Add strings program.

Some more cleanups in libelf.

3 files changed, 731 insertions, 1 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 7707ac17..d0928825 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,10 @@
+2005-08-28  Ulrich Drepper  <drepper@redhat.com>
+
+	* strings.c: New file.
+	* Makefile.am (bin_PROGRAMS): Add strings.
+	(strings_no_Wstring): Define.
+	(strings_LDADD): Define.
+
 2005-08-24  Ulrich Drepper  <drepper@redhat.com>
 
 	* elflint.c (check_versym): Versioned symbols should not have
diff --git a/src/Makefile.am b/src/Makefile.am
index 234d1b6f..ef944776 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -38,7 +38,7 @@ native_ld = @native_ld@
 base_cpu = @base_cpu@
 
 bin_PROGRAMS = readelf nm size strip ld elflint findtextrel addr2line \
-	       elfcmp objdump ranlib
+	       elfcmp objdump ranlib strings
 
 
 ld_dsos = libld_elf_i386_pic.a
@@ -78,6 +78,7 @@ libeu = ../lib/libeu.a
 
 nm_no_Wformat = yes
 size_no_Wformat = yes
+strings_no_Wformat = yes
 # XXX While the file is not finished, don't warn about this
 ldgeneric_no_Wunused = yes
 
@@ -96,6 +97,7 @@ addr2line_LDADD = $(libdw) $(libmudflap)
 elfcmp_LDADD = $(libebl) $(libelf) $(libmudflap) -ldl
 objdump_LDADD  = $(libebl) $(libelf) $(libeu) $(libmudflap) -ldl
 ranlib_LDADD = $(libelf) $(libeu) $(libmudflap)
+strings_LDADD = $(libelf) $(libeu) $(libmudflap)
 
 ldlex.o: ldscript.c
 ldlex_no_Werror = yes
diff --git a/src/strings.c b/src/strings.c
new file mode 100644
index 00000000..f9be40e3
--- /dev/null
+++ b/src/strings.c
@@ -0,0 +1,721 @@
+/* Print the strings of printable characters in files.
+   Copyright (C) 2005 Red Hat, Inc.
+   Written by Ulrich Drepper <drepper@redhat.com>, 2005.
+
+   This program is Open Source software; you can redistribute it and/or
+   modify it under the terms of the Open Software License version 1.0 as
+   published by the Open Source Initiative.
+
+   You should have received a copy of the Open Software License along
+   with this program; if not, you may obtain a copy of the Open Software
+   License version 1.0 from http://www.opensource.org/licenses/osl.php or
+   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
+   3001 King Ranch Road, Ukiah, CA 95482.   */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <argp.h>
+#include <assert.h>
+#include <ctype.h>
+#include <endian.h>
+#include <errno.h>
+#include <error.h>
+#include <fcntl.h>
+#include <gelf.h>
+#include <inttypes.h>
+#include <libintl.h>
+#include <locale.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdio_ext.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+
+#include <system.h>
+
+
+/* Prototypes of local functions.  */
+static int read_fd (int fd, const char *fname, off64_t fdlen);
+static int read_elf (Elf *elf, int fd, const char *fname, off64_t fdlen);
+
+
+/* Name and version of program.  */
+static void print_version (FILE *stream, struct argp_state *state);
+void (*argp_program_version_hook) (FILE *, struct argp_state *) = print_version;
+
+/* Bug report address.  */
+const char *argp_program_bug_address = PACKAGE_BUGREPORT;
+
+/* Definitions of arguments for argp functions.  */
+static const struct argp_option options[] =
+{
+  { NULL, 0, NULL, 0, N_("Output Selection:"), 0 },
+  { "all", 'a', NULL, 0, N_("Scan entire file, not only loaded sections"), 0 },
+  { "bytes", 'n', "MIN-LEN", 0,
+    N_("Only NUL-terminated sequences of MIN-LEN characters or more are printed"), 0 },
+  { "encoding", 'e', "SELECTOR", 0, N_("\
+Select character size and endianess: s = 7-bit, S = 8-bit, {b,l} = 16-bit, {B,L} = 32-bit"),
+    0},
+  { "print-file-name", 'f', NULL, 0,
+    N_("Print name of the file before each string."), 0 },
