Differential Revision: http://reviews.llvm.org/D7249

llvm-svn: 234477

compiler-rt/lib/dfsan/dfsan.cc

@@ -24,6 +24,7 @@
 #include "sanitizer_common/sanitizer_flags.h"
 #include "sanitizer_common/sanitizer_flag_parser.h"
 #include "sanitizer_common/sanitizer_libc.h"
+#include "sanitizer_common/sanitizer_internal_defs.h"
 
 #include "dfsan/dfsan.h"
 
@@ -110,8 +111,7 @@ static void dfsan_check_label(dfsan_label label) {
 
 // Resolves the union of two unequal labels.  Nonequality is a precondition for
 // this function (the instrumentation pass inlines the equality test).
-extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+dfsan_label __dfsan_union_internal(dfsan_label l1, dfsan_label l2, uptr pc) {
-dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) {
   DCHECK_NE(l1, l2);
 
   if (l1 == 0)
@@ -143,6 +143,7 @@ dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) {
       dfsan_check_label(label);
       __dfsan_label_info[label].l1 = l1;
       __dfsan_label_info[label].l2 = l2;
+      __dfsan_label_info[label].pc = pc;
     }
     atomic_store(table_ent, label, memory_order_release);
   } else if (label == kInitializingLabel) {
@@ -155,13 +156,18 @@ dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) {
   return label;
 }
 
+extern "C" SANITIZER_INTERFACE_ATTRIBUTE
+dfsan_label __dfsan_union(dfsan_label l1, dfsan_label l2) {
+  return __dfsan_union_internal(l1, l2, GET_CALLER_PC());
+}
+
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 dfsan_label __dfsan_union_load(const dfsan_label *ls, uptr n) {
   dfsan_label label = ls[0];
   for (uptr i = 1; i != n; ++i) {
     dfsan_label next_label = ls[i];
     if (label != next_label)
-      label = __dfsan_union(label, next_label);
+      label = __dfsan_union_internal(label, next_label, GET_CALLER_PC());
   }
   return label;
 }
@@ -196,7 +202,7 @@ SANITIZER_INTERFACE_ATTRIBUTE dfsan_label
 dfsan_union(dfsan_label l1, dfsan_label l2) {
   if (l1 == l2)
     return l1;
-  return __dfsan_union(l1, l2);
+  return __dfsan_union_internal(l1, l2, GET_CALLER_PC());
 }
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
@@ -206,6 +212,7 @@ dfsan_label dfsan_create_label(const char *desc, void *userdata) {
   dfsan_check_label(label);
   __dfsan_label_info[label].l1 = __dfsan_label_info[label].l2 = 0;
   __dfsan_label_info[label].desc = desc;
+  __dfsan_label_info[label].pc = GET_CALLER_PC();
   __dfsan_label_info[label].userdata = userdata;
   return label;
 }

compiler-rt/lib/dfsan/dfsan.h

@@ -24,6 +24,7 @@ struct dfsan_label_info {
   dfsan_label l1;
   dfsan_label l2;
   const char *desc;
+  uptr pc;
   void *userdata;
 };
 

compiler-rt/lib/dfsan/dfsan_custom.cc

@@ -847,138 +847,153 @@ __dfsw_write(int fd, const void *buf, size_t count,
   *ret_label = 0;
   return write(fd, buf, count);
 }
+}
 
 // Type used to extract a dfsan_label with va_arg()
 typedef int dfsan_label_va;
 
