From: Paul Eggert <eggert@cs.ucla.edu>
Date: Tue, 30 Apr 2024 08:20:12 +0000 (-0700)
Subject: etags: fix #line parsing (\\", long lines)
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=3bc1a3e881039cbf8c91cc8ce543aad812be6d3b;p=emacs.git

etags: fix #line parsing (\\", long lines)

* lib-src/etags.c (readline): Don’t mishandle lines like
‘#line 1 "a//"’, which has an escaped backslash before ‘"’.
Don’t mishandle lines so long that sscanf overflows %n.

(cherry picked from commit 7e2309c6fc67b8149cc4c75f8d7f5f93e60b86c7)
---

diff --git a/lib-src/etags.c b/lib-src/etags.c
index c316b3c7649..57ffbce380c 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -7375,26 +7375,26 @@ readline (linebuffer *lbp, FILE *stream)
       /* Check whether this is a #line directive. */
       if (result > 12 && strneq (lbp->buffer, "#line ", 6))
 	{
-	  intmax_t lno;
-	  int start = 0;
+	  char *lno_start = lbp->buffer + 6;
+	  char *lno_end;
+	  intmax_t lno = strtoimax (lno_start, &lno_end, 10);
+	  char *quoted_filename
+	    = lno_start < lno_end ? skip_spaces (lno_end) : NULL;
 
-	  if (sscanf (lbp->buffer, "#line %"SCNdMAX" \"%n", &lno, &start) >= 1
-	      && start > 0)	/* double quote character found */
+	  if (quoted_filename && *quoted_filename == '"')
 	    {
-	      char *endp = lbp->buffer + start;
+	      char *endp = quoted_filename;
+	      while (*++endp && *endp != '"')
+		endp += *endp == '\\' && endp[1];
 
-	      while ((endp = strchr (endp, '"')) != NULL
-		     && endp[-1] == '\\')
-		endp++;
-	      if (endp != NULL)
+	      if (*endp)
 		/* Ok, this is a real #line directive.  Let's deal with it. */
 		{
 		  char *taggedabsname;	/* absolute name of original file */
 		  char *taggedfname;	/* name of original file as given */
-		  char *name;		/* temp var */
+		  char *name = quoted_filename + 1;
 
 		  discard_until_line_directive = false; /* found it */
-		  name = lbp->buffer + start;
 		  *endp = '\0';
 		  canonicalize_filename (name);
 		  taggedabsname = absolute_filename (name, tagfiledir);