Fix read/write of existing file using mmap and different layout of the ELF

file.

diff --git a/libelf/ChangeLog b/libelf/ChangeLog
index 2714ff34ee9a0efec2bc77062937494681abb1cd..c69b3d392e33e05839c20650078bf7ce00322cd6 100644 (file)
--- a/libelf/ChangeLog
+++ b/libelf/ChangeLog
@@ -1,3 +1,16 @@
+2006-04-04  Ulrich Drepper  <drepper@redhat.com>
+
+       * elf32_updatefile.c (updatemmap): Cleanups.  Remove shdr_dest
+       variable.  Before writing sections, make a copy of the section
+       header data if necessary.  Don't write section header while
+       writing the section constent, it might overwrite some sections.
+       Restore the pointer afterwards.
+       * elf32_updatenull.c (updatenull): If the offset of a section in a
+       file changed make sure we read the section so that it'll be written
+       out.
+
+       * elf_update.c: Remove debug message.
+
 2005-12-07  Roland McGrath  <roland@redhat.com>
 
        * gelf_xlate.c [! ALLOW_UNALIGNED] (union unaligned): New type.

diff --git a/libelf/elf32_updatefile.c b/libelf/elf32_updatefile.c
index 260fb3468ae74e83f568225cd24ddd791761c521..906989746a5a4e47d2285d7f6800bfc3716ac790 100644 (file)
--- a/libelf/elf32_updatefile.c
+++ b/libelf/elf32_updatefile.c
@@ -1,5 +1,5 @@
 /* Write changed data structures.
-   Copyright (C) 2000, 2001, 2002, 2004, 2005 Red Hat, Inc.
+   Copyright (C) 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc.
    Written by Ulrich Drepper <drepper@redhat.com>, 2000.
 
    This program is free software; you can redistribute it and/or modify
@@ -26,6 +26,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/mman.h>
 #include <sys/param.h>
 
 #include <system.h>
@@ -82,7 +83,6 @@ internal_function_def
 __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
 {
   ElfW2(LIBELFBITS,Ehdr) *ehdr;
-  xfct_t fctp;
   char *last_position;
 
   /* We need the ELF header several times.  */
@@ -100,6 +100,7 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
        {
          /* Today there is only one version of the ELF header.  */
 #if EV_NUM != 2
+         xfct_t fctp;
          fctp = __elf_xfctstom[__libelf_version - 1][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_EHDR];
 #else
 # undef fctp
@@ -137,6 +138,7 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
        {
          /* Today there is only one version of the ELF header.  */
 #if EV_NUM != 2
+         xfct_t fctp;
          fctp = __elf_xfctstom[__libelf_version - 1][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_PHDR];
 #else
 # undef fctp
@@ -166,12 +168,11 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
   /* Write all the sections.  Well, only those which are modified.  */
   if (shnum > 0)
     {
-      ElfW2(LIBELFBITS,Shdr) *shdr_dest;
       Elf_ScnList *list = &elf->state.ELFW(elf,LIBELFBITS).scns;
       Elf_Scn **scns = (Elf_Scn **) alloca (shnum * sizeof (Elf_Scn *));
-      char *shdr_start = ((char *) elf->map_address + elf->start_offset
-                         + ehdr->e_shoff);
-      char *shdr_end = shdr_start + ehdr->e_shnum * ehdr->e_shentsize;
+      char *const shdr_start = ((char *) elf->map_address + elf->start_offset
+                               + ehdr->e_shoff);
+      char *const shdr_end = shdr_start + ehdr->e_shnum * ehdr->e_shentsize;
 
 #if EV_NUM != 2
       xfct_t shdr_fctp = __elf_xfctstom[__libelf_version - 1][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_SHDR];
@@ -179,26 +180,43 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
 # undef shdr_fctp
 # define shdr_fctp __elf_xfctstom[0][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_SHDR]
 #endif
-      shdr_dest = (ElfW2(LIBELFBITS,Shdr) *)
-       ((char *) elf->map_address + elf->start_offset + ehdr->e_shoff);
+#define shdr_dest ((ElfW2(LIBELFBITS,Shdr) *) shdr_start)
 
       /* Get all sections into the array and sort them.  */
       sort_sections (scns, list);
 
