Diagnose error if macro expansion makes a line too long for its buffer

PhilipHazel · Aug 11, 2024 · a690304 · a690304
1 parent 84cc672
commit a690304
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diff --git a/ChangeLog b/ChangeLog
@@ -1,6 +1,13 @@
 ChangeLog file for xfpt
 -----------------------
 
+Release 1.01 XX-XXX-2024
+------------------------
+
+1. Diagnose an error when inserting an inline macro would overflow a line 
+   buffer.
+
+
 Release 1.00 08-March-2023
 --------------------------
 

diff --git a/src/dot.c b/src/dot.c
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* This module contains code for processing a line that starts with a dot. */
@@ -482,6 +482,7 @@ while (*p != 0)
   *pp = as;
   pp = &(as->next);
   as->string = misc_readitem(p, NULL, &length, NULL, 0);
+  as->length = length;
   p += length;
   }
 
@@ -503,7 +504,9 @@ for (;;)
   as->next = NULL;
   *pp = as;
   pp = &(as->next);
-  as->string = misc_copystring(line, Ustrlen(line));
+  length = Ustrlen(line);
+  as->string = misc_copystring(line, length);
+  as->length = length;
   }
 
 /* If there aren't any replacement lines, fake up a comment so that there's
@@ -514,6 +517,7 @@ if (md->lines == NULL)
   md->lines = misc_malloc(sizeof(argstr));
   md->lines->next = NULL;
   md->lines->string = misc_copystring(US". Dummy line\n", 13);
+  md->lines->length = 13;
   }
 }
 
@@ -913,6 +917,7 @@ while (*p != 0)
   *pp = as;
   pp = &(as->next);
   as->string = misc_readitem(p, NULL, &length, NULL, 0);
+  as->length = length;
   p += length;
   }
 }

diff --git a/src/error.c b/src/error.c
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* Error handling routines */
@@ -81,7 +81,8 @@ static error_struct error_data[] = {
 /* 30-34 */
 { ec_serious,  "bad macro argument substitution: %s follows \"%s\"" },
 { ec_serious,  "binary zero in input ignored" },
-{ ec_disaster, "input sources too deeply nested" }
+{ ec_disaster, "input sources too deeply nested" },
+{ ec_disaster, "maximum line length exceeded during macro substitution" }
 };
 
 #define error_maxerror (int)(sizeof(error_data)/sizeof(error_struct))
@@ -151,7 +152,7 @@ else for (int i = from_type_ptr; i >= 0; i--)
     {
     if (fe != NULL)
       {
-      if (fe->linenumber > 0) 
+      if (fe->linenumber > 0)
         (void)fprintf(stderr, "   Detected near line %d of %s\n",
           fe->linenumber, fe->filename);
       fe = fe->prev;

diff --git a/src/functions.h b/src/functions.h
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* This header defines all the global functions. */
@@ -23,7 +23,7 @@ extern void        para_process(uschar *);
 
 extern uschar     *read_nextline(void);
 extern uschar     *read_paragraph(uschar *, int *);
-extern void        read_process_macroline(uschar *, uschar *);
+extern void        read_process_macroline(uschar *, uschar *, int);
 
 extern int         tree_insertnode(tree_node **, tree_node *);
 extern tree_node  *tree_search(tree_node *, uschar *);

diff --git a/src/globals.c b/src/globals.c
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* Allocate storage and initialize global variables */
@@ -11,7 +11,7 @@
 
 
 uschar    *xfpt_share                = US DATADIR;
-uschar    *xfpt_version              = US "1.00 01-March-2023";
+uschar    *xfpt_version              = US "1.01-DEV 10-August-2024";
 
 tree_node *entities                  = NULL;
 

diff --git a/src/para.c b/src/para.c
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* This module contains code for processing a paragraph by looking for flag
@@ -69,6 +69,7 @@ while (*q != 0 && *q != ')')
   *pp = as;
   pp = &(as->next);
   as->string = misc_readitem(q, US",)", &length, NULL, 0);
+  as->length = length; 
   q += length;
   if (*q == ',') while (isspace(*(++q)));
   }
@@ -91,7 +92,7 @@ for (;;)
   {
   uschar buffer[INBUFFSIZE];
 
-  read_process_macroline(macrocurrent->nextline->string, buffer);
+  read_process_macroline(macrocurrent->nextline->string, buffer, INBUFFSIZE);
 