+  { "radix", 't', "{o,d,x}", 0,
+    N_("Print location of the string in base 8, 10, or 16 respectively."), 0 },
+  { NULL, 'o', NULL, 0, N_("Alias for --radix=o"), 0 },
+
+  { NULL, 0, NULL, 0, N_("Miscellaneous:"), 0 },
+  { NULL, 0, NULL, 0, NULL, 0 }
+};
+
+/* Short description of program.  */
+static const char doc[] = N_("\
+Print the strings of printable characters in files.");
+
+/* Strings for arguments in help texts.  */
+static const char args_doc[] = N_("[FILE...]");
+
+/* Prototype for option handler.  */
+static error_t parse_opt (int key, char *arg, struct argp_state *state);
+
+/* Data structure to communicate with argp functions.  */
+static struct argp argp =
+{
+  options, parse_opt, args_doc, doc, NULL, NULL, NULL
+};
+
+
+/* Global variables.  */
+
+/* True if whole file and not only loaded sections are looked at.  */
+static bool entire_file;
+
+/* Minimum length of any sequence reported.  */
+static size_t min_len = 4;
+
+/* Number of bytes per character.  */
+static size_t bytes_per_char = 1;
+
+/* Minimum length of any sequence reported in bytes.  */
+static size_t min_len_bytes;
+
+/* True if multibyte characters are in big-endian order.  */
+static bool big_endian;
+
+/* True unless 7-bit ASCII are expected.  */
+static bool char_7bit;
+
+/* True if file names should be printed before strings.  */
+static bool print_file_name;
+
+/* Location print format string.  */
+static const char *locfmt;
+
+/* Page size in use.  */
+static size_t ps;
+
+
+/* Mapped parts of the ELF file.  */
+static unsigned char *elfmap;
+static unsigned char *elfmap_base;
+static size_t elfmap_size;
+static off64_t elfmap_off;
+
+
+int
+main (int argc, char *argv[])
+{
+  /* We use no threads.  */
+  __fsetlocking (stdin, FSETLOCKING_BYCALLER);
+  __fsetlocking (stdout, FSETLOCKING_BYCALLER);
+
+  /* Set locale.  */
+  (void) setlocale (LC_ALL, "");
+
+  /* Make sure the message catalog can be found.  */
+  (void) bindtextdomain (PACKAGE, LOCALEDIR);
+
+  /* Initialize the message catalog.  */
+  (void) textdomain (PACKAGE);
+
+  /* Parse and process arguments.  */
+  int remaining;
+  (void) argp_parse (&argp, argc, argv, 0, &remaining, NULL);
+
+  /* Tell the library which version we are expecting.  */
+  elf_version (EV_CURRENT);
+
+  /* Determine the page size.  We will likely need it a couple of times.  */
+  ps = sysconf (_SC_PAGESIZE);
+
+  struct stat64 st;
+  int result = 0;
+  if (remaining == argc)
+    /* We read from standard input.  This we cannot do for a
+       structured file.  */
+    result = read_fd (STDOUT_FILENO,
+		      print_file_name ? "{standard input}" : NULL,
+		      fstat64 (STDOUT_FILENO, &st) == 0
+		      ? st.st_size : INT64_C (0x7fffffffffffffff));
+  else
+    do
+      {
+	int fd = (strcmp (argv[remaining], "-") == 0
+		  ? STDIN_FILENO : open (argv[remaining], O_RDONLY));
+	if (unlikely (fd == -1))
+	  {
+	    error (0, errno, gettext ("cannot open '%s'"), argv[remaining]);
+	    result = 1;
+	  }
+	else
+	  {
+	    const char *fname = print_file_name ? argv[remaining] : NULL;
+	    int fstat_fail = fstat64 (fd, &st);
+	    off64_t fdlen = (fstat_fail
+			     ? INT64_C (0x7fffffffffffffff) : st.st_size);
+	    if (fdlen > (off64_t) min_len_bytes)
+	      {
+		Elf *elf = NULL;
+		if (entire_file
+		    || fstat_fail
+		    || !S_ISREG (st.st_mode)
+		    || (elf = elf_begin (fd, ELF_C_READ, NULL)) == NULL
+		    || elf_kind (elf) != ELF_K_ELF)
+		  result |= read_fd (fd, fname, fdlen);
+		else
+		  result |= read_elf (elf, fd, fname, fdlen);
+
+		/* This call will succeed even if ELF is NULL.  */
+		elf_end (elf);
+	      }
+
+	    if (strcmp (argv[remaining], "-") != 0)
+	      close (fd);