-// A chunk of data representing the output of formatting either a constant
+// Formats a chunk either a constant string or a single format directive (e.g.,
-// string or a single format directive.
+// '%.3f').
-struct Chunk {
+struct Formatter {
-  // Address of the beginning of the formatted string
+  Formatter(char *str_, const char *fmt_, size_t size_)
-  const char *ptr;
+      : str(str_), str_off(0), size(size_), fmt_start(fmt_), fmt_cur(fmt_),
-  // Size of the formatted string
+        width(-1) {}
+
+  int format() {
+    char *tmp_fmt = build_format_string();
+    int retval =
+        snprintf(str + str_off, str_off < size ? size - str_off : 0, tmp_fmt,
+                 0 /* used only to avoid warnings */);
+    free(tmp_fmt);
+    return retval;
+  }
+
+  template <typename T> int format(T arg) {
+    char *tmp_fmt = build_format_string();
+    int retval;
+    if (width >= 0) {
+      retval = snprintf(str + str_off, str_off < size ? size - str_off : 0,
+                        tmp_fmt, width, arg);
+    } else {
+      retval = snprintf(str + str_off, str_off < size ? size - str_off : 0,
+                        tmp_fmt, arg);
+    }
+    free(tmp_fmt);
+    return retval;
+  }
+
+  char *build_format_string() {
+    size_t fmt_size = fmt_cur - fmt_start + 1;
+    char *new_fmt = (char *)malloc(fmt_size + 1);
+    assert(new_fmt);
+    internal_memcpy(new_fmt, fmt_start, fmt_size);
+    new_fmt[fmt_size] = '\0';
+    return new_fmt;
+  }
+
+  char *str_cur() { return str + str_off; }
+
+  size_t num_written_bytes(int retval) {
+    if (retval < 0) {
+      return 0;
+    }
+
+    size_t num_avail = str_off < size ? size - str_off : 0;
+    if (num_avail == 0) {
+      return 0;
+    }
+
+    size_t num_written = retval;
+    // A return value of {v,}snprintf of size or more means that the output was
+    // truncated.
+    if (num_written >= num_avail) {
+      num_written -= num_avail;
+    }
+
+    return num_written;
+  }
+
+  char *str;
+  size_t str_off;
   size_t size;
-
+  const char *fmt_start;
-  // Type of DFSan label (depends on the format directive)
+  const char *fmt_cur;
-  enum {
+  int width;
-    // Constant string, no argument and thus no label
-    NONE = 0,
-    // Label for an argument of '%n'
-    IGNORED,
-    // Label for a '%s' argument
-    STRING,
-    // Label for any other type of argument
-    NUMERIC,
-  } label_type;
-
-  // Value of the argument (if label_type == STRING)
-  const char *arg;
 };
 
-// Formats the input. The output is stored in 'str' starting from offset
-// 'off'. The format directive is represented by the first 'format_size' bytes
-// of 'format'. If 'has_size' is true, 'size' bounds the number of output
-// bytes. Returns the return value of the vsnprintf call used to format the
-// input.
-static int format_chunk(char *str, size_t off, bool has_size, size_t size,
-                        const char *format, size_t format_size, ...) {
-  char *chunk_format = (char *) malloc(format_size + 1);
-  assert(chunk_format);
-  internal_memcpy(chunk_format, format, format_size);
-  chunk_format[format_size] = '\0';
-
-  va_list ap;
-  va_start(ap, format_size);
-  int r = 0;
-  if (has_size) {
-    r = vsnprintf(str + off, off < size ? size - off : 0, chunk_format, ap);
-  } else {
-    r = vsprintf(str + off, chunk_format, ap);
-  }
-  va_end(ap);
-
-  free(chunk_format);
-  return r;
-}
-
 // Formats the input and propagates the input labels to the output. The output
-// is stored in 'str'. If 'has_size' is true, 'size' bounds the number of
+// is stored in 'str'. 'size' bounds the number of output bytes. 'format' and
-// output bytes. 'format' and 'ap' are the format string and the list of
+// 'ap' are the format string and the list of arguments for formatting. Returns
-// arguments for formatting. Returns the return value vsnprintf would return.
+// the return value vsnprintf would return.
 //
 // The function tokenizes the format string in chunks representing either a
 // constant string or a single format directive (e.g., '%.3f') and formats each
 // chunk independently into the output string. This approach allows to figure
 // out which bytes of the output string depends on which argument and thus to
 // propagate labels more precisely.
-static int format_buffer(char *str, bool has_size, size_t size,
+//
-                         const char *format, dfsan_label *va_labels,
+// WARNING: This implementation does not support conversion specifiers with
-                         dfsan_label *ret_label, va_list ap) {
+// positional arguments.
-  InternalMmapVector<Chunk> chunks(8);
+static int format_buffer(char *str, size_t size, const char *fmt,
-  size_t off = 0;
+                         dfsan_label *va_labels, dfsan_label *ret_label,
+                         va_list ap) {
+  Formatter formatter(str, fmt, size);
 
-  while (*format) {
+  while (*formatter.fmt_cur) {
-    chunks.push_back(Chunk());
+    formatter.fmt_start = formatter.fmt_cur;
-    Chunk& chunk = chunks.back();
+    formatter.width = -1;
-    chunk.ptr = str + off;
+    int retval = 0;
-    chunk.arg = nullptr;
 
