PATCH: wide character extension for strings in binutils-2.11.2

[Markus Kuhn]

The "strings" tool in the GNU binutils-2.11.2 could only find strings
consisting of 8-bit characters. Therefore it was not useable to find
16-bit Unicode strings in Win32 EXE files or 32-bit wchar_t strings in
GNU/Linux binaries. The patch below adds a new option -e with which
strings can now also be used to locate 16/32-bit strings, both big
and little endian. I found that little extension extremely useful and
therefore hope you can add it to strings in the next binutils
release.

Cheers,

Markus

-- 
Markus G. Kuhn, Computer Laboratory, University of Cambridge, UK
Email: mkuhn at acm.org,  WWW: <http://www.cl.cam.ac.uk/~mgk25/>


--- strings.1   2001-07-04 18:44:23+01  1.1
+++ strings.1   2001-07-04 18:52:59+01
@@ -104,6 +104,16 @@
 hexadecimal, or decimal.
 
 .TP
+.BR "\-e " {s,b,l,B,L}
+.TP
+.BR "\-\-encoding=" {s,b,l,B,L}
+Select the character encoding of the strings that are to be found:
+`s' = single-byte characters (ASCII, ISO 8859, etc., default),
+`b' = 16-bit bigendian, `l' = 16-bit littleendian,
+`B' = 32-bit bigendian, `L' = 32-bit littleendian. Useful for finding
+wide character strings.
+
+.TP
 .BI "\-\-target=" "bfdname"
 Specify an object code format other than your system's default format.
 See 
--- strings.c   2001-07-04 14:02:13+01  1.1
+++ strings.c   2001-07-04 17:35:19+01
@@ -39,6 +39,11 @@
    -o          Like -to.  (Some other implementations have -o like -to,
                others like -td.  We chose one arbitrarily.)
 
+   --encoding={s,b,l,B,L}
+   -e {s,b,l,B,L}
+               Select character encoding: single-byte, bigendian 16-bit,
+               littleendian 16-bit, bigendian 32-bit, littleendian 32-bit
+
    --target=BFDNAME
                Specify a non-default object file format.
 
@@ -113,12 +118,17 @@
 /* The BFD object file format.  */
 static char *target;
 
+/* The character encoding format.  */
+static char encoding;
+static int encoding_bytes;
+
 static struct option long_options[] =
 {
   {"all", no_argument, NULL, 'a'},
   {"print-file-name", no_argument, NULL, 'f'},
   {"bytes", required_argument, NULL, 'n'},
   {"radix", required_argument, NULL, 't'},
+  {"encoding", required_argument, NULL, 'e'},
   {"target", required_argument, NULL, 'T'},
   {"help", no_argument, NULL, 'h'},
   {"version", no_argument, NULL, 'v'},
@@ -156,8 +166,9 @@
   print_filenames = false;
   datasection_only = true;
   target = NULL;
+  encoding = 's';
 
-  while ((optc = getopt_long (argc, argv, "afn:ot:v0123456789",
+  while ((optc = getopt_long (argc, argv, "afn:ot:e:v0123456789",
                              long_options, (int *) 0)) != EOF)
     {
       switch (optc)
@@ -213,6 +224,12 @@
          target = optarg;
          break;
 
+       case 'e':
+         if (optarg[1] != '\0')
+           usage (stderr, 1);
+         encoding = optarg[0];
+         break;
+
        case 'v':
          print_version ("strings");
          break;
@@ -232,6 +249,23 @@
   if (string_min < 0)
     string_min = 4;
 
+  switch (encoding)
+    {
+    case 's':
+      encoding_bytes = 1;
+      break;
+    case 'b':
+    case 'l':
+      encoding_bytes = 2;
+      break;
+    case 'B':
+    case 'L':
+      encoding_bytes = 4;
+      break;
+    default:
+      usage (stderr, 1);
+    }
+
   bfd_init ();
   set_default_bfd_target ();
 