+	  }
+
+	if (elfmap != NULL && elfmap != MAP_FAILED)
+	  munmap (elfmap, elfmap_size);
+      }
+    while (++remaining < argc);
+
+  return result;
+}
+
+
+/* Print the version information.  */
+static void
+print_version (FILE *stream, struct argp_state *state __attribute__ ((unused)))
+{
+  fprintf (stream, "strings (%s) %s\n", PACKAGE_NAME, VERSION);
+  fprintf (stream, gettext ("\
+Copyright (C) %s Red Hat, Inc.\n\
+This is free software; see the source for copying conditions.  There is NO\n\
+warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\
+"), "2005");
+  fprintf (stream, gettext ("Written by %s.\n"), "Ulrich Drepper");
+}
+
+
+/* Handle program arguments.  */
+static error_t
+parse_opt (int key, char *arg,
+	   struct argp_state *state __attribute__ ((unused)))
+{
+  switch (key)
+    {
+    case 'a':
+      entire_file = true;
+      break;
+
+    case 'e':
+      /* We expect a string of one character.  */
+      switch (arg[1] != '\0' ? '\0' : arg[0])
+	{
+	case 's':
+	case 'S':
+	  char_7bit = arg[0] == 's';
+	  bytes_per_char = 1;
+	  break;
+
+	case 'b':
+	case 'B':
+	  big_endian = true;
+	  /* FALLTHROUGH */
+
+	case 'l':
+	case 'L':
+	  bytes_per_char = isupper (arg[0]) ? 4 : 2;
+	  break;
+
+	default:
+	  error (0, 0, gettext ("invalid value '%s' for %s parameter"),
+		 arg, "-e");
+	  argp_help (&argp, stderr, ARGP_HELP_SEE, "strings");
+	  return ARGP_ERR_UNKNOWN;
+	}
+      break;
+
+    case 'f':
+      print_file_name = true;
+      break;
+
+    case 'n':
+      min_len = atoi (arg);
+      break;
+
+    case 'o':
+      goto octfmt;
+
+    case 't':
+      switch (arg[0])
+	{
+	case 'd':
+	  locfmt = "%7" PRId64 " ";
+	  break;
+
+	case 'o':
+	octfmt:
+	  locfmt = "%7" PRIo64 " ";
+	  break;
+
+	case 'x':
+	  locfmt = "%7" PRIx64 " ";
+	  break;
+
+	default:
+	  error (0, 0, gettext ("invalid value '%s' for %s parameter"),
+		 arg, "-t");
+	  argp_help (&argp, stderr, ARGP_HELP_SEE, "strings");
+	  return ARGP_ERR_UNKNOWN;
+	}
+      break;
+
+    case ARGP_KEY_FINI:
+      /* Compute the length in bytes of any match.  */
+      if (min_len <= 0 || min_len > INT_MAX / bytes_per_char)
+	error (EXIT_FAILURE, 0,
+	       gettext ("invalid minimum length of matched string size"));
+      min_len_bytes = min_len * bytes_per_char;
+      break;
+
+    default:
+      return ARGP_ERR_UNKNOWN;
+    }
+  return 0;
+}
+
+
+static void
+process_chunk_mb (const char *fname, const unsigned char *buf, off64_t to,
+		  size_t len, char **unprinted)
+{
+  size_t curlen = *unprinted == NULL ? 0 : strlen (*unprinted);
+  const unsigned char *start = buf;
+  while (len >= bytes_per_char)
+    {
+      uint32_t ch;
+
+      if (bytes_per_char == 2)
+	{
+	  if (big_endian)
+	    ch = buf[0] << 8 | buf[1];
+	  else
+	    ch = buf[1] << 8 | buf[0];
+	}
+      else
+	{
+	  if (big_endian)
+	    ch = buf[0] << 24 | buf[1] << 16 | buf[2] << 8 | buf[3];
+	  else
+	    ch = buf[3] << 24 | buf[2] << 16 | buf[1] << 8 | buf[0];
+	}
+
+      if (ch <= 255 && (ch == '\t' || isprint (ch)))
+	{
+	  ++buf;
+	  ++curlen;
+	}
+      else
+	{
+	  if (curlen >= min_len)
+	    {
+	      /* We found a match.  */
+	      if (unlikely (fname != NULL))
+		{
+		  fputs_unlocked (fname, stdout);
+		  fputs_unlocked (": ", stdout);
+		}
+
+	      if (unlikely (locfmt != NULL))
+		printf (locfmt, (int64_t) to - len);
+
+	      if (unlikely (*unprinted != NULL))
+		{
+		  fputs_unlocked (*unprinted, stdout);
+		  free (*unprinted);
+		  *unprinted = NULL;
+		}
+
+	      /* There is no sane way of printing the string.  If we
+		 assume the file data is encoded in UCS-2/UTF-16 or
+		 UCS-4/UTF-32 respectively we could covert the string.