-    int status = 0;
+    if (*formatter.fmt_cur != '%') {
-
-    if (*format != '%') {
       // Ordinary character. Consume all the characters until a '%' or the end
       // of the string.
-      size_t format_size = 0;
+      for (; *(formatter.fmt_cur + 1) && *(formatter.fmt_cur + 1) != '%';
-      for (; *format && *format != '%'; ++format, ++format_size) {}
+           ++formatter.fmt_cur) {}
-      status = format_chunk(str, off, has_size, size, format - format_size,
+      retval = formatter.format();
-                            format_size);
+      dfsan_set_label(0, formatter.str_cur(),
-      chunk.label_type = Chunk::NONE;
+                      formatter.num_written_bytes(retval));
     } else {
       // Conversion directive. Consume all the characters until a conversion
       // specifier or the end of the string.
-      bool end_format = false;
+      bool end_fmt = false;
-#define FORMAT_CHUNK(t)                                                  \
+      for (; *formatter.fmt_cur && !end_fmt; ) {
-      format_chunk(str, off, has_size, size, format - format_size,  \
+        switch (*++formatter.fmt_cur) {
-                   format_size + 1, va_arg(ap, t))
-
-      for (size_t format_size = 1; *++format && !end_format; ++format_size) {
-        switch (*format) {
         case 'd':
         case 'i':
         case 'o':
         case 'u':
         case 'x':
         case 'X':
-            switch (*(format - 1)) {
+          switch (*(formatter.fmt_cur - 1)) {
           case 'h':
             // Also covers the 'hh' case (since the size of the arg is still
             // an int).
-                status = FORMAT_CHUNK(int);
+            retval = formatter.format(va_arg(ap, int));
             break;
           case 'l':
-                if (format_size >= 2 && *(format - 2) == 'l') {
+            if (formatter.fmt_cur - formatter.fmt_start >= 2 &&
-                  status = FORMAT_CHUNK(long long int);
+                *(formatter.fmt_cur - 2) == 'l') {
+              retval = formatter.format(va_arg(ap, long long int));
             } else {
-                  status = FORMAT_CHUNK(long int);
+              retval = formatter.format(va_arg(ap, long int));
             }
             break;
           case 'q':
-                status = FORMAT_CHUNK(long long int);
+            retval = formatter.format(va_arg(ap, long long int));
             break;
           case 'j':
-                status = FORMAT_CHUNK(intmax_t);
+            retval = formatter.format(va_arg(ap, intmax_t));
             break;
           case 'z':
-                status = FORMAT_CHUNK(size_t);
-                break;
           case 't':
-                status = FORMAT_CHUNK(size_t);
+            retval = formatter.format(va_arg(ap, size_t));
             break;
           default:
-                status = FORMAT_CHUNK(int);
+            retval = formatter.format(va_arg(ap, int));
           }
-            chunk.label_type = Chunk::NUMERIC;
+          dfsan_set_label(*va_labels++, formatter.str_cur(),
-            end_format = true;
+                          formatter.num_written_bytes(retval));
+          end_fmt = true;
           break;
 
         case 'a':
@@ -989,124 +1004,90 @@ static int format_buffer(char *str, bool has_size, size_t size,
         case 'F':
         case 'g':
         case 'G':
-            if (*(format - 1) == 'L') {
+          if (*(formatter.fmt_cur - 1) == 'L') {
-              status = FORMAT_CHUNK(long double);
+            retval = formatter.format(va_arg(ap, long double));
           } else {
-              status = FORMAT_CHUNK(double);
+            retval = formatter.format(va_arg(ap, double));
           }
-            chunk.label_type = Chunk::NUMERIC;
+          dfsan_set_label(*va_labels++, formatter.str_cur(),
-            end_format = true;
+                          formatter.num_written_bytes(retval));
+          end_fmt = true;
           break;
 
         case 'c':
-            status = FORMAT_CHUNK(int);
+          retval = formatter.format(va_arg(ap, int));
-            chunk.label_type = Chunk::NUMERIC;
+          dfsan_set_label(*va_labels++, formatter.str_cur(),
-            end_format = true;
+                          formatter.num_written_bytes(retval));
+          end_fmt = true;
           break;
 
-          case 's':
+        case 's': {
-            chunk.arg = va_arg(ap, char *);
+          char *arg = va_arg(ap, char *);
-            status =
+          retval = formatter.format(arg);
-                format_chunk(str, off, has_size, size,
+          va_labels++;
-                             format - format_size, format_size + 1,
+          internal_memcpy(shadow_for(formatter.str_cur()), shadow_for(arg),
-                             chunk.arg);
+                          sizeof(dfsan_label) *
-            chunk.label_type = Chunk::STRING;
+                              formatter.num_written_bytes(retval));
-            end_format = true;
+          end_fmt = true;
           break;
+        }
 
         case 'p':
-            status = FORMAT_CHUNK(void *);
+          retval = formatter.format(va_arg(ap, void *));
-            chunk.label_type = Chunk::NUMERIC;
+          dfsan_set_label(*va_labels++, formatter.str_cur(),
-            end_format = true;
+                          formatter.num_written_bytes(retval));
+          end_fmt = true;
           break;
 
