From: Roland McGrath <roland@redhat.com>
Date: Wed, 5 Jan 2011 03:29:24 +0000 (-0800)
Subject: strip: Add --strip-sections option.
X-Git-Tag: elfutils-0.151~14
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=0b9d1fb534604a9ba19999cd8ce8e7efce28da24;p=thirdparty%2Felfutils.git

strip: Add --strip-sections option.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index 7a151927a..9d42c55e8 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+2011-01-04  Roland McGrath  <roland@redhat.com>
+
+	* strip.c (remove_shdrs): New variable.
+	(options, parse_opt): Grok --strip-sections to set it.
+	(handle_elf): When that's set, truncate off .shstrtab and shdrs.
+
 2010-11-10  Roland McGrath  <roland@redhat.com>
 
 	* findtextrel.c (process_file): Don't assume order of sections.
diff --git a/src/strip.c b/src/strip.c
index 7b2b889a8..9b2d24a3e 100644
--- a/src/strip.c
+++ b/src/strip.c
@@ -65,6 +65,7 @@ ARGP_PROGRAM_BUG_ADDRESS_DEF = PACKAGE_BUGREPORT;
 /* Values for the parameters which have no short form.  */
 #define OPT_REMOVE_COMMENT	0x100
 #define OPT_PERMISSIVE		0x101
+#define OPT_STRIP_SECTIONS	0x102
 
 
 /* Definitions of arguments for argp functions.  */
@@ -80,6 +81,8 @@ static const struct argp_option options[] =
   { "strip-debug", 'g', NULL, 0, N_("Remove all debugging symbols"), 0 },
   { NULL, 'd', NULL, OPTION_ALIAS, NULL, 0 },
   { NULL, 'S', NULL, OPTION_ALIAS, NULL, 0 },
+  { "strip-sections", OPT_STRIP_SECTIONS, NULL, 0,
+    N_("Remove section headers (not recommended)"), 0 },
   { "preserve-dates", 'p', NULL, 0,
     N_("Copy modified/access timestamps to the output"), 0 },
   { "remove-comment", OPT_REMOVE_COMMENT, NULL, 0,
@@ -140,6 +143,9 @@ static bool remove_comment;
 /* If true remove all debug sections.  */
 static bool remove_debug;
 
+/* If true remove all section headers.  */
+static bool remove_shdrs;
+
 /* If true relax some ELF rules for input files.  */
 static bool permissive;
 
@@ -268,6 +274,10 @@ parse_opt (int key, char *arg, struct argp_state *state)
       remove_debug = true;
       break;
 
+    case OPT_STRIP_SECTIONS:
+      remove_shdrs = true;
+      break;
+
     case OPT_PERMISSIVE:
       permissive = true;
       break;
@@ -1639,6 +1649,7 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
   newehdr->e_entry = ehdr->e_entry;
   newehdr->e_flags = ehdr->e_flags;
   newehdr->e_phoff = ehdr->e_phoff;
+
   /* We need to position the section header table.  */
   const size_t offsize = gelf_fsize (elf, ELF_T_OFF, 1, EV_CURRENT);
   newehdr->e_shoff = ((shdr_info[shdridx].shdr.sh_offset
@@ -1692,6 +1703,53 @@ handle_elf (int fd, Elf *elf, const char *prefix, const char *fname,
       result = 1;
     }
 
+  if (remove_shdrs)
+    {
+      /* libelf can't cope without the section headers being properly intact.
+	 So we just let it write them normally, and then we nuke them later.  */
+
+      if (newehdr->e_ident[EI_CLASS] == ELFCLASS32)
+	{
+	  assert (offsetof (Elf32_Ehdr, e_shentsize) + sizeof (Elf32_Half)
+		  == offsetof (Elf32_Ehdr, e_shnum));
+	  assert (offsetof (Elf32_Ehdr, e_shnum) + sizeof (Elf32_Half)
+		  == offsetof (Elf32_Ehdr, e_shstrndx));
+	  const Elf32_Off zero_off = 0;
+	  const Elf32_Half zero[3] = { 0, 0, SHN_UNDEF };
+	  if (pwrite_retry (fd, &zero_off, sizeof zero_off,
+			    offsetof (Elf32_Ehdr, e_shoff)) != sizeof zero_off
+	      || (pwrite_retry (fd, zero, sizeof zero,
+				offsetof (Elf32_Ehdr, e_shentsize))
+		  != sizeof zero)
+	      || ftruncate64 (fd, shdr_info[shdridx].shdr.sh_offset) < 0)
+	    {
+	      error (0, errno, gettext ("while writing '%s'"),
+		     fname);
+	      result = 1;
+	    }
+	}
+      else
+	{
+	  assert (offsetof (Elf64_Ehdr, e_shentsize) + sizeof (Elf64_Half)
+		  == offsetof (Elf64_Ehdr, e_shnum));
+	  assert (offsetof (Elf64_Ehdr, e_shnum) + sizeof (Elf64_Half)
+		  == offsetof (Elf64_Ehdr, e_shstrndx));
+	  const Elf64_Off zero_off = 0;
+	  const Elf64_Half zero[3] = { 0, 0, SHN_UNDEF };
+	  if (pwrite_retry (fd, &zero_off, sizeof zero_off,
+			    offsetof (Elf64_Ehdr, e_shoff)) != sizeof zero_off
+	      || (pwrite_retry (fd, zero, sizeof zero,
+				offsetof (Elf64_Ehdr, e_shentsize))
+		  != sizeof zero)
+	      || ftruncate64 (fd, shdr_info[shdridx].shdr.sh_offset) < 0)
+	    {
+	      error (0, errno, gettext ("while writing '%s'"),
+		     fname);
+	      result = 1;
+	    }
+	}
+    }
+
  fail_close:
   if (shdr_info != NULL)
     {