+		 But there is no such guarantee.  */
+	      fwrite_unlocked (start, 1, buf - start, stdout);
+	      putc_unlocked ('\n', stdout);
+	    }
+
+	  start = ++buf;
+	  curlen =  0;
+
+	  if (len <= min_len)
+	    break;
+	}
+
+      --len;
+    }
+
+  if (curlen != 0)
+    *unprinted = xstrndup ((const char *) start, curlen);
+}
+
+
+static void
+process_chunk (const char *fname, const unsigned char *buf, off64_t to,
+	       size_t len, char **unprinted)
+{
+  /* We are not going to slow the check down for the 2- and 4-byte
+     encodings.  Handle them special.  */
+  if (unlikely (bytes_per_char != 1))
+    {
+      process_chunk_mb (fname, buf, to, len, unprinted);
+      return;
+    }
+
+  size_t curlen = *unprinted == NULL ? 0 : strlen (*unprinted);
+  const unsigned char *start = buf;
+  while (len > 0)
+    {
+      if ((*buf == '\t' || isprint (*buf))
+	       && (! char_7bit || *buf <= 127))
+	{
+	  ++buf;
+	  ++curlen;
+	}
+      else
+	{
+	  if (curlen >= min_len)
+	    {
+	      /* We found a match.  */
+	      if (unlikely (fname != NULL))
+		{
+		  fputs_unlocked (fname, stdout);
+		  fputs_unlocked (": ", stdout);
+		}
+
+	      if (unlikely (locfmt != NULL))
+		printf (locfmt, (int64_t) to - len);
+
+	      if (unlikely (*unprinted != NULL))
+		{
+		  fputs_unlocked (*unprinted, stdout);
+		  free (*unprinted);
+		  *unprinted = NULL;
+		}
+	      fwrite_unlocked (start, 1, buf - start, stdout);
+	      putc_unlocked ('\n', stdout);
+	    }
+
+	  start = ++buf;
+	  curlen =  0;
+
+	  if (len <= min_len)
+	    break;
+	}
+
+      --len;
+    }
+
+  if (curlen != 0)
+    *unprinted = xstrndup ((const char *) start, curlen);
+}
+
+
+/* Map a file in as large chunks as possible.  */
+static void *
+map_file (int fd, off64_t start_off, off64_t fdlen, size_t *map_sizep)
+{
+  /* Maximum size we mmap.  We use an #ifdef to avoid overflows on
+     32-bit machines.  64-bit machines these days do not have usable
+     address spaces larger than about 43 bits.  Not that any file
+     should be that large.  */
+#if SIZE_MAX > 0xffffffff
+  const size_t mmap_max = 0x4000000000lu;
+#else
+  const size_t mmap_max = 0x40000000lu;
+#endif
+
+  /* Try to mmap the file.  */
+  size_t map_size = MIN ((off64_t) mmap_max, fdlen);
+  const size_t map_size_min = MAX (MAX (SIZE_MAX / 16, 2 * ps),
+				   roundup (2 * min_len_bytes + 1, ps));
+  void *mem;
+  while (1)
+    {
+      /* We map the memory for reading only here.  Since we will
+	 always look at every byte of the file it makes sense to
+	 use MAP_POPULATE.  */
+      mem = mmap64 (NULL, map_size, PROT_READ, MAP_PRIVATE | MAP_POPULATE,
+		    fd, start_off);
+      if (mem != MAP_FAILED)
+	{
+	  /* We will go through the mapping sequentially.  */
+	  (void) posix_madvise (mem, map_size, POSIX_MADV_SEQUENTIAL);
+	  break;
+	}
+      if (errno != EINVAL && errno != ENOMEM)
+	/* This is an error other than the lack of address space.  */