+      /* We possibly have to copy the section header data because moving
+        the sections might overwrite the data.  */
+      for (size_t cnt = 0; cnt < shnum; ++cnt)
+       {
+         Elf_Scn *scn = scns[cnt];
+
+         if ((scn->shdr_flags & ELF_F_MALLOCED) == 0
+             && scn->shdr.ELFW(e,LIBELFBITS) != &shdr_dest[scn->index])
+           {
+             assert ((char *) elf->map_address + elf->start_offset
+                     < (char *) scn->shdr.ELFW(e,LIBELFBITS));
+             assert ((char *) scn->shdr.ELFW(e,LIBELFBITS)
+                     < (char *) elf->map_address + elf->maximum_size);
+
+             void *p = alloca (sizeof (ElfW2(LIBELFBITS,Shdr)));
+             scn->shdr.ELFW(e,LIBELFBITS)
+               = memcpy (p, scn->shdr.ELFW(e,LIBELFBITS),
+                         sizeof (ElfW2(LIBELFBITS,Shdr)));
+           }
+       }
+
       /* Iterate over all the section in the order in which they
         appear in the output file.  */
       for (size_t cnt = 0; cnt < shnum; ++cnt)
        {
          Elf_Scn *scn = scns[cnt];
-         ElfW2(LIBELFBITS,Shdr) *shdr;
-         char *scn_start;
-         Elf_Data_List *dl;
 
-         shdr = scn->shdr.ELFW(e,LIBELFBITS);
+         ElfW2(LIBELFBITS,Shdr) *shdr = scn->shdr.ELFW(e,LIBELFBITS);
 
-         scn_start = ((char *) elf->map_address
-                      + elf->start_offset + shdr->sh_offset);
-         dl = &scn->data_list;
+         char *scn_start = ((char *) elf->map_address
+                            + elf->start_offset + shdr->sh_offset);
+         Elf_Data_List *dl = &scn->data_list;
 
          if (shdr->sh_type != SHT_NOBITS && scn->data_list_rear != NULL)
            do
@@ -236,10 +254,11 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
                    if (unlikely (change_bo))
                      {
 #if EV_NUM != 2
+                       xfct_t fctp;
                        fctp = __elf_xfctstom[__libelf_version - 1][dl->data.d.d_version - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type];
 #else
 # undef fctp
-                       fctp = __elf_xfctstom[0][0][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type];
+# define fctp __elf_xfctstom[0][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type]
 #endif
 
                        /* Do the real work.  */
@@ -265,7 +284,23 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
            /* We have to trust the existing section header information.  */
            last_position += shdr->sh_size;
 
-         /* Write the section header table entry if necessary.  */
+         scn->flags &= ~ELF_F_DIRTY;
+       }
+
+      /* Fill the gap between last section and section header table if
+        necessary.  */
+      if ((elf->flags & ELF_F_DIRTY)
+         && last_position < ((char *) elf->map_address + elf->start_offset
+                             + ehdr->e_shoff))
+       memset (last_position, __libelf_fill_byte,
+               (char *) elf->map_address + elf->start_offset + ehdr->e_shoff
+               - last_position);
+
+      /* Write the section header table entry if necessary.  */
+      for (size_t cnt = 0; cnt < shnum; ++cnt)
+       {
+         Elf_Scn *scn = scns[cnt];
+
          if ((scn->shdr_flags | elf->flags) & ELF_F_DIRTY)
            {
              if (unlikely (change_bo))
@@ -277,25 +312,28 @@ __elfw2(LIBELFBITS,updatemmap) (Elf *elf, int change_bo, size_t shnum)
                        scn->shdr.ELFW(e,LIBELFBITS),
                        sizeof (ElfW2(LIBELFBITS,Shdr)));
 
+             /* If we previously made a copy of the section header
+                entry we now have to adjust the pointer again so
+                point to new place in the mapping.  */
+             if ((scn->shdr_flags & ELF_F_MALLOCED) == 0)
+               scn->shdr.ELFW(e,LIBELFBITS) = &shdr_dest[scn->index];
+
              scn->shdr_flags  &= ~ELF_F_DIRTY;
            }
-
-         scn->flags &= ~ELF_F_DIRTY;
        }
-
-      /* Fill the gap between last section and section header table if
-        necessary.  */
-      if ((elf->flags & ELF_F_DIRTY)
-         && last_position < ((char *) elf->map_address + elf->start_offset
-                              + ehdr->e_shoff))
-       memset (last_position, __libelf_fill_byte,
-               (char *) elf->map_address + elf->start_offset + ehdr->e_shoff
-               - last_position);
     }
 
   /* That was the last part.  Clear the overall flag.  */
   elf->flags &= ~ELF_F_DIRTY;
 