   /* A directive such as .eacharg can skip to the end of the macro if there
   is no .endeach. Detect this by looking for a change of macrocurrent value,

diff --git a/src/read.c b/src/read.c
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2023 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* This module contains code for reading the input. */
@@ -30,7 +30,7 @@ Returns:    nothing
 */
 
 void
-read_process_macroline(uschar *p, uschar *b)
+read_process_macroline(uschar *p, uschar *b, int blen)
 {
 int optend = 0;
 
@@ -49,17 +49,23 @@ while (*p != 0)
     continue;
     }
 
+  /* Ensure at least 3 bytes left in the buffer because all cases except an
+  argument substitution (which does its own test) add no more than two bytes,
+  and the third is for the terminating zero. */
+
+  if (blen < 3) error(33);   /* Hard error; does not return. */
+
   /* Until we hit a dollar, just copy verbatim */
 
-  if (*p != '$') { *b++ = *p++; continue; }
+  if (*p != '$') { *b++ = *p++; blen--; continue; }
 
   /* If dollar is at the end of the string, treat as literal. */
 
   if (p[1] == 0) { *b++ = '$'; break; }
 
   /* If the character after $ is another $, insert a literal $. */
 
-  if (p[1] == '$') { p++; *b++ = *p++; continue; }
+  if (p[1] == '$') { p++; *b++ = *p++; blen--; continue; }
 
   /* If the character after $ is +, we are dealing with arguments
   relative to macro_arg0 in a ".eacharg" section. Otherwise, we are dealing
@@ -73,6 +79,7 @@ while (*p != 0)
       error(18);
       *b++ = '$';
       *b++ = *p++;
+      blen -= 2;
       continue;
       }
     argbase = macro_argbase;
@@ -90,6 +97,7 @@ while (*p != 0)
         else error(17, p[1], "$=");
       *b++ = '$';
       *b++ = *p++;
+      blen -= 2;
       continue;
       }
     while (isdigit(*(++p))) argn = argn * 10 + *p - '0';
@@ -126,6 +134,7 @@ while (*p != 0)
     if (*p == 0 || *p == '\n') error(30, "end of line", "$");
       else error(17, p[1], "$");
     *b++ = *p++;
+    blen--;
     continue;
     }
   while (isdigit(*(++p))) argn = argn * 10 + *p - '0';
@@ -161,7 +170,12 @@ while (*p != 0)
 
   /* If we have found an argument, substitute it. */
 
-  if (arg != NULL) b += sprintf(CS b, "%s", arg->string);
+  if (arg != NULL)
+    {
+    blen -= arg->length;
+    if (blen < 1) error(33);  /* Hard; does not return */
+    b += sprintf(CS b, "%s", arg->string);
+    }
   }
 
 *b = 0;
@@ -294,7 +308,8 @@ for (;;)
       }
     else
       {
-      read_process_macroline(macrocurrent->nextline->string, inbuffer);
+      read_process_macroline(macrocurrent->nextline->string, inbuffer,
+        INBUFFSIZE);
       macrocurrent->nextline = macrocurrent->nextline->next;
       break;
       }

diff --git a/src/structs.h b/src/structs.h
@@ -2,7 +2,7 @@
 *     xfpt - Simple ASCII->Docbook processor     *
 *************************************************/
 
-/* Copyright (c) University of Cambridge, 2012 */
+/* Copyright (c) University of Cambridge, 2024 */
 /* Written by Philip Hazel, started in 2006 */
 
 /* This module contains definitions of structures that are used throughout the
@@ -44,6 +44,7 @@ typedef struct pushstr {
 typedef struct argstr {
   struct argstr *next;
   uschar *string;
+  int length; 
 } argstr;
 
 /* Macro definition item */

diff --git a/testing/infiles/07 b/testing/infiles/07
@@ -0,0 +1,5 @@
+.macro m1 one
+$1
+.endmacro
+&m1(111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111)
+
diff --git a/testing/outfiles/07 b/testing/outfiles/07
@@ -0,0 +1 @@
+<para>
diff --git a/testing/outfiles/07.err b/testing/outfiles/07.err
@@ -0,0 +1,4 @@
+** Error: maximum line length exceeded during macro substitution
+   Processing macro m1
+   Detected near line 6 of infiles/07
+** xfpt abandoned
diff --git a/testing/outfiles/cmd.err b/testing/outfiles/cmd.err
@@ -9,7 +9,7 @@ Usage: xfpt [[-]-help]
             [-S <share-directory>]
             [-v or --version]
             [input-file]
-xpft version 1.00 01-March-2023
+xpft version 1.01-DEV 10-August-2024
 Usage: xfpt [[-]-help]
             [-o <output-file>]
             [-S <share-directory>]