+	break;
+
+      /* Maybe the size of the mapping is too big.  Try again.  */
+      map_size /= 2;
+      if (map_size < map_size_min)
+	/* That size should have fit.  */
+	break;
+    }
+
+  *map_sizep = map_size;
+  return mem;
+}
+
+
+/* Read the file without mapping.  */
+static int
+read_block_no_mmap (int fd, const char *fname, off64_t from, off64_t fdlen)
+{
+  char *unprinted = NULL;
+#define CHUNKSIZE 65536
+  unsigned char *buf = xmalloc (CHUNKSIZE + min_len_bytes
+				+ bytes_per_char - 1);
+  size_t ntrailer = 0;
+  int result = 0;
+  while (fdlen > 0)
+    {
+      ssize_t n = TEMP_FAILURE_RETRY (read (fd, buf + ntrailer,
+					    MIN (fdlen, CHUNKSIZE)));
+      if (n == 0)
+	{
+	  /* There are less than MIN_LEN+1 bytes left so there cannot be
+	     another match.  */
+	  assert (unprinted == NULL || ntrailer == 0);
+	  break;
+	}
+      if (unlikely (n < 0))
+	{
+	  /* Something went wrong.  */
+	  result = 1;
+	  break;
+	}
+
+      /* Account for the number of bytes read in this round.  */
+      fdlen -= n;
+
+      /* Do not use the signed N value.  Note that the addition cannot
+	 overflow.  */
+      size_t nb = (size_t) n + ntrailer;
+      if (nb >= min_len_bytes)
+	{
+	  /* We only use complete charactesr.  */
+	  nb &= ~(bytes_per_char - 1);
+
+	  process_chunk (fname, buf, from + nb, nb, &unprinted);
+
+	  /* If the last bytes of the buffer (module the character
+	     size) have been printed we are not copying them.  */
+	  size_t to_keep = unprinted != NULL ? 0 : min_len_bytes;
+
+	  memmove (buf, buf + nb - to_keep, to_keep + nb);
+	  ntrailer = to_keep + nb;
+	  from += nb;
+	}
+      else
+	ntrailer = nb;
+    }
+
+  free (buf);
+
+  /* Don't print anything we collected so far.  There is no
+     terminating NUL byte.  */
+  free (unprinted);
+
+  return result;
+}
+
+
+static int
+read_block (int fd, const char *fname, off64_t fdlen, off64_t from, off64_t to)
+{
+  assert ((off64_t) min_len_bytes < fdlen);
+
+  if (elfmap == NULL)
+    {
+      /* We need a completely new mapping.  */
+      elfmap_off = from & ~(ps - 1);
+      elfmap_base = elfmap = map_file (fd, elfmap_off, fdlen, &elfmap_size);
+
+      if (unlikely (elfmap == MAP_FAILED))
+	/* Let the kernel know we are going to read everything in sequence.  */
+	(void) posix_fadvise (fd, 0, 0, POSIX_FADV_SEQUENTIAL);
+    }
+
+  if (unlikely (elfmap == MAP_FAILED))
+    {
+      /* Read from the file descriptor.  For this we must position the
+	 read pointer.  */
+      // XXX Eventually add flag which avoids this if the position
+      // XXX is known to match.
+      if (lseek64 (fd, from, SEEK_SET) != from)
+	error (EXIT_FAILURE, errno, gettext ("lseek64 failed"));
+
+      return read_block_no_mmap (fd, fname, from, to - from);
+    }
+
+  if (to < (off64_t) elfmap_off || from > (off64_t) (elfmap_off + elfmap_size))
+    {
+      /* The existing mapping cannot fit at all.  Map the new area.