@@ -366,6 +400,74 @@
   return true;
 }
 
+/* Read the next character, return EOF if none available.
+   Assume that STREAM is positioned so that the next byte read
+   is at address ADDRESS in the file.
+
+   If STREAM is NULL, do not read from it.
+   The caller can supply a buffer of characters
+   to be processed before the data in STREAM.
+   MAGIC is the address of the buffer and
+   MAGICCOUNT is how many characters are in it. */
+
+static long
+get_char (stream, address, magiccount, magic)
+     FILE *stream;
+     file_ptr *address;
+     int *magiccount;
+     char **magic;
+{
+  int c, i;
+  long r;
+  unsigned char buf[4];
+
+  for (i = 0; i < encoding_bytes; i++)
+    {
+      if (*magiccount)
+       {
+         (*magiccount)--;
+         c = *(*magic)++;
+       }
+      else
+       {
+         if (stream == NULL)
+           return EOF;
+         c = getc (stream);
+         if (c == EOF)
+           return EOF;
+       }
+      (*address)++;
+      buf[i] = c;
+    }
+
+  switch (encoding)
+    {
+    case 's':
+      r = buf[0];
+      break;
+    case 'b':
+      r = (buf[0] << 8) | buf[1];
+      break;
+    case 'l':
+      r = buf[0] | (buf[1] << 8);
+      break;
+    case 'B':
+      r = ((long) buf[0] << 24) | ((long) buf[1] << 16) |
+       ((long) buf[2] << 8) | buf[3];
+      break;
+    case 'L':
+      r = buf[0] | ((long) buf[1] << 8) | ((long) buf[2] << 16) |
+       ((long) buf[3] << 24);
+      break;
+    }
+
+  if (r == EOF)
+    return 0;
+
+  return r;
+}
+
+
 /* Find the strings in file FILENAME, read from STREAM.
    Assume that STREAM is positioned so that the next byte read
    is at address ADDRESS in the file.
@@ -387,13 +489,13 @@
      int magiccount;
      char *magic;
 {
-  char *buf = (char *) xmalloc (string_min + 1);
+  char *buf = (char *) xmalloc (sizeof(char) * (string_min + 1));
 
   while (1)
     {
       file_ptr start;
       int i;
-      int c;
+      long c;
 
       /* See if the next `string_min' chars are all graphic chars.  */
     tryline:
@@ -402,21 +504,10 @@
       start = address;
       for (i = 0; i < string_min; i++)
        {
-         if (magiccount)
-           {
-             magiccount--;
-             c = *magic++;
-           }
-         else
-           {
-             if (stream == NULL)
-               return;
-             c = getc (stream);
-             if (c == EOF)
-               return;
-           }
-         address++;
-         if (!isgraphic (c))
+         c = get_char (stream, &address, &magiccount, &magic);
+         if (c == EOF)
+           return;
+         if (c > 255 || c < 0 || !isgraphic (c))
            /* Found a non-graphic.  Try again starting with next char.  */
            goto tryline;
          buf[i] = c;
@@ -448,21 +539,10 @@
 
       while (1)
        {
-         if (magiccount)
-           {
-             magiccount--;
-             c = *magic++;
-           }
-         else
-           {
-             if (stream == NULL)
-               break;
-             c = getc (stream);
-             if (c == EOF)
-               break;
-           }
-         address++;
-         if (! isgraphic (c))
+         c = get_char (stream, &address, &magiccount, &magic);
+         if (c == EOF)
+           break;
+         if (c > 255 || c < 0 || !isgraphic (c))
            break;
          putchar (c);
        }
@@ -524,9 +604,9 @@
      int status;
 {
   fprintf (stream, _("\
-Usage: %s [-afov] [-n min-len] [-min-len] [-t {o,x,d}] [-]\n\
-       [--all] [--print-file-name] [--bytes=min-len] [--radix={o,x,d}]\n\
-       [--target=bfdname] [--help] [--version] file...\n"),
+Usage: %s [-afov] [-n min-len] [-min-len] [-t {o,x,d}] [-e {s,b,l,B,L}]\n\
+       [-] [--all] [--print-file-name] [--bytes=min-len] [--radix={o,x,d}]\n\
+       [--target=bfdname] [--encoding {s,b,l,B,L}] [--help] [--version] 
file...\n"),
           program_name);
   list_supported_targets (program_name, stream);
   if (status == 0)