[PATCH] libdep plugin: fix bugs in parser and improve escaping

[Harmen Stoppels]

Fix bugs in the __.LIBDEP string to argument list parser in the libdep
plugin.

	PR ld/31906
	* libdep_plugin.c (st2vec): fix bug where null byte was not copied
	  on memmove, repeating the last character.  Allow literal \ by escaping
	  it with \\.  Allow escaping of quotes inside quoted strings.  Fix out
	  of bounds errors leading to segfaults on input strings like
	  `-L/'a\'b'`.

Signed-off-by: Harmen Stoppels <me@harmenstoppels.nl>
---
 ld/libdep_plugin.c | 63 +++++++++++++++++++---------------------------
 1 file changed, 26 insertions(+), 37 deletions(-)

diff --git a/ld/libdep_plugin.c b/ld/libdep_plugin.c
index 414f3cffe12..44fb7cbd588 100644
--- a/ld/libdep_plugin.c
+++ b/ld/libdep_plugin.c
@@ -138,7 +138,7 @@ str2vec (char *in)
 {
   char **res;
   char *s, *first, *end;
-  char *sq, *dq;
+  char *quote;
   int i;
 
   end = in + strlen (in);
@@ -157,55 +157,44 @@ str2vec (char *in)
     return res;
 
   i = 0;
-  sq = NULL;
-  dq = NULL;
+  quote = NULL;
   res[0] = first;
-  for (s = first; *s; s++)
+  for (s = first; *s;)
     {
       if (*s == '\\')
 	{
-	  memmove (s, s+1, end-s-1);
-	  end--;
+	  /* trailing backslash is not an escape character */
+	  if (s + 1 == end)
+	    break;
+	  memmove (s, s + 1, end - s);
+	  --end;
+	  ++s;
 	}
-      if (isspace ((unsigned char) *s))
+      else if (*s == '\'' || *s == '\"')
 	{
-	  if (sq || dq)
-	    continue;
-	  *s++ = '\0';
-	  while (isspace ((unsigned char) *s)) s++;
-	  if (*s)
-	    res[++i] = s;
-	}
-      if (*s == '\'' && !dq)
-	{
-	  if (sq)
+	  if (!quote)
+	    quote = s++;
+	  else if (*s == *quote)
 	    {
-	      memmove (sq, sq+1, s-sq-1);
-	      memmove (s-2, s+1, end-s-1);
+	      memmove (quote, quote + 1, s - quote - 1);
+	      memmove (s - 1, s + 1, end - s);
 	      end -= 2;
-	      s--;
-	      sq = NULL;
+	      --s;
+	      quote = NULL;
 	    }
 	  else
-	    {
-	      sq = s;
-	    }
+	    ++s;
 	}
-      if (*s == '"' && !sq)
+      else if (!quote && isspace ((unsigned char) *s))
 	{
-	  if (dq)
-	    {
-	      memmove (dq, dq+1, s-dq-1);
-	      memmove (s-2, s+1, end-s-1);
-	      end -= 2;
-	      s--;
-	      dq = NULL;
-	    }
-	  else
-	    {
-	      dq = s;
-	    }
+	  *s++ = '\0';
+	  while (isspace ((unsigned char) *s))
+	    s++;
+	  if (*s)
+	    res[++i] = s;
 	}
+      else
+	++s;
     }
   res[++i] = NULL;
   return res;
-- 
2.40.1