-          case 'n':
+        case 'n': {
-            *(va_arg(ap, int *)) = (int)off;
+          int *ptr = va_arg(ap, int *);
-            chunk.label_type = Chunk::IGNORED;
+          *ptr = (int)formatter.str_off;
-            end_format = true;
+          va_labels++;
+          dfsan_set_label(0, ptr, sizeof(ptr));
+          end_fmt = true;
           break;
+        }
 
         case '%':
-            status = format_chunk(str, off, has_size, size,
+          retval = formatter.format();
-                                  format - format_size, format_size + 1);
+          dfsan_set_label(0, formatter.str_cur(),
-            chunk.label_type = Chunk::NONE;
+                          formatter.num_written_bytes(retval));
-            end_format = true;
+          end_fmt = true;
+          break;
+
+        case '*':
+          formatter.width = va_arg(ap, int);
+          va_labels++;
           break;
 
         default:
           break;
         }
       }
-#undef FORMAT_CHUNK
     }
 
-    if (status < 0) {
+    if (retval < 0) {
-      return status;
+      return retval;
     }
 
-    // A return value of {v,}snprintf of size or more means that the output was
+    formatter.fmt_cur++;
-    // truncated.
+    formatter.str_off += retval;
-    if (has_size) {
-      if (off < size) {
-        size_t ustatus = (size_t) status;
-        chunk.size = ustatus >= (size - off) ?
-            ustatus - (size - off) : ustatus;
-      } else {
-        chunk.size = 0;
-      }
-    } else {
-      chunk.size = status;
-    }
-    off += status;
-  }
-
-  // TODO(martignlo): Decide how to combine labels (e.g., whether to ignore or
-  // not the label of the format string).
-
-  // Label each output chunk according to the label supplied as argument to the
-  // function. We need to go through all the chunks and arguments even if the
-  // string was only partially printed ({v,}snprintf case).
-  for (size_t i = 0; i < chunks.size(); ++i) {
-    const Chunk& chunk = chunks[i];
-    void *chunk_ptr = const_cast<char *>(chunk.ptr);
-
-    switch (chunk.label_type) {
-      case Chunk::NONE:
-        dfsan_set_label(0, chunk_ptr, chunk.size);
-        break;
-      case Chunk::IGNORED:
-        va_labels++;
-        dfsan_set_label(0, chunk_ptr, chunk.size);
-        break;
-      case Chunk::NUMERIC: {
-        dfsan_label label = *va_labels++;
-        dfsan_set_label(label, chunk_ptr, chunk.size);
-        break;
-      }
-      case Chunk::STRING: {
-        // Consume the label of the pointer to the string
-        va_labels++;
-        internal_memcpy(shadow_for(chunk_ptr),
-                        shadow_for(chunk.arg),
-                        sizeof(dfsan_label) * (strlen(chunk.arg)));
-        break;
-      }
-    }
   }
 
   *ret_label = 0;
 
   // Number of bytes written in total.
-  return off;
+  return formatter.str_off;
 }
 
+extern "C" {
 SANITIZER_INTERFACE_ATTRIBUTE
 int __dfsw_sprintf(char *str, const char *format, dfsan_label str_label,
                    dfsan_label format_label, dfsan_label *va_labels,
                    dfsan_label *ret_label, ...) {
   va_list ap;
   va_start(ap, ret_label);
-  int ret = format_buffer(str, false, 0, format, va_labels, ret_label, ap);
+  int ret = format_buffer(str, ~0ul, format, va_labels, ret_label, ap);
   va_end(ap);
   return ret;
 }
@@ -1118,7 +1099,7 @@ int __dfsw_snprintf(char *str, size_t size, const char *format,
                     dfsan_label *ret_label, ...) {
   va_list ap;
   va_start(ap, ret_label);
-  int ret = format_buffer(str, true, size, format, va_labels, ret_label, ap);
+  int ret = format_buffer(str, size, format, va_labels, ret_label, ap);
   va_end(ap);
   return ret;
 }

compiler-rt/test/dfsan/custom.cc

@@ -870,6 +870,11 @@ void test_sprintf() {
   test_sprintf_chunk("z", "%c", 'z');
 
   // %n, %s, %d, %f, and %% already tested
+
+  // Test formatting with width passed as an argument.
+  r = sprintf(buf, "hi %*d my %*s friend %.*f", 3, 1, 6, "dear", 4, 3.14159265359);
+  assert(r == 30);
+  assert(strcmp(buf, "hi   1 my   dear friend 3.1416") == 0);
 }
 
 void test_snprintf() {