+	 We always map the full range of ELFMAP_SIZE bytes even if
+	 this extend beyond the end of the file.  The Linux kernel
+	 handles this OK if the access pages are not touched.  */
+      elfmap_off = from & ~(ps - 1);
+      if (mmap64 (elfmap, elfmap_size, PROT_READ,
+		  MAP_PRIVATE | MAP_POPULATE | MAP_FIXED, fd, from)
+	  == MAP_FAILED)
+	error (EXIT_FAILURE, errno, gettext ("re-mmap failed"));
+      elfmap_base = elfmap;
+    }
+
+  char *unprinted = NULL;
+
+  /* Use the existing mapping as much as possible.  If necessary, map
+     new pages.  */
+  if (from >= (off64_t) elfmap_off
+      && from < (off64_t) (elfmap_off + elfmap_size))
+    /* There are at least a few bytes in this mapping which we can
+       use.  */
+    process_chunk (fname, elfmap_base + (from - elfmap_off),
+		   MIN (to, (off64_t) (elfmap_off + elfmap_size)),
+		   MIN (to, (off64_t) (elfmap_off + elfmap_size)) - from,
+		   &unprinted);
+
+  if (to > (off64_t) (elfmap_off + elfmap_size))
+    {
+      unsigned char *remap_base = elfmap_base;
+      size_t read_now = elfmap_size - (elfmap_base - elfmap);
+
+      assert (from >= (off64_t) elfmap_off
+	      && from < (off64_t) (elfmap_off + elfmap_size));
+      off64_t handled_to = elfmap_off + elfmap_size;
+      assert (elfmap == elfmap_base
+	      || (elfmap_base - elfmap
+		  == (ptrdiff_t) ((min_len_bytes + ps - 1) & ~(ps - 1))));
+      if (elfmap == elfmap_base)
+	{
+	  size_t keep_area = (min_len_bytes + ps - 1) & ~(ps - 1);
+	  assert (elfmap_size >= keep_area + ps);
+	  /* The keep area is used for the content of the previous
+	     buffer we have to keep.  This means copying those bytes
+	     and for this we have to make the data writable.  */
+	  if (unlikely (mprotect (elfmap, keep_area, PROT_READ | PROT_WRITE)
+			!= 0))
+	    error (EXIT_FAILURE, errno, gettext ("mprotect failed"));
+
+	  elfmap_base = elfmap + keep_area;
+	}
+
+      while (1)
+	{
+	  /* Map the rest of the file, eventually again in pieces.
+	     We speed things up with a nice Linux feature.  Note
+	     that we have at least two pages mapped.  */
+	  size_t to_keep = unprinted != NULL ? 0 : min_len_bytes;
+
+	  assert (read_now >= to_keep);
+	  memmove (elfmap_base - to_keep,
+		   remap_base + read_now - to_keep, to_keep);
+	  remap_base = elfmap_base;
+
+	  assert ((elfmap_size - (elfmap_base - elfmap)) % bytes_per_char
+		  == 0);
+	  read_now = MIN (to - handled_to,
+			  (ptrdiff_t) elfmap_size - (elfmap_base - elfmap));
+
+	  assert (handled_to % ps == 0);
+	  assert (handled_to % bytes_per_char == 0);
+	  if (mmap64 (remap_base, read_now, PROT_READ,
+		      MAP_PRIVATE | MAP_POPULATE | MAP_FIXED, fd, handled_to)
+	      == MAP_FAILED)
+	    error (EXIT_FAILURE, errno, gettext ("re=mmap failed"));
+	  elfmap_off = handled_to;
+
+	  process_chunk (fname, remap_base - to_keep,
+			 elfmap_off + (read_now & ~(bytes_per_char - 1)),
+			 to_keep + (read_now & ~(bytes_per_char - 1)),
+			 &unprinted);
+	  handled_to += read_now;
+	  if (handled_to >= to)
+	    break;
+	}
+    }
+
+  /* Don't print anything we collected so far.  There is no
+     terminating NUL byte.  */
+  free (unprinted);
+
+  return 0;
+}
+
+
+static int
+read_fd (int fd, const char *fname, off64_t fdlen)
+{
+  return read_block (fd, fname, fdlen, 0, fdlen);
+}
+
+
+static int
+read_elf (Elf *elf, int fd, const char *fname, off64_t fdlen)
+{
+  assert (fdlen >= 0);
+
+  /* We will look at each section separately.  The ELF file is not
+     mmapped.  The libelf implementation will load the needed parts on
+     demand.  Since we only interate over the section header table the
+     memory consumption at this stage is kept minimal.  */
+  Elf_Scn *scn = elf_nextscn (elf, NULL);
+  if (scn == NULL)
+    return read_fd (fd, fname, fdlen);
+
+  int result = 0;
+  do
+    {
+      GElf_Shdr shdr_mem;
+      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
+
+      /* Only look in sections which are loaded at runtime and
+	 actually have content.  */
+      if (shdr != NULL && shdr->sh_type != SHT_NOBITS
+	  && (shdr->sh_flags & SHF_ALLOC) != 0)
+	result |= read_block (fd, fname, fdlen, shdr->sh_offset,
+			      shdr->sh_offset + shdr->sh_size);
+    }
+  while ((scn = elf_nextscn (elf, scn)) != NULL);
+
+  if (elfmap != NULL && elfmap != MAP_FAILED)
+    munmap (elfmap, elfmap_size);
+  elfmap = NULL;
+
+  return result;
+}