);
-
-	  assert (ehdr->e_ident[EI_DATA] != MY_ELFDATA
-		  || (! ALLOW_UNALIGNED
-		      && ((uintptr_t) file_shdr
-			  & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0));
-
-	  /* Now copy the data and at the same time convert the byte order.  */
-	  if (ehdr->e_ident[EI_DATA] == MY_ELFDATA)
-	    {
-	      assert (! ALLOW_UNALIGNED);
-	      memcpy (shdr, file_shdr, size);
-	    }
+	  if (ALLOW_UNALIGNED
+	      || ((uintptr_t) file_shdr
+		  & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) == 0)
+	    notcvt = (ElfW2(LIBELFBITS,Shdr) *)
+	      ((char *) elf->map_address
+	       + elf->start_offset + ehdr->e_shoff);
 	  else
 	    {
-	      if (ALLOW_UNALIGNED
-		  || ((uintptr_t) file_shdr
-		      & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) == 0)
-		notcvt = (ElfW2(LIBELFBITS,Shdr) *)
-		  ((char *) elf->map_address
-		   + elf->start_offset + ehdr->e_shoff);
-	      else
-		{
-		  notcvt = (ElfW2(LIBELFBITS,Shdr) *) alloca (size);
-		  memcpy (notcvt, ((char *) elf->map_address
-				   + elf->start_offset + ehdr->e_shoff),
-			  size);
-		}
-
-	      for (size_t cnt = 0; cnt < shnum; ++cnt)
-		{
-		  CONVERT_TO (shdr[cnt].sh_name, notcvt[cnt].sh_name);
-		  CONVERT_TO (shdr[cnt].sh_type, notcvt[cnt].sh_type);
-		  CONVERT_TO (shdr[cnt].sh_flags, notcvt[cnt].sh_flags);
-		  CONVERT_TO (shdr[cnt].sh_addr, notcvt[cnt].sh_addr);
-		  CONVERT_TO (shdr[cnt].sh_offset, notcvt[cnt].sh_offset);
-		  CONVERT_TO (shdr[cnt].sh_size, notcvt[cnt].sh_size);
-		  CONVERT_TO (shdr[cnt].sh_link, notcvt[cnt].sh_link);
-		  CONVERT_TO (shdr[cnt].sh_info, notcvt[cnt].sh_info);
-		  CONVERT_TO (shdr[cnt].sh_addralign,
-			      notcvt[cnt].sh_addralign);
-		  CONVERT_TO (shdr[cnt].sh_entsize, notcvt[cnt].sh_entsize);
-
-		  /* If this is a section with an extended index add a
-		     reference in the section which uses the extended
-		     index.  */
-		  if (shdr[cnt].sh_type == SHT_SYMTAB_SHNDX
-		      && shdr[cnt].sh_link < shnum)
-		    elf->state.ELFW(elf,LIBELFBITS).scns.data[shdr[cnt].sh_link].shndx_index
-		      = cnt;
-
-		  /* Set the own shndx_index field in case it has not yet
-		     been set.  */
-		  if (elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index == 0)
-		    elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index
-		      = -1;
-		}
+	      notcvt = (ElfW2(LIBELFBITS,Shdr) *) alloca (size);
+	      memcpy (notcvt, ((char *) elf->map_address
+			       + elf->start_offset + ehdr->e_shoff),
+		      size);
 	    }
-	}
-      else if (likely (elf->fildes != -1))
-	{
-	  /* Read the header.  */
-	  ssize_t n = pread_retry (elf->fildes,
-				   elf->state.ELFW(elf,LIBELFBITS).shdr, size,
-				   elf->start_offset + ehdr->e_shoff);
-	  if (unlikely ((size_t) n != size))
+
+	  for (size_t cnt = 0; cnt < shnum; ++cnt)
 	    {
-	      /* Severe problems.  We cannot read the data.  */
-	      __libelf_seterrno (ELF_E_READ_ERROR);
-	      goto free_and_out;
+	      CONVERT_TO (shdr[cnt].sh_name, notcvt[cnt].sh_name);
+	      CONVERT_TO (shdr[cnt].sh_type, notcvt[cnt].sh_type);
+	      CONVERT_TO (shdr[cnt].sh_flags, notcvt[cnt].sh_flags);
+	      CONVERT_TO (shdr[cnt].sh_addr, notcvt[cnt].sh_addr);
+	      CONVERT_TO (shdr[cnt].sh_offset, notcvt[cnt].sh_offset);
+	      CONVERT_TO (shdr[cnt].sh_size, notcvt[cnt].sh_size);
+	      CONVERT_TO (shdr[cnt].sh_link, notcvt[cnt].sh_link);
+	      CONVERT_TO (shdr[cnt].sh_info, notcvt[cnt].sh_info);
+	      CONVERT_TO (shdr[cnt].sh_addralign,
+			  notcvt[cnt].sh_addralign);
+	      CONVERT_TO (shdr[cnt].sh_entsize, notcvt[cnt].sh_entsize);
+
+	      /* If this is a section with an extended index add a
+		 reference in the section which uses the extended
+		 index.  */
+	      if (shdr[cnt].sh_type == SHT_SYMTAB_SHNDX
+		  && shdr[cnt].sh_link < shnum)
+		elf->state.ELFW(elf,LIBELFBITS).scns.data[shdr[cnt].sh_link].shndx_index
+		  = cnt;
+
+	      /* Set the own shndx_index field in case it has not yet
+		 been set.  */
+	      if (elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index == 0)
+		elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index
+		  = -1;
 	    }
-
-	  /* If the byte order of the file is not the same as the one
-	     of the host convert the data now.  */
-	  if (ehdr->e_ident[EI_DATA] != MY_ELFDATA)
-	    for (size_t cnt = 0; cnt < shnum; ++cnt)
-	      {
-		CONVERT (shdr[cnt].sh_name);
-		CONVERT (shdr[cnt].sh_type);
-		CONVERT (shdr[cnt].sh_flags);
-		CONVERT (shdr[cnt].sh_addr);
-		CONVERT (shdr[cnt].sh_offset);
-		CONVERT (shdr[cnt].sh_size);
-		CONVERT (shdr[cnt].sh_link);
-		CONVERT (shdr[cnt].sh_info);
-		CONVERT (shdr[cnt].sh_addralign);
-		CONVERT (shdr[cnt].sh_entsize);
-	      }
 	}
-      else
+    }
+  else if (likely (elf->fildes != -1))
+    {
+      /* Read the header.  */
+      ssize_t n = pread_retry (elf->fildes,
+			       elf->state.ELFW(elf,LIBELFBITS).shdr, size,
+			       elf->start_offset + ehdr->e_shoff);
+      if (unlikely ((size_t) n != size))
 	{
-	  /* The file descriptor was already enabled and not all data was
-	     read.  Undo the allocation.  */
-	  __libelf_seterrno (ELF_E_FD_DISABLED);
+	  /* Severe problems.  We cannot read the data.  */
+	  __libelf_seterrno (ELF_E_READ_ERROR);
+	  goto free_and_out;
+	}
 
-	free_and_out:
-	  free (shdr);
-	  elf->state.ELFW(elf,LIBELFBITS).shdr = NULL;
-	  elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 0;
+      /* If the byte order of the file is not the same as the one
+	 of the host convert the data now.  */
+      if (ehdr->e_ident[EI_DATA] != MY_ELFDATA)
+	for (size_t cnt = 0; cnt < shnum; ++cnt)
+	  {
+	    CONVERT (shdr[cnt].sh_name);
+	    CONVERT (shdr[cnt].sh_type);
+	    CONVERT (shdr[cnt].sh_flags);
+	    CONVERT (shdr[cnt].sh_addr);
+	    CONVERT (shdr[cnt].sh_offset);
+	    CONVERT (shdr[cnt].sh_size);
+	    CONVERT (shdr[cnt].sh_link);
+	    CONVERT (shdr[cnt].sh_info);
+	    CONVERT (shdr[cnt].sh_addralign);
+	    CONVERT (shdr[cnt].sh_entsize);
+	  }
+    }
+  else
+    {
+      /* The file descriptor was already enabled and not all data was
+	 read.  Undo the allocation.  */
+      __libelf_seterrno (ELF_E_FD_DISABLED);
 
-	  goto out;
-	}
+    free_and_out:
+      free (shdr);
+      elf->state.ELFW(elf,LIBELFBITS).shdr = NULL;
+      elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 0;
 
-      /* Set the pointers in the `scn's.  */
-      for (size_t cnt = 0; cnt < shnum; ++cnt)
-	elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shdr.ELFW(e,LIBELFBITS)
-	  = &elf->state.ELFW(elf,LIBELFBITS).shdr[cnt];
+      goto out;
+    }
 
-      result = scn->shdr.ELFW(e,LIBELFBITS);
-      assert (result != NULL);
+  /* Set the pointers in the `scn's.  */
+  for (size_t cnt = 0; cnt < shnum; ++cnt)
+    elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shdr.ELFW(e,LIBELFBITS)
+      = &elf->state.ELFW(elf,LIBELFBITS).shdr[cnt];
+
+  result = scn->shdr.ELFW(e,LIBELFBITS);
+  assert (result != NULL);
+
+out:
+  return result;
+}
+
+static bool
+scn_valid (Elf_Scn *scn)
+{
+  if (scn == NULL)
+    return false;
 
-    out:
-      rwlock_from_wrlock (locked, &elf->lock);
+  if (unlikely (scn->elf->state.elf.ehdr == NULL))
+    {
+      __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);
+      return false;
+    }
+
+  if (unlikely (scn->elf->class != ELFW(ELFCLASS,LIBELFBITS)))
+    {
+      __libelf_seterrno (ELF_E_INVALID_CLASS);
+      return false;
+    }
+
+  return true;
+}
+
+ElfW2(LIBELFBITS,Shdr) *
+__elfw2(LIBELFBITS,getshdr_rdlock) (scn)
+     Elf_Scn *scn;
+{
+  /* XXX: no read locking here, figure out why is it not necessary. */
+  ElfW2(LIBELFBITS,Shdr) *result;
+
+  if (!scn_valid (scn))
+    return NULL;
+
+  result = scn->shdr.ELFW(e,LIBELFBITS);
+  if (result == NULL)
+    {
+      rwlock_unlock (scn->elf->lock);
+      rwlock_wrlock (scn->elf->lock);
+      result = scn->shdr.ELFW(e,LIBELFBITS);
+      if (result == NULL)
+	result = load_shdr_rwlock (scn);
     }
 
   return result;
 }
 
 ElfW2(LIBELFBITS,Shdr) *
+__elfw2(LIBELFBITS,getshdr_wrlock) (scn)
+     Elf_Scn *scn;
+{
+  ElfW2(LIBELFBITS,Shdr) *result;
+
+  if (!scn_valid (scn))
+    return NULL;
+
+  result = scn->shdr.ELFW(e,LIBELFBITS);
+  if (result == NULL)
+    result = load_shdr_rwlock (scn);
+
+  return result;
+}
+
+ElfW2(LIBELFBITS,Shdr) *
 elfw2(LIBELFBITS,getshdr) (scn)
      Elf_Scn *scn;
 {
-  return __elfw2(LIBELFBITS,getshdr_internal) (scn, LS_UNLOCKED);
+  ElfW2(LIBELFBITS,Shdr) *result;
+
+  if (!scn_valid (scn))
+    return NULL;
+
+  rwlock_rdlock (scn->elf->lock);
+  result = __elfw2(LIBELFBITS,getshdr_rdlock) (scn);
+  rwlock_unlock (scn->elf->lock);
+
+  return result;
 }