+  /* Make sure the content hits the disk.  */
+  char *msync_start = ((char *) elf->map_address
+                      + elf->start_offset / sysconf (_SC_PAGESIZE));
+  char *msync_end = ((char *) elf->map_address
+                    + elf->start_offset + ehdr->e_shoff
+                    * ehdr->e_shentsize * shnum);
+  (void) msync (msync_start, msync_end - msync_start, MS_SYNC);
+
   return 0;
 }
 
@@ -349,7 +387,6 @@ __elfw2(LIBELFBITS,updatefile) (Elf *elf, int change_bo, size_t shnum)
 {
   char fillbuf[FILLBUFSIZE];
   size_t filled = 0;
-  xfct_t fctp;
 
   /* We need the ELF header several times.  */
   ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr;
@@ -369,6 +406,7 @@ __elfw2(LIBELFBITS,updatefile) (Elf *elf, int change_bo, size_t shnum)
        {
          /* Today there is only one version of the ELF header.  */
 #if EV_NUM != 2
+         xfct_t fctp;
          fctp = __elf_xfctstom[__libelf_version - 1][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_EHDR];
 #else
 # undef fctp
@@ -419,6 +457,7 @@ __elfw2(LIBELFBITS,updatefile) (Elf *elf, int change_bo, size_t shnum)
        {
          /* Today there is only one version of the ELF header.  */
 #if EV_NUM != 2
+         xfct_t fctp;
          fctp = __elf_xfctstom[__libelf_version - 1][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][ELF_T_PHDR];
 #else
 # undef fctp
@@ -525,10 +564,11 @@ __elfw2(LIBELFBITS,updatefile) (Elf *elf, int change_bo, size_t shnum)
                    if (unlikely (change_bo))
                      {
 #if EV_NUM != 2
+                       xfct_t fctp;
                        fctp = __elf_xfctstom[__libelf_version - 1][dl->data.d.d_version - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type];
 #else
 # undef fctp
-                       fctp = __elf_xfctstom[0][0][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type];
+# define fctp __elf_xfctstom[0][EV_CURRENT - 1][ELFW(ELFCLASS, LIBELFBITS) - 1][dl->data.d.d_type]
 #endif
 
                        buf = tmpbuf;

diff --git a/libelf/elf32_updatenull.c b/libelf/elf32_updatenull.c
index ed7242b2420b5e3e2031c7b249b3f7626cb6e724..9c61cd77742479d33dde76f5d969d35478b11220 100644 (file)
--- a/libelf/elf32_updatenull.c
+++ b/libelf/elf32_updatenull.c
@@ -1,5 +1,5 @@
 /* Update data structures for changes.
-   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005 Red Hat, Inc.
+   Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006 Red Hat, Inc.
    Written by Ulrich Drepper <drepper@redhat.com>, 2000.
 
    This program is free software; you can redistribute it and/or modify
@@ -319,8 +319,18 @@ __elfw2(LIBELFBITS,updatenull) (Elf *elf, int *change_bop, size_t shnum)
                                     scn->shdr_flags);
 
                  size = (size + sh_align - 1) & ~(sh_align - 1);
+                 int offset_changed = 0;
                  update_if_changed (shdr->sh_offset, (GElf_Word) size,
-                                    changed);
+                                    offset_changed);
+                 changed |= offset_changed;
+
+                 if (offset_changed && scn->data_list_rear == NULL)
+                   {
+                     /* The position of the section in the file
+                        changed.  Create the section data list.  */
+                     if (INTUSE(elf_getdata) (scn, NULL) == NULL)
+                       return -1;
+                   }
 
                  /* See whether the section size is correct.  */
                  update_if_changed (shdr->sh_size, (GElf_Word) offset,

diff --git a/libelf/elf_update.c b/libelf/elf_update.c
index f380e2b9d162d3174daab4c602f4eb992a3917c2..ee1760d421892279467019995e313bd04ecf0aab 100644 (file)
--- a/libelf/elf_update.c
+++ b/libelf/elf_update.c
@@ -1,5 +1,5 @@
 /* Update data structures for changes and write them out.
-   Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005 Red Hat, Inc.
+   Copyright (C) 1999, 2000, 2001, 2002, 2004, 2005, 2006 Red Hat, Inc.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 1999.
 
    This program is free software; you can redistribute it and/or modify
@@ -181,15 +181,7 @@ elf_update (elf, cmd)
          size = -1;
        }
       else
-       {
-         if (elf->parent != NULL)
-           {
-             extern int puts (const char *);
-             puts ("this is an archive member");
-           }
-
-         size = write_file (elf, size, change_bo, shnum);
-       }
+       size = write_file (elf, size, change_bo, shnum);
     }
 
  out: