Optimize memory handling. Copy pread if possible. Handle EINTR.

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index c687539d3e01fdd790f8af765f2e336dbfd3de90..acb026ef2d5254f5f58d74709c050d8231c06028 100644 (file)
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -3,6 +3,7 @@
        * elf_begin.c (get_shnum): Optimize memory handling.  Always read from
        mapped file if available.  Fix access to 64-bit sh_size.  Recognize
        overflow.
+       (file_read_elf): Likewise.
 
 2005-08-12  Roland McGrath  <roland@redhat.com>
 

diff --git a/libelf/elf_begin.c b/libelf/elf_begin.c
index bed3f5509ab19277d6c15e004c8f8c93edc67cea..56c7a481521ce6cf84fb155b9ca3417c953d3543 100644 (file)
--- a/libelf/elf_begin.c
+++ b/libelf/elf_begin.c
@@ -220,6 +220,7 @@ file_read_elf (int fildes, void *map_address, off_t offset, size_t maxsize,
 {
   /* We only read the ELF header now.  */
   unsigned char *e_ident;
+  unsigned char e_ident_mem[EI_NIDENT];
   size_t scncnt;
   Elf *elf;
 
@@ -229,9 +230,10 @@ file_read_elf (int fildes, void *map_address, off_t offset, size_t maxsize,
     e_ident = (unsigned char *) map_address + offset;
   else
     {
-      e_ident = (unsigned char *) alloca (EI_NIDENT);
+      e_ident = e_ident_mem;
 
-      if (pread (fildes, e_ident, EI_NIDENT, offset) != EI_NIDENT)
+      if (TEMP_FAILURE_RETRY (pread (fildes, e_ident, EI_NIDENT, offset))
+         != EI_NIDENT)
        {
          __libelf_seterrno (ELF_E_READ_ERROR);
          return NULL;
@@ -312,14 +314,21 @@ file_read_elf (int fildes, void *map_address, off_t offset, size_t maxsize,
        }
       else
        {
-         /* Read the data.  */
-         if (pread (elf->fildes, &elf->state.elf32.ehdr_mem,
-                    sizeof (Elf32_Ehdr), offset) != sizeof (Elf32_Ehdr))
-           {
-             /* We must be able to read the ELF header.  */
-             __libelf_seterrno (ELF_E_INVALID_FILE);
-             return NULL;
-           }
+         if (likely (map_address != NULL))
+           /* Copy the data.  */
+           memcpy (&elf->state.elf32.ehdr_mem,
+                   (char *) map_address + offset, sizeof (Elf32_Ehdr));
+         else
+           /* Read the data.  */
+           if (TEMP_FAILURE_RETRY (pread (elf->fildes,
+                                          &elf->state.elf32.ehdr_mem,
+                                          sizeof (Elf32_Ehdr), offset))
+               != sizeof (Elf32_Ehdr))
+             {
+               /* We must be able to read the ELF header.  */
+               __libelf_seterrno (ELF_E_INVALID_FILE);
+               return NULL;
+             }
 
          if (e_ident[EI_DATA] != MY_ELFDATA)
            {
@@ -397,9 +406,16 @@ file_read_elf (int fildes, void *map_address, off_t offset, size_t maxsize,
        }
       else
        {
-         /* Read the data.  */
-         if (pread (elf->fildes, &elf->state.elf64.ehdr_mem,
-                    sizeof (Elf64_Ehdr), offset) != sizeof (Elf64_Ehdr))
+         if (likely (map_address != NULL))
+           /* Copy the data.  */
+           memcpy (&elf->state.elf64.ehdr_mem,
+                   (char *) map_address + offset, sizeof (Elf64_Ehdr));
+         else
+           /* Read the data.  */
+           if (TEMP_FAILURE_RETRY (pread (elf->fildes,
+                                          &elf->state.elf64.ehdr_mem,
+                                          sizeof (Elf64_Ehdr), offset))
+               != sizeof (Elf64_Ehdr))
            {
              /* We must be able to read the ELF header.  */
              __libelf_seterrno (ELF_E_INVALID